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Helgoland Marine Research

Open Access

Ultrastructure of paraspermatozoa, euspermatozoa and eusperm-like spermatozoa ofObtortio cf.fulva (Prosobranchia: Cerithiacea)

  • John M. Healy1
Helgoländer Meeresuntersuchungen35:BF01999137

The Erratum to this article has been published in Helgoländer Meeresuntersuchungen 1982 35:BF02289841


The cerithiaceanObtortio cf.fulva produces three distinct types of spermatozoa: (1) paraspermatozoa, (2) euspermatozoa and (3) eusperm-like spermatozoa. Like most mesogastropods, euspermatozoa ofObtortio are composed of a conical acrosome, short posteriorly invaginated nucleus, elongate midpiece and glycogen piece, and short terminal region. The midpiece, however, is distinctly cerithiacean in structure and is composed of four non-helical midpiece elements. Eusperm-like spermatozoa closely resemble euspermatozoa, but have a very short nucleus only one half to one third the length of the euspermatozoon nucleus. Paraspermatozoa of this species are composed of (1) “head” (mosaic sheath of dense blocks enveloping multiple axonemes which attach anteriorly to a long apical structure), (2) “midpiece” (multiple axonemes interspersed with elongate mitochondria), and (3) multiple tail tuft (axonemes each ensheathed by glycogen granules). The possible role of eusperm-like spermatozoa is briefly discussed together with the taxonomic implications of the structure of the three sperm types.