SPHENOPHRYNE - American Museum of Natural History
SPHENOPHRYNE - American Museum of Natural History
SPHENOPHRYNE - American Museum of Natural History
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2000 ZWEIFEL: PARTITION OF <strong>SPHENOPHRYNE</strong><br />
47<br />
many body proportions falling in the midrange<br />
for the genus as a whole. Head average<br />
in width (HW/SVL, 0.38), narrower than<br />
body. Snout obtusely pointed in dorsal view,<br />
similar and projecting in pr<strong>of</strong>ile; loreal region<br />
sloping, very shallowly concave, canthus<br />
rostralis verging on angular, but not<br />
sharply defined; nostrils lateral, barely visible<br />
from above, appearing close to end <strong>of</strong><br />
snout in pr<strong>of</strong>ile. Eyes large, visible from beneath,<br />
EY/SVL about 0.13, rarely equaled<br />
and not exceeded in any other Austrochaperina;<br />
eyelid slightly narrower than interorbital<br />
space. Tympanum present but no external<br />
sign <strong>of</strong> it or its annulus. Relative lengths<br />
<strong>of</strong> fingers 3 4 2 1, first well developed,<br />
each with a prominent disc bearing a<br />
terminal groove; disc on third finger about<br />
2.5 width <strong>of</strong> penultimate phalanx, typically<br />
slightly narrower than disc on fourth toe but<br />
occasionally equal or a little broader. Relative<br />
lengths <strong>of</strong> toes 4 3 5 2 1, all<br />
with well-developed discs, largest <strong>of</strong> any<br />
Austrochaperina, disc on fourth toe about<br />
twice width <strong>of</strong> penultimate phalanges; toes<br />
webbed to base <strong>of</strong> disc <strong>of</strong> fifth toe and about<br />
to proximal subarticular elevation on both<br />
sides <strong>of</strong> fourth toe. Fingers and toes with<br />
low, rounded subarticular elevations; a low,<br />
elongate inner metacarpal elevation flanked<br />
by a broader, round middle-outer elevation;<br />
a low, elongate inner metatarsal elevation but<br />
no outer. A narrow, straight, postorbital fold<br />
passing diagonally from eye to forearm insertion.<br />
Dorsal body surface generally<br />
smooth, without conspicuous folds, but with<br />
a tendency to develop an elevated network<br />
<strong>of</strong> low ridges; ventral surfaces smooth. Males<br />
lack vocal sac openings.<br />
There are no maxillary or premaxillary<br />
teeth. Near its medial end each vomer typically<br />
possesses a bony spike (fig. 65O) projecting<br />
from the ro<strong>of</strong> <strong>of</strong> the mouth. This<br />
structure is not always so spikelike as illustrated.<br />
It may be more broadly buttressed, or<br />
less <strong>of</strong>ten is represented by a mere nubbin<br />
scarcely evident in the preserved specimen.<br />
COLOR AND PATTERN: Color in preservative<br />
is dull gray-brown dorsally with vague darker<br />
markings rarely well enough defined to be<br />
called a pattern. A narrow dark line follows<br />
the lower edge <strong>of</strong> the postorbital fold and<br />
below that a broader pale streak. The dor-<br />
solateral area <strong>of</strong> the body may be somewhat<br />
darker than the middle <strong>of</strong> the back, and the<br />
lateral area is slightly mottled. In some specimens<br />
there is a pattern associated with the<br />
dorsal fold network mentioned above. The<br />
ventral ground color is pale tan, with conspicuous<br />
darker mottling on the throat, a variable<br />
scattering <strong>of</strong> melanophores on the chest<br />
and abdomen, and a dusky shade to the undersides<br />
<strong>of</strong> the hind limbs. Occasional individuals<br />
are dark beneath on all ventral body<br />
surfaces, with coarse light mottling. There is<br />
no conspicuous patterning to the groin or<br />
thighs.<br />
The dorsal color in life is brown or a mixture<br />
<strong>of</strong> brown and green. Menzies (1976, pl.<br />
11c) published a color photo. My field notes<br />
mention ‘‘brown without any distinct pattern<br />
. . . faint light interocular bar. . . . Greenish<br />
brown with obscure darker markings . . . Wshaped<br />
scapular mark. . . . Dark brown with<br />
light green flecks. . . . greenish brown with<br />
. . . darker brown mottling.’’ The undersurfaces<br />
are gray or greenish gray with darker<br />
gray or brown spotting and mottling on the<br />
chin, with this pattern being fainter on or entirely<br />
absent from the chest and abdomen.<br />
There are no flash colors in the groin or on<br />
the thighs. The iris is dark, much the same<br />
as the dorsal ground color, with the horizontally<br />
elliptical pupil narrowly margined with<br />
gold.<br />
VARIATION IN SIZE AND PROPORTIONS:<br />
Adult A. palmipes have sexual dimorphism<br />
in the shape and color <strong>of</strong> the snout. In males<br />
the snout is slightly more projecting and is<br />
pale, almost white, in larger individuals,<br />
whereas females retain a less projecting<br />
snout, with the darker ground color common<br />
to juveniles <strong>of</strong> both sexes. Male palmipes<br />
lack a vocal sac, so my usual criterion <strong>of</strong><br />
male maturity, presence <strong>of</strong> vocal slits, is inapplicable.<br />
Hence, I have used the presence<br />
<strong>of</strong> a distinctly pale snout as indication <strong>of</strong> sexual<br />
maturity in males.<br />
There is geographic variation in maximum<br />
size and size at sexual maturity, with frogs<br />
on Normanby Island attaining a larger size<br />
than those elsewhere. Seven adult females<br />
measure 43 to 49 mm SVL (six <strong>of</strong> them 45<br />
mm or greater), whereas the largest in any<br />
other sample is only 44 mm. Males are<br />
smaller than females in all samples, but again