The spermatozoon ofLumbrineris (Scoletoma) impatiens(Claparède, 1868) (Polychaeta, Lumbrineridae)

Abstract

The sperm morphology of the polychaete Lumbrineris (Scoletoma) impatiens (Claparède, 1868) (Polychaeta, Lumbrineridae) of a sub-tidal population from the Gulf of Naples was studied both by transmission electron microscopy (TEM) and highresolution scanning electron microscopy (HRSEM). In particular, the ultrastructural characteristics of mature male cells, the shape and structure of the acrosome, the nucleus and the flagellum were investigated by TEM. HRSEM images show the sperm external morphology and allow to classify the male gamete as an ect-aquasperm, by having a short head, four to five rounded mitochondria and a long tail, and generally associated with free-spawning. The structure of the spermatozoon of L. impatiens strictly recalls that of the male cell of the Lumbrineris sp. collected in New South Wales, Australia, the only one of the genus so far examined. On the other hand, by comparing these findings with those obtained on the external morphology of male gametes of the Lumbrineris sp. from Grappler Inlet, Vancouver Island, it emerges once again that significant variations are present. This confirms the extraordinary variability of polychaetes' reproductive characters even at genus level.

The Current State of Eunicida (Annelida) Systematics and Biodiversity

“…Mature specimens of Lumbrineris latreilli Audouin and Milne Edwards, 1834 have been reported swimming [298]. In the few existing studies [299][300][301], the morphology of the sperm is described as of the ect-aquasperm type (sensu [302]) suggesting broadcast spawning [84]. Osman et al [57] described three maturity stages according to yolk deposition during the oogenesis of Scoletoma funchalensis , the first previtellogenic stage and the other two within the vitellogenic phase.…”