Hylarana flavescens ( Jerdon, 1853 )

Raj, Prudhvi, Vasudevan, Karthikeyan, Dutta, Sushil Kumar, Sahoo, Gunanidhi, Mahapatra, Susmita & Sharma, Richa, 2023, Larval morphology of selected anuran species from India, Alytes 39 - 40, pp. 1-140 : 86-90

S21. Hylarana flavescens ( Jerdon, 1853) ( fig. 43‒44 )

Larval series examined. WT 073 and WT 158.2109 ( Meppada , Sulthan bathery, Kerala, India; 11.70350 N, 76.40364). Tadpoles of the species were collected in side streams with little or no water current. The substratum of the stream was rocky with a high proportion of gravel .

Notes. A partial sequence of 16S rRNA (OQ079497) generated from the tadpole voucher WT 073 showed a 1 % sequence divergence compared to the published Genbank sequence (M 068930) from a taxonomically identified specimen of Indosylvirana flavescens . Morphological descriptions of tadpoles of Indosylvirana temporalis were made by and Inger et al. (1984, 1985) and Hiragond & Saidapur (1999). However, currently, it is difficult to ascertain the taxonomic identity of these descriptions given the recent systematic work on this group by Biju et al. (2014).

External morphology. Description of a tadpole at Gosner stage 35. Body ovoid and globular in dorsal and lateral perspectives ( fig. 43a‒b ). Body length 32.6 % of total length; maximum body diameter at the centre of abdomen. Snout rounded in dorsal and lateral perspectives. Eyes large, located and oriented dorsolaterally; distance between eye and nostril 41.6 % of distance between eye and snout. Nostril opening elliptical, closer to eye than to snout, placed wide apart and parallel to eye in dorsal view; inter-narial distance 67 % of inter-orbital distance; distance between nostril and snout 17.9 % of body length. Spiracle sinistral and short; inner wall of tube completely formed but attached to body wall; tube oriented posterolateral; its opening located above the middle of the lateral side of venter. Distance between spiracle and snout 64.1 % of body length. Opening of vent tube dextral with a broad aperture; origin of right wall anterior to origin of left wall. Tail tip acute and pointed; musculature linear on first third length of tail, tapering beyond. Dorsal fin originating at junction between body tail, ventral fin originating at ventral terminus; dorsal fin wider than ventral fin; maximum height of caudal fin at mid-length. Height of tail muscle 1.18 times width of tail muscle at body-tail junction. Tail (caudal) musculature accounting for 53 % of height of tail. Lateral line visible. Numerous glands present on body; pair of large glands present near each eye (a smaller anterior gland and a larger posterior gland); few tiny glands present laterally extending till vent; ventrally, pair of glands present immediately behind lateral commissures of oral disc, and a pair of glands located at posterior end of the body before the vent.

Oral disc anteroventral in location ( fig. 43c ). Rostral width of oral disc 38 % of maximum body width, emarginated, not visible dorsally; single row of marginal papillae on both labia, with an anterior gap on upper labium; three to four submarginal papillae at lateral commissures and few submarginal papillae below P3 labial tooth row; both labia of equal size. Labial tooth row formula A2(2)/P3(1). Order of lengths of labial tooth rows A1> P1> P2> P3> A2. Jaw sheaths well developed and thinly keratinized. Jaw sheath margins uniformly serrated with tiny serrations; supra-rostrodont wide and convex, with extended and thin lateral process; infra-rostrodont Vshaped, convex laterally and concave medially.

Measurements of 17 tadpoles at various Gosner stages (27, 31‒35) are given in tab. 20 .

Coloration. In life, dorsal body and flanks dirty yellow; integument olive diffused with tiny melanophores randomly; flanks darker than dorsum. Ventral integument translucent and dirty white with gut coils visible; gular and breast regions spotted with numerous tiny melanophores. Caudal fin musculature spotted black for most part except tail region which is diffused. Both fins banded. Spiracle, oral disc and vent tube dotted with few melanophores.

Buccopharyngeal morphology. Buccal roof ( fig. 44a‒b ). Prenarial arena of roof with a flat pustulose ridge that branches medially towards posterior; pustules present along ridge on both sides and two to three medially. Internal nares transverse, oriented medially; gap between nares narrow; about less than half the length of nare; anterior narial wall pustulose with a papilla at lateral corner having rugose surface; posterior wall smooth, valvular and raised. Postnarial arena with a broad papilla immediately behind posterior narial wall oriented medially; surface of papilla rugose with many tiny pustules; two to three pustules present in front of median ridge papilla. Median ridge papilla triangular flap with a pustulated tip. Lateral ridge papillae absent. BRA demarcated with six pairs of stubby papillae present along lateral border of roof; about 60 tiny pustules spread across entire BRA. Glandular zone thick and prominent, with anterior margin as an elevated ridge; secretory pits sparse on lateral sides and abundant medially. Dorsal velum margin smooth and continuous; with few tiny projections medially.

Buccal floor ( fig. 44c‒d ). Prelingual arena composed of a large dilated palp located at posterolateral corner on each side of jaw sheath; palps dilated and oriented anteromedially with concavity and a rugose margin. Tongue anlage broad and raised; a pair of long conical lingual papillae located medially. BFA well defined; five pairs of long conical BFA papillae delineate BFA; BFA with 20 pustules. Region between tongue anlage and buccal pockets free of pustules. Buccal pockets opening narrow and transverse, oriented anteromedially; pocket papillae absent. region between BFA and margin of ventral velum broad and smooth. Ventral velum wide and sinuate; ventral velum margin consisting 10 projections; outer two projections on each side spaced wide apart with rest concentrated around the centre; median notch absent. Glottis exposed immediately behind ventral velum.

Denticles ( fig. 44e ) moderately spaced and strongly curved towards mouth at apex. Oral angle obtuse with tip of head slightly curved. Sheath and body of equal width and with a slight concavity and an aboral surface; head broad with eight long and moderately curved cusps.

Each serration ( fig. 44f ) on jaw sheath with a wide base and long pointed head.

Figures

Figure 43. Hylarana flavescens, Gosner stage 31. External morphology: (a) Lateral view, (b) Dorsal view, (c) Ventral view. Scale = 10 mm.

Figure 44. Hylarana flavescens, Gosner stage 35. Buccopharyngeal and denticles: (a) Buccal roof, Scanning Electron Microscopy photograph, scale = 0.2 mm, (b) Buccal roof, Alcian Blue stained photograph, ventral view, scale = 1 mm, (c) Buccal floor, Scanning Electron Microscopy photograph, scale = 0.2 mm, (d) Buccal floor, Alcian Blue stained photograph, ventral view, scale = 1 mm, (e) Individual denticles, scale = 0.01 mm, (f) Jaw sheath serrations = 0.01 mm.