SPERMATOZOAL ULTRASTRUCTURE IN THE SPINY LOBSTER JASUS-NOVAEHOLLANDIAE HOLTHUIS, 1963 (PALINURIDAE, PALINURA, DECAPODA)

The spermatozoal ultrastructure of the spiny lobster Jasus novaehollan diae is most similar to that in other investigated palinurans and, in particular, to the spermatozoa of Parulirus species. Shared characters include the globular nucleus penetrated by the bases of three or more microtubular arms; an anteriorly situated cytoplasmic zone with mitoc hondria and conspicuous lamellar bodies; a complex, four-zoned acrosom al vesicle (however, lacking the crystalline region present in Panulir us) with a homogeneous region; a scroll region; a flocculent region; a nd a region of periacrosomal material that farms finger-like involutio ns into the flocculent region. The related scyllarid slipper lobsters (Scyllarus and Thenus) possess spermatozoa with acrosome morphology si milar to that of Jasus, but the sperm is generally more flattened, num erous radiating acrosome fins are present, and the microtubular arms ( in Scyllarus) are cytoplasmic in origin and not nuclear. Sperm morphol ogy provides preliminary evidence in support of the hypothesis of two independent lines of evolution in the Palinuridae but investigation in to additional taxa within this group is required.