Microhyla annectens Boulenger, 1900

Ming, Leong Tzi, 2004, Larval Descriptions Of Some Poorly Known Tadpoles From Peninsular Malaysia (Amphibia: Anura), Raffles Bulletin of Zoology 52 (2), pp. 609-620 : 610-611

Microhyla annectens Boulenger, 1900

( Fig. 1 , Table 1)

Larval microhabitat. – Presumably, this montane species would breed in temporary to semi-permanent forest pools or puddles, although the larval series was found in a square concrete drainage corner (ca. 80 x 80cm). The water was ca. 30cm deep, with abundant submerged leaf litter, which gave the water a clear brown tinge. There was an abundance of dipteran larvae throughout the water column, and the entire substratum was teeming with tubificid worms. This artificial breeding habitat was located at the summit of Gunong Batu Brinchang (4 31’N, 101 23’E; 2,032m asl.), Cameron Highlands, just beside the telecommunications tower. At night, the calls of adults were heard from the undergrowth surrounding this pool, but could not be detected. Adults of this species have been sighted previously at this vicinity (Jeet Sukumaran pers. comm.). At the time of discovery, the larvae were found in low numbers and only five specimens were obtained ( ZRC.1.5194-5198; coll. T. M. Leong, 25 Jun.2000). No other anurans were observed in the immediate vicinity, although the resonant and distinctive “poop” calls of Metaphrynella pollicaris (another montane microhylid) were audible in surrounding montane forest .

Larval diagnosis. – A small tadpole (TL not more than 18mm); colour in life reddish brown; mouth anteriorly directed, lower labium not expanded; spiracular flap with crenulate margin; tail without terminal filament. As with all larvae in the genus Microhyla , labial teeth, mandibles are absent from the oral disc.

Larval morphology. – ( Fig. 1 ) Body elliptical, BL 1.44-1.47 of BW, dorsum rather flat, venter rounded, BH 0.73-0.76 of BW; snout rounded, nostril equidistant between eye and snout tip; eyes laterally directed, IOD 4.37-4.42 of IND; spiracle median, spiracular margin crenulated, snout-spiracle 0.71-0.75 of BL; vent median, continuous with ventral fin, opening directed ventrally. Tail gradually tapering towards a narrowly pointed tip, without terminal filament, dorsal fin as deep as ventral fin, TAL 1.58-1.62 of BL, MTH 0.23- 0.26 of TAL.

regenerated forest of the Forest Research Institute of Malaysia (FRIM; 3 14’N, 101 38’E), Kepong, Selangor, in the vicinity of Sungai Kroh (ZRC.1.7192-7432, coll. T. M. Leong & Norsham Yaakob, 18 Feb.2001). Larvae were mostly suspended at midwater level. They were also found together with the larvae of Rana chalconota (ZRC.1.6916-6930) and Bufo parvus (ZRC.1.6931-7191). In yet another locality within FRIM, a large number of larvae (ZRC.1.11161, coll. T. M. Leong, 21 Nov.2003) were collected from a rainflooded pool (ca. eight metres diameter, 80cm deep) along the Engkabang Trail. Adult vouchers of this species (ZRC.1.11170-11174, coll. T. M. Leong et al., 22 Nov.2003) were also collected on the ground, among leaf litter, from around this temporary pool.

Larval diagnosis. – A small tadpole (TL not exceeding 23mm); colour in life yellowish, fins largely clear; mouth facing anterior, lower labium not expanded, with distinct median ‘U’-shaped arch; spiracular flap with smooth, curved margin, not crenulated; tail without terminal filament.

Colour/Markings. – In life, dorsum and flanks reddish brown; venters largely free of pigment; tail muscle and dorsal fin uniform dark gray, ventral fin largely unpigmented, except for posterior end.

Oral Disc. – Mouth directed towards anterior, lower labium not expanded; papillae, labial teeth or jaw sheaths absent.

Developmental changes. – In the metamorph, the characteristic reddish brown colour and dark scapular markings are prominent, but fade upon preservation. The size changes of the small developmental series are presented in Table 1.

Figures

Fig.1. Dorsal aspect of larval Microhyla annectens; depicting (from left to right) early (Stage 31), advanced (Stage 42) and emergent (Stage 46). Note anteriorly directed mouth (lower labium not expanded) and lack of thread-like terminal tail filament.