SPHENOPHRYNE - American Museum of Natural History

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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.
2000 ZWEIFEL: PARTITION OF SPHENOPHRYNE 87 Fig. 45. Ventral surfaces of Oxydactyla stenodactyla from Mt. Wilhelm showing variation in amount of dark spotting. ILLUSTRATIONS: Ventral pattern, fig. 45; 3rd finger terminal phalanx, fig. 71A; tip of 3rd finger, fig. 49; premaxilla, fig. 63A; hyoid, fig. 69A; sacral region, fig. 72A; vomer, fig. 65A; skull, fig. 67A; hand and foot, fig. 53A; jaw musculature, figs. 74, 78A. CALL: I have no recording of the call, which Loveridge (1948: 422, citing information from P. J. Darlington) described as ‘‘woodeny croaking.’’ M.M.J. van Balgooy (collector’s notes accompanying RMNH specimens) stated: ‘‘Its sound, a soft chirping ‘krrr, krrr’ not unlike that of a cricket, can be heard all day.’’ Hobart M. Van Deusen, who collected this species on Mt. Wilhelm on the Sixth Archbold Expedition, wrote in the field catalog: ‘‘Call note a single short ‘enh,’ rapidly repeated (40 or 50 in 30 seconds).’’ COMPARISONS WITH OTHER SPECIES: Only O. alpestris could be confused with this species (see Diagnosis). HABITAT AND HABITS: The principal habitat of this species is alpine grassland, although the elevations at which some specimens were taken suggest that it may also occur in subalpine forests. Brass (1964) described in de- tail the cold, wet habitat at the type locality. Wade and McVean (1969: 31) stated that these frogs form ‘‘an extensive network of burrows in the tussock grassland.’’ Notes by R. Rice accompanying a BPBM specimen stated: ‘‘Very sluggish species. Sit in shallow holes in soil and duff of tussocks and clumps of vegetation.’’ In notes accompanying RMNH specimens, M.M.J. van Balgooy characterized stenodactyla as ‘‘a very common species in the alpine region where it hides away in hollows in the soil, under shrubs and grass-tussocks from 3300–4000 m.’’ P. J. Darlington found one, together with 14 eggs, in moss under a tussock (Loveridge, 1948). The foregoing notes all refer to Mt. Wilhelm. DISTRIBUTION: This species is known from elevations of 2490 to 4000 m in the central highlands of Papua New Guinea in Western Highlands, Simbu and Eastern Highlands Provinces (fig. 41). Populations in the four major areas of distribution—the Sepik Wahgi Divide, Mt. Wilhelm, Mt. Otto, and Mt. Kerigomna—probably are disjunct from one an-
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SPHENOPHRYNE - American Museum of Natural History

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