The ultrastructure of the spermatozoa of the lizard Micrablepharus maximiliani (Squamata, Gymnophthalmidae), with considerations on the use of sperm ultrastructure characters in phylogenetic reconstruction

We describe, for the first time, the ultrastructure of the spermatozoa of a member of the family Gymnophthalmidae. Mature spermatozoa of Micrablepharu s maximiliani are characterized by: acrosome circular in transverse section , absence of perforatorial base plate, perforatorial tip pointed, absence o f epinuclear lucent zone, midpiece short, mitochondria in transverse sectio n forming a circlet interrupted by dense bodies, trapezoid mitochondria, de nse bodies solid and arranged in regular rings and linear series, linear mi tochondrial cristae, rounded nuclear shoulders, elongate nuclear shape, abs ence of endonuclear canal, fibers 3 and 8 enlarged, absence of multilaminar membranes, and fibrous sheath in midpiece. Phylogenetic analysis of the Sq uamata after the addition of the Gymnophthalmidae to the ultrastructure dat a set previously published by Jamieson, resulted in 8733 equally parsimonio us trees that conflicted with phylogenetic hypotheses derived from morpholo gical data sets. An analysis of tree-length distribution skewness, however, indicated that the ultrastructure data set contains significant phylogenet ic information. We suggest that rates of evolution for spermatozoa ultrastr ucture characters might be higher than currently thought, resulting in inco ngruent tree topologies derived from distinct data sets. Finally, we sugges t that because only optimal trees were selected, the heterogeneity between the data sets might be apparent and more analyses are necessary to evaluate the nature and degree of the heterogeneity between them.