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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

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