Limnonectes nitidus (Smedley)

Leong, T. M. & Lim, Kelvin K. P., 2003, Herpetofaunal Records From Fraser’S Hill, Peninsular Malaysia, With Larval Descriptions Of Limnonectes Nitidus And Theloderma Asperum (Amphibia: Ranidae And Rhacophoridae), Raffles Bulletin of Zoology 51 (1), pp. 123-136 : 126-127

Limnonectes nitidus (Smedley)

( Figs. 2 , 3)

Distribution. – Endemic to the highlands of Peninsular Malaysia. Fraser’s Hill is the second montane locality where the species has been recorded. Type locality: Peninsular Malaysia; Pahang, Cameron Highlands, Tanah Rata, elevation ca. 1,300m asl.

Microhabitat. – The larvae were found in a flat, water-logged seepage area behind a concrete embankment at edge of montane forest just adjacent to a bend in the road leading towards the Jeriau waterfalls. The elevation at this site was ca. 1,000m asl. The entire seepage area (ca. 5 x 1m) consisted of shallow (ca. 5cm depth) pools with dense leaf litter/humus substrate. Voucher specimens of adult and sub-adult L. nitidus were collected from this same locality (DWNP.A.1186, ZRC.1.9356-9361, Fig. 1 ). Apart from L. nitidus , other anuran larvae encountered at this microhabitat included L. blythii (ZRC.1.9310-9311), Rana luctuosa (ZRC.1.9312-9315) and Rhacophorus prominanus (ZRC.1.9316-9318). The calls of Polypedates leucomystax and a Microhyla (possibly M. annectens ) were also heard in the area.

Diagnosis. – A benthic larva which inhabits the lentic microhabitat of clear, shallow forest pools or puddles. A dorso-lateral pair of symmetrical, black patches at the anterior-most portion of tail muscle (body-tail junction) clearly visible from dorsal perspective. Body lightly speckled with fine pigments, whereas tail randomly interspersed with light dustings and concentrated patches. LTRF 2(2)/3(1); P- 1 divided, each half with lateral extremities arched on both ends, P-2 undivided but arranged in a symmetrical sinusoidal curve, P-3 shortest and assuming a crescent-shaped arch.

Morphology. – ( Fig. 2 ) Body ovoid, snout tip rounded, BW 0.49-0.61 of BL; slightly depressed, BH 0.62-0.74 of BW; maximum width around mid-body; eyes dorsal, directed laterally, not visible from below, IOD 0.40-0.49 of BW, 1.53- 1.93 of oral disc width; nostrils dorsal, open, midway between eye and snout tip; IND 0.35-0.52 of IOD; spiracle sinistral, located on lateral surface, continuous with body wall, spiracular opening directed posterio-dorsally, snout-spiracle 0.40-0.45 of BL; anal tube dextral, continuous with ventral fin. Tail lanceolate; dorsal margin slightly convex, gradually tapering towards a narrow, rounded tip; ventral fin with straight margin, curving only at posterior _ of tail towards tail tip. TAL 1.50-1.99 of BL, MTH 0.21-0.22 of TAL; caudal muscle deeper than both fins for proximal 2/ 3 of tail. Dorsal fin originating a little after body-tail junction, forming a gentle gradient towards mid-tail convex, dorsal fin deeper than ventral at mid-tail only. Lateral line pores observable only in the earlier (Stages 25-27) larvae. No observable sub-dermal glands.

Colour and markings. – (In life) Dorsum and sides light olive, rather translucent. Tail muscle olive, fins translucent.

Body lightly speckled with melanophores, without concentrated blotches. Tail with heterogeneous arrangement of fine specklings and larger blotches. Venters, including anal tube and ventral margin of tail, unpigmented. Ventral fin without pigment for proximal 2/3 to 3/4 of tail length. Two dark patches located dorsally at body-tail junction. Pigmentation on snout tip extending onto anterior labium.

Oral disc morphology. – ( Fig. 3) Mouth ventral, subterminal, width 0.25-0.31 of BW, single row of marginal papillae on anterior labium confined to lateral portions only; lower labium with continuous row of short, conical papillae along margin, with an extra infra-marginal row towards the centre. Jaw sheaths finely serrated, upper jaw sheath with gentle median convexity, both upper and lower jaw sheaths heavily pigmented black. LTRF: 2(2)/3(1); A-1 continuous, A-2 broadly divided by upper jaw sheath, each half confined to lateral portions, 1/5th width of first row. P-1 narrowly divided, with the lateral extremities arched upwards; P-2 undivided, but arranged in the form of a symmetrical, sinusoidal curve; P-3 undivided as well, shortest (less than 1/2 width of second row), and arched to resemble a partial crescent. Individual labial teeth of anterior and posterior labia uniform in shape and length.

Developmental changes. – Although recent metamorphs were not encountered at the microhabitat site, the most advanced larva (Stage 40) already developed well formed hind limbs, which demonstrated diagnostic characters of adult L. nitidus . These include slightly expanded, bulbous toe tips and incompletely webbed hind feet (fourth toe with two phalanges free of webbing). The developmental series was measured and reported in Table 1.

Interspecific comparisons. – In Peninsular Malaysia, there is one species of Limnonectes [ L. tweediei ( Smith, 1935) ], which had been previously considered a junior synonym of L. nitidus , according to Kiew (1974). Both species have subsequently been regarded as valid names each, with the diagnostic larval form of L. tweediei having been recently described (Leong & Yaakob, 2002). The finding of larval L. nitidus , along with determination of its diagnostic characters, reinforces the fact that both are indeed distinct species. The larvae of both species, while sharing basic characters, may be distinguished from each other by consistent differences in their (a) pigmentation patterns, and (b) LTRF. In larval L. tweediei , a distinct single dark patch is present at the body tail junction, whereas in L. nitidus , this marking at the same region consists of two separate patches not meeting in the middle. In L. tweediei , there is a uniform pattern of evenly distributed dark patches along the dorsal margin of its tail muscle, whereas in L. nitidus , such dark patches are randomly arranged throughout the tail. In L. tweediei , the LTRF is 2(2)/ 2(1); whereas in L. nitidus , it is 2(2)/3(1), exhibiting an additional row of labial teeth in the posterior labium.

Figures

Fig. 2. Lateral (a) and dorsal (b) aspects of Stage 40 larval Limnonectes nitidus.

Fig. 1. Adult male Limnonectes nitidus (ZRC.1.9356, SVL 40.7mm).