SPHENOPHRYNE - American Museum of Natural History

2000 ZWEIFEL: PARTITION OF SPHENOPHRYNE
107
Fig. 64. Left premaxillae of Austrochaperina and Sphenophryne in ventral view. Scale lines indicate
1 mm unless otherwise stated. A. A. gracilipes, AMNH A90407 (scale 0.5 mm). B. A. novaebritanniae,
AMNH A88569 (scale 0.5 mm). C. A. blumi, UPNG 9559. D. S. cornuta, AMNH A92804. E. A.
basipalmata, AMNH A129495. F. A. rivularis, AMNH A88445. G. A. palmipes, AMNH A92807. H.
A. derongo, AMNH A145507.
most species examined here, but the degree
is variable. To some extent this variation may
be specific: six specimens of Austrochaperina
derongo all show mineralization, whereas
among four Oxydactyla stenodactyla that can
be scored, three lack mineralization and one
has slight mineralization.
There is conspicuous variation in the anterolateral
and posterolateral processes of the
hyoid plate. The former may be absent (fig.
69C) to very well developed (Zweifel,
1985b: fig. 50E) or some intermediate form
(figs. 69A, B; Zweifel, 1985:, figs. 50A–D).
The posterolateral processes are less variable
(see figures cited).
I direct attention to an anatomical feature
of the microhylid hyoid that has been largely
ignored in the literature. Trewavas (1933:
519) described ‘‘a median ventral thickening
of the cartilage between the origins of the
postero-medial processes, and often a midventral
ridge in front of this’’ in species of
Dyscophinae, Genyophryninae, Microhylinae,
and Scaphiophryninae. She referred to
those species possessing this morphology as
the ‘‘Gastrophryne-group’’ and stated that in
this and some other respects they ‘‘contrast
sharply with other firmisternal families.’’ The
feature was found lacking in Breviceps and
Hemisus. These last two genera have been
variously considered as microhylids or Hemisus
has been referred to its own family.
Most recently, Blommers-Schlösser (1993)
has removed the Brevicipitinae from the Microhylidae
and placed it with the Hemisotinae
in the Hemisotidae.
One worker to take notice of this feature
was Roux (1944, fig. 9), who described and
illustrated a ‘‘ventro-median anteriorly directed
process . . . . between the origins of
the thyroid processes [bony posteromedial
processes of Duellman and Trueb, 1986]’’ of
Gastrophryne carolinensis. DeSáand Trueb
(1991: 316, fig. 2) illustrated the hyoid of a
South American microhyline, Hamptophryne
boliviana, and described this structure as a
‘‘small bony projection.’’ What appears to be
the same process is shown in an illustration