Leptopelis sp.

Conradie, Werner, Keates, Chad, Verburgt, Luke, Baptista, Ninda L. & Harvey, James, 2023, Contributions to the herpetofauna of the Angolan Okavango- Cuando-Zambezi river drainages. Part 3: Amphibians, Amphibian & Reptile Conservation (e 325) 17 (1), pp. 19-56 : 26

Leptopelis sp.

Unidentified Tree Frog ( Figs. 5–6 ; Map 5 )

Material (34 specimens, 2 tadpole lots): PEM A12801–2, Cuanavale River source lake, -13.08934° 18.89485°, 1,359 m asl; PEM A12882–8, Quembo River source lake, -13.13624° 19.04591°, 1,396 m asl; PEM A12794–5, INBAC: WC-4685 and no number, Cuanavale River source lake, -13.09442° 18.89372°, 1,368 m asl; PEM A12747–51, INBAC: WC-4754 and no number, Cuando River source, -13.00346° 19.12751°, 1,353 m asl; PEM A14118 (tadpoles), Calua River source, 6 km SE of Cuito River source, -12.73675° 18.39310°, 1,446 m asl; PEM A13845–6, PEM A14123 (tadpoles), Cuiva River source, -12.66825° 18.35282°, 1,407 m asl; PEM A12786, Cuando River source, trap 4, -13.00164° 19.12960°, 1,361 m asl; PEM A12819– 21, Cuiva River source, -12.66856° 18.35307°, 1,433 m asl; PEM A14775, INBAC: WC-6852, Quembo River bridge camp, -13.52746° 19.28060°, 1,241 m asl; PEM A14767–74, Quembo River right side tributary (Micongo River) past village, -13.51877° 19.28487°, 1,248 m asl. Additional material (3 specimens): P2- 277, wetland near old quarry east of Quemba, -12.16960° 18.22965°, 1,353 m asl; SAIAB 209098 (2 specimens), Quembo River source lake, -13.14025° 19.04822°, 1,365 m asl. Description: Small terrestrial tree frog; large protruding eyes; tympanum clearly visible; well-developed rounded inner metatarsal tubercle; reduced webbing; digit tips slightly dilated (slightly wider than finger), finger tips more dilated than toe tips. Dorsum tan-brown; dark brown interorbital bar often present; dark brown vertebral stripe from just behind head to vent; some individuals with extra paravertebral bands; dark brown facial mask extending past arm onto side of body; scattered white speckles; groin with scattered unpigmented skin, extending onto the limbs; throat darkly pigmented; ventrum immaculate. Males with weakly developed pectoral glands and darkened throats. Adult females (n = 2) varied from 36.6–40.7 (38.7) mm (largest female: PEM A12786); adult males (n = 35) varied from 29.0–34.6 (31.1) mm (largest male: PEM A12883). Elongated brown tadpoles; 40.7–52.2 mm total length, with tail 3.2 times body length; strong tail muscle starting just behind eye; thin fin margin above and below; LTRF 2(1)/3(1); jaw sheaths heavily keratinized, anterior part free of elongated marginal papillae. Habitat and natural history notes: Males were found calling in trees and shrubs (0.5–3 m above the ground), which were often located far from water, in grasslands with sparse tree cover. As the rainy season progressed, calls were heard progressively closer to water bodies, until eventually being heard among vegetation in the wetlands. The call resembles a chuckle. The eel-like tadpoles were found in wetlands among dense aquatic vegetation. Comments: Unusual light pink/red eel-like tadpoles were initially found in wetlands at the source of two different river systems, the Cuito and Kwanza rivers, in February 2016. A small number of these tadpoles were raised to adults in captivity. Nearly seven months were required to reach metamorphosis, during which time they changed from light pink/red to a more brownish coloration. They seemed to be sensitive to light as they swam eratically when removed from a dark environment and exposed to bright light. During the start of the rainy season in October 2016, unusual calls were heard which could not be assigned to a known species. After triangulation, several individuals were found calling from trees or shrubs, which were often far from water. On closer inspection, these specimens were found to be morphologically identical to the ones raised in captivity. We subsequently found these frogs at all major river sources and along rivers. Barcode analysis (16S rRNA) recovered the unknown Leptopelis as similar to L. ocellatus (94% similarity; KY080253), but the latter is a forest species with well-developed discs on toes. Schmidt and Inger (1959) described Leptopelis parvus from the Democratic Republic of the Congo ( DRC), which resembles our Leptopelis sp. because of its small size and the shared absence of a white stripe above the vent that stretches onto the legs. However, our specimens differ from L. parvus in dorsal coloration pattern (para- and vertebral stripe present versus absent in L. parvus ), lack of discs (dilated toe tips, but no clear discs versus clear discs in L. parvus ), and pectoral glands (present versus absent in L. parvus ). Further phylogenetic and morphological work is needed to resolve the taxonomic status of this species.

Figures

Map 5. Distribution of Leptopelis sp. in Angola.

Fig. 5.Adult male Leptopelis sp. from Cuanavale River source. Photo by Luke Verburgt.

Fig. 6. Tadpole of Leptopelis sp. from Cuiva River source. Photo by Werner Conradie.