Rana chalconota (Inger, 1985)

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 : 534

Rana chalconota group (Family Ranidae )

Remarks. – It has recently been determined that there are two species of this group in Borneo, Rana raniceps (Peters) and Rana megalonesa Inger, Stuart & Iskandar (2009) . The former species has been found so far only in swampy and low-lying coastal areas of Sarawak whereas R. megalonesa has been collected over a wide area of western and northern Borneo ( Sarawak and Sabah) ( Inger et al., 2009). Both species have been collected at four localities in the Bintulu Division of Sarawak. Two of those localities, Bukit Sarang and Sungai Penyilam, are swamp forests. At Bukit Sarang we found both species along the same slowly flowing streams, but R. raniceps more often along non-riparian trails: raniceps 6 non-riparian of 8 total; megalonesa 2 non-riparian of 11 total. At Sungai Penyilam both species were found along the banks of slowly flowing streams. We collected both species at two localities, Sungai Mina and Samarakan that have both flat and hilly terrain. At Samarakan we found R. raniceps in swamps and along streams, but R. megalonesa only along streams. At Samarakan both were found in a single night along a small stream (width 2 m) flowing through secondary forest. The lower reaches of that stream passed through a sedge marsh where the bottom was deep mud. Upstream from that segment, the stream flowed over a rocky bed with moderate gradient. On that night 15 R. raniceps (FMNH 272602–4, 272797–810) were caught in the marshy portion of the stream, but none in the rocky portion, whereas two R. megalonesa (FMNH 272604, 272867) were found in the rocky area and one in the marshy segment (FMNH 272605). At the Sungai Mina site, both species were found along stream banks, but only one (of four) R. megalonesa was found along a small stream (width 2 m) with four (of seven) raniceps . At Bukit Kana, an area of steep topography lying at 200–300 m ASL in the Bintulu Division, we found only R. megalonesa , all on the banks of streams 3–15 m wide.

These observations indicate that, in the region where the two species occur, Rana megalonesa has a wider ecological distribution than R. raniceps , which seems to be restricted to flat, even swampy, habitats.

Tadpoles belonging to the Rana chalconota group were collected at Bukit Kana and at Samarakan. The 16S gene of three tadpoles, two from Bukit Kana and one from Samarakan, differs by 0–9 of 572 bp from two adults of Rana megalonesa but by 60–64 bp plus six single bp gaps out of 576 bp of three adults of Rana raniceps . All five adults were from Samarakan. We assign the tadpoles to R. megalonesa . These tadpoles agree with the description of larval R. chalconota ( Inger, 1985) which, given the localities of the latter, were probably R. megalonesa . The single difference from those earlier described tadpoles is that in the present ones the ventral post-oral glandular patch is divided into two separate round groups ( Fig. 9 ).

Figures

Fig. 9. Ventral view of larval Rana megalonesa showing post-oral patches of glands.