Ultrastructure of the mature spermatozoon of the king crab Lithodes maja (Lithodidae, anomura, decapoda): Further confirmation of a lithodid-pagurid relationship

• Published in: Invertebrate Biology
• Main Authors: Tudge, Christopher C., Jamieson, Barrie G. M., Sandberg, Lennart, Erséus, Christer
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Microscopical Society 1998
• Subjects: Hermit crabs; Phylogeny; Spermatophore; Spermatozoa; 1103 Animal Science and Zoology; Lithodes maja
• Online Access: https://espace.library.uq.edu.au/view/UQ:7982319

Ultrastructure of the spermatophore and spermatozoon of the king crab Lithodes maja is described and illustrated. The spermatophore is a pedunculate structure of which the major components are the sperm-filled ampulla, stalk, pedestal, and a smaller accessory ampulla at the base of the main ampulla. Each spermatozoon features a subspherical, concentrically zoned acrosomal vesicle, capped by a centrally perforate operculum and posteriorly embedded in the cytoplasm, and a large globular nucleus. Three microtubular arms emerge from the cytoplasm below the acrosomal vesicle. The spermatophores and spermatozoa share many features with those of their nearest postulated relatives - members of the Paguridae (the genus Pagurus in particular). Spermatophore characters that link L. maja with pagurids are the presence of the accessory ampulla (synapomorphy, also with the parapagurids) and the homogeneous granular nature of the spermatophore wall. Sperm characters include the simple concentric zonation of the acrosomal vesicle, the shape and differentiation of the operculum (synapomorphic with Paguridae), the electron-dense plume in the base of the acrosomal chamber (synapomorphy with Pagurus), and absence of microvillar projections in this chamber. Several features in which L. maja differs from species in the genus Pagurus include the central perforation in the operculum, the absence of reticulated acrosome zones, and indications of an irregular flange in some planes of the acrosomal vesicle (possible autapomorphy).