Megophrys (Atympanophrys) gigantica

Megophrys (Atympanophrys) gigantica

Figs. 1, 2A, 3A, and 4

Molecular data: 16S sequences were generated from tissue samples of two tadpoles. Uncorrected p -distance between the tadpoles in this study and sequences from M. gigantica specimens collected approximately 390 km to the northwest in the proximity of the type locality; Mount Wuliang, Yunnan Province, China (GenBank accession numbers; MH 406775; MH 406776 & KX 811898) were 0.2 %.

Collection site: The following tadpole description is based on 5 specimens VNMN010898, VNMN010899, VNMN010900, HLNP 20180320 00009 & HLNP 20180320 00010) at Stage 35. Specimens were found actively feeding near the bank in a large pool in a 2 m wide stream in heavily disturbed evergreen forest on Mount Pu Ta Leng, Bat Xat Nature Reserve, Bat Xat District, Lao Cai Province, Vietnam (22.4322°N 103.6297°E, 1912 m asl; Figs. 1 and 2A), collected at 15:00 h on 20 March 2018 by Luan Nguyen, Christopher Portway, Chung Nguyen and Benjamin Tapley.

Morphology: The body is longitudinally oval shaped and dorsally compressed; the nares are oval and are closer to the eyes than to the snout, the rims of the nares are serrated, raised from the body wall and open anterolaterally; the internarial distance is less than the interorbital distance; the eyes are positioned dorsolaterally, the pupils are round; the spiracle is sinistral and the spiracular tube protrudes from nearly two thirds of the way along the body wall just anterior to the maximal trunk width, the spiracular tube opens laterally; the mean tail length is 66.6% (63.2–68.4%, n =5) of the total length; the dorsal tail fin inserts behind the body-tail junction, the dorsal fin is low, particularly at the proximal half of the tail length; the mean basal tail width is 42.1% (37.2–45.1%, n =5) of the maximal trunk width, the tail tip is broadly rounded; the oral disc is subterminal and antero-dorsal, the lateral corners fold medially and turn upward when not fully extended (and in preservative), the mean width of the umbelliform oral disc makes up 92.4% (82.4–96.7%, n =5) of the maximal width of the trunk; in life the maximal BW is 62.6% the maximal width of the fully extended ODW (n =1); the lower lip is triangular with basal lobes when the mouthparts are fully expanded in life, we define this as hastate shaped (Fig. 4B), marginal papillae are absent; six rows of submarginal papillae are present on the upper lip when they are counted medially at the maximal width of the oral disc; these are regularly positioned; those present medially at the maximal width of the oral disc are rounded, but those in the innermost two rows become increasingly oblong shaped towards the edges of the disc; five rows of rounded submarginal papillae are present on the lower lip when they are counted medially at the maximal width of the oral disc; these are regularly positioned, longitudinally oblong shaped on the three inner rows and they become smaller and circular in shape on the outermost row; the lower lip is deeper than the upper lip; labial teeth are absent; the upper jaw sheath is serrated and has a deep medial notch; the lower jaw sheath is serrated and lacks a medial notch. See Table 1 for measurements.

Colour in life: (Fig. 4) Dorsally, the head and body are light brown with pale neuromasts; the area surrounding the nares is dark brown; the oral disc is a translucent tan brown with dark brown submarginal papillae; the dorsal and ventral fins are opaque, pale yellowish brown without speckles; the lower fin is more yellow in colour than the upper fin and also without speckles; the ventral and lateral sides of the body are a translucent dark grey and speckled with white; the underside of the oral disc is speckled with white; the gills and coils of the gut are visible in the ventral view through the transparent ventral skin; the sclera of the eye is black with green-gold flecks; the pupil is black and rounded; the iris is orange and speckled with black dots; the outer margin of the upper jaw sheath is dark brown.

Colour in preservative: (Fig. 3A) Body brown; the gills and coils of the gut are visible in the ventral view through the transparent ventral skin; the oral disc is translucent grey brown with darker brown submarginal papillae; the dorsal and ventral fins are an opaque, pale grey brown; the venter is grey; the iris is dark grey.

Variation: VNMN010899 has a shorter tail than the other M. gigantica specimens collected from the Hoang Lien Range, this is probably due to a historic tail injury and subsequent regeneration (Figs. 3A and 4A). The tadpole of M. gigantica at Stage 34 was described previously by Fei et al. (2009) although it is not clear if species identity was supported with molecular data. The description is broadly congruent with the Stage 35 specimens collected in this study but there are some notable differences.At stage 34 the TTL is reported as 39.0 mm (Fei et al. 2009); this is considerably smaller than the mean TTL of 50.7 mm in this study. Fei et al. (2009) describe the body and tail muscle as having grey patterns (also depicted in the associated line drawing). The specimens we collected in the Hoang Lien Range lacked grey patterns on the body and on the tail muscle.