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Last edited: March 5, 2004
Fred G. Thompson
Curator of Malacology
Florida Museum of Natural History
University of Florida
Gainesville, Florida 32611-7800
The aquatic snail fauna of the southeastern United States has long been recognized for its richness and diversity. Throughout the 19th and 20th Centuries malacologists made frequent field trips to explore river systems that were poorly known, and to revisit others that were renown for their rich and unique assemblages of species. The focus on most investigations was on rivers north of Florida, and little attention was given to the Florida fauna. Until recently the entire knowledge of the Florida freshwater snail fauna was based on miscellaneous papers dealing with single species, groups of closely related species or single river systems. Wm. J. Clench & Ruth P. Turner (1956) published a survey of the fauna from the Suwannee River west to the Escambia River. This study was a landmark contribution to the malacology of the southeast, and it summarized the known fauna of western Florida. It also was the first adequately illustrated faunal summary published on the Southeast. Since then a great amount of fieldwork has taken place throughout Florida, and many additions to the fauna have fome to light. Some were range extensions for species known to occur in adjacent areas. Others were new taxa not found in earlier surveys.
It became increasingly important to provide an identification manual of the freshwater snails of Florida for many reasons. There were no references to cover the entire state. Those available covered only part of the state or part of the fauna. Our knowledge of the fauna has greatly increased during recent years, and a summary of this information was desirable to facilitate other kinds of study. The bioeconomic importance of snails to environmental issues has become increasingly relevant because of the impact that economic development has on Florida waterways. The first edition of The Freshwater Snails of Florida: a Manual for Identification was published in 1984. It was well received, and it served the interests and needs of many people. As was anticipated, further work on the systematics of the southeastern freshwater snail fauna created the need for subsequent revision in 1999, and for this updated version.
Vernacular manes used in this manual are consistent with the standardized list of vernacular names for North American freshwater snails recently established by the American Fisheries Society (Turgeon, et al, 1998). Vernacular names are given only for species. Subspecies bear the same name as the nominate subspecies, as is consistent with the standard used by the American Fisheries Society for fishes, and by other societies for other classes of animals. This manual recognizes 113 species and subspecies that occurring in Florida and the list will increase with time.
The Manual treats only those genera that occur in freshwater. It is presented in the form of key supplements with illustrations and habitat information to facilitate identifications. It should be remembered that it is only a key which emphasizes shell characters. Occasionally it may be necessary to turn to other information sources to determine identifications with a greater degree of certainty.. It should also be remembered that many groups have not been studied sufficiently, and the reader may have material that adds to or contradicts previously recorded information. It is hoped that this manual will stimulate other biologists to contribute to our knowledge of freshwater mollusks. The reader will discover how very little we know about any genus occurring in Florida.
A principal difficulty encountered in the identification of snail specimens arises from improper methods used to prepare them. Adequate preservation begins when the specimens are collected. Live snails for shell studies should be preserved in 70 percent alcohol. Never preserve shell specimens in formalin. Formalin will corrode the shell and thereby eliminate color, delicate sculpture, and the periostracum. Formalin does not even serve as a good fixative or preservative for long-term anatomical studies. After a few years in storage glandular tissues in the female reproductive system deteriorate, and the process gradually spreads to destroy all but the terminal genital structures. It matters not that the specimens are stored in 70% alcohol after having been fixed in formalin. The deterioration process is not reversible. This is particularly so in the Pulmonata. However, formalin is an excellent fixative for short-term preservation.
It is important to save some specimens for anatomical studies. This is essential in the case of the Hydrobiidae. Live field samples should be divided into two groups, one to be preserved for shells, the other to be preserved for anatomical specimens. The latter are placed in a small container filled with pond water. Do not use tap water since copper ions from the plumbing system may contaminate the tap water and kill the snails prematurely. Scatter a few granulated menthol crystals on the water surface and allow the container to sit for 10-15 hours, at which time the snails should be extended from the shell and insensitive to probing with a needle. A little practice may be necessary to perfect this relaxing procedure. Specimens then are placed in a fixative such as 10 percent formalin or Bouin's Solution. The fixative may damage the shell, but that is unimportant for anatomical purposes. After the snails have been in the fixative for a few minutes to several hours, depending upon their sizes, they should be rinsed in water and transferred to 70 percent ethyl alcohol. The radula can be studied by dissecting out the buccal mass and macerating it in clorox or sodium hydroxide. The radula is then thoroughly rinsed in distilled water, stained, and mounted on a microscope slide.
Shell specimens should be cleaned and air-dried. Some shells may be heavily encrusted with mineral deposit and algae, which may obscure details of the sculpture and color. Dipping them in a dilute solution of oxalic acid and gently scrubbing them with a fine brush can clean such specimens. The shells should be rinsed frequently in tap water during the cleaning process to prevent etching by the acid. After the shells are thoroughly rinsed, they can be air-dried in cardboard trays. The bodies of large snails, such as viviparids and pilids, should be pulled from the shell. Opercula should be glued to cotton plugs and replaced within the aperture.
Small- or medium-sized snails need to be identified with the aid of a binocular dissecting microscope that is equipped with an ocular micrometer calibrated to 0.1 mm accuracy so that precise measurements can be made. Opercula of minute snails can be studied most easily by removing them from the animal and viewing them with transmitted light.
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la. Aperture of shell closed by an operculum (snail must be collected live because the operculum is lost soon after death). Mantle cavity with gill on dorsal surface ------------------------------------------------------------- Subclass PROSOBRANCHIA --- 2.
lb. Aperture non-operculate; mantle cavity modified into a lung ------------------------------------ Subclass PULMONATA --- 59.
2a. Operculum calcareous with two pegs on inner surface (Figs. 1, 2). Aperture relatively large with fine, uneven, serrate denticles along parietal wall (Fig. 3) -------------------------------- NERITIDAE (Olive Nerite) Neritina usnea (Röeding, 1798).
Fig1., 2.
The only freshwater neritid in Florida. Height 15-20 mm; width 14-19 mm. Shell solid, relatively heavy, dark green with numerous, narrow black stripes. Widely distributed in brackish water in the Caribbean and Gulf of Mexico region. invades freshwater zone in lower parts of some rivers. Found in Florida along both coasts. This species generally was listed as Neritina reclivata (Say, 1822) in previous literature. The name is a junior synonym of Neritina usnea.
Fig. 3.
2b. Operculum corneas, without pegs on inner or outer surface. Aperture without serrate denticles on parietal wall ----- 3.
Operculum with concentric growth rings around nucleus (Figs. 4, 5). Shell medium to large (12-75 mm) ---------------------------------------------------------------------------------------------------------------------------------------------- Superfamily VIVIPAROIDEA --- 4.
3b. Operculum spiral, consisting of two or more rapidly increasing whorls (Fig. 6). Shell usually small to medium (2-25 mm)----------------------------------------------------------------------------------------------------------------------------------------------------------14
Figs. 4, 5, 6
4a. Umbilicus of shell perforated or broadly open. Spire depressed, much less than height of aperture, occasionally planular (Figs. 7-9). Aperture relatively ample (Figs. 10- 12). In some genera, eggs are deposited above the water in dry clusters on stems, trees, walls, etc. In others they are deposited in the water in gelatinous clusters. Males with penis at anterior right corner of mantle cavity --------------------------------------------------------------------------------- AMPULLARIIDAE --- 5.
4b. Umbilicus of shell closed. Spire usually about equal to or greater than height of aperture (Figs. 17-29). Females with live embryos in brood pouch in mantle; males with right eye stalk modified as a penis. ------------------ VIVIPARIDAE --- 7.
5. Family AMPULLARIIDAE---------------------------------------------------------------------------------------------------------------------------------- 5a.
Medium- to large-sized tropical freshwater snails. One species occurs naturally in Florida, and three others have been introduced. The family contains many genera and numerous species in South America, Central America, Mexico, Africa, and Southeast Asia. Frequently the shells of ampulariids and viviparids are very similar. The shell characters given above for separating the families apply only to Florida species. The primary differences between the two families are based on soft anatomy. Ampullariids have been referred to as PILIDAE in earlier editions of this manual. The International Commision on Zoological Nomenclature has ruled that AMPULLARIIDAE is the valid name for this family of snails.
5a. Shell planispiral, adults large, 35-50 mm (Figs. 7-9)---(Goldenhorn Marisa) Marisa cornuaurietus (Linnaeus, 1758).
Introduced from northern South America into South Florida canals, marshes, and ponds. Currently known in Florida from Palm Beach, Broward, Dade, and Monroe counties. The eggs are laid in gelatinous clusters in the water.
Figs. 7, 8, 9
5b. Shell oval in shape.------------------------------------------------------------------------------------------------------------- Pomacea --- 6.
6 Genus Pomacea Perry, 1810 ------------------------------------------------------------------------------------------------------------------- 6a.
A tropical American genus that is widely distributed from Argentina north to Tamaulipas, Mexico, and also occurs in the West Indies, the Windward Islands, Jamaica, Cuba, and Florida. Pomacea paludosa, a native Florida species, apparently reached its present range via northern Mexico and the gulf coastal plains during a warmer geologic interval. It is most closely related to P. flagellate of eastern Mexico and not to Cuban or Jamaican species.
Pomacea contains over 150 named species, some of which are very large and colorful. They are favorite items in the aquarium trade, and occasionally various species are released into Florida waters. Pomacea bridgesi, P. canaliculata and Marisa cornuaurietus have become established in Florida through human introduction.
6a. Whorls of spire pointed and scalariform (steplike with nearly flat shoulders and deep sutures). Apical whorls raised to form a point on top of spire. Adult shells about 40-60 mm high (Fig. 10) ------------------------------------------------------------------------------------------------------------------------------------------------- (Spiketopped Applesnail) Pomacea bridgesi (Reeve, 1856).
A South American species introduced into South Florida in Monroe, Dade, Broward, Palm Beach and Pinellas Counties. Generally the shell is greenish with darker and lighter bands.
Fig. 10
6b. Apical whorls pointed and raised, but not scalariform. Shell large, 80-100 mm wide. Suture deeply impressed, forming a channel. Umbilicus wide (Fig. 11). ----------- (Channeled Applesnail) Pomacea canaliculata (Lamark, 1822).
This is another South American species that has been introduced into canals and ditches in southeast Florida (Thompson, 1997).
Fig. 11
6c. Whorls of spire strongly arched or rounded. Apical whorls bluntly rounded and not conspicuously elevated. Adult shells about 40 - 70 mm high (Fig. I2) -------------------------------------------- (Florida Applesnail) Pomacea paludosa (Say, 1829).
Widely distributed throughout the Florida peninsula, and occurring sporadically west of the Suwannee River to the Choctawhatchee River. The Florida Applesnail occurs in Cuba. It is found in Georgia in isolated springs along the Flint and Ocmulgee rivers and is introduced in Covington County, Alabama, in a small reservoir artificially heated by industrial wastewater. Otherwise the species is not able to survive the lower winter temperatures that occur along the northern tier of Florida counties and northward. It has been introduced extensively into Pacific islands and southeast Asia, where it is raised for human consumption. The species has existed continuously in the Florida peninsula since the Pliocene. A small, reddish, thick-shelled form with a wider umbilicus, which occurs in Dade and Broward counties, has been named as a distinct species, Pomacea miamiensis (Pilsbry, 1899) (Fig. 13). Its taxonomic status is uncertain.
Figs. 12, 13
7. Family VIVIPARIDAE ----------------------------------------------------------------------------------------------------------------------------------------- 7a.
Medium to large freshwater snails found on all continents except South America. The family attains its greatest diversity in Southeast Asia. Two subfamilies occur in North America. The LIOPLACINAE is endemic and include Campeloma, Lioplax, and Tulotoma. The VIVIPARINAE is widely distributed throughout Europe, Asia and eastern North America. It is represented in North America by Viviparus. Various species of Cipangopaludina also have been introduced from the Orient into North America. One species, C. chinensis malleatus (Reeve, 1863) (Fig. 14), was introduced into a fishpond in St. Petersburg about 1921 and into lakes in Orlando about 1940. The current status of these introductions is not known.
Fig. 14
7a. Nucleus of operculum spiral and then surrounded by concentric growth rings (Fig. 5). Outer lip of aperture strongly sinuous in lateral profile (Fig. 15) ------------------------------------------------------------------------------ Lioplax Troschel, 1856 --- 8.
7b. Operculum constructed entirely of concentric rings (Fig. 4). Outer lip of aperture nearly straight in lateral profile (Figs. 16, 17) ----------------------------------------------------------------------------------------------------------------------------------------------------- 9.
Figs. 15, 16, 17
8 Genus Lioplax Troschel, 1856 ------------------------------------------------------------------------------------------------------------------------------ 8a.
A single species consisting of two highly variable subspecies occurs in Florida. Three other species occur farther north.
