Philautus tanu, Meegaskumbura, Madhava, Manamendra-Arachchi, Kelum & Pethiyagoda, Rohan, 2009

Meegaskumbura, Madhava, Manamendra-Arachchi, Kelum & Pethiyagoda, Rohan, 2009, Two new species of shrub frogs (Rhacophoridae: Philautus) from the lowlands of Sri Lanka, Zootaxa 2122, pp. 51-68 : 62-64

Philautus tanu , new species

( Figs. 7–10 )

Material examined. Holotype: mature male, 13.5 mm SVL, WHT6348, Kanneliya Forest Reserve (near Galle), alt. 45 m (6°15'N, 80°20'E), coll. 5 May 1999.

Paratypes: mature males, 13.6 mm SVL, WHT6343; 13.9 mm SVL, WHT6342, Pituwala (Galle), alt. 24 m (6°16'N, 80°12'E), coll. 4 March 1999.

Diagnosis. Philatus tanu is distinguished from all other Sri Lankan congeners by the following combination of characters: small size, mature individuals 13.5–13.9 mm SVL; canthal edges rounded; tympanum distinct; vomerine ridge absent; supratympanic fold absent; a very narrow dermal fold along middorsum, from tip of the snout to vent; venter granular; nuptial pads absent; vocal sac indistinct.

Description. Body stout. Head laterally convex. Snout obtusely pointed in both dorsal and lateral aspect. Canthal edges rounded. Loreal region flat. Interorbital space flat. Internasal space flat. Nostrils oval. Pupil rounded or (horizontally) oval. Tympanum distinct, oval, vertical. Pineal ocellus absent. Vomerine ridge absent. Tongue moderate, emarginate, not bearing a lingual papilla. Supratympanic fold absent. Cephalic ridges absent. Co-ossified skin on head absent. Both upper and lower arms slender. Fingers slender. Relative length of fingers, 1 <2 <4 <3. Tips of fingers with discs bearing circum-marginal grooves. Fingers without lateral dermal fringe. Webbing on fingers absent. Subarticular tubercles on fingers prominent, oval, single (absent on finger IV; n = 2). Prepollex oval. Two palmar tubercles, oval, flat. Supernumerary tubercles present on fingers I–III and on palm. Thigh and shank slender. Toes thin. Relative length of toes 1 <2 <5 <3 <4 or 1 <2 <3 <5 <4 (WHT6343, WHT6342). Tips of toes with discs bearing circum-marginal grooves. Webbing on toes present. Subarticular tubercles on toes prominent, oval, single. Inner metatarsal tubercle distinct, oval. Outer metatarsal tubercle absent. Tarsal fold absent. Supernumerary tubercles present on toes and on foot. Tarsal tubercle absent. Dorsal and lateral parts of head and body shagreened. Both upper and lower parts of flank granular. Dorsolateral dermal fold absent. Dorsal and lateral parts of upper arm, lower arm, thigh, shank and foot smooth. A very narrow dermal fold present on mid dorsum, extending from tip of snout to vent. Ventral parts of throat, chest, abdomen, both upper and lower arms, anterior thigh, shank, and foot granular. Nuptial pad absent. Vocal sacs indistinct. Internal vocal slits present.

Coloration in life. Dorsal parts of head and body pale brown ( Fig. 8 ). A dark-brown stripe about as wide as pupil extends backwards from snout, fading away on mid-flank. About eight dark-brown stripes of varying width on dorsum. Ground color of body creamy-light brown. A narrow creamy-brown stripe extends from snout, over eye to flank. Lower flank pale yellow or white. Inguinal zone white with light brown pigments. Loreal and tympanic regions dark brown. Both upper and lower lips light brown with dark-brown pigments. Dorsal and lateral parts of both upper and lower arms, fingers, thigh, shank, foot and toes pale brown. Ventral parts of head, body, upper and lower arms, fingers, thigh, shank, foot and toes white with scattered brown pigments. Posterior edge of orbit light blue.

Coloration in alchohol (description based on holotype, WHT6348). Dorsal and lateral parts of head and body pale brown. Anterior half of upper flank dark brown, posterior half yellow or white. Lower flank pale yellow or white. Inguinal zone white with light-brown pigments. Loreal and tympanic regions dark brown. Both upper and lower lips white with dark-brown pigments. Dorsal and lateral parts of both upper and lower arms, fingers, thigh, shank, foot and toes pale brown. Ventral parts of head, body, upper and lower arms, fingers, thigh, shank, foot and toes white with scattered brown pigments.

Measurements of holotype (WHT6348, in mm): DBE, 4.6; DFE, 3.1; DL, 0.6; DW, 0.7; ED, 2.3; EN, 1.7; ES, 2.6; FEL, 6.0; FL I, 0.8; FL II, 1.3; FL III, 2.1; FL IV, 1.6; FOL, 8.7; HL, 5.2; HW, 5.2; IML, 0.6; IN, 1.4; IO, 1.6; LAL, 2.2; MBE, 1.6; MFE, 3.1; MN, 4.6; NS, 1.0; PAL, 3.7; SVL, 13.5; TBL, 6.8; TL I, 0.9; TL II, 1.1; TL III, 1.8; TL IV, 2.9; TL V, 1.7; TYD, 0.4; TYE, 0.7; UAW, 1.8; UEW, 1.4.

Etymology. The species name is Sinhala for ‘slender,’ a reference to the habitus of P. tanu ; applied as a noun in apposition.

Remarks. Philautus tanu morphologically resembles P. decoris , P. mittermeieri and P. singu new species, but it can be distinguished from them as follows: no prominent tubercle on the upper eyelid (present in P. singu ); snout obtuse in lateral aspect (pointed in P. mittermeieri ); tarsal tubercle absent (present in both P. mittermeieri and P. d e c o r i s); no lateral dermal fringe or webbing on fingers (present in both P. mittermeieri and P. d e c o r i s); no tarsal fold (present in both P. mittermeieri and P. d e c o r i s).

Distribution. We observed males of P. t a n u sitting on leaves of shrubs, 0.5-1.0 m above ground level, in shrubs adjacent to (10-25 m from) the canopy covered forests. Philautus tanu was recorded from Kanneliya (6°15'N, 80°20'E) and Pituwela (6°16'N, 80°12'E) Forest Reserves, and probably occurs also in other open habitats close to patches of rainforest elsewhere in the wet-zone lowlands of Sri Lanka.

Figures

FIGURE 7. South-western Sri Lanka, showing the distribution of Philautus singu (squares) and P. t a n u (circles), and place-names cited in the text.

FIGURE 8. Philautus tanu (WHT 6342), in life, Beraliya Forest Reserve, Pituwela.

FIGURE 9. Philautus tanu: a, lateral; b, dorsal; and c, ventral aspects, respectively, of head of holotype, male, WHT 6348, 13.5 mm SVL. Scale bar: 1 mm.

FIGURE 10. Philautus tanu: a, ventral aspect of left manus; b, ventral aspect of left pes; and c, semi-diagrammatic representation of the left-pes webbing pattern of the holotype, male, WHT 6348, 13.5 mm SVL. Scale bar: 1 mm.