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.