SPHENOPHRYNE - American Museum of Natural History

86 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 253
Fig. 44. Oxydactyla stenodactyla, AMNH
A135272, SVL 26 mm from Mt. Wilhelm (type
locality), Simbu Prov., Papua New Guinea.
mature; a large (SVL 30 mm) specimen from
Mt. Otto contained 23 ova about 3 mm in
diameter.
Variation in the color pattern of this species
has individual, ontogenetic, and geographic
components. Adult frogs from Mt.
Wilhelm are quite variable, but generally
show modifications of the theme described
for the holotype—mottling of two shades of
brown on a paler ground color. At the darkest
extreme, only small, vermiform spots of the
pale ground color may show, or at the other
extreme large areas of the back may be occupied
by pale ground color alone. Dark
mottling may be fine or coarse. Some individuals
have moderately well-developed
lumbar ocelli and a pale postorbital-dorsolateral
streak (fig. 44). The ventral surfaces
range from immaculate to heavily spotted,
with no obvious anterior-posterior differentiation
(fig. 45). Small frogs tend to show a
dark postorbital streak that broadens and extends
along the flank, sharply defined from
the paler and largely unmarked dorsum.
Traces of the dark lateral area persist in some
adults.
In contrast to frogs from Mt. Wilhelm,
most from the summit of Mt. Otto are quite
uniform in dorsal color pattern, being unmarked
light brown (fig. 43). Juveniles, like
those on Mt. Wilhelm, may have a dark postocular
streak that expands to cover the flank,
and this pattern persists faintly in some adult
frogs. Dark or light markings in the flank region
may hint at the contrasting patterns seen
in Mt. Wilhelm frogs, but they rarely approach
this degree of patterning even in the
least developed pattern. Ventral coloration is
variable: A rather uniform brown color with
no macroscopic pattern is the mode, but this
may be broken up by pale splotches of various
sizes, or the venter may be pale with
coarse, irregular dark marks.
The sample of one juvenile and five adult
frogs from the Wahgi Dividing Range presents
a third facies. The dorsal pattern in
these resembles the juvenile pattern at the
other localities. The dorsum from snout to
cloaca is largely unmarked, pale tan, or has
faint, indistinct darkening. Two specimens
show an indistinct pale vertebral hairline, and
all show dark marks in the lumbar region. A
dark streak passes from the tip of the snout
along the canthus rostralis and the edge of
the eyelid, and from there toward the groin,
usually becoming ill defined posteriorly. The
facial region and the area below the streak
posterior to the tympanum are more or less
darkened, almost as dark as the streak in
some instances and almost as pale as the
back in others. The ventral pattern shows the
sort of variation described for the Mt. Wilhelm
frogs. Two adult specimens from Mt.
Kerigomna resemble those from the Sepik-
Wahgi Divide, but differ in having a pale inner
edge to the canthal-dorsolateral streak.
The foregoing descriptions all refer to preserved
specimens. Notes by M.M.J. van Balgooy
on RMNH specimens from Mt. Wilhelm
stated: ‘‘Orange with black markings
darker above than below,’’ and ‘‘dark grey
above with orange markings, below light orange
with grey spots.’’ Color transparencies
of a frog from Mt. Otto (fig. 43) show a deep
gray dorsal color, with markings of a similar
shade on a dull orange ventral background.