SPHENOPHRYNE - American Museum of Natural History

96 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 253
Fig. 51. SEM photographs of tip of third finger of Austrochaperina palmipes AMNH A60178 in
palmar (left) and end-on views. Scale line spans 800 m.
that are low, rounded, and inconspicuous,
sometimes virtually absent, with none deserving
the common appellation ‘‘subarticular
tubercle.’’ This group include scansorial,
litter-dwelling, and burrowing forms. The six
species of Liophryne have subarticular ele-
Fig. 52. Lower surfaces of foot and hand of
Sphenophryne cornuta, AMNH A130546. Scale
bar marked in 1-mm intervals.
vations of a more angular, protruding nature
(fig. 54A–E; similis identical to rhododactyla).
Elevations on the palms and soles are
inconspicuous in all species. The inner metatarsal
elevation is usually elongate and
rounded, and there is no outer metatarsal elevation.
None of the Australopapuan microhylids
possesses a prominent, compressed
outer metatarsal tubercle such as is seen in
some genera of microhylids in all other parts
of the world inhabited by the family. Presumably
the scant development of the tubercle is
related to head-first as opposed to feet-first
burrowing (Menzies and Tyler, 1977).
PHARYNGEAL FOLDS: The presence of one
to (rarely) three smooth, lobate or serrate
transverse folds or ridges across the palate
just anterior to the pharynx is common to
most genera and species of microhylids and
is ‘‘almost diagnostic of the group’’ Parker
(1934: 6). The exceptions that lack folds are
three genera of the Melanobatrachinae (of
Madagascar, Parker, 1934) and four genera of
Cophylinae (also of Madagascar, where two
genera have folds; Parker, 1934). This feature
remains undescribed for three cophyline genera
of Madagascar. Given the frequency of
lack of folds in microhylids of Madagascar,
it is curious that the only literature reference
to lack of folds in a species of microhylid