8a. Shell larger, reaching a maximum diameter of 18 mm. Spiral angulation on whorls sharp and prominent in juveniles, usually becoming convex-rounded or smooth on last whorl in adults. Prominent minor spiral sculpture along periphery. Outer lip strongly sinuous. Newborn young about 4.5 mm in diameter (this can be determined by removing juveniles from brood pouch). Height of shell about 23-26 mm (Figs. 15, 18) --------------------------------------------------------------------------------------------------------------------------------------------------------------------- (Choctaw Lioplax) Lioplax pilsbryi pilsbryi Walker, 1905.
Confined to the Chipola River, and small streams along the west side of the Apalachicola River.
Fig. 18
8b. Shell smaller, reaching a maximum diameter of 13 mm. Spiral angulation on last whorl obsolete or bluntly rounded and forming a shallow sulcus below shoulder of last whorl. Minor spiral sculpture weak or absent. Outer lip less sinuous. Newborn young about 3 mm in diameter. Height of shell about 14-16 mm; width, 10-12 mm (Figs. 19-21) -------------------------------------------------------------------------------------- (Choctaw Lioplax) Lioplax pilsbryi choctawhatchensis Vanatta, 1935.
Found in the Escambia, Yellow, Choctawhatchee (Fig. 19), Chattahoochee, Flint, Ochlockonee (Fig. 20), and Suwannee Rivers (Fig. 21) and their tributaries in Florida, Alabama, and Georgia. The populations from the Ochlockonee and Yellow rivers were named as a distinct species (Lioplax talquinensis Vail, 1979b) on the basis that they have a distinct sulcus on the last whorl causing the aperture to be pinched above (Fig. 20). Populations from other rivers lack the sulcus and have a more broadly open aperture (Fig. 19). The examination of large series of specimens from the Choctawhatchee, Yellow, Ochlockonee, and Suwannee rivers and Holmes Creek show that these distinctions are inconsistent.
Figs. 19, 20, 21
9a. Shell thick and solid; whorls weakly convex or flattened (Figs. 16, 22-28). Shell unicolor, never banded ----------------------------------------------------------------------------------------------------------------------------------- Campeloma Rafinesque, 1819 ---10.
9b. Shell generally thin but strong; whorls of spire strongly convex with deep suture (Figs. 17, 29-32), shell usually banded in Florida forms. --------------------------------------------------------------------------------------------------Viviparus Montfort, 1810 ---13.
10. Genus Campeloma Rafinesque, 1819 ---------------------------------------------------------------------------------------------------------------10a.
Moderately large, thick-shelled operculate snails. Some species are dioecious with a normal representation of males and females. In others, some or all populations may be parthenogenetic, consisting only of females, or they may have a disproportionately small number of males. In parthenogenetic organisms each population is inbred in the strictest genetic sense, and frequently a population will have minor characteristics that distinguish it from others. There is no consensus in systematic biology about how to treat these forms. The criterion of inbreeding for defining species cannot be applied, and other objective criteria are not yet been established.
In Florida four types of Campeloma have been recognized. Campeloma geniculum (Conrad, 1834) is readily recognized by its obese, solid shell; it usually has a normal proportion of males in its populations, although some populations are apomictic parthenogens. The other three forms, C. limum (Anthony, 1860), C. floridense Call,1866 and C. parthenum Vail, 1979, are exclusively apomictic parthenogens and have been separated on the basis of aperture coloration, embryonic shell coloration, and contour of the outer lip (Vail 1979a). The coloration of the aperture and the embryonic shell is not consistent within single population samples, and the contour of the outer lip is highly variable within single drainage systems and with the age of the specimens examined. In view of the inconsistency of these shell characters, these three forms may represent only a single species, Campeloma limum, which is widely distributed from the Escambia River system of Florida and Alabama east and north into North Carolina and Virginia. More data based on many population samples from throughout this range will be necessary before the validity of the three forms can be determined. For the purpose of completeness, the three parthenogenetic forms and C. geniculum are included in the key.
10a. Shell obese and ponderous. Spire short and compact, about 0.5-0.7 times height of aperture in mature specimens, proportionally longer in juveniles (Fig. 22) ------------------- (Ovate Campeloma) Campeloma geniculum (Conrad, 1834).
Height of adult shell about 22-26 mm; width about 16-19 mm. Abundant from the Suwannee River system west through Florida, southern Georgia and Alabama to the Escambia River system.
Fig. 22
10b. Shell more slender and attenuate; spire more elongate in adults, about 0.7- 1.0 times height of aperture -----------11.
1la. Interior of adult aperture with brownish tinge. Newborn shells brown. Outer lip continuously rounded (Figs. 23, 26) -------------------------------------------------------------------------- (Purple-throated Campeloma) Campeloma floridense Call, 1886.
Height of adult shell about 23-27 mm; width about 15-20 mm. Confined to the St. Johns River system and the upper part of the Santa Fe River in Florida. The brown tinge of the aperture is absent in many specimens.
Figs. 23, 24, 25
1lb. Interior of aperture livid white. Newborn shells white. Outer lip partially flattened in adults ----------------------------------12.
12a. Outer lip nearly straight and parallel to axis of shell in adults (Fig. 24, 27) ------------------------------------------------------------------------------------------------------------------------------------------- (Maiden Campeloma) Campeloma parthenum Vail, 1979.
Height of adult shell about 23-27 mm, width about 16-19 mm. Reported from the Ochlockonee River and its tributaries in Florida. Similar specimens are found in the Conecuh and Pea rivers in southern Alabama.
12b. Outer lip straightened just below shoulder; straightened portion lying at an angle to axis of shell (Figs. 16, 25, 28) ----------------------------------------------------------------------------------------- (File Campeloma) Campeloma limum (Anthony, 1860).
Height of adult shell about 25-32 mm; width about 17-19 mm. Populations with these characteristics are found from the upper tributaries of the Escambia, Choctawhatchee, Suwannee, and St. Mary's river systems in Alabama, Georgia, and northeast Florida, and north along the Atlantic coast to North Carolina and Virginia.
13 Genus Viviparus Montdort, 1810 ---------------------------------------------------------------------------------------------------------- 13a.
Medium- to large-sized, globose, freshwater snails that usually live in silty or mud-bottomed streams, ponds, lakes, and marshes. These snails are more tolerant to pollution and stagnation than are Campeloma and Lioplax, and they thrive in aquatic environments that are too adverse for most other genera. Two species are included in the key. One, V. intertextus, has not been recorded from Florida, but it occurs in immediately adjacent river systems in Alabama and Georgia and may be anticipated in the northern tier of Florida counties. The second species, V. georgianus, is widely distributed and is found in most freshwater habitats in Florida.
Figs. 26, 27, 28
13a. Shell ovate in shape, about 1.2-1.5 times as high as wide. Shell relatively thick (Figs. 16, 29). -------------------------------------------------------------------------------------------------------------- (Banded Mysterysnail) Viviparus georgianus (Lea, 1834).
Adult shells about 20-45 mm high and about 18-36 mm wide exist in locally isolated populations and inhabit a wide diversity of aquatic environments. Populations are highly variable in banding patterns and in size of individuals, although each population tends to be uniform in its characteristics. As a consequence, fourteen subspecies names have been proposed for various Florida forms based upon color and shell obesity. Any given population may have individuals with 0-4 spiral bands. No geographic patterns exist that permit recognition of them as subspecies. They are regarded as variations of V. georgianus without taxonomic significance although some populations may differ strikingly from others.
Viviparus georgianus is distributed from Palm Beach County north and west to the Choctawhatchee River and in portions of the Apalachicola River, Suwannee River, and Altamaha River systems in Georgia. From there the range is disjunct. The snail is widely distributed from Louisiana and northern Alabama north to the Great Lakes region and the St. Lawrence River. Clench (1962), Clench and Fuller (1965), and Clench and Turner (1956) discuss the snail's taxonomy and distribution. Katoh and Foltz (1993) recognize three distinct species on the basis of biochemical data (Viviparus georgianus Lea, 1834, Viviparus goodrichi, Archer, 1933, and Viviparus limi Pilsbry, 1918). Taxonomic problems remain unresolved in the use of these names. Viviparus goodrichi (Fig. 30) occurs in the Choctawhatchee River system east to the Apalachicola River. The species called Viviparus limi (Fig. 31) is endemic to the Ochloconee River. However, the name Viviparus limi is based on a population from the Flint River, a tributary of the Apalachicola. The taxonomic and nomeclatorial status of the name limi will depend on study of populations from near Albany, Georgia, the type locality of Viviparus limi.
Figs. 29, 30, 31
13b. Shell globose with a relatively depressed spire; about 1.0- 1.2 times as high as wide. Suture of whorls more deeply impressed than in previous species. Shell relatively thin. Color uniform olive-green, never banded (Fig. 32) ----------------------------------------------------------------------------------------------------- (Rotund Mysterysnail) Viviparus intertextus (Say, 1829).
Height of adult shell about 20-30 mm; width about 20-25 mm. Distributed from east Texas and throughout the Mississippi River east to the Alabama River with disjunct populations in the Altamaha River system in Georgia and elsewhere into South Carolina. Viviparus intertextus is replaced in this disjunct area by Viviparus georgianus. Viviparus intertextus may occur in west Florida.
Fig. 32
14a. Shell elongate-conical; 10-40 mm long in adult specimens; apex of spire usually eroded; shell with 8-12 whorls although eroded specimens may have fewer; shell usually strongly sculptured with spiral and/or vertical ribs and threads (except in Elimia dickinsoni); central tooth of radula without basal or lateral cusps (Fig. 33); males without copulatory structures.---------------------------------------------------------------------------------------------------- Superfamily CERITHIOIDEA ---15.
14b. Shell variable in shape, elongate to globose; usually not more than 5 mm in length; apex of spire seldom eroded (except in Somatogyrus); 4-6 whorls; shell smooth (except in Pyrgophorus and Tryonia); central tooth of radula with basal cusps (Figs. 34, 35) (Pomatiopsis, Fig. 36); males with a copulatory appendage, a penis (Fig. 37), which is important for generic and specific diagnosis. (The penis is normally recurved into the mantle cavity, except during mating.----------------------------------------------------------------------------------------------------------- Superfamily RISSOOIDEA --- 24.
Figs. 33, 34, 35, 36, 37
15a. Operculum paleomelanian, with a large sub-centrally located nucleus (Fig. 38). (This character separates only the genera under consideration; genera from other areas of the world do not conform to this distinction.) Females with an egg-laying groove or sinus on right side of foot; eggs deposited on substrate. -------------------- PLEUROCERIDAE --- 18.
15b. Operculum neomelanian, with a small, rapidly expanding nucleus located near the basal margin (Fig. 39). Primarily parthenogenetic; females viviparous with young snails in a brood pouch in nape.---------------------------- THIARIDAE ---16.
Figs. 38, 39
16. Family THIARIDAE ----------------------------------------------------------------------------------------------------------------------------------------16a.
Thiarids are found in tropical and subtropical regions of the world. Most inhabit fresh water, but some also occur in brackish water. The greatest diversity of genera and species is in the Indo-Australian region. Endemic New World genera occur in Cuba, Jamaica, and northern South America. Three species in Florida were introduced from Southeast Asia. Two, Melanoides tuberculata and Tarebia granifera, are medically important because they can serve as first intermediate host for the human lung fluke, Paragonimus westermani. Thiarids are ecologically significant because they tend to replace native snails where they are introduced and because of their abundance. In 1976 in the St. Johns River 1 found Melanoides tuberculatus with population densities of 10,000/sq. m.
16a. Shell sculptured with prominent nodes overlapping suture and forming crenulations. Base of last whorl with prominent spiral ridges. Shell unicolor brown, never mottled with reddish spots. Shell about 0.38-0.41 times as wide as high and about 20-27 mm long. Sides of spire concave in outline (Fig. 40). ------------------------------------------------------------------------------------------------------------------------------------------------------- (Quilted Melania) Tarebia granifera (Lamarck, 1822).
Abundant in some springs and small streams in Florida. Some authors identify this species as Tarebia lateritia (Lea, 1850). Considerable variation in obesity and sculpture rugosity exists between different populations, and there is disagreement as to how many species occur in Florida.
Fig. 40
16b. Shell sculptured with fine spiral striations, and in some cases curved axial ribs. Suture simple, not crenulated. Shell usually marked with red or rust-colored spots, flames, or bands (most apparent on juvenile specimens). Shell more slender, about 0.30-0.35 times as wide as high. Sides of spire straight-sided in outline.---------------------------------------------------------------------------------------------------------------------------------------------------------------------- Melanoides Oliver, 1904 ---17.
17a. Shell sculptured with vertical, weakly curved ribs and much finer spiral striations. Prominent vertical ribs on middle and upper whorls. Base of shell with dark red spiral band. Shell light brown and frequently mottled with rust-colored spots that may form a spiral row below the suture. Attains a length of about 30-36 mm (Figs. 41-43). ---------------------------------------------------------------------------------------------------------------- (Red-rimmed Melania) Melanoides tuberculata (Müller, 1774).
Widely introduced throughout Florida. Most commonly found in rivers, streams, canals, and springs.
