SPHENOPHRYNE - American Museum of Natural History

26 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 253
coming obscure on flank. Dorsal surfaces of
hind legs somewhat warty; a few scattered,
small protuberances on back; ventral surfaces
smooth.
COLOR AND PATTERN: Dorsal surfaces of
preserved specimens range from pale yellowish
tan to dark grayish brown, more often
tending to the darker shades. Usually there is
little dorsal pattern except for a thin, pale,
midvertebral line that is always at least partly
evident. There may be a few dark spots, often
associated with small warts. Lumbar eye
spots are present in a few specimens but are
indistinct. The facial region, including upper
and lower lips, is dusky but rarely dark
enough to produce a face-mask effect. A narrow
area below the canthus rostralis is darkened,
and a similarly situated dark band follows
the postocular fold. Many individuals
have a more or less distinct light line along
the canthus rostralis. The ventral surfaces are
mottled with brown on pale gray, more
densely so on the chin and coarser under the
hind limbs. A dark, triangular area has its
apex just below the vent.
The colors in life are not greatly different
from those of the preserved specimens. A
frog from Myola (field notes) was reddish
brown on all dorsal surfaces with a yellow
vertebral line. The loreal area was dark
brown, almost black, and the chin, chest, and
undersurfaces of hind limbs gray had lighter
gray flecks, palms gray, and soles dark gray.
The abdominal region is similar to the other
ventral surfaces except for being somewhat
translucent. Other individuals as seen in color
photographs had a brown to yellowish
brown dorsal ground color rather than reddish
brown. The iris is golden above the hor-
izontal pupil and dark gray elsewhere except
for a gold spot beneath the pupil.
VARIATION IN SIZE AND PROPORTIONS: The
largest specimen among 37 measured is a female
28.0 mm SVL. Females of 20.0 and
21.9 mm appear to be maturing, and others
21.9 mm or longer (n 12) are adult. The
largest of 18 males measures 23.9 mm. Specimens
18.3 mm and smaller lack vocal slits
and thus presumably are immature, whereas
those 19.7 mm and larger have slits. (See table
2 for statistics on proportions, and table
3 for regression data.)
ILLUSTRATIONS: 3rd finger terminal phalanx,
fig. 71E; premaxilla, fig. 63D; hyoid,
fig. 69B; sacral region, fig. 72D; vomer, fig.
65D; skull, fig. 67C; ear, fig. 60; hand and
foot, fig. 57E.
CALL: The call is a series of short, harsh
chirps uttered at intervals of one to several
minutes (fig. 77E). Based on 20 tape-recorded
calls of six frogs (table 4), calls range
from about 1.4 to 3.4 sec and include 20–37
notes, with each note being 0.03–0.05 sec
long. Notes are pulsed, with 11–13 pulses in
a note and the first two or three pulses more
widely spaced than the remaining ones. The
dominant frequency lies at 2900–3200 Hz.
Note repetition rate ranges from 10.1 to 14.4
notes per sec. The expected positive correlation
with temperature is evident: Calls of
one frog recorded at 16.7C had a mean of
14.3 notes per sec, whereas those of four others
recorded at 12.5–12.9 averaged 10.4–
11.4 notes per sec. The correlation (negative)
of duration with temperature is less close,
and that of notes per call (positive) is even
poorer.
COMPARISONS WITH OTHER SPECIES: Austro-