117
Lee, M.S.Y. and Jamieson, B.G.M. 1992g. The
ultrastructure of the spermatozoa of three species of myobatrachid
frogs (Anura, Amphibia) with phylogenetic considerations. Acta
Zoologica (Stockholm) 73, 213-222.
Comparison of the spermatozoa of three
genera of limnodynastines (Myobatrachidae: Anura) with those of 42
other
species of frogs (in 11 families) previously examined allows the
following
phylogenetic inferences. The bufonoid neobatrachians (corresponding
with the
Arcifera of some classifications) form a monophyletic assemblage which
is
characterized by the possession, unique for the Anura, of a conical
perforatorium; the rod-like perforatorium, which is plesiomorphic for
tetrapods, is absent. Of the taxa investigated, the myobatrachids
appear to be
the sister-group of the remaining bufonoids, here termed eubufonoids
(leptodactylids, rhinodermatids, hylids, and bufonids). The spermatozoa
of the
myobatrachids Limnodynastes, Neobatrachus, and Mixophyes are very
similar to
each other despite extremely varied fertilization biology.
Symplesiomorphies
for the Anura which they exhibit include the conical acrosome with
subacrosomal
material, the elongate, cylindrical nucleus, single flagellum and,
paralleling
this, an undulating membrane which is supported by a longitudinal
element, the
axial (major) fibre, the latter being accompanied in the midpiece by
mitochondria. A myobatrachid synapomorphy appears to be the presence of
a
periaxial sheath enclosing the axial fibre of the flagellum. Forward
extension
of the axial fibre into the centriolar fossa in myobatrachids is seen
elsewhere
only exceptionally (in the bufonid Nectrophynides).
Bufonids, and most
other
eubufonoids including leptodactylids, differ apomoprhically from
Limnodynastes,
and Neobatrachus in location
of the mitochondria at the axonemal end
(and in a
collar) rather than the axial fibre end of the undulating membrane. In
Mixophyes, mitochondria
surround the nuclear-axonemal junction in a
cytoplasmic
droplet and are probably shed with this at maturity.