Figs. 41, 42, 43
17b. Shell sculptured with fine spiral threads. Fine vertical ribs present on uppermost whorls. Base of shell usually without spiral band. Shell olive-green with vertical reddish flames and spots. Attains a length of 30-40 mm (Fig. 44). --------------------------------------------------------------------------------------------------------------- (Fawn Melania) Melanoides turricula (Lea, 1862).
A Philippine snail that has been introduced into springs and spring-fed streams in Florida and Texas. Melanoides tuberculata and Melanoides turricula may be ecological variations of a single species. In Florida, the two types are ecologically segregated; Melanoides tuberculata is generally found in quieter, eutrophic, turbid habitats; Melanoides turricula is found in cleaner oligotrophic springs and streams.
Fig. 44
18. Family PLEUROCERIDAE ----------------------------------------------------------------------------------------------------------------------------- 8a.
This family contains twelve genera in North America. Additional genera occur in the Orient, Southeast Asia, Africa, and South America. Only Elimia is found in Florida. Over 500 species of Elimia have been described, most on the basis of shell characters. Many have been synonymized, some undeservingly so. Biochemical studies show that in Elimia shell characters are conservative indicators of genetic divergence (Mihalcik and Thompson, 2002). Overshadowing this genetic divergence are frequent examples of convergent evolution of similar adult shell characters among distantly related species. This causes problems in species identification and yield an undermeasure of the actual number of species that exist in nature. Fortunately in Florida, the species are relatively easy to distinguish.
18a. Last whorl of adult shell smooth or with growth striations, but not with ribs and spiral chords. --------------------------19.
18b. Shell with prominent ribs and spiral chords on all whorls.--------------------------------------------------------------------------- 20.
Figs. 45, 46, 47, 48
19a. Earlier whorls of adult shell with vertical ribs and spiral chords. Sides of spire straight in lateral profile. Last few whorls in large adults scalariform. Embryonic shell with fine vertical ribs and a heavy spiral chord on periphery and two basal spiral chords (Fig. 45). Adult large, about 23-27 mm long (Figs. 49, 50). ------------------------------------------------------------------------------------------------------------------------------------------ (Stately Elimia) Elimia dickinsoni (Clench & Turner, 1956).
Confined to small creeks in the upper part of the Choctawhatchee River. Named for Joshua C. Dickinson, Jr. (1916-), former director of the Florida Museum of Natural History.
Figs. 49, 50
19b. Earlier whorls of adult shell with heavy vertical ribs crossed by knobby folds or a strong spiral chord; sides of spire straight or weakly convex in lateral profile; embryonic shell with a single spiral chord on periphery and heavy vertical ribs, but without basal spiral chord (Fig. 46). -------------------------------------------------------------------------------------------------------- 20.
20a. Spire of adults with heavy vertical ribs; unicolor dark brown; usually less than 18 mm long (Figs. 51, 52). -------------------------------------------------------------------------------------------------------------- (Graphite Elimia) Elimia doolyensis (Lea, 1962).
Distributed from the lower part of the Apalachicola River system in Georgia and Florida west to the Chipola River system in Florida and Alabama. This snail primarily inhabits smaller streams and tributaries and also occurs in subterranean aquifers in Washington County, Florida.
In earlier editions of the manual this snail was listed as Elimia curvicostata. The name was based on Melania curvicoststa Reeve, 1861,but that name is preoccupied by Melania curvicostata Melleville, 1843, a European Miocene fossil. The next name to be refered to this species in the literature, Melania densicostata Reeve, 1860, is not identifiable with certainty. The only available name that can be applied to this species is Goniobasis doolyensis Lea, 1862.
Figs. 51, 52
20b. Spire of adults without distinct vertical ribs -------------------------------------------------------------------------------------------------------- 21.
21a. Shell brightly banded and with large, wide and wavey vertical folds; robust, usually 21-25 mm long (Fig. 53). --------------------------------------------------------------------------- (Choctawhatchee Elimia) Elimia buffyae Mihalcik & Thompson, 2002.
Widely distributed in the Choctawhatchee River system as far south as Washington and Walton Counties, Florida.
21b. Shell with or without bright bands; with low wavy growth wrinkles; large but not robust, 23-28 mm long. (Fig. 54). -----------------------------------------------------------------------------------(Escambia Elimia) Elimia annae Mihalcik & Thompson, 2002.
Found in the Conecuh River and some of it's larger tributaries in Conecuh, Covington and Escambia Counties, Alabama. It may occur in the Conecuh River in Santa Rosa County, Florida, but it has not yet been found in Florida.
Figs. 53, 54, 55
21c. Shell with or without bands; slender; Suture deeply impressed; upper whorls with a strongly carinate periphery (Fig, 55). ----------------------------------------------------------------------------------------------------------------------- (Dented Elimia) Elimia sp..
This and similar species are known from small streams in the Alabama River system in Sumpter, Marengo, Monroe and Wilcox Counties, and from small streams in the Escambia River system in Conecuh and Escambia Escambia Counties, Alabama. This group of species requires further study to resolve the number of species that are involved. The specimen in Fig. 55 is from Escambia Co., Alabama. It has not been found in Florida, but it may occur in small stream in Escambia and Santa Rosa Counties, Florida.
22a. Shell with spiral chords or spirally arranged series of nodes.----------------------------------------------------------------------21.
22b. Shell with strong vertical ribs on spire; spiral chords vestigial, confined to spiral series of knobs on top of vertical ribs; adults small, about 13-16 mm long (Fig. 56).--------------- (Goblin Elimia) Elimia vanhyningiana (Goodrich, 1921).
Confined to springs and smaller streams in the St Johns River system in the Florida Peninsula. Named after O. C. Van Hyning, founder of the Florida State Museum (Florida Museum of Natural History) and an ardent collector of mollusks.
Fig. 56
23a. Shell unicolor, with distinct vertical sculpture in addition to strong spiral sculpture. Embryonic shell with a strong peripheral spiral chord that continues onto following whorls (Fig. 47). ----------------------------------------------------------------24.
23b. Shell with darker colored spiral chords that may be smooth or wavy. Vertical sculpture reduced to irregularly spaced and uneven growth striations or low undulating ribs. Embryonic shell smooth, without spiral chords (Fig. 48). Rather stocky, adult about 15-20 mm long (Fig. 57).---------------------- (Black-crested Elimia) Elimia albanyensis (Lea, 1864).
A shoal species living in shallow water flowing over rock substrates. In Florida it is confined to the shoal immediately below the Jim Woodruff Dam on the Apalachicola River. Also found in Georgia in the Flint River and tributaries from the area near near Albany and downstream to the confluence with the Chatttahoochee River.
Fig. 57
24a. Sculpture above periphery of whorls consisting of nodes arranged in vertical and spiral rows. Shell short and stocky. Adult size small, about 12-16 mm long (Fig. 58).--------------- (Knobby Elimia) Elimia athearni (Clench & Turner, 1956).
Occurs in the Chipola River in Jackson and Calhoun counties and in the Santa Fe River system, Columbia County. Frequently found with E. floridensis. When the two occur together, E. athearni usually inhabits rocks, while E. floridensis inhabits woody objects and the sandy substrata. Named after Herbert D. Athearn (1923 - ) of Cleveland, Tennessee, who has added greatly to our knowledge of the southeastern freshwater mollusks though his collecting efforts.
Fig. 58
24b. Sculpture above periphery of whorls consisting of sharp spiral chords and distinct vertical ribs; shell attenuate.-- 25.
25a. Whorls straight-sided, not scalariform; suture hardly distinct; aperture terminating at periphery of last whorl; vertical ribs weaker and closely spaced; adult size about 25-30 mm long (Fig. 59).-------------------------------------------------------------------------------------------------------------------------------------------------------- (Slackwater Elimia) Elimia clenchi (Goodrich, 1924).
Confined to the Choctawhatchee River system in Florida and adjacent Alabama. Frequently found in quiet water on a silty substrate. Named after William J. Clench, a scholar of malacology.
Fig. 59
25b. Whorls of spire weakly scalariform, causing the suture to be deeply incised. Aperture terminating below periphery of body whorl. Vertical ribs relatively strong and more widely spaced.-------------------------------------------------------------------- 26.
26a. Vertical ribs smooth along the periphery, strongly developed (Fig. 60) ------------------------------------------------------------------------------------------------------------------------------------------------------------------- (Waccasassa Elimia) Elimia floridensis ssp.
Confined to the Waccasassa River, Levy County
26b. Vertical ribs serrate along the periphery ------------------------------------------------------------------------------------------------- 27.
27a. Vertical ribs strongly developed, crossed by nearly equal sized spiral threads that form low spines where they cross the ribs, adults about 20-25 mm long (Fig. 61). -------------------------------- (Rasp Elimia) Elimia floridensis (Reeve, 1860).
Distributed from the Chipola River east and south to the Manatee River and the St. Johns Rivers systems in central Florida. Some populations are quite distinct in sculpture, and more than one species may be involved. Six forms have been named as different species. The typical form is illustrated.
Figs. 60, 61, 62
27b. Vertical ribs reduced in size, but with bold spines at the periphery; spiral threads above periphery relatively weak; adults up to 35 mm long (Fig. 62). ------------------------------------------------------------------------------ (Spring Elimia) Elimia sp.
Confined to Holmes Creek, and headwater springs of the Chipola River, Florida.
28a. Central tooth of radula with long basocones along base (Fig. 36). Amphibious; moves by step-like mode of progression (Fig. 63).------------------------------- POMATIOPSIDAE (Slender Walker) Pomatiopsis lapidaria (Say, 1817).
This family of fresh and brackish water snails is found in Australia, southeast Asia, southern Africa, North America and South America. Pomatiopsis lapidaria is the only freshwater species that occurs in Florida. Shell elongate-conical, consisting of about seven strongly convex whorls, sculptured with fine growth striations; spiral sculpture absent; Peristome complete around aperture; adults about 6-7 mm long. Distributed from the Great Lakes region south to Virginia along the east coast and south through Alabama to Florida. In Florida it is found only in the Apalachicola River system. Amphibious, lives on damp ground and along seepage's among dead leaves, sticks, and rocks.
Fig. 63
28b. Central tooth of radula with basocones located on fore or lateral wing of tooth (Figs. 34, 35). Aquatic; moves by gliding motion. Shell of various shapes and sculpture.----------------------------------------------------------- HYDROBIIDAE --- 29.
29. Family HYDROBIIDAE -----------------------------------------------------------------------------------------------------------------------------------29a.
Hydrobiids are small- to medium-sized operculate snails that live primarily in brackish and fresh water. The HYDROBIIDAE include over 200 genera and approximately 1000 species. Most have monotonously simple, conical or depressed-conical shells that are nearly devoid of taxonomically useful characteristics. Essentially identical shells occur repeatedly among unrelated genera and subfamilies. Evolution has proceeded primarily through reproductive and trophic specializations. Important diagnostic characteristics for subfamilies, genera, and species are found in the female reproductive system, the male reproductive organ (the penis), and modifications of the radular teeth. The shell are secondarily useful for identification, but only when supplemented with anatomical information. The number of subfanilies recognized in the Hydrobiida is unsettled. Recent studies treat amnicolids as a separate families.
The author has attempted to simplify the key to include the minimum anatomical data needed for accurate identification. In the event that only shell specimens are available, picture-matching may be necessary to eliminate some choices in the couplets. Identification should conform with all data in the key and with geographic distributions. Only genera that enter fresh water are treated. wo brackish-water genera, Onobops and Heleobops, that are common in Florida are omitted. Critical Florida references are Thompson 1968, 1969, 2000; Thompson and Hershler, 1991, and Hershler and Thompson, 1992.
Most freshwater hydrobiids in the eastern United States are annual species. They complete their life cycles in one year. Some species that are endemic to Florida springs live in environments with nearly constant temperatures and apparently reproduce continuously throughout the year. Other species deposit eggs during the period of March through May, at which time the adults die and immature forms dominate the population through August or September. Many samplings of hydrobiids collected during the period of May through September are not identifiable because only immature forms are present, and important diagnostic anatomical characteristics have not yet developed.
29a. Shell globose with a short depressed spire; body whorl ample; umbilicus closed.----------------------------------------- 30.
29b. Shell conical or cylindrical-conical in shape; spire elevated; body whorl not disproportionately voluminous; umbilicus closed or open.---------------------------------------------------------------------------------------------------------------------------------------- 32.
30a. Columellar margin of aperture wide, flat-faced; apex of spire usually erroded; apical whorls, when present, with minute spiral striations; central tooth of radula with basocones located on ridged surface of tooth (Fig. 34); penis frlattened, blade-like (Fig. 67). ------------------------------------------------------------------------------------- LITHOGLYPHINAE --- 31.
30b. Columellart margin of aperture not flat-faced; apex of shell usually entire; penis with large terminal lobe on left side and small appendage-like flagellum on right margin (Fig. 68); lobe and flagellum with various patterns of dermal glands; central tooth of radula with basocones located on reflected margin of tooth (Fig. 35).---------------------------------------------------------------------------------------------------------------------------------------------------------------------- NYMPHOPHILINAE (in part) --- 48.
