ULTRASTRUCTURE OF THE SPERMATOZOA OF CORYSTES-CASSIVELAUNUS (CORYSTIDAE), PLATEPISTOMA-NANUM (CANCRIDAE) AND CANCER-PAGURUS (CANCRIDAE) SUPPORTS RECOGNITION OF THE CORYSTOIDEA (CRUSTACEA, BRACHYURA, HETEROTREMATA)
Bgm. Jamieson et al., ULTRASTRUCTURE OF THE SPERMATOZOA OF CORYSTES-CASSIVELAUNUS (CORYSTIDAE), PLATEPISTOMA-NANUM (CANCRIDAE) AND CANCER-PAGURUS (CANCRIDAE) SUPPORTS RECOGNITION OF THE CORYSTOIDEA (CRUSTACEA, BRACHYURA, HETEROTREMATA), Helgolander Meeresuntersuchungen, 51(1), 1997, pp. 83-93
A combination of characters, not individually unique, possessed by the
corystid, Corystes cassivelaunus, and the two cancrids, Platepistoma
nanum and Cancer pagurus, defines a corystoid-type of spermatozoon: th
e basally bulbous, anteriorly narrowing perforatorium, the extent of t
his almost to the plasma membrane through a widely perforate operculum
, and the simple inner acrosome zone, lacking an acrosome ray zone. Th
e sperm of the two cancrids are closely similar, that of the corystid
differing, for instance, in the less pointed, and less tapered, form o
f the perforatorium. This relative uniformity of spermatozoal ultrastr
ucture in the cancrid+corystid assemblage so far investigated supports
inclusion of the two families in the superfamily Corystoidea by Guino
t (1978). The combination of perforation of the operculum and absence
of an acrosome ray zone (at least in a clearly recognizable form) are
features of the Potamidae which possibly indicate that the latter fami
ly, modified for a freshwater existence, is related to the cancrid+cor
ystid assemblage. Some elongation of the centrioles, apparent at least
in Corystes, may be a further link with potamids in which they are gr
eatly elongated. The coenospermial spermatophores of cancridoids are a
notable difference from the cleistospermia of potamids; but the latte
r is probably an apomorphic modification for fertilization biology.