PEET - Bivalves Project: Bivalve Sperm Ultrastructure

Trainee: John M. Healy, Postdoctoral Researcher, Queensland Museum, American Museum of Natural History, and Field Museum of Natural History, 2004-2008.

Using transmission electron microscopy, sperm morphology is being investigated for a suite of veneroidean taxa for their potential value in phylogenetic analyses. Data on the first representative, from the family Glauconomidae, are complete. Spermatozoa of Glauconome plankta consist of a head (acrosomal complex + nucleus), short midpiece and a flagellum. The acrosomal vesicle is attenuate-conical. The nucleus is rod-shaped and straight, tapering toward the apex. The midpiece consists of a pair of triplet-microtubular centrioles surrounded by four, spherical mitochondria. Comparison of sperm results does not suggest any especially close relationship between Glauconomidae and other members of Veneroidea. Elsewhere within the Heterodonta, no close relationship with the Corbiculoidea, Myoidea, Mactroidea, Tellinoidea or the Crassatelloidea is indicated by sperm morphology. Most promising seems a connection with Arctica (Arcticidae, Arcticoidea), which shows similar acrosomal and nuclear features.  Supporting morphological and molecular evidence for this relationship is inconclusive but suggests further study.

Publications: Healy, J. M., R. Bieler, and P. M. Mikkelsen. 2008. Spermatozoa of the Anomalodesmata (Bivalvia, Mollusca) with special reference to relationships within the group. Acta Zoologica, 88 (appeared online March 2008).

Healy, J. M., P. M. Mikkelsen, and R. Bieler. 2008. Sperm ultrastructure in Hemidonax pictus (Hemidonacidae, Bivalvia, Mollusca): comparison with other heterodonts, especially Cardiidae, Donacidae, and Crassatelloidea. Zoological Journal of the Linnean Society, 153: 325-347.

Healy, J. M., P. M. Mikkelsen, and R. Bieler. 2006. Sperm ultrastructure in Glauconome plankta and its relevance to the affinities of the Glauconomidae (Bivalvia: Heterodonta). Invertebrate Reproduction and Development, 49(1-2): 29-39.