Somatogyrus is distributed from the Mississippi River drainage system east to Atlantic coastal streams, and south to the Gulf coastal drainage systems. Approximately 35 species have been described. Three species are known from rivers entering northwest Florida from Georgia and Alabama.
31a. Adult shell about 4-5 mm high; umbilicus wide; columellar margin of the aperture concave in outline (Fig. 64). ---------------------------------------------------------------------------- (Gulf Coast Pebblesnail) Somatogyrus walkerianus (Aldrich, 1905).
Found in western Florida and southern Alabama from the Choctawhatchee River west to the Escambia River. This species inhabits silt and fine sand in quiet zones along the sides of larger rivers and streams.
Figs. 64, 65, 66
31b. Adult shell small, less than 3 mm high; umbilicus narrow but not occluded by the columellar lip; columellar margin of the aperture weakly concave (Fig. 65).----------------------------------- (Choctawhatchee Pebblesnail) Somatogyrus sp.
Found on rock outcrops in the Pea and Choctawhatchee Rivers in Geneva Co. Alabama. Not yet recorded from Florida.
31c. Adult shells small, less than 3 mm high; umbilicus closed by the reflected columellar lip; columellar margin of the aperture nearly straight, barely convex (Fig. 66). ------------------------------------- (Apalachi Pebblesnail) Somatogyrus sp.
Known only from the shoals below Jim Woodruff Dam on the Apalachicola River, where it occurs on the limestone substrata.
32a. Penis of males with papillae along sides (Figs. 69, 70). -------------------------------------------------------------------------------------- 33.
32b. Penis with large a terminal lobe on the left side and a smaller appendix-like flagellum on the right side. Lobe and flagellum with various patterns of dermal glands (Fig. 68). -----------------------------------Subfamily NYMPHOPHILINAE---48.
Figs. 67, 68, 69
33a. Penis with a single papilla along left margin (Fig. 69). Papilla with a duct that leads to a blind caecum in nape of snail. Vas deferens independent of blind caecum and its duct.-------------------------------------- Family AMNICOLIDAE --- 64.
33b. Penis with papillae along both margins, or right margin only (papillae absent in some Aphaostracon). Vas deferens the only duct present in penis (Fig. 70). -------------------------------------------------------------- Subfamily COCHLIONINAE --- 34.
34 Subfamily COCHLIOPINAE--------------------------------------------------------------------------------------------------------------------34a.
The Cochliopinae consists of about thirty-five genera that are found in North America, South America, west Africa and Mediterranean Europe (Hershler and Thompson, 1992). In the previous edition of the manual the subfamily was refereed to as LITTORIDININAE.
34a. Shell usually with raised spiral threads around periphery, frequently the uppermost thread has conical or triangular spines (Figs. 72-74). Female ovoviviparous with about 50 embryos in uterus; embryos clearly evident through clean shells. Penis with 3-7 papillae along right margin and a projection with 1-4 papillae near end on left side (Figs. 70, 71).-------------------------------------------------------------------------- (Serrated Crownsnail) Pyrgophorus platyrachis Thompson, 1968.
Shell elongate-conical with 5-6 whorls. Spire straight-sided. Suture deeply impressed. Color brown or olivaceous. Peristome complete around aperture. Length of female shell 3-5 mm. Sexually dimorphic in size; males about half as large as females. Found in brackish and freshwater throughout the southern quarter of the Florida peninsula. Abundant on aquatic vegetation.
Figs. 70, 71
Figs. 72, 73, 74
34b. Shell without conical spines, although spiral threads may be present. Penis with different arrangement of papillae than above. Females ovoviviparous or oviparous.------------------------------------------------------------------------------------------ 35 .
35a. Shell elongate, thin, transparent, grayish. Suture deeply impressed. Female ovoviviparous with about 15 large embryos in uterus. Penis with large papilla on right margin near base and one or two papillae on left margin near distal end (Figs. 75, 76). Shell sexually dimorphic in size, males about one-third as long as females.------------------------------ 36.
Figs. 75, 76
35b. Shell variable in shape. Female oviparous, never with embryos in uterus. Penis without a conspicuously enlarged papilla near right base, although other papillae usually are present ------------------------------------------------------------------ 37.
36a. Shell elongate-conical, with about 5-7 whorls. Aperture broadly in contact with preceding whorl. Peristome incomplete around aperture. Umbilicus closed or narrowly perforate. Spiral or costate sculpture usually present. Female shell about 4-6 mm long (Figs. 77-79). Penis with 2 or 3 papillae on left margin (Fig. 75).--------------------------------------------------------------------------------------------------------------------- (Smooth-ribbed Hydrobe) Tryonia aequicostatus (Pilsbry, 1889).
Generally distributed in the central part of the Florida peninsula in rivers, springs, and lakes.
Figs. 77, 78, 79
36b. Shell cylindric-conical with 4.5-5.0 whorls. Aperture free from, or only in slight contact with, preceding whorl. Peristome complete around aperture. Umbilicus open. Shell sculpture with incremental striations only. Female shell about 3.5-4.0 mm long (Fig. 80). Penis with one papilla on left margin (Fig. 76).----------------------------------------------------------------------------------------------------------------------------------------------- (Regal Hydrobe) Pseudotryonia brevissimus (Pilsbry, 1890).
Restricted to a small area in the central part of the Florida peninsula where it is found in marshy lakes and rivers.
Fig. 80
37a. Shell conical, olivaceous in color. Peristome incomplete around aperture. Whorls flat-sided with suture weakly impressed. Sculptured with fine incremental striations and a few fine spiral striations (difficult to distinguish except with transmitted light). Sexes not conspicuously dimorphic in size. Penis with 7-50 papillae along right margin and 1-4 papillae along distal third of left margin (Figs. 81-83).-------------------------------------------- Littoridinops Pilsbry, 1952 --- 38.
37b. Shell conical or cylindric-conical; light to dark brown. Peristome complete around aperture. Whorls generally arched. Spiral sculpture absent. Sexes strongly dimorphic in size, males about half as long as females. Penis with 0-6 papillae confined to right margin (Figs. 89-91).--------------------------------------------------------- Aphaostracon Thompson, 1968 --- 40.
Figs. 81, 82, 83
38. Genus Littoridinops Pilsbry, 1952 -------------------------------------------------------------------------------------------------------------------- 38a.
Littoridinops is found most frequently in brackish water, although the three species found in Florida also occur in frehswater. The genus is found along the east coast of North America from Maryland south to Tabasco, Mexico.
38a. Penis with 3 - I 0 small papillae around base and 7-15 papillae along right margin in a single row (Fig. 81). Sides of spire slightly convex. Parietal margin of operculum concave (Fig. 85). Shell with a brownish hue. Shell with 5.0-6.5 whorls; about 3-5 mm long (Fig. 84). ------------------------------------ (Henscomb Hydrobe) Littoridinops tenuipes (Couper, 1844).
Found in fresh and brackish water along the Atlantic coast of Florida north to Maryland.
Fig. 84
Figs. 85, 86
38b. Penis without papillae around base.------------------------------------------------------------------------------------------------------- 39.
39a. Penis with 17-50 papillae along right margin arranged in 3-5 rows (Fig. 82). Parietal margin of operculum slightly convex in outline (Fig. 86). Shell highly variable in shape; freshwater forms olivaceous or brown; adults with about 4.5-6.0 whorls; about 3.5-4.5 mm long (Fig. 87).--------- (Cockscomb Hydrobe) Littoridinops monroensis (Frauenfeld, 1863).
Widely distributed in brackish marshes and streams from Georgia to Mississippi. Enters fresh water in Florida throughout the St. Johns River. An extremely variable species in which most variations occur in brackish habitats. The freshwater form is conservative in its shell characteristics.
Fig. 87
39b. Penis with 5-15 papillae along right margin arranged in 1-2 rows (Fig. 83). Parietal margin of operculum convex. Shellolive-colored; spire straight-sided. Shell with 5.6-6.8 whorls; about 3.2-4.5 mm long (Fig. 88).------------------------------------------------------------------------------------------------------ (Bantam Hydrobe) Littoridinops palustris Thompson, 1968.
Confined to brackish marshes from Tampa Bay, Florida,north and west to Mobile Bay, Alabama.
Fig. 88
This genus of minute freshwater snails is endemic to the Florida peninsula.
40a. Penis with papillae along right margin (Figs. 89, 90).-------------------------------------------------------------------------------- 41.
Figs. 89, 90, 91
40b. Penis simple, elongate-conical, without papillae (Fig. 91).------------------------------------------------------------------------- 42.
41a. Penis with 1-2 papillae.------------------------------------------------------------------------------------------------------------------------ 44.
41b. Penis with 3-5 papillae.------------------------------------------------------------------------------------------------------------------------ 46.
42a. Shell squat, compact, cylindric-conical in shape, thick and opaque. About 4.2-4.6 weakly arched whorls with a weakly impressed suture. Aperture comma-shaped, tightly appressed against preceding whorl. Length of shell about 2.2-2.8 mm long (Fig. 92).-------------------------------------------------- (Dense Hydrobe) Aphaostracon pycnus Thompson, 1968.
Endemic to Alexander Spring Run, Ocala National Forest, Lake County.
Fig. 92
42b. Shell conical with strongly arched whorls and a deeply impressed suture.----------------------------------------------------- 43.
43a. Shell translucent. Body whorl inflated. Aperture elliptical and loosely attached to or slightly separated from preceding whorl; 4.5-4.9 whorls. Length of shell 2.6-3.0 mm (Fig. 93).--------------------------------------------------------------------------------------------------------------------------------------------------- (Clifton Spring Hydrobe) Aphaostracon theiocrenetus Thompson, 1968.
Endemic to Clifton Springs on the south shore of Lake Jessup, Seminole County, Florida.
Fig. 93
43b. Shell very thin, fragile, transparent. Aperture elliptical and usually attached to preceding whorl; 4.1-4.5 whorls present. Length of shell 2.0-2.4 mm (Fig. 94).------- (Blue Spring Hydrobe) Aphaostracon asthenes Thompson, 1968.
Endemic to Blue Springs, Volusia County, Florida.
Fig. 94
44a. Shell narrow, terete or cylindric-conical with a moderately impressed suture. Aperture broadly attached to preceding whorl across parietal wall. Whorls 4.6-5.3. Length of shell 2.4-3.4 mm (Fig. 95).----------------------------------------------------------------------------------------------------------------------------------------- (Slough Hydrobe) Aphaostracon rhadinus Thompson, 1968.
Abundant along the northern third of the St. Johns River system, Florida.
Fig. 95
44b. Shell conical to elongate-conical; whorls 4.0-4.5 with a deeply impressed suture. Aperture narrowly in contact or free from preceding whorl. --------------------------------------------------------------------------------------------------------------------------------- 45.
45a. Shell conical to ovate-conical. Aperture broadly elliptical. Operculum with about 3 whorls (Fig. 96). Length of shell 2.0-2.4 mm (Fig. 98).-------------------------------------- (Suwannee Hydrobe) Aphaostracon hypohyalina Thompson, 1968.
Figs. 96, 97
Occurs in a small area in north-central Florida from the Suwannee River system west to small streams in Wakulla County.
Fig. 98
45b. Shell elongate-conical. Aperture broadly ovate. Operculum with about 6 slowly expanding whorls (Fig. 97). Length of shell 2.2-2.6 mm (Fig. 99). ---------------------------------------------- (Wekiwa Hydrobe) Aphaostracon monas (Pilsbry, 1899).
Endemic to Wekiwa Springs, Orange County, Florida.
Fig. 99
46a. Shell cylindric-conical, solid opaque; 4.5-4.9 moderately rounded whorls. Aperture ovate; broadly attached to preceding whorl. Length of shell 2.1-2.8 mm (Fig. 100). --------------------------------------------------------------------------------------------------------------------------------------------------------- (Thick-shelled Hydrobe) Aphaostracon pachynotus Thompson, 1968.
Found along the southeastern half of the Florida peninsula from the St. Johns River south to Dade County.
Fig. 100
46b. Shell conical; thin and transparent; 4.0-4.5 strongly arched whorls. Aperture loosely attached to or widely separated from preceding whorl. ------------------------------------------------------------------------------------------------------------------------------- 42.
47a. Aperture loosely attached to or slightly free from preceding whorl. Length of shell 2.0-2.5 mm (Fig. 101). Penis with 3 papillae along right margin (Fig. 90). --------- (Fenney Spring Hydrobe) Aphaostracon xynoelictus Thompson, 1968.
Endemic to Fenney Springs, near Coleman, Sumter County, Florida.
Fig. 101
47b. Aperture widely separated from preceding whorl. Length of shell 3.0-4.0 mm (Fig. 102a, 102b). Penis with 4-6 papillae along right margin (Fig. 89). -------------- (Freemouth Hydrobe) Aphaostracon chalarogyrus Thompson, 1968.
Endemic to Magnesia Springs, 3.7 miles west of Hawthorne, Alachua County, Florida.
