PODOTREME AFFINITIES OF RANINOIDES SP AND LYREIDUS BREVIFRONS - EVIDENCE FROM SPERMATOZOAL ULTRASTRUCTURE (CRUSTACEA, BRACHYURA, RANINOIDEA)

Spermatozoal synapomorphies which singly or collectively distinguish R aninoidea are: (1) the presence of single (Ranina, Raninoides) or mult iple (Lyreidus) keel-like projections of the acrosomal capsule; (2) a very large, weakly electron-opaque peripheral acrosomal zone (Ranina, Raninoides) and an homologous large outer zone in Lyreidus; (3) poor d ifferentiation of the operculum from the capsule (autapomorphy); (4) a very well developed, perforate subopercular zone, of variable form; ( 5) presence of unique inward longitudinal projections (septa or corrug ations) in the wall of the subacrosomal chamber (autapomorphy). Shared , presumably synapomorphic characters of Ranina and Raninoides but not of Lyreidus within the Raninidae, are: (1) branching of some of the s ubacrosomal septa (unbranched in Lyreidus); (2) the subspheroidal form of the acrosome in Ranina with a length : width ratio (L:W) of 0.76, and, although slightly more depressed, in Raninoides (L:W 0.73), consi dered apomorphic relative to the more depressed form in Lyreidus (L:W 0.52); (3) single or multiple coiled perforatorial filaments (Ranina, Raninoides) contrasting with a capitate perforatorium with ''amoeboid' ' head in Lyreidus; (4) division of the capsule wall to give one poste rior (Ranina) or multiple enclaves, plesiomorphically (?) absent in Ly reidus. Similarities of Lyreidus with other podotremes include the cap itate perforatorium, questionably related to the radiate spiked-wheel structure of homolids in which acromsome proportions are similar or le ss closely to the bilateral capitate perforatorium of dromiids and dyn omenids, and basal capsular projections as in the dromiid Stimdromia ( = Petamolera) lateralis and in cyclodorippoids. No spermatozoal synapo morphies support a sister-group relationship of raninoids and heterotr eme-thoracotreme crabs.