Jamieson, B.G.M., Guinot, D. and Richer de Forges, B. 1994a. Podotreme affinities of Raninoides sp. and Lyreidus brevifrons: evidence from spermatozoal ultrastructure (Crustacea: Brachyura: Raninoidea). Marine Biology 120, 239-249.

Spermatozoal synapomorphies which singly or collectively distinguishRaninoidea are: (1) the presence of single (Ranina, Raninoides) or   multiple (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   differentiation 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 corrugations)   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 subacrosomal 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), considered 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 posterior (Ranina) or multiple enclaves,   plesiomorphically (?) absent in Lyreidus. Similarities of Lyreidus with   other podotremes include the capitate perforatorium, questionably related   to the radiate spiked-wheel structure of homolids in which acrosome   proportions are similar or less closely to the bilateral capitate   perforatorium of dromiids and dynomenids, and basal capsular projections   as in the dromiid Stimdromia (=Petamolera) lateralis and in   cyclodorippoids. No spermatozoal synapomorphies support a sister-group   relationship of raninoids and heterotreme-thoracotreme crabs.