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A New Species of Pachysentis Meyer, 1931 (Acanthocephala: Oligacanthorhynchidae) in the Brown-Nosed Coati Nasua nasua (Carnivora: Procyonidae) from Brazil, with Notes on the Genus and a Key to Species

Introduction Pachysentis comprises 10 species, which have been reported parasitizing mammals in Africa and the American continent. However, species of Pachysentis have not been described in brow-nosed coatis. Pachysentis lauroi n. sp. (Oligacanthorhynchidae: Acanthocephala) is described from the brown-nosed coati Nasua nasua (Linnaeus, 1766) Storr, 1780 (Procyonidae: Carnivora) in the Brazilian Pantanal wetlands of the Mato Grosso do Sul State, Brazil. Methods Specimens were studied using light and scanning electron microscopy. Result The new species is distinguished from other species of Pachysentis by the number of hooks in each longitudinal row (12 rows of 4 hooks, total of 48 hooks), presence of barbs on all hooks, and the organization of the cement glands. Notes on the genus Pachysentis [14] and a key to its species are provided. Critical comments on some species with a dubious diagnosis and questionable or missed key taxonomic characteristics are also reviewed. We also discuss the zoogeography of the members of the genus.

In this study, a new species, Pachysentis lauroi n. sp. is described using light microscopy and scanning electron microscopy (SEM) from the brown-nosed coati in the Brazilian Pantanal wetlands.

Materials and Methods
Two adult brown-nosed coatis were found between 2007 and 2008 at the Nhumirin Ranch (18°59′S, 56°39′W), a research station of the Brazilian Agricultural Research Corporation (Embrapa/Pantanal) in the Nhecolândia subregion of the Pantanal, Mato Grosso do Sul State in the Brazilian Pantanal wetlands. The animals were collected during a research project investigating the ecology and health of wild carnivores. This research project included an inventory of helminth endoparasites. Acanthocephalan specimens were made available to parasitologists at the Oswaldo Cruz Foundation in Rio de Janeiro (FIOCRUZ/RJ). Animal procedures approved by the Brazilian Federal Environmental Agency (IBAMA, first license #183/2005, CGFAU/LIC; last license #11772-2) were followed.
The animals were necropsied and acanthocephalan specimens were collected from the small intestine of each individual host and stored in AFA (alcohol + formalin + acetic acid) for 24 h and stored in 70% alcohol. Worms used for microscopical studies were stained with acid (hydrochloric) carmine, dehydrated in a graded ethanol series, cleared in phenol 90% and mounted in Canada balsam (modified from [2], examined using an Axion Scope A1Light Microscope (Zeiss,Göttingen, Germany), and illustrated with the aid of a drawing tube attached to a Zeiss standard 20 light microscope (Zeiss, Göttingen, Germany).
Generic identification was based on the taxonomic key proposed by Schmidt [17] and specific taxonomic descriptions. The description of the new species of Pachysentis was based on 11 specimens (six males and five females).
For SEM, the specimens were fixed for 1 h at room temperature in 2.5% glutaraldehyde in 0.1 M Na-cacodylate buffer, washed in the same buffer and post-fixed for 3 h at room temperature in 1% osmium tetroxide in 0.1 M Na-cacodylate buffer. The material was then dehydrated in ascending ethanol series, critical point dried with CO 2 , mounted with silver cello tape on aluminum stubs, and sputter coated with a 20-nm-thick layer of gold. Samples were examined using a Jeol JSM-6390 LV microscope (JEOL, Akishima, Tokyo, Japan) at an accelerating voltage of 15 kV at the Electron Microscopy Platform of the Oswaldo Cruz Institute. General With characters of Pachysentis is designated by Schmidt [17]. Trunk wider anteriorly. Proboscis subspherical with 12 longitudinal rows of four hooks each, totaling 48 hooks (Figs. 1, 2). Proboscis hooks similar in size and shape in both sexes. Apical hooks (types I and II) large with posterior curvature, complex manubria and double roots expanding laterally (Fig. 2). Proximal rows with short hooks (types III and IV) and simple discoid roots
Site of infection: Small intestine.
Etymology: The new species is named in honour of Dr. Lauro Travassos, who contributed greatly to our knowledge of the Brazilian Acanthocephala.

Remarks
In this study, we identified the specimens obtained from Nasua nasua (Linnaeus, 1766) Storr, 1780 as belonging to the Oligacanthorhynchidae and Pachysentis due to the presence of a subspherical proboscis, anterior trunk wider than posterior, proboscis with 48 hooks in 12 longitudinal rows of four hooks each using [17]. In addition, Machado-Filho [13] considered the number of hooks on the proboscis and the size of the testes as the best characteristics for identifying and distinguishing species of the genus. Pachysentis lauroi n. sp. is compared with the other valid species of Pachysentis in Table 1 and further distinguished in the dichotomous key presented below.

The Status of Pachysentis septemserialis [13]
The specimens from CHIOC (17812 a-b and 10593) were carefully studied and it was observed that they exhibited some morphological characters not mentioned in the original description. The paratype (permanent slides CHIOC 17812 a-b) was not informative regarding the number of hooks, and a collar was observed at the base of the proboscis, suggesting affiliation with the genus Prosthenorchis [18]. The female paratype from CHIOC 10593 has 12 longitudinal rows of four hooks with total of 48 hooks, which contradicts the number of the hooks given in the original description (seven rows of seven hooks, total 49 hooks) with no collar at the base of the proboscis [13]. Additionally, there is a lack of some information on this species, such as the taxonomic and morphometric characters of adult males. Therefore, we suggest that the specimens designated as P. septemserialis [13,17] may be synonymous with P. lenti [13,17], as to the number of the hooks, other morphometric characteristics and the fact that both are parasites of primates of the family Callitrichidae. The taxonomy of this species needs to be revised.