Figs. 102, 102a
This subfamily includes about fifteen North American and European genera (Thompson 1979). It is characterized by the lobed shape and glandular patterns of the penis. Evolution has occurred through reproductive specialization, with each genus and most species having distinctive patterns of dermal glands. Identifications are difficult in many instances without properly preserved specimens.
48a. Shell globose or tear-shaped. Umbilicus closed. ------------------------------------------------------------------------------------- 49.
48b. Shell conical or cylindric-conical. Umbilicus open, although very narrow in some species; occasionally closed.-- 50.
49a. Shell medium-sized or large; 5.4-7.5 mm long; thick and opaque; ovate or globose; apical whorls depressed; sides of spire rounded; body whorl conspicuously enlarged, ample, rapidly descending to aperture along last half whorl. Columellar margin of aperture very thick but not reflected over umbilical area (Fig.103). Outer lip straight in lateral profiles. Penis with a small blade-like flagellum along right margin and a heavy mid-ventral ridge that bears 8-11 narrow transverse dermal glands; other glands present on terminal lobe and flagellum (Figs. 105, 106).------------------------------------------------------------------------------------------------------------------------------ (Alligator Siltsnail) NotogiIlia wetherby (Dall, 1885).
Widely distributed throughout the northern half of the Florida peninsula north to the Suwannee River and also in southern Alabama and western Florida in the Choctawhatchee River system. A second species, Notogillia sathon Thompson, (Satyr Siltsnail) (Fig. 104), occurs in the Ocmulgee River system in Georgia.
Figs. 103, 104
Figs. 105, 106, 107, 108
49b. Shell medium-sized, 3.0-3.8 mm long; thinner, translucent or transparent in life; tear-shaped; spire raised and nearly straight-sided, pointed; body whorl less conspicuously enlarged, not descending to aperture along last half whorl. Columellar margin of aperture wide, rounded in front like a spindle. Outer lip of aperture arched forward (Figs. 109a, 109b). Penis with a very long slender flagellum that extends beyond terminal lobe. A single glandular crest present on apex of terminal lobe (Figs. 107, 108).------------------------------- (Teardrop Snail) Rhapinema dacryon Thompson, 1969.
Rhapinema is a monotypic genus confined to the Chipola River and Holmes Creek in Jackson, Holmes, and Washington counties, Florida, and tributaries of' the lower Chattahoochee and Flint rivers in southeastern Alabama and southwestern Georgia. Found in quiet water among aquatic plants.
Figs. 109a, 109b
50a. Mantle richly marked with reddish-brown blotches and spots. Terminal lobe of penis slender. Penis with a large, blade-like flagellum with continuous heavy dermal glands along each side (Figs. 110, 111, 68). ------------------------------------------------------------------------------------------------------------------------------------------------- Spilochlamys Thompson, 1968 --- 51.
Figs. 110, 111, 112
50b. Mantle spotted with black, shaded or unmarked; terminal lobe of penis with complex crests that cause it to look like an animal's head; flagellum slender, with scattered and discontinuous glands along edge (Figs. 115, 116). ---------------------------------------------------------------------------------------------------------------------- Floridobia Thompson and Hershler, 2002 ---52.
51. Genus Spilochlamys Thompson ----------------------------------------------------------------------------------------------------------------------- 51a.
This genus contains three species. Two occur in Florida. One species, Spilochlamys turgida Thompson, 1969, the Pumpkin Siltsnail, (Fig. 112), occurs in the Ocmulgee River system in Georgia. The genus is difficult to diagnose by shell characters because the three species are very dissimilar. Spilochlamys is most similar to the next genus, Cincinnatia, from which its shell usually differs by having a more deeply impressed suture, more strongly shouldered whorls, and a wider umbilical perforation.
51a. Umbilicus narrow, without a strong circum-umbilical ridge, outer lip without a callus on inner surface. Penis as illustrated (Fig. 110). Shell with about 4.5-5.0 whorls; about 3.0-4.8 mm long (Fig. 113).--------------------------------------------------------------------------------------------------------------------------------- (Conical Siltsnail) Spilochlamys conica Thompson, 1968.
Found in springs and spring-fed streams in north-central Florida from the Withlacoochee north and west to the Choctawhatchee River system.
Fig. 113
51b. Umbilicus widely perforate, accentuated by a strong circum-umbilical keel. Outer lip of aperture with a thick callus on inner surface. Penis as illustrated (Fig. 111). Shell with 4.4-5.0 whorls; about 3.7-5.2 mm long. (Fig.114). ------------------------------------------------------------------------------------------------------- (Armored Siltsnail) Spilochlamys gravis Thompson, 1968.
Confined to north-central Florida in the St. Johns drainage system from near Palatka south to the Wekiva River.
Fig. 114
In previous editions of the manual species of Floridobia were placed in the genus Cincinnatia. The latter genus includes a single species, Cincinnatia integra (Say, 1817). Floridobia is known from peninsular Florida north along the Atlantic seaboard to Maine.
52a. Penis with a few simple scattered superior tubercles on outer surface; parapical crest on a low ridge; accessory crest and inferior crest absent (Fig. 115a, 115b). -------------------------------------- Floridobia floridana species-group --- 53.
This group contains six species in the Florida peninsula.
Figs. 115a, 115b, 116a, 116b
52b. Penis with some superior tubercles fused into a U-shaped crest; parapical crest raised on a fleshy pedicel; accessory crest and inferior crest usually present (Fig. 116a, 116b). --------- Floridobia vanhyningi species-group --- 58.
A group of seven species confined to the St. Johns drainage system. Important diagnostic features occur in the arrangement of glands on the penis.
53a. Spire long, 1.3-1.7 times length of aperture, convex in outline; shell relatively large and nearly cylindrical; 4.0-4.9 mm long; whorls 5.0-5.7, strongly rounded with a deeply impressed suture (Fig. 117). ---------------------------------------------------------------------------------------------------------------------------------------- (Crystal Siltsnail) Floridobia helicogyra (Thompson, 1968).
Endemic to springs and a spring-fed lagoon at Crystal River, Citrus County, Florida.
Fig. 117 here
53b. Spire shorter, conical, 0.7-1.3 times length of aperture, nearly straight-sided in outline, suture of whorls weakly or moderately impressed. ----------------------------------------------------------------------------------------------------------------------------- 54.
54a. Shell minute, 2.0-2.3 mm long; thin and transparent; spire 0.7-1.1 times length of aperture; flagellum lacking glandular crests. shell with 3.9-4.2 whorls (Fig. 118).--------- (Ichetucknee Siltsnail) Floridobia mica (Thompson, 1968).
Confined to a small spring along the west bank of the Ichetucknee River, about a mile northeast of US Highway 27, Suwannee County, Florida.
Fig. 118
54b. Shell larger, thicker, and opaque; spire 0.9-1.3 times length of aperture; with more than 4.2 whorls; penis flagellum with glandular crests. -------------------------------------------------------------------------------------------------------------------------------- 55.
55a. Shell medium-sized, 2.8 - 3.5 mm long; spire 0.9 - 1.1 times length of aperture; shell with 4.2-4.7 whorls (Fig. 119). ------------------------------------------------------------------------------ (Hyacinth Siltsnail) Floridobia floridana (Frauenfeld, 1863).
Found throughout the northern half of the Florida peninsula from Hillsborough and Orange counties north to the Suwannee River. Replaced along the northern half of the St. Johns River by the vanhyningi species group.
55b. Shell moderately large, 3.7-4.5 mm long; spire 1.00-1.35 times length of aperture; shell with 4.8-5.4 whorls. ------ 56.
56a. Aperture broadly ovate in shape; parietal wall weakly in contact or solute from body whorl; whorls more prominently arched and with a deeper impressed suture. (Fig. I20).------- (Enterprise Siltsnail) Floridobia monroensis (Dall, 1885).
Known only from Benson's Mineral Spring near Enterprise, Volusia County, Florida. Presently thought to be extinct, recent reports to the contrary not withstanding.
Fig. 120
56b. Aperture elliptical or trapezoidal in shape. ---------------------------------------------------------------------------------------------- 57.
57a. Aperture elliptical in shape; spire slenderer and slightly convex in outline; suture moderately impressed suture; parapical crest reduced in size. (Fig. 121) ------------------------------------ -------------------------------(Flatwood siltsnail) Floridobia leptospira (Thompson, 2000).
Found in Glen Branch, about 0.5 miles south of the national forest Road 539, Ocala National Forest, Lake County, Florida. The type locality is reached where a hiking trail crosses the slough formed by the creek. The snail lives on dead leave, debris and in silt.
Fig. 121
57b. Aperture trapezoidal in shape; spire more robust, straight sided; with a shallower suture; parapical crest large (Fig. 122) -------------------------------------------------------------------- (Alexander Siltsnail) Floridobia alexander (Thompson, 2000).
Occurs in Alexander Spring Run, Ocala National Forest, Lake Co., Florida. The shell is very similar to that of Floridobia petrifons, which is in a different species-group by virtue of the glandular pattern on the verge. In addition, the Alexander Siltsnail has an operculum of the type described in 58b. The operculum of Floridobia petrifons is differentiated in 58a.
Fig. 122
58a. Operculum nearly multispiral with four large, slowly expanding whorls (Fig. 123). ----------------------------------------- 59.
58b. Operculum paucispiral, with about three rapidly expanding whorls (Fig. 124).---------------------------------------------- 60.
Fig. 123, 124
59a. Shell small, about 3.0-3.5 mm long; adult with 4.4-4.8 whorl; lower corner of aperture tending to be angulate with fluted channel (Fig. 125); accessory crest absent on penis.-------------------------------------------------------------------------------------------------------------------------------------------------------------------- (Seminole Siltsnail) Floridobia vanhyningi (Vanatta, 1934).
Confined to Seminole Springs, 3.4 miles northeast of Sorrento, Lake County, Florida.
Fig. 125
59b. Shell large, 3.7-4.5 mm long; adults with 4.6-5.3 whorls; lower corner of aperture slightly extended forward as a weak, tongue-like projection (Fig. 126); accessory crest present on penis.----------------------------------------------------------------------------------------------------------------------------------------- (Rock Springs Siltsnail) Floridobia petrifons (Thompson, 1968).
Emdemic to Rock Springs, 6.5 miles north of Apopka, Orange County, Florida.
Fig. 126
60a. Shell minute, 2.4-2.7 mm long; adults with 3.9-4.2 whorls; spire short, 0.8- 1.1 times height of aperture (Fig. 127); superior tubercles on penis arranged in oblique longitudinal series.----------------------------------------------------------------------------------------------------------------------------------------------------------------- (Pygmy Siltsnail) Floridobia parva (Thompson, 1968).
Endemic to Blue Springs, Volusia County, Florida.
Fig. 127
60b. Shell larger, 2.8-4.6 mm long; adults with 4.0-4.9 whorls; spire longer, 0.9-1.3 times height of aperture; superior tubercles not arranged in oblique longitudinal series.-------------------------------------------------------------------------------------- 61.
61a. Shell large, 4.0-4.6 mm long; thick and opaque. Whorls globose, with a deeply impressed suture. Penis with two or more longitudinal crests within U-shaped superior tubercle (Fig. 128).----------------------------------------------------------------------------------------------------------------------------------------------- (Ponderous Siltsnail) Floridobia ponderosa (Thompson, 1968).
Endemic to Sanlando Springs,Seminole County, Florida.
Fig. 128
61b. Shell 2.8-3.7 mm long. Thin and translucent or transparent. U-shaped superior crest not enclosing longitudinal crests.----------------------------------------------------------------------------------------------------------------------------------------------------- 62.
62a. Shell conical, spire moderatly high. Suture relatively deep, Whorls of spire rounded. Penis with invaginated cave-like pit within U-shaped superior tubercles.---------------------------------------------------------------------------------------------------------- 63.
62b. Shell elongate conical, spire high. Suture relatively shallow. Whorls of spire less rounded. Penis with superior tubercles forming a vague broken loop; invaginated cave-like pit absent. Parapical crest of verge greatly enlarged. Penis filament white. (Fig. 129).--------------------------------------------------- (Creek Siltsnail) Floridobia fraterna (Thompson, 1968).
Found in small streams along the east side of the St. Johns River from Palatka north and in some streams of Putnam County, Florida.
Fig. 129
63a. Penis with a dense pattern of superior tubercles. Inferior crest absent. Accessory crest present. Penis filament white. (Fig. 130).---------------------------------------------------------- (Wekiwa Siltsnail) Floridobia wekiwae (Thompson, 1968).
Endemic to Wekiwa Springs, Seminole County, Florida.
Fig. 130
63b. Dorsl surface of penis with a few elongate superior tubercles that form a weakly defined U-shaped pattern. Accessory crest absent. Inferior crest usually present. Penis filament black. (Fig. 131).------------------------------------------------------------------------------------------------------------------------ (Green Cove Springsnail) Floridobia porterae Thompson, 2000).
Endemic to Green Cove Spring Run, in the municipality of Green Cove Springs, Clay County. Florida. The shell is strikingly similar to Floridobia wekiwae. No constant difference between the two species is apparent in the shell. They are separated geographically by a distance of about 75 miles.
