Comparative morphology of spermatozoa from five marsupial families.

The spermatozoa of 18 marsupial species derived from five families have been examined and of these only the spermatozoon of the bandicoot Perameles nasuta has previously been described adequately. The spermatozoon morphology within the families Macropodidae, Dasyuridae, Phascolarctidae, and Peramelidae was relatively homogeneous. A distinctive morphology occured between these families. Within the family Phalangeridae spermatozoa were morphologically diverse, however, as a group they were relatively separate from those of the other families studied. The spermatozoa of the Phascolarctidae (koala, Phascolarctos cinereus, and wombat, Phascolomis mitchelli) have a unique, somewhat rat-like morphology which clearly separates them from those of the other marsupial sperm studied. This finding is of considerable taxonomic interest as most authorities consider the koala to be more closely related to the phalangerid marsupials than to the wombat.