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HISTOLOGY AND HISTOCHEMISTRY OF THE MALE REPRODUCTIVE SYSTEM OF THE KING CRAB LITHODES SANTOLLA (ANOMURA)

Lithodes santolla (Molina, 1782) is target of fishery since the 30’s. Despite of this impact for natural populations, one of key-aspect the male reproductive system has not been analysed in details. Here we describe the anatomy and histochemistry of this system in order to use these characters as taxonomic parameter to contextualize phylogenetic relationships. The animals were collected off shore of Chiloe coast (45°S) in Chile by commercial fishery. The reproductive system and squeezed spermatophoric cord were fixed and submitted to routine for historesin and slides were stained to proteins, neutral and acid polysaccharides. The male reproductive system anatomy is composed of a paired testis and vas deferens (VD). The VD is a long tube without any anatomical changes producing different areas as proximal, medium or distal regions. Along of the VD, the flat epithelium is formed with basophilic cells, laying on a strong musculature depicting three or more fibers. The lumen is filled with two kinds of secretions: the type I secretion is compact and acidophilic where the spermatophores are attached forming spermatophore cord. The spermatophore cord is distributed as a helicoidal pattern along of the VD. The secretion type II is basophilic and filling the spaces among spermatophores. The secretion type I is glicoproteic, strongly reactive to both proteins and neutral polysaccharides with absence of acid ones. The secretion type II is weak stained to proteins, being positive to neutral and strong positive to acid polysaccharides. The spermatophores show acidophilic ampulla, stalk and foot. Close to the foot at the spermatophore base, is possible to notice a small spermatophore or accessory ampulla. All three spermatophoric regions are glicoproteic without acidic polysaccharides. The spermatophoric cord squeezed out from VD depicts both large and small basal spermatophores in an up position on the secretion type I while the secretion type II is absent. The secretion type I is less reactive to neutral polysaccharides, when compared to de secretion in de VD, maintaining the strong reaction to proteins. The acid polysaccharides are absent in the spermatophoric cord. The male reproductive system and the spermatophores are close related to the hermit crabs, despite of the large amount of secretion II and the unique small spermatophore in the stalk, which is peculiar character found in Lithodes santolla, Lithodes maja (Linnaeus, 1758) and probably to the family.