Richer de Forges, B., Jamieson, B.G.M., Guinot, D. and Tudge, C.C.
1997g. Ultrastructure of the spermatozoa of Hymenosomatidae (Crustacea:
Brachyura) and the relationships of the family. Marine Biology
130, 233-242.
The spermatozoa of the genus Odiomaris Ng
and Richer de Forges, 1996 (=Amarinus
Lucas, 1980) have the components
typical
of eubrachyuran (Heterotremata + Thoracotremata) sperm, but differ
significantly
from all other investigated eubrachyurans in at least ten
characteristics: (1)
presence of an epiopercular dome; (2) separation of all but the central
region
of the operculum from the remainder of the acrosome by an
infra-opercular rim;
(3) the fact that the acrosome is smaller in volume than the nucleus;
(4) the
acrosome is strongly emergent from the nucleus, being surrounded only
basally
by nuclear material; (5) the cytoplasmic sheath, ending anteriorly with
the
nucleus, is also basal; (6) division of the acrosome contents into an
inner and
outer acrosome zone is scarcely apparent in longitudinal section as the
inner
zone is narrow and of doubtful homology; (7) the thin, putative inner
acrosome
zone is anteriorly almost septate owing to several longitudinal
corrugations;
(8) basally there is a unique "fringe zone"; (9) the acrosome,
including the epinuclear dome, is longer than wide; (10) the unique
helical and
posterolateral disposition of the nuclear arms. From a purely
spermatological
viewpoint, Odiomaris (as
exemplified by O. pilosus and
O. estuarius),
and
provisionally the Hymenosomatidae, are thus excluded from the
Thoracotremata,
in which they were formerly placed, nor are they readily placeable in
the
Heterotremata.