RELATIONSHIPS OF THE CYCLODORIPPOIDEA ORTMANN - EVIDENCE FROM SPERMATOZOAL ULTRASTRUCTURE IN THE GENERA XEINOSTOMA, TYMOLUS AND CYMONOMUS (CRUSTACEA, DECAPODA)

Citation
Bgm. Jamieson et al., RELATIONSHIPS OF THE CYCLODORIPPOIDEA ORTMANN - EVIDENCE FROM SPERMATOZOAL ULTRASTRUCTURE IN THE GENERA XEINOSTOMA, TYMOLUS AND CYMONOMUS (CRUSTACEA, DECAPODA), INVERTEBRATE REPRODUCTION & DEVELOPMENT, 26(2), 1994, pp. 153-164
Citations number
24
Categorie Soggetti
Reproductive Biology",Zoology
ISSN journal
07924259
Volume
26
Issue
2
Year of publication
1994
Pages
153 - 164
Database
ISI
SICI code
0792-4259(1994)26:2<153:ROTCO->2.0.ZU;2-F
Abstract
The spermatozoa of two genera and species of Cyclodorippidea, Xeinosto ma richeri (Xeinostominae) and Tymolus sp. (Cyclodorippinae), and one species of Cymonomus sp. (Cymonomidae) are found to constitute a disti nctive cyclodorippoid sperm-type characterized by (1) sperm anteropost eriorly depressed, mean ratio of length to width 0.54-0.63; (2) opercu lum extending to the lateral limits of the acrosome (autapomorphy of c yclodorippoids) and centrally perforate or (Cymonomus sp.) thinner; (3 ) contents of acrosome vesicle with two major horizontal zones, as in homolids and dynomenids, including a dense lower (posterior) zone; (4) perforatorium very wide (0.3 width of acrosome), anteriorly rounded, not capitate, lacking radiate projections; (5) acrosomal capsule with external projections over its posterior half; (6) slender dense filame nts extending into the perforatorium from its walls, their bases assoc iated with corrugations of its basal wall; (7) nucleus, cupping the ac rosome and cytoplasm, with well-developed posterior median process; (8 ) nuclear arms lacking microtubules; (9) cytoplasm, a narrow postacros omal band extending anteriorly as far as the operculum, associated wit h a few degenerate mitochondria. The noncapitate form of the perforato rium differs from the capitate condition in dromiids, the related dyno menids, homolids and the raninoid Lyreidus. The cyclodorippoid sperm r esembles homolid and raninoid sperm in possessing a posterior nuclear process (questionably apomorphic) and resembles homolid sperm in the h orizontal zonation of the acrosome with a dense lower zone. Features w hich resemble the sperm of raninoids are: the periacrosomal flange (Xe inostoma richeri) and smaller evaginations of the acrosome membrane (o r capsule?) (X. richeri, less distinctly Cymonomus sp. and Tymolus sp. ) reminiscent of the single acrosomal flange of Ranina and Raninoides sperm and the multiple keels of the Lyreidus sperm; and corrugations o f the wall of the perforatorial chamber, as in raninoids though with s ignificant differences. A dynomenid similarity (homoplasy?) is the dis continuous flange-like peripheral continuation of the lower zone of th e acrosome contents in Cymonomus sp.