Fig. 131
This family includes four North American genera, Amnicola, Dasyscia, Colligyrus and Lyogyrus, and the European genus Marstoniopsis and some Asian genera.
64a. Shell small, 2.0-2.8 mm long. Nuclear whorl slightly protruding, 0.29-0.41 mm in diameter transverse to initial suture. Mantle diffusely pigmented or unpigmented. ------------------------------------------------------------------------------------------------- 65.
64b. Shell larger, 2.2-4.8 mm long. Nuclear whorl flattened, 0.41-0.48 mm in diameter transverse to initial suture. Mantle mottled with black spots and blotches. ---------------------------------------------------------------------- Amnicola Gould, 1841--- 66.
65a. Shell smooth. Conical with relatively slender whorls. Widely umbilicate. Basal lip of peristome deeply receded. Nuclear whorl 0.29-0.33 mm in diameter. Mantle diffusely pigmented with melanophores (Fig. 132).--------------------------------------------------------------------------------------------------------- (Indented Duskysnail) Lyogyrus retromargo Thompson, 1968.
Fig. 132
Known from a narrow zone across the neck of Florida peninsula. The extent of distribution north and west of there is not yet determined. Commonly found in quiet water among dead leaves and vegetation.
Lyogyrus Gill, 1863 consists of two subgenera, Lyogyrus s. s. with eight species, and Spirogyrus with a single species confined to south-central Georgia. The latter, (Cobble Sprite) Lyogyrus (Spirogyrus) latus Thompson and Hershler, 1991, occurs under flat rocks and wood. It is found in the Ocmulgee River and in the lower Flint River system. It may occur in Florida (Fig. 133).
Fig. 133
65b. Shell shaggy with numerous spiral fimbriations that are broken into synchronized tufts. Conical with relatively obese whorls. Narrowly umbilicate. Nuclear whorl 0.41 mm in diameter transverse to initial suture. Transparent white (134). ---------------------------------------------------------------------------- (Shaggy Ghostsnail) Dasyscia franzi Thompson & Hershler, 1991.
A montotypic genus nown only from a subterranean stream at Blue Spring Cave, Washington County. The species is named for Richard Franz, in recognition for his many contributions to the biology of cave systems in Florida and adjacent regions of the Southeast.
Fig. 134
Amnicola is a widespread genus in temperate North America. Four species currently are recognized, but the genus has received very little study over most of its range. The specie prefer quite clear water, of lakes and backwaters of streams andsprings.
66a. Shell conical, thick, opaque. Umbilical perforation wide, 1/6 to 1/8 diameter of shell. Whorls 3.8-4.3. Incremental striations intensified near nucleus and umbilicus. Aperture rhomboid; baso-columellar angle extended as slight tonguelike projection; basal lip broadly but shallowly indented (Fig. 135).------------------------------------------------------------------------------------------------------------------------------------ (Squaremouth Amnicola) Amnicola rhombostoma Thompson, 1968.
Confined to sluggish small creeks and streams along the west side of the St. Johns River in Clay and Putnam Counties, Florda.
Fig. 135
Figs. 136, 137
66b. Shell conical or globose-conical; thin, translucent, occasionally opaque. Umbilical perforation narrow, 1/8 - 1/10 diameter of shell. Whorls 3.0-4.0. Incremental striations uniformly weak. Aperture ovate; baso-columellar angle not extended; basal lip not indented.------------------------------------------------ (Peninsula Amnicola) Amnicola dalli ssp.--- 67.
67a. Operculum tightly coiled with four slowly expanding whorls (Figs. 136, 138).------------------------------------------------------------------------------------------------------------------------------------------------------ Amnicola dalli. dalli (Pilsbry and Beacher, 1892).
Widely distributed in springs and streams in northern Florida from the St. Johns River system west to Leon County. Intergrades extensively with the following subspecies.
Fig. 138
67b. Operculum loosely coiled, with 3.75 large whorls, the outer one expanding more rapidly than the others (Figs. 137, 139).------------------------------------------------------------------------------------------------------ Amnicola dalli johnsoni Pilsbry, 1899.
Found throughout the middle third of Florida peninsula. Most commonly found in sand-bottomed lakes and streams.
Fig. 139
68a. Shell cap-shaped or limpet-like with a wide, open aperture forming base of shell (Figs. 197-209). ------------------------------------------------------------------------------------------------------------------------------------------------------------------ ANCYLIDAE --- 88.
68b. Shell coiled.--------------------------------------------------------------------------------------------------------------------------------------- 69.
69a. Shell planular or disc-shaped; spire flat when raised above succeeding whorls (Figs. 159-196).--------------------------------------------------------------------------------------------------------------------------------------------------------------- PLANORBIDAE --- 78.
69b. Shell elongate with pointed conical spire.----------------------------------------------------------------------------------------------- 70.
70a. Shell coiled to the right, with the aperture on the right side (Figs. 140-146).------------------------- LYMNAEIDAE --- 71.
70b. Shell coiled to the left, with the aperture on the left side (Figs.147-158).---------------------------------- PHYSIDAE --- 73.
71. Family LYMNAEIDAE ------------------------------------------------------------------------------------------------------------------------------------- 71a.
Lymnaeids are a nearly cosmopolitan family of freshwater snails. They achieve their greatest diversity in genera and species in temperate North America. The lymnaeid fauna of the southeast is particularly depauperate compared to more northern and western regions of the continent. Only three widely distributed species occur in Florida.
71a. Aperture large, oval, much more than half the length of shell. Sculpture consisting of distinct spiral striations and threads superimposed on growth striations (Fig. 140).---- (Mimic Pondsnail) Pseudosuccinea columella (Say, 1825).
The genus Pseudosuccinea contains a single species that is widespread in North America east of the Rocky Mountains and occurs in the West Indies and Central America as far south as Venezuela. This is an amphibious species that is particularly common on mats of floating vegetation such as hyacinths and water-lettuce. Occasional specimens have a long, slender apex. These have been named Pseudosuccinea columellar casta (Lea, 1841).
Fig. 140
71b. Aperture relatively shorter, about half or less the length of the shell. Sculpture consisting of incremental striations only.-------------------------------------------------------------------------------------------------------------------------------------------------------- 72.
72. Genus Fossaria Westerlund, 1883--------------------------------------------------------------------------------------------------------------------- 72a.
Fossaria is found throughout North America, and in northern Europe. It contains about a dozen species in North America. The species are highly variable, and there is no consensus regarding the number of valid species.
72a. Aperture narrow, about half as wide as high. Whorls shouldered above near suture (Fig. 143). Body whorl compressed (Fig. 141). Radula with tricuspid lateral teeth (Fig. 145).--------------------------------------------------------------------------------------------------------------------------------------------------------------------- (Rock Fossaria) Fossaria modicella (Say, 1825).
Sparse throughout the northern half of the Florida peninsula and panhandle. Primarily aquatic. Most commonly found on algae-covered rocks and logs.
Fig. 141
72b. Aperture oval, about 0.75 times as wide as high. Whorls uniformly rounded, not flattened above (Fig.144). Body whorl rounded (Fig. 142). Radula with bicuspid lateral teeth (Fig. 146).-------------------------------------------------------------------------------------------------------------------------------------------------------------- (Carib Fossaria) Fossaria cubensis (Pfeiffer, 1839).
Generally common throughout Florida. Most frequently found in small streams and ditches. An amphibious species that usually occurs on damp soil among vegetation along the edge of the water.
Fig. 142
Figs. 143, 144
Figs. 145, 146
73. Family PHYSIDAE------------------------------------------------------------------------------------------------------------------------------------------- 73a.
Taylor (2003) recently monographed the family Physidae. This monumental work changed all previous concepts concerning subfamilies, genera and species in the family. Taylor recognizes twenty-three genera based on the soft anatomy. In previous editions of the manual the Florida species were placed in the genus Physella. This revision follows the classification proposed by Taylor. The reader may be troubled by the imprecise shell characteristics that are used in the key. Physid species have similar and superficially featureless, variable shells, and the shell is imprecise for identifying most genera and many species. Definitive identifications may require anatomical dissections and reference to other literature..
73a. Apex very short, only slightly raised above body whorl. Size small I I to medium, 8-12 mm in length. Sculpture consisting of axial striations only (Fig.147).---------------------------- (Low-dome Physa) Haitia bermudezi (Aguayo, 1935).
Known from the Everglades region of south Florida, where it also occurs in Pleistocene fossil deposits. It also occurs in Cuba.
Fig. 147
73b. Apex proportionally longer, about 0.3-0.5 times length of shell.------------------------------------------------------------------ 74.
74a. Shell elliptical-ovate in shape. Apex distinctly convex in outline. Shell usually opaque in adults, with a dark red callus inside the lip (Fig. 148).------------------------------------------------------- (Tadpole Physa) Physella gyrina aurea (Lea, 1838).
Widely distributed in the southeastern United States. In the Florida panhandle it occurs in river systems that drain south from Georgia and Alabama. .
74b. Shell generally elliptical in outline. Apex nearly straight-sided or concave in outline. Shell transparent or opaque. Inside of lip with or without a reddish callus but callus never dark red in color.------------------------------------------------------ 75.
Fig. 148
Fig. 149, 150
75a. Shell slender, attenuate. Apex about 0.4-0.5 times length of shell. Suture weakly impressed. Base of shell open when viewed from below, showing most of preceding whorl due to curved basal lip (Fig. 149). Surface smooth, glossy, striations when present very weak. Amber to milky white in color (Figs. 151, 152).--------------------------------------------------------------------------------------------------------------------------------------------------------------- (Bayou Physa) Haitia hendersoni ssp.
Widely distributed in southeastern United States from Virginia to Mississippi and throughout Florida.
Figs. 151, 152
75b. Apex less than 0.4 times length of shell. Suture more deeply impressed. Base of shell when viewed from below showing about half of preceding whorl due to straight basal lip (Fig. 149). Sculpture variable. Color of fresh shell never milky white.---------------------------------------------------------------------------------------------------------------------------------------------- 76.
76a. Shell usually large, about 12-16 mm long. Generally with distinct axial and spiral striations. Brownish-yellow in color (Fig. 153).------------------------------------------------------------------ (Bayou Physa) Hatia pomilia hendersoni (Clench, 1925).
Widely distributed in the southeastern United States and occurs throughout peninsular Florida. Two forms exist in addition to the attenuate subspecies cited above. The typical form (Fig. 152) has a rounded last whorl and a shallower suture. The second form has a flattened body whorl so that the sides of the last whorl and aperture are nearly parallel, and the suture is deeply impressed. This second form of Haitia pomilia hendersoni and has been given a separate subspecific name, Haitia pomilia arioma (Clench, 1925) (Fig. 154).
Figs. 153, 154
76b. Shell smaller, generally less than 12 mm long. Spiral sculpture absent. Shell transparent or translucent. Gray to brownish-yellow in color.-----------------------------------------------------------------------------------------------------------------------------77.
77a. Shell elliptical in shape. Suture not as deeply impressed as in 77b. Last whorl not shouldered (Figs.155, 156).--------------------------------------------------------------------------------------------------------- (Carib Physa) Haitia cubensis (Pfeiffer, 1839).
Two subspecies are recognized. Haitia cubensis cubensis has a relatively short apex (Figs. 155, 156). It is widely distributed in the West Indies, Central America, and northern South America, and it occurs throughout Florida and the adjacent areas of' Alabama and Georgia. It occurred in Florida during the late Pleistocene. Haitia cubensis peninsulare (Pilsbry, 1889) has a more elongate apex (Fig. 157). It occurs throughout the Florida peninsula, and also in the West Indies, Mexico, and Central America.
Figs. 155, 156
Fig. 157
77b. Shell usually squarish or rectangular in shape. Suture more deeply impressed than in 77a. Last whorl distinctly shouldered. Texture dull. Axial striations distinct (Fig. 158).----- (Pewter Physa) Haitia pomilia pomilia (Conrad, 1834).
Widely distributed in the southeastern United States and found throughout Florida.
Fig. 158
78. Family PLANORBIDAE --------------------------------------------------------------------------------------------------------------------------------- 78a.
Planorbid snails are restricted to fresh water and occur worldwide, being found on all continental landmasses and many oceanic islands. Most species are disc-shaped or planular, as is implied by the name PLANORBIDAE. The basic shell morphology of the PLANORBIDAE is left-handed, or sinistral (FIGS. 180-193). Many species are secondarily modified to appear right-handed or pseudo-dextral (FIGS. 159-179). The family contains numerous genera and species, some of which are important medically as intermediate hosts for trematode parasites. Genera that serve as intermediate hosts for schistosomatid trematodes have been studied extensively. Most other genera have received relatively minor attention, and their systematics are in flux. Few of the North American species have been studied to the extent that their taxonomy, geographic distributions, life histories, and ecology are documented. The planorbid fauna of the southeastern states is particularly poorly known. The following key includes all of the species that occur in Florida and some that occur in Alabama, Georgia, and South Carolina.