The Status of Pachysentis ehrenbergi [14]
Specimens of Pachysentis ehrenbergi deposited in the Museum für Naturkunde from Vulpes vulpes (No. 2426) and Naja haje (No. 2432, 6033) were also examined. Specimens from both hosts had barbs on the tip of all hooks, which was not mentioned by Meyer [14] in the original description. Other morphological characteristics, such as the number of hooks, short neck, the presence and size of nuclei in the leminisci and the reproductive organs agree with the original description. Pachysentis lauroi n. sp. distinguished from the other species of Pachysentis by a combination of morphological characters, including the number of the hooks in each longitudinal row, the presence of barbs on the hooks and the arrangement of the cement glands ( Table 1). The following key and Table 1 do not include P. septemserialis, because of its uncertain taxonomic status, but enable the new taxon to be distinguished from the other nine recognized species of the genus.    . Hooks with visible barbs ("arrow-shaped hook tip")…8 -Hooks without barbs……………… P. lenti [13] [17] 6. Parasite of carnivores in Africa…P. angolensis [9] [17] -Parasite of carnivores in the Americas ……………… ……………………………………… P. gethi [13] [17] 7. Very short lemnisci not reaching anterior testis. Parasites of carnivores …………P. procyonis [13] Schmidt, [17] -Leminisci reaching anterior testis. Parasites of pri-mates……………………P. rugosus [13] Schmidt, [17] 8. Cement glands in pairs …P. dollfusi [13] Schmidt, [17] -Cement glands in clusters……………P. lauroi n. sp. 9. Proboscis 0.55 mm wide, with a total of 90 hooks without barbs ………………………… P. procumbens [14] -Proboscis 0.8-0.9 mm wide, with a total of 102 hooks with barbs …………………… P. ehenbergi [14] Pachysentis lauroi n. sp. is further distinguished from P. angolesis, P. canicola, P. procumbens, P. ehrenbergi, P. gethi, P. procyonis and P. rugosus by the number of hooks in each row, with 12 longitudinal rows of four hooks each, totaling 48 hooks (Table 1). Our specimens were similar to P. lenti and P. dollfusi in the number of hooks (48) on the proboscis. The new species can, however, be distinguished from P. lenti by having barbs on all hooks and from P. dollfusi by the organization of the cement glands (in cluster vs in uniform pairs), the size of trunk and the definitive host (Table 1). In addition, when Machado-Filho [13] described P. dollfusi, he indicated that this acanthocephalan infected a zoo animal in Brazil and that is native of Madagascar. Golvan [10], however, warned that the origin of this species might not have been Madagascar. Nevertheless, it is not known whether the species originates in Brazil or Madagascar. Meyer [14] proposed Pachysentis with the type species P.canicola [14] from a domestic dog in Brazil. The same species was found infecting a gray fox Urocyon cinereoargenteus (Schreber, 1775) (Carnivora: Canidae) in the United States [6]. Two additional species, P. ehrenbergi [14] and P. procumbens Meyer, [14], were described from Vulpes vulpes (Linnaeus, 1758) in Egypt [14,22], suggesting that species from this genus are parasites of carnivores (Order Carnivora).

Discussion
Van Cleave [22] also studied acanthocephalan parasites from North American mammals and recorded P. canicola in the gray fox and the skunks Mephitis mephitis mesomelas (Lichtenstein, 1832), Conepatus leuconotus (Lichtenstein, 1832) and Spilogale gracilis leucoparia (Merriam, 1890), and recognized the three previous species of the genus. Yamaguti [24] revised the classification of the Acanthocephala and considered their geographic distributions, revised the diagnosis of the genus Pachysentis and followed the classification of Meyer [14] and Van Cleave [22] with three species in the genus. Schmidt [17] revised the family Oligacanthorhynchidae and transferred six species of Prosthenorchis [18] to the genus Pachysentis, i.e., P. dollfusi, P. gethi, P. lenti, P. procyonis, P. rugosus, P. septemserialis and P. angolensis [syn. Oncicola angolensis [9]. Pachysentis [14] then included a total of 10 species based on morphological features, such as an anterior trunk wider than the posterior trunk; the absence of a festooned collar; a globular proboscis with 12 longitudinal rows of 3-12 hooks, totaling 42-102 hooks; larger anterior hooks with complex manubria and roots, as well as rootless posterior hooks; tips of the hooks with or without barbs; long and flattened lemnisci arranged a band; testes in tandem in the mid-trunk; eight compacted cement glands; and oval eggs with sculptured outer membranes (Yamaguti [17,24].
Our study provides details of Pachysentis lauroi n. sp. by scanning electron microscopy showing the presence of barbs on hooks in the proboscis, and the apical and lateral papillae-like structure on the proboscis, as morphological character to identify the new species. Furthermore, we are adding new information of morphology of two species, P. septemserialis and Pachysentis ehrenbergi and their status in the genus. Finally, we report a new definitive host in a new geographical area for the Pachysentis genus.