Jamieson, B.G.M. 1995c. The
ultrastructure of
spermatozoa of the Squamata (Reptilia) with phylogenetic
considerations. In Advances in Spermatozoal Phylogeny and Taxonomy.
Jamieson, B.G.M., Ausio, J. and Justine, J.-L. eds. pp. 359-383.
Mémoires du Muséum national d'Histoire Naturelle, vol.
166, Paris.
Comparative ultrastructure of squamate
families is reviewed, with new data for the South African chamaeleon,
Bradypodion karroicum.
Parsimony analysis is conducted, using Chelonia
as the
outgroup and branch and bound searching. Two major spermatozoal
autapomorphies
for the Squamata are extension of the fibrous sheath into the midpiece
and (not
computed) the paracrystalline subacrosomal cone. Further synapomorphies
defining
the Squamata sensu strictu are a single perforatorium in place of the
two or
three of Sphenodontida and Chelonia; loss of the endonuclear canal;
presence of
sinuous mitochondria (possibly an artefactual parsimony resolution as a
columnar form is intuitively preferred); intermitochondrial location of
dense
bodies (mitochondrial transformations); presence of a well developed
epinuclear
electron lucent region and, equivocally, arrangement of the dense
bodies as
periodic rings. A major inference is polyphyly of the 'Sauria', the
Scincomorpha and the Scincidae. Sphenomorphus group and egemid skinks
show no
close relationship to Eugongylus-group skinks which form the
sister-group of
the pygopodid Lialis. Snakes
are the sister-group of the
Eugongylus+pygopod
clade. Gekkonidae appear to be a relatively plesiomorphic group,
separated by
several families from the Pygopodidae. The Iguania is not a
monophyletic
assemblage, iguanids and Pogona occur
in the same clade but Pogona
appears to
be the sister-taxon of Varanus.
Another iguanian, the chamaeleon
Bradypodion,
has an unresolved relationship with the
gekkonid+snake+pygopodid+Eugongylus-clade. Sphenomorph and egemid
skinks form
an unresolved clade with Chalcides and
lacertids but linkage of
lacertids with
the Teiidae in the Lacertoidea is not upheld. Pending further
investigations of
a larger number of taxa, these results can only be considered heuristic.