ULTRASTRUCTURE OF SPERMIOGENESIS AND SPERM OF AN UNDESCRIBED SPECIES OF LURIDAE (PLATYHELMINTHES, RHABDOCOELA)

Testis follicles of an undescribed species of Luridae (Dalyellioida) c ontain nurse cells with cytoplasmic processes branching between the sp ermatids. Spermatids elongate to form aflagellate and non-axonemal spe rm containing an elongate nucleus, mitochondria and dense bodies. Up t o 15 peripheral microtubules are longitudinally directed in mature spe rm, but are arranged in a screw-like fashion in elongating spermatids. Non-axonemal sperm have evolved independently in species of several p latyhelminth taxa: Monogenea, Prolecithophora, Dalyellioida, and Caten ulida.