Jamieson, B.G.M., Tudge, C.C. and Scheltinga, D.M.
1993i. The ultrastructure of the spermatozoon of Dromidiopsis
edwardsi Rathbun, 1919 (Crustacea : Brachyura : Dromiidae):
confirmation of a dromiid sperm type. Australian Journal of Zoology
41, 537-548.
The dromiid spermatozoon, as exemplified by
Dromidiopsis edwardsi, Stimdromia (= Petalomera) lateralis
and Dromidia
antillensis, accords with that of the Homolidae and differs
markedly
from
spermatozoa of other crabs (the raninid-heterotreme-thoracotreme
assemblage) in
the discoidal form of the acrosome and the capitate form of the
perforatorium.
Dromiids differ from homolids in the greater depression of the acrosome
and the
form of the head of the perforatorium, thus exhibiting a distinctive
dromiid
sperm type. The head is bilaterally prolonged in D. edwardsi and also
shows
bilateral symmetry, though this is less pronounced in S. lateralis. In
homolids
the head of the perforatorium has the form of a horizontally disposed
spiked
wheel. Centrioles are unknown in dromiid sperm but are present in
homolids.
Nuclear arms in D. edwardsi,
as in homolids, have the form of three
small
radial vertices. Dromiids, homolids, raninids, higher heterotremes and
thoracotremes differ (homoplastically?) from lower heterotremes in
lacking
microtubules in the nuclear arms. Dromiid sperm lack the posterior
median
process of the nucleus seen in homolids, anomurans and lower
heterotremes. The
sperm of D. edwardsi differs
from other investigated dromiid sperm in
the
asymmetrical location of the opercular perforation relative to the
longitudinal
axis of the sperm, and in more complex zonation of the acrosome
vesicle. The
acrosome is deeply embedded in the nucleus in D. edwardsi whereas in S.
lateralis it is superficial on the nucleus. Both have an apical
protuberance of
subopercular material through the opercular perforation, known
elsewhere only
in dynomenid crabs. Sperm structure in the Dromiidae thus differs
significantly
from that in the Eubrachyura.