The spermatozoa of Homologenus
sp., Latreillopsis sp., Homolomannia sibogae
and Paromolopsis
boasi confirm characteristics of a distinctive homolid
spermatozoon
previously established for Homola sp., Paromola sp. and
Paromola
petterdi. Homolid features are (1) moderate anteroposterior
depression of the
acrosome (ratio of length: width 0.4-0.6) as in
lyreidine raninids
(0.5), depression being greater in dromiids and
dynomenids (both
0.3); (2) the capitate form of the perforatorium, shared
with dromiids,
dynomenids and lyreidine raninids; (3) the autapomorphic
spiked-wheel form
of the anterior expansion of the perforatorium; (4)
horizontal
zonation of the acrosome is possibly a unique synapomorphy of
homolids with
dromiids and dynomenids, and therefore an autapomorphy of
the
dromioid-homolid assemblage. In dromiids the posterior zone is
proportionately
the larger, while in homolids the anterior zone is the
larger. The
anterior zone is complexly subdivided in dynomenids; (5) the
autapomorphic
presence of numerous radial arranged extensions of the
acrosomal
operculum into the perforatorium; (6) presence of nuclear arms,
a symplesiomorphy
of all investigated crabs, but small or questionably
sometimes absent
in Dromiidae; (7) absence of microtubules from the
nuclear arms, as
in dromiids, raninids, higher heterotremes and
thoracotremes; (8)
transient presence of a posterior median process of the
nucleus. The
process is not seen in dromiids but occurs in anomurans and
lower
heterotremes; (9) apical perforation of the operculum, also seen,
apparently
symplesiomorphically, in dromiids, raninids, and lower
heterotreme
families; (10) absence of an acrosome ray zone, probably
homoplasic with
absence in raninids; (11) location of most of the
cytoplasm,
including tortuous membranes and degenerating mitochondria,
below the
acrosome, also seen in Lyreidus; (12) presence, in at least some
species, of
centrioles, unknown in dromiids and raninids and variable in
occurrence in
heterotremes.