78a. Size small, discoidal, adults seldom exceeding 4 mm in width.------------------------------------------------------------------ 79.
78b. Size larger, adults 7 mm or more in width. Shell usually planispiral, but two species may have a flat-topped, elevated spire.------------------------------------------------------------------------------------------------------------------------------------------------------- 83.
79a. Shell keeled or strongly angular at the periphery (Figs. 161, 164, 167). Weak spiral striations present on top of growth striations (Figs. 159, 162, 165). Shell with three whorls. Umbilicus narrow (Figs. 160, 163, 166).------------------ 80.
79b. Shell rounded at the periphery (Figs. 170, 173). Spiral sculpture faint or absent (Figs. 169, 172). Shell with 3-4 whorls. Umbilicus variable.-------------------------------------------------------------------------------------------------------------------------- 82.
80a. Body whorl relatively narrow, not conspicuously enlarging near aperture (Fig. 159). Apex of shell slightly convex in outline. Body whorl strongly keeled as though pinched at the periphery (Figs. 159-161).--------------------------------------------------------------------------------------------------------------------------------- (Marsh Sprite) Micromenetus brogniartiana (Lea, 1842).
Known in Florida only from marshy habitats within the Chipola River basin in Jackson County and the Wacissa River basin in Jefferson County. Most frequently encountered on dead leaves and submerged vegetation in quiet water. This species was listed in the previous edition as Micromenetus alabamensis (Pilsbry, 1895) which is a junior synonym of Micromentus brogniartiana.
Figs. 159, 160, 161
80b. Body whorl relatively rapidly expanding in diameter (Fig. 162). Aperture enlarged (dilated). Apex of shell flat, though it may be raised above the periphery of the last whorl (Figs. 164, 167). Periphery variable.---------------------------------- 81.
81a. Periphery of last whorl bluntly angular, lying below plane of apex (Figs. 162-164).--------------------------------------------------------------------------------------------------------------------------------------- (Bugle Sprite) Micromenetus d. dilatus (Gould, 1841).
Widely distributed in northern Florida, and northward. Frequent on stones, gravel, submerged sticks, and vegetation in streams, springs, and lakes. This form intergrades with Micromentus dilatatus avus in northern Florida. It occurs with Micromenetus floridanus and Micromenetus brogniartiana without showing intergradation.
Figs. 162, 163, 164
81b. Body whorl angular. Last whorl flattened above. Apex suppressed to form a nearly flat plane with the peripheral angle (Figs.165-167).---------------------------------------------------------------------- Micromenetus dilatatus avus (Pilsbry, 1905).
Found throughout the Florida peninsula in all major freshwater habitats, and in Haiti, Jamaica, and Panama (Thompson 1983). This subspecies was first described as a fossil from the Pliocene Caloosahatchee Formation in southern Florida.
Figs. 165, 166, 167
82a. Shell dark brown. Umbilicus narrow, deep (Fig. 169). Body whorl uniformly rounded peripherally (Fig. 170). Aperture moderately oblique. Shell sculptured with very fine, uniformly spaced axial threads (Figs.168-170). Marginal teeth of radula spatulate and bearing 8-10 weakly differentiated cusps.--------------------------------------------------------------------------------------------------------------------------------------------------------------------- (Penny Sprite) Micromenetus floridensis (Baker, 1945).
Widely but sparsely distributed in Florida. Most frequently in marshy habitats along streams. This snail was described by Baker (1945) as a subspecies of M. dilatatus. The two are recognized as distinct species because they occur syntopically and without intergradation in the Suwannee River system.
Figs. 168, 169, 170
82b. Shell grayish-white. Umbilicus broad, shallow (Fig. 172). Periphery of body whorl below middle, side of whorl flattened and sloping toward apex (Fig. 173). Aperture strongly oblique. Shell nearly smooth, sculptured with irregularly spaced incremental striations (Figs.171-173). Marginal teeth of radula trapezoidal with well-differentiated cusps.---------------------------------------------------------------------------------------------------------------------- (Ash Gyro) Gyraulus parvus (Say, 1817).
Found throughout most of North America. It is abundant particularly on aquatic vegetation.
Figs. 171, 172,173
83a. Adults with six teeth in aperture, two on the parietal wall and four on the palatal wall. Apical whorls depressed; body whorl obtusely angular above and sharply carinated around funnel-shaped umbilicus. Lip of adult shell usually with a thick crest externally and an internal callus. Adults about 6-8 mm wide (Figs. 174-176).--------------------------------------------------------------------------------------------------------------------- (Thick-lipped Rams-horn) Planorbula armigera wheatleyi (Lea, 1858).
Known only from southeastern Alabama and the Chipola River, Jackson County, Florida.
Figs. 174, 175, 176
83b. Adult shell without lamella on interior walls of aperture.----------------------------------------------------------------------------- 84.
84a. Shell discoidal, grayish-white in color; transparent when fresh. Shell nearly smooth, sculptured with irregular growth striations. Adults with about 5 whorls, and 10-13 mm wide (Figs.177-179).----------------------------------------------------------------------------------------------------------------------------------------- (Ghost Rams-horn) Biomphalaria havanensis (Pfeiffer, 1839).
Common in ditches and ponds in southeast Florida from Brevard and Okeechobee Counties south to Monroe County. Widely distributed in the West Indies and Central America. Generally found in oligotrophic habitats on submerged vegetation.
Figs. 177, 178, 179
84b. Shell usually corpulent, brown or green, generally opaque, but occasionally translucent in juveniles.------------------ 85.
85a. Shell distinctly carinated above and below; both apex and base funnel-shaped. Sculpture consisting of fine incremental threads, and spiral striations that may become obsolete at maturity. Adults 9-15 mm wide (Figs. 180-182).--------------------------------------------------------------------- (Two-ridged Rams-horn) Helisoma anceps anceps (Menke, 1839).
Widely distributed over North America but uncommon in the southeastern states. It has been found only once in Florida, in Holmes County. Seventeen subspecies are listed by Baker (1945). The Florida specimens are typical H. a. anceps, though smaller than usual. Specimens from southern Georgia intergrade between the typical subspecies anceps and the subspecies eucosmius (Bartsch, 1908) described from Lake Waccamaw, North Carolina.
Figs. 180, 181, 182
85b. Whorls rounded, not carinate above; occasionally angular below. Apex of shell flat-topped, but sunken below periphery of last whorl. Base of shell regularly expanding, not funnel-shaped.----------------------------------------------------- 86.
86. Genus Planorbella ----------------------------------------------------------------------------------------------------------------------------- 86a.
86a. Shell dull. Sculptured with regularly spaced, fine, incremental threads and spiral striations; spiral striations evident only on base of whorls in some specimens. Apex flat with narrow threadlike keel. One to several dark growth-rest varixes usually present on last whorl. Adults about 15-18 mm wide with about 5.5 whorls (Figs.183-185).------------------------------------------------------------------------------------------------------ (Marsh Rams-horn) Planorbella trivolvis intertexta (Sowerby, 1878).
Widely distributed throughout the Florida Peninsula and extending northeast along the coastal plain to southeastern North Carolina. In western Florida it intergrades with Planorbella trivolvis lenta (Say, 1834) (Figs.186-188).
Figs. 183, 184, 185, 186, 187, 188
86b. Shell glossy. Surface smooth or dented with hammer marks.- ------------------------------------------------------------------- 87.
87a. Shape highly variable, usually disc-shaped but some specimens with flat-topped raised spire. Lower margin of aperture advanced beyond upper margin so that plane of aperture slopes posteriorly when viewed from the side (Figs.189-193).------------------------------------------------------- (Seminole Rams-horn) Planorbella duryi (Weatherby, 1879).
This species is endemic to the Florida peninsula, occurring northwest as far north and west as Taylor County. Introduced widely into other areas in North America, tropical America, Asia, the Pacific Islands and Africa. The species is highly variable in size and shape, and six subspecies have been described (Pilsbry 1934).
Figs. 189, 190, 191, 192, 193
87b. Spire raised and flat-topped. Lower margin of aperture not advanced beyond upper margin. Plane of aperture nearly vertical when viewed from the side. Size smaller than last species, seldom exceeding 10 mm in width (Figs.194-196).-------------------------------------------------------------------------------- (Mesa Rams-horn) Planorbella scalaris (Jay, 1839).
Endemic to the central and southern part of the Florida peninsula where it is found in marshes and lakes.
Figs. 194, 195, 196
88. Family ANCYLIDAE.-------------------------------------------------------------------------------------------------------------------------------------- 88a.
Ancylid gastropods are small, fragile limpets found in most freshwater habitats. All freshwater limpets in the southeast belong to this family. Other families occur elsewhere in North America and in other continents. Little is known about these animals, and diverse opinions exist as to how many species are recognizable. Many North American snail species were described near the turn of the century by Walker (I 918). Basch ( 1963) revised the classification and recognized only twelve species. However, this appears to be an over reduction, and several southern species were synonymized that appear worthy of recognition. Six species are known to occur in Florida. They are variable in their shell characteristics, and some samples may be difficult to identify. The following key is modified from Basch (1963). It is essential that clean specimens be examined under proper lighting to observe diagnostic sculpture characteristics.
Figs. 197, 198, 199, 200 201, 202, 203
88a. Shell usually elevated, but variable. Apex with fine radial striations (Figs. 204-207), often eroded in older specimens. Peristome narrow to broadly ovate. Aperture usually open; occasionally with a horizontal, shelf-like septum closing posterior part (Fig. 199).----------------------------------------------------------------------------- Ferrissia Walker, 1903 --- 89.
88b. Shell depressed. Apex smooth, with no trace of radial striations (Fig. 208, 209), although radial striations may be present on other areas of shell. Peristome ovate to subcircular. Aperture never with a septum.------------------------------ 90.
Ferrissia is widely distributed in the northern hemisphere. About fifteen species have been described from North America. Basch (1963) recognized five valid species. There is much disagreement as to how many species actually exist. Two species occur in Florida.
89a. Shell thin, fragile, very much depressed, less than 0.25 times as high as long. Color often glossy reddish brown. Apex fairly prominent as a rounded knob in the right posterior quadrant (Figs. 197, 204). Length of shell up to 5 mm.-------------------------------------------------------------------------------------------------------------------------- (Hood Ancylid) Ferrissia mcneilli Walker, 1925.
Confined to small creeks in the area around Mobile Bay east to the Apalachicola River system.
Fig. 204
89b. Shell moderately elevated, over 0.25 times as high as long. Apex in the posterior right third, domelike and evenly rounded. Adults about 2-3 mm long (Figs. 198, 205).--------------- (Blackwater Ancylid) Ferrissia hendersoni Walker, 1908.
Basch (1963) refers to this form as a subspecies of F. fragilis (Tyron, 1863). It's apical characters appear to be sufficiently distinct from the northern F. fragilis to deserve specific recognition. Known from the southeastern coastal plains of North Carolina, South Carolina, Georgia, and Florida. Found in ditches, ponds, and quiet backwaters in streams and lakes. It commonly occurs on stems of aquatic plants, dead leaves, and sticks. Some specimens form a partial septum in the middle of the shell (Fig. 199), apparently in response to seasonal drying of their habitats.
Fig. 205
90a. Apex very obtuse, almost in the middle of the shell. Radial striations present or absent Laevapex Walker, 1903------ 91.
90b. Apex subacute, distinctly eccentric to the right of the midline. Radial striations present on shell but not on apex. Average length about 4 mm (Figs. 200, 206).------------------------------- (Excentric Ancylid) Hebetancylus excentricus (Morelet, 1851).
A monotypic genus widely deployed in Middle America, extending northward into southeastern Texas and the southeastern coastal plains. Commonly found on dead wood, leaves, plant stems, bottles, and cans.
Fig. 206
Laevapex is a North American genus. Eight species have been proposed. Three occur in Florida. They are commonly found on live aquatic plant stems, dead leaves and sticks, and on bottles and cans.
91a. Shell elongate. Radial riblets on entire surface of shell except apex. Apex slightly behind and slightly to the right of midline. Adults about 5 mm long (Figs. 201, 207).----------------------------------------------------------------------------------------------------------------------------------------------------------------.(Peninsula Ancylid) Laevapex peninsulas (Pilsbry and Johnson, 1903).
Known only from the Florida peninsula where it occurs east and south of the Suwannee River system.
Fig. 207
91b. Shell ovate or subcircular in shape, smooth or with radial sculpture localized anteriorly.--------------------------------- 92.
92a. Shell ovate, smooth or with fine raised riblets; riblets usually on the anterior slope when present. Apex behind center of shell. Average length about 5 mm (Figs. 202, 208).----------- (Dusky Ancylid) Laevapex fuscus (C.B. Adams, 1841).
Usually found in still backwaters of rivers and lakes living on dead leaves and stems. Widely distributed in eastern North America.
Fig. 208
92b. Shell subcircular, smooth, often encrusted with dark material. Apex in about middle of shell. Average length about 5.5 mm (Figs. 203, 209).-------------------------------------------- (Cymbal Ancylid) Laevapex diaphanus (Haldeman, 1841).
