SPERMATOZOAL ULTRASTRUCTURE IN 4 GENERA OF HOMOLIDAE (CRUSTACEA, DECAPODA) - EXEMPLIFIED BY HOMOLOGENUS SP, LATREILLOPSIS SP, HOMOLOMANNIA-SIBOGAE AND PAROMOLOPSIS-BOASI

The spermatozoa of Homologenus sp., Latreillopsis sp., Homolomannia si bogae and Paromolopsis boasi confirm characteristics of a distinctive homolid spermatozoon previously established for Homola sp., Paromola s p. and Paromola petterdi. Homolid features are (1) moderate anteropost erior depression of the acrosome (ratio of length: width 0.4-0.6) as i n lyreidine raninids (0.5), depression being greater in dromiids and d ynomenids (both 0.3); (2) the capitate form of the perforatorium, shar ed with dromiids, dynomenids and lyreidine raninids; (3) the autapomor phic spiked-wheel form of the anterior expansion of the perforatorium; (4) horizontal zonation of the acrosome is possibly a unique synapomo rphy of homolids with dromiids and dynomenids, and therefore an autapo morphy of the dromioid-homolid assemblage. In dromiids the posterior z one is proportionately the larger, while in homolids the anterior zone is the larger. The anterior zone is complexly subdivided in dynomenid s; (5) the autapomorphic presence of numerous radial arranged extensio ns of the acrosomal operculum into the perforatorium; (6) presence of nuclear arms, a symplesiomorphy of all investigated crabs, but small o r questionably sometimes absent in Dromiidae; (7) absence of microtubu les from the nuclear arms, as in dromiids, raninids, higher heterotrem es and thoracotremes; (8) transient presence of a posterior median pro cess of the nucleus. The process is not seen in dromiids but occurs in anomurans and lower heterotremes; (9) apical perforation of the operc ulum, also seen, apparently symplesiomorphically, in dromiids, raninid s, and lower heterotreme families; (10) absence of an acrosome ray zon e, probably homoplasic with absence in raninids; (11) location of most of the cytoplasm, including tortuous membranes and degenerating mitoc hondria, below the acrosome,also seen in Lyreidus; (12) presence, in a t least some species, of centrioles, unknown in dromiids and raninids and variable in occurrence in heterotremes.