Micrixalus candidus

Micrixalus candidus View in CoL

External morphology. Specimen numbers (BNHS 6827–6830). Based on a single specimen at Stage 26, BNHS6827 ( Table 2 View TABLE 2 ; Fig. 3A View FIGURE 3 ). Tadpole has an overall eel-like appearance. Body elliptic dorsally, longer than wide (BL/BW 2.4). In the lateral view, body depressed (BW/BH 1.3). Eyes moderate in size, ED is 12.1% of BL, positioned dorsally (ED/BW 0.3). Nares oval, dorso-laterally positioned, closer to the eyes than snout. Distance between the nares larger than between eyes (IOD/IND 0.6). Snout nearly rounded in dorsal and lateral view. Spiracle tube single, free from body wall, sinistral, positioned laterally, directed posteriorly, and located closer to the snout than to the tail base. Coiled gut is feebly visible from ventral view as the skin is only semitransparent. In the dorsal view, the body gradually narrows down into tail, with subtle marginalisation. Tail twice as long as the body (TL/BL 2.14). Tail musculature robust, with well-marked myotomes. TMH remains almost intact until the final quarter of the tail length and then tapers sharply. Dorsal fin, initially shallow, originated slightly after the body-tail junction. Ventral fin originated at the body-tail junction, wider than the dorsal fin but eventually evens out to match its size. Vent tube, dextral and directed posteriorly ( Fig. 3A View FIGURE 3 ). Variations among individuals (N = 4, Stage 26–27) are given in Table 2 View TABLE 2 . Oral disc ( Fig. 3B View FIGURE 3 ) horizontally oval, protruding from the antero-ventral region, mid-sized (ODW/BW 0.34). Oral margin with dorsal, lateral, and ventrolateral indentations. Small, pointy marginal papillae and relatively large, blunt submarginal papillae present. Jaw sheaths keratinized with finely serrated and saw-like edge. Labial teeth absent.

Colouration. In life, tadpoles are lustrous, light to dark purple, body has a darker hue than the tail. Lateral and dorsal sides are almost evenly coloured and are devoid of any pigmented patterns ( Figs. 3D,E View FIGURE 3 ). Pupil is black. Ventrally tadpoles are very light purple and the skin is partially opaque. In preservation, colouration fades slightly yet closely resembles its appearance in its live state. The colour on the ventral side becomes paler and more translucent.

Natural history. Tadpoles of M. candidus were observed in a small, slow-flowing stream within a coffee estate, during February and March ( Figs. 3F,G View FIGURE 3 ). Ambient temperature and relative humidity of the site were measured at 26.5°C and 59.7%, respectively. The stream water had a temperature of 20.3°C, pH 5.77, contained 0.03 ppt of total dissolved solids and a water conductivity of 0.05 mS. Overall depth of the stream ranged between 3 and 6 cm and the stream was bounded by ample vegetation mostly composed of ferns. The stream bed was mostly covered in gravel and small rocks, and the tadpoles were found buried beneath rocks or sand closer to the stream banks. The stream was well-shaded with a canopy of about 80% cover. Most tadpoles in advanced stages of development were observed to be solitary, while those in early stages were found in small groups, typically consisting of two or three individuals. Adult and larval forms of Nyctibatrachus shiradi were found in sympatry with this species.