Occurs in slow-flowing streams in western parts of Florida and northward.
Fig. 209
Baker, F.C. 1945. The molluscan family Planorbidae. University of Illinois Press, Urbana. i-xxxvi, 1-530 pls.
Basch, P.F. 1963. A review of the recent freshwater limpet snails of North America. Bulletin of the Museum of Comparative Zoology, 129: 401-61.
Burch, J. B. 1980. Freshwater snails (Mollusca: Gastropoda) of North America. Bulletin of the Environmental Protection Agency, EPA-600/3-82-026: i-vi, 1-294.
Burch, J.B. 1989. North American freshwater snails: species list, ranges and illustrations. Walkerana, 1: 81-365.
Clench, W.J. 1962. A catalogue of the Viviparidae of North America with notes on the distribution of Viviparus georgianus Lea. Occasional Papers on Mollusks, 2: 261-87.
Clench, W.J. 1969. Melanoides tuberculata (Muller) in Florida. Nautilus, 83: 72.
Clench, W.J., & S. L. H. Fuller. 1965. The genus Viviparus (Viviparidae) in North America. Occasional Papers on Mollusks, 2: 385-412.
Clench, W.J., & R. D. Turner. 1956. Freshwater mollusks of Alabama, Georgia and Florida from the Escambia to the Suwannee River. Bulletin of the Florida State Museum, Biological Sciences, 1: 97-239.
Davis, G.M., M. Mazurkiewicz, & M. Mandracchia. 1982. Spurwinkia: Morphology, systematics, and ecology of' a new genus of North American marshland Hydrobiidae (Mollusca: Gastropoda). Proc. Acad. Nat. Sci. Philadelphia, 134: 143-77.
Goodrich, C. 1942. The Pleuroceridae of the Atlantic Coastal Plain. Occasional Papers of the Museum of Zoology, University of Michigan, (456): 1-6.
Hershler, R. & F. G. Thompson. 1992. A review of the aquatic gastropod subfamily Cochliopinae (Prosobranchia, Hydrobiidae). Malacological Review, Suppl. 5: 1-140.
Pilsbry, H. A. 1905. Planorbis alabamensis and dilatatus in the Floridian Pliocene. Nautilus, 19: 34.
Pilsbry, H. A. 1918. Viviparus contectoides limi, new name for V. c. compactus Pils. Nautilus, 32: 71.
Pilsbry, H. A. 1934. Review of the Planorbidae of Florida with notes on other members of the family. Proceedings of the Academy of Natural Sciences of Philadelphia, 86: 29-66.
Mihalcik, E. L. & F. G. Thompson. A taxonomic revision of the feshwater snails referred to as Elimia curvicostata, and related secies. Walkerana, 13: 1-108.
Taylor, D. W. 2003. Introduction to the Physidae (Gastropoda, Hydophila): biogeograhy, classification, morphology. Revista de Biologia Trpical, 51 (supplement): 1-299.
Te, G.A. 1978. A systematic study of' the Family Physidae (Basommatophora: Pulmonata). Ph.D. thesis, University of Michigan, i-xii, 1-324.
Thompson, F.G. 1968. The aquatic snails of the Family Hydrobiidae of peninsular Florida. Univ. Florida Press, Gainesville: i-xv, 1-68; pls. 1-69.
Thompson, F. G. 1969. Some hydrobiid snails from Georgia and Florida. Quarterly Journal of the Florida Acaemy of Sciences, 32: 241-65.
Thompson, F.G. 1979. The systematic relationships of the hydrobiid snail genus Nymphophilus Taylor, 1966 and the status of the Subfamily Nymphophilinae. Malacological Review, 12: 41-49.
Thompson, F. G. 1982. On sibling species and genetic diversity in Florida Goniobasis (Gastropoda, Prosobranchia, Pleuroceridae). Malacologia, 23: 81-82.
Thompson, F. G. 1983. The planorbid snail Micromenetus dilatatus avus in the West Indies and Central America. Nautilus, 97: 68-69.
Thompson, F. G. 1997. Pomacea canaliculata (Lamarck, 1822) (Gastropoda, Prosobranchia, Pilidae): A freshwater snail introduced into Florida, U. S. A. Malacological Review, 30:91.
Thompson, F. G. 2000. Three new freshwater snails of the genus Cincinnatia from peninsular Florida.
Thompson, F. G. & R. Hershler. 1991. Two new species of hydrobiid snails from Florida and Georgia, and a discussion of the biogeography of south Georgia streams. Malacological Review, 24: 55-72.
Thompson, F. G. & R. Hershler. 2002. Two genera of North American freshwater snails: Marstonia Baker, 1926 resureected to generic status, and Floridobia, new genus (Prosobranchia, Hydrobiidae, Nymphophilinae). Veliger, 45:269-271.
Vail, V. A. 1979a. Campeloma parthenum (Gastropoda: Viviparidae), a new species from north Florida. Malacological Review, 19: 85-86.
Vail, V. A. 1979b. A preliminary revision of Florida Lioplax (Gastropoda: Viviparidae), with a description of Lioplax talquinensis n.sp. Malacological Review, 12: 87-88.
Walker, B. 1918. A synopsis of the classification of the freshwater Mollusca of North America north of Mexico and a catalogue of the more recently described species with notes. Miscellaneous Publication of the Museum of Zoology, University of Michigan, 6: 1-213.
Alexander Siltsnail
Alligator Siltsnail
Apalachi Peblesnail
Armored Siltsnail
Ash Gyro
Banded Mysterysnail
Bantam Hydrobe
Bayou Physa
Black-crested Elimia
Blackwater Ancylid
Blue Spring Hydrobe
Bugle Sprite
Carib Fossaria
Carib Physa
Choctaw Lioplax
Choctawhatchee Elimia
Choctawhatchee Pebblesnail
Clifton Spring Hydrobe
Cobble Sprite
Cockscomb Hydrobe
Conical Siltsnail
Creek Siltsnail
Crystal Siltsnail
Cymbal Ancylid
Dense Hydrobe
Dusky Ancylid
Enterprise Siltsnail
Escambia Elimia
Excentric Ancylid
Fawn Melania
Fenney Spring Hydrobe
File Campeloma
Florida Applesnail
Freemouth Hydrobe
Ghost Rams-horn
Goblin Elimia
Goldenhorn Marisa
Ghostsnail, Shaggy
Graphite Elimia
Green Cove Springsail
Gulf Coast Pebblesnail
Henscomb Hydrobe
Hood Ancylid
Hyacinth Siltsnail
Blue Spring
Clifton Spring
Fenney Spring
Ichetucknee Siltsnail
Indented Duskysnail
Knobby Elimia
Low-dome Physa
Maiden Campeloma
Marsh Rams-horn
Marsh Sprite
Mesa Rams-horn
Mimic Pondsnail
Olive Nerite
Ovate Campeloma
Gulf Coast
Peninsula Amnicola
Peninsula Ancylid
Penny Sprite
Pewter Physa
Ponderous Siltsnail
Pumpkin Siltsnail
Purple-throated Campeloma
Pygmy Siltsnail
Quilted Melania
Rasp Elimia
Red-rimmed Melania
Regal Hydrobe
Rock Fossaria
Rock Springs Siltsnail
Rotund Mysterysnail
Satyr Siltsnail
Seminole Rams-horn
Seminole Siltsnail
Serrated Crownsnail
Shaggy Ghostsnail
Rock Springs
Slackwater Elimia
Slender Siltsnail
Slender Walker
Slough Hydrobe
Smooth-ribbed Hydrobe
Spiketopped Applesnail
Spring Elimia
Springsnail, Green Cove
Squaremouth Amnicola
Stately Elimia
Suwannee Hydrobe
Tadpole Physa
Teardrop Siltsnail
Thick-lipped Rams-horn
Thick-shelled Hydrobe
Two-ridged Rams-horn
Wacasassa Elimia
Wekiwa Hydrobe
Wekiwa Siltsnail
aequicostatus, Tryonia
alabamensis, Micromenetus
albanyensis, Elimia
dalli dalli
dalli johnsoni
anceps, Helisoma
arioma, Physella hendersoni
armigera, Planorbula
asthenes, Aphaostracon
athearni, Elimia
aurea, Physella gyrina
avus, Micromenetus dilatatus
bermudezi, Physella
Biomphalaria havanensis
brevissima, Tryonia
bridgesi, Pomacea
brogniartianus, Micromenetus
canaliculata, Pomacea
chalarogyrus, Aphaostracon
choctawhatchensis, Lioplax pilsbryi
chinensis malleata
clenchi, Elimia
columella, Pseudosuccinea
conica Spilochlamys
cornuaurietus, Marisa
crocata, Physa
cubensis, Fossaria
cubensis, Physella
curvicostata, Elimia
dacryon, Rhapinema
dalli dalli, Amnicola
dalli johnsoni, Amnicola
Dasyscias franzi
diaphanus, Laevapex
dickinsoni, Elimia
dilatatus, Micromenetus
duryi, Planorbella
eucosmius, Helisoma anceps
excentricus, Hebetancylus
flagellate, Pomacea
floridana, Cincinnatia
floridense, Campeloma
floridensis, Elimia
floridensis, Micromenetus
fragilis, Ferrissia
fraterna Cincinnatia
franzi, Dasyscias
fuscus, Laevapex
geniculum, Campeloma
georgianus, Viviparus
granifera, Tarebia
gravis, Spilochlamys
Gyraulus parvus
gyrina aurea, Physella
havanensis, Biomphalaria
helicogyra, Cincinnatia
hendersoni, Ferrissia
hendersoni, Physella
hendersoni arioma, Physella
hendersoni hendersoni, Physella
heterostropha pomila, Physella
hypohyalina, Aphaostracon
intertexta, Planorbella trivilvis
intertextus, Viviparus
lapidaria, Pomatiopsis
lata, Lyogyrus
lenta, Planorbella trivolvis
limi, Viviparus
limum, Campeloma
pilsbryi choctawhatchensis
pilsbryi pilsbryi
malleata, Cipangopaludina chinensis
Marisa cornuaurietus
mcneilli, Ferrissia
miamiensis, Pomacea
mica, Cincinnatia
modicella, Fossaria
monas, Aphaostracon
monroensis, Cincinnatia
monroensis, Littoridinops
Neritina reclivata
pachynotus, Aphaostracon
paludosa, Pomacea
palustris, Littoridinops
parthenum, Campeloma
parva, Cincinnatia
parvus, Gyraulus
peninsulae, Laevapex
peninsulare, Physella cubensis
petrifons, Cincinnatia
cubensis peninsulare
gyrina aurea
hendersoni arioma
hendersoni hendersoni
heterostropha heterostropha
heterostropha pomila
pilsbryi choctawhatchensis
pilsbryi pilsbryi, Lioplax
Planorbula armigera wheatleyi
platyrachis, Pyrogophorus
Pomatiopsis lapidaria
pomila, Physella heterotropha
ponderosa, Cincinnatia
Pseudosuccinea columella
pycnus, Aphaostracon
Pyrogophorus platyrachis
reclivata, Neritina
retromargo, Lyogyrus
rhadinus, Aphaostracon
Rhapinema dacryon
rhombostoma, Amnicola
sathon, Notogillia, 46
scalaris, Planorbella
substriatus, Somatogyrus
Tarebia granifera
tenuipes, Littoridinops
theiocrenetus, Aphaostracon
trivolvis intertexta, Planorbella
tuberculata, Melanoides
turgida, Spilochamys
turricula, Melanoides
vanhyningi, Cincinnatia
vanhyningiana, Elimia
walkerianus, Somatogyrus
wekiwae, Cincinnatia
wetherbyi, Notogillia
xynoelictus, Aphaostracon
Fig. 1, operculum of Neritina usnea – inner view
Fig. 2 operculum of Neritina usnea – exterior view
Fig. 3 shell - Neritina usnea
Fig. 4 operculum - concentric
Fig. 5 operculum – modified concentric (Lioplax)
Fig. 6 operculum - spiral
Fig. 7
Fig. 8
Fig. 9
Fig. 10 shell – Pomacea bridgesi
Fig. 11 shell – Pomacea canaliculata
Fig. 12 shell – Pomacea paludosa
Fig. 13 shell – Pomacea miamiense
Fig. 14 shell – Cipingopaludina chinensis malleata
Fig. 15
Fig. 16
Fig. 17
Fig. 18 shell – Lioplax pilsbryi pilsbryi
Fig. 19
Fig. 20
Fig. 21 shell – Campeloma geniculum
Fig. 22
Fig. 23
Fig. 24
Fig. 25
Fig. 26 shell – Campeloma floridense
Fig. 27
Fig. 28 shell – Campeloma limum
Fig. 29
Fig. 30
Fig. 31
Fig. 32
Fig. 33
Fig. 34
Fig. 35
Fig. 36
Fig. 37
Fig. 38
Fig. 39
Fig. 40
Fig. 41
Fig. 42
Fig. 43