Spermatophore morphology of the endemic hermit crabLoxopagurus loxochelis(Anomura, Diogenidae) from the southwestern Atlantic—Brazil and Argentina

Abstract

The spermatophore morphology of the endemic and monotypic hermit crab Loxopagurus loxochelis from the southwestern Atlantic is described. The spermatophores show similarities with those described for other members of the family Diogenidae (especially the genus Clibanarius), and are composed of three major regions: a sperm-filled, circular flat ampulla; a columnar stalk; and a pedestal. The morphology and size of the spermatophore of L. loxochelis, along with a distinguishable constriction or neck that penetrates almost halfway into the base of the ampulla, are characteristic of this species. The size of the spermatophore is related to hermit crab size. Direct relationships were found between the spermatophore ampulla width, total length, and peduncle length with carapace length of the hermit crab. These morphological characteristics and size of the spermatophore of L. loxochelis are species-specific, distinguishing them from other members of the family Diogenidae, and can be used to infer phylogenetic relationships among them.

Reproductive apparatus of the male giant hermit crab Petrochirus diogenes (Anomura, Diogenidae): morphology and phylogenetic implications

“…The male gonopores of Petrochirus diogenes are ovoid in shape, the same pattern described in other species of Diogenidae, such as Calcinus tibicen (Mantelatto et al 2009b), and Loxopagurus loxochelis Moreira, 1901 (Scelzo et al 2004). However, the gonopores of P. diogenes differ significantly from those of other species with respect to the number of associated setae.…”

“…We selected 15 males covering the widest possible range of sizes. All procedures followed the protocols described by Scelzo et al (2004Scelzo et al ( , 2010, Amadio & Mantelatto (2009) and Mantelatto et al (2009a).…”

“…Whereas the gonopores of P. diogenes are completely surrounded by setae, the gonopores of some species, such as Calcinus tibicen (Amadio & Mantelatto 2009) and Clibanarius sclopetarius Herbst, 1796 (Santos & Mantelatto 2011), exhibit few or no setae. Other species, such as I. sawayai (Mantelatto et al 2009b), L. loxochelis (Scelzo et al 2004), Clibanarius erythropus Latreille, 1818 (Tirelli et al 2007), and Diogenes pugilator (Manjón-Cabeza & García-Raso 2000), exhibit an intermediate number of gonopore setae, but these are still far fewer than in P. diogenes. During reproduction, the setae surrounding the gonopore might play an important role as sensors of the female cephalothorax and genital openings in addition to facilitating the transfer of spermatophores to females during copulation (Manjón-Cabeza & García-Raso 2000, Tirelli et al 2007), thereby in creasing transfer efficiency and reproductive success.…”

“…However, some continuous characters, such as spermatophore measurements, should not be used to infer relationships or, as proposed by Scelzo et al (2004), as a criterion to characterize and distinguish species, because the dimensions are strongly associated with the individual size and cannot be used alone in phylo genetic comparisons (Amadio & Mantelatto 2009, Santos & Mantelatto 2011. None theless, proportions between spermatophore regions can indicate shape (such as an ovoid or cylindrical am pulla or an ampulla much bigger than the stalk) and can be used to infer phylogenetic relationships.…”

“…The production of these structures is habitat-related, and in marine species, the spermatophores appear to reduce spermatozoal loss (Subramoniam 1993). In addition, spermato phores provide an energy-rich substrate, allowing for spermatozoal storage over long periods (Subramoniam 1991, Scelzo et al 2004, Mantelatto et al 2009a.…”