Meristogenys whiteheadi (Boulenger) (Ranidae)

Inger, Robert F. & Stuebing, Robert B., 2009, New Species And New Records Of Bornean Frogs (Amphibia: Anura), Raffles Bulletin of Zoology 57 (2), pp. 527-535 : 533-534

Meristogenys whiteheadi (Boulenger) (Ranidae)

Remarks. – Large samples of Meristogenys frogs and tadpoles were collected at Bukit Kana, Bintulu Division, Sarawak. These frogs are relatively large for species of Meristogenys . Males measure 48.8–57.4 mm SVL (mean ± SE = 54.07 ± 0.39, n = 32); females measure 77.2–79.7 mm (n = 3) (FMNH 272607–41). The rear of the thigh in these frogs is brown with large, irregular areas of lighter color (yellow in life?). The ventral surface of the calf is dusted with scattered melanophores. All but two have round black spots on the back, usually covering most of the surface. The sides of the body are much lighter than the back and are heavily spotted in most individuals. The throat is densely dusted. Only one type of Meristogenys tadpole was collected at Bukit Kana (FMNH 272642–78, Gosner stages 25–40). The labial tooth formula of the upper lip is 7(4-7) (n = 22), that of the lower lip 6(1) (n = 2), 7(1) (n = 15), or 8(1) (n = 4). The upper jaw sheath is divided with 8–16 ribs in each half. The lower jaw sheath is single with 14–23 ribs. There are 0–5 glands in the ventral fin (median = 2). Two tadpoles of this sample differ from three adults in only three sites of a 442 bp fragment of 12S, verifying association of these larvae with the adult species.

Four species of Meristogenys have been described from Sarawak, one from the southwestern corner of the state and three from central Sarawak. Meristogenys jerboa ( Günther, 1872) from southwestern Sarawak (type locality Matang 1°36'N 110°20'E, Kuching Division) is relatively small. Males are 32–41 mm SVL (mean 35.50 ± 0.25, n = 48), and females 61–68 mm (mean 63.66 ± 0.77, n = 9). The rear of the thigh is brown with irregular large and small light spots. The sides are darker brown than the back. The light median strip of the ventral surface of the calf is immaculate white or, less often, with a few scattered melanophores. The tympanum of the male is distinctly enlarged compared to that of the female. The tadpoles of this species have both jaw sheaths divided, three divided rows of labial teeth on the upper lip and six (rarely five) undivided rows of labial teeth on the lower lip (Inger, unpublished data).

Meristogenys macrophthalmus ( Matsui, 1986) (type locality Sg Pesu, 3°07'N 113°48'E) from the Bintulu Division is small, the unique holotype male measures 36.7 mm. It lacks dark spots on the back. The tympanum is enlarged, TYM/ SVL = 0.114. Larvae have not been assigned to this species, but three were collected at the type locality. These are small ( HBL 5.2–6.7 mm) stage 25 tadpoles having the lower jaw sheath divided, each half with 6 ribs, and denticular formula 6(4–6)/5(1) (Inger, unpublished data) .

Meristogenys poecilus and M. phaeomerus (Inger & Gritis, 1983) were described from the Kapit District (Nanga Tekalit, 1°37'N 113°35'E). Males of M. poecilus , the larger of these two species, measure 34.5–51.0 (mean 44.08), and thus are significantly smaller than the Bukit Kana males (see above). The rear of the thigh in M. poecilus has large light areas on a dark brown background. The area behind the tympanum and above the axilla is dark brown. About 10% of the paratypes have dark spots dorsally. Tadpoles of M. poecilus have both jaw sheaths divided and have only three divided rows of labial teeth on the upper lip and only 4–5 undivided rows on the lower lip (Inger & Gritis, 1983).

Males of M. phaeomerus measure 33.0–43.0 mm (mean 38.25) and have the rear of the thigh brown dusted with fine light spots. The side from behind the tympanum and extending almost to the groin is dark brown. The back is marked with small dark spots. Tadpoles of this species have both jaw sheaths divided and only three undivided rows of labial teeth on the upper lip and five undivided rows on the lower lip (Inger & Gritis, 1983).

The Bukit Kana species differs from all four of the Sarawak species— M. jerboa , macrophthalmus , phaeomerus , and poecilus –– in several ways. Adults are larger than all four of those. The relative size of the tympanum in males of the Bukit Kana form (median 0.079) is smaller than in males of the four Sarawak species (median TYM/SVL 0.096, 0.114, 0.100, 0.099, respectively Larvae of the Bukit Kana species differ from larvae of jerboa , phaeomerus , and poecilus and from the larvae found at the type locality of macrophthalmus in the denticular formula and in the lack of division of the lower jaw sheath.

The Bukit Kana species is most similar in size of adults and larval characters to M. whiteheadi , which is known so far only from Sabah at elevations between 200 and 990 m ASL (unpublished data). Males of M. whiteheadi from Sabah measure 48.7–62.4 mm (mean 53.90, n = 72) and females 77.9–86.5 mm (n = 3). Larvae of M. whiteheadi have the lower jaw sheath single and have four divided rows of labial teeth in the upper lip. Thus in both size of adults and these larval characters there is agreement between the Bukit Kana species and M. whiteheadi . There are several differences, however. Larvae of M. whiteheadi from Sabah usually have five undivided rows of labial teeth in the lower lip, in contrast to six in the Bukit Kana species. Adults of M. whiteheadi in our Sabah samples lack black spots dorsally, though some individuals have an obscure dark mottling.