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

We describe the male reproductive apparatus of the giant hermit crab Petrochirus diogenes, with morphological and biometric analyses of the spermatophore, the gonopore and the ultrastructure of the spermatozoa. Specimens were collected from the southern coast of Sao Paulo, Brazil. Morphological analyses were done using stereoscopic, light, transmission and scanning electron microscopy. The reproductive system of this hermit crab is composed of elongate and lobular testes followed by vasa deferentia that connect to the exterior via gonopores. The gonopores are ovoid and surrounded by setae, and each gonopore is composed of a membranous operculum that forms a depression constituting the gonopore opening. The gonopore constitutes a unique structure among the Diogenidae due to its number of setae. The spermatophores are tripartite, composed of a sperm-containing ampulla, a peduncle and a proximal foot. The spermatozoon has 3 main regions (acrosomal vesicle, nucleus and cytoplasm). The structure of the spermatophore indicates that this species can be considered an exception within Diogenidae with regard to spermatophore morphology and can therefore be used for phylogenetic inferences.

A novel spermatozoan ultrastructure in the shrimp Hippolyte obliquimanus Dana, 1852 (Decapoda: Caridea: Hippolytidae)

The aim of this study was to describe and illustrate the morphology of the spermatozoon of the Western Atlantic shrimp, Hippolyte obliquimanus. Individuals were sampled from Itagua Beach (Ubatuba, southern Brazil). The male reproductive system was dissected and morphological analysis was undertaken using a stereomicroscope, a light microscope, and transmission electron and scanning electron microscopes. When viewed from the nuclear or acrosomal poles, each spermatozoon has many translucent radiating arms (about 20) from a denser cell body, while laterally the cell body and arms resemble a "cnidarian medusa", with all the arms projecting away from the bell-like cell body. This sperm morphology is distinct from the "thumbtack"-shaped spermatozoa observed in the majority of carideans but has similarities to the spermatozoa of Rhynchocinetes spp. The morphology of sperm of several species of the genus Hippolyte resembles the spermatozoon of H. obliquimanus with the presence of posterior nuclear arms, but it is necessary to study other Hippolyte species to place these arms in the context of the genus.