Pseudophilautus hankeni, Meegaskumbura, Madhava & Manamendra-Arachchi, Kelum, 2011

Meegaskumbura, Madhava & Manamendra-Arachchi, Kelum, 2011, Two new species of shrub frogs (Rhacophoridae: Pseudophilautus) from Sri Lanka, Zootaxa 2747, pp. 1-18 : 13-17

Pseudophilautus hankeni , new species

( Figs. 7–10 )

Material examined. Holotype: mature male, 21.9 mm SVL, WHT6304, Bambarella, Knuckles, alt. 1490 m (7°26’N, 80°46’E), M.M., coll. 23 V 1999.

Paratypes: mature males, 19.0 mm SVL, WHT6310; 19.6 mm SVL, WHT6300; 20.7 mm SVL, WHT6302; 20.0 mm SVL, WHT6298; 21.4 mm SVL, WHT6295; 18.3 mm SVL, WHT6308; Bambarella, Knuckles, alt. 1600 m (7° 25’N, 80° 47’E), coll. 23 V 1999, M.M..

Diagnosis. Philatus hankeni is distinguished from all Sri Lankan congeners by the combination of the following characters: size small, mature individuals 18.3–21.9 mm SVL; tympanum distinct; canthal edges rounded; vomerine ridge absent; outer edge of lower arm and outer edge of foot with a tuberculated dermal fold; throat, chest and belly granular. (For diagnosis from its sister species, P. schmarda , see Remarks, below.)

Description. (based on holotype, WHT6304, and six paratypes, WHT6310, WHT6300, WHT6302, WHT6298, WHT6295, WHT6308). Pseudophilautus hankeni is assigned to the genus Pseudophilautus as they are well nested ( Figs. 1 & 2 ) within the Sri Lankan monophyletic group of frogs ( Meegaskumbura et al. 2002; Bossuyt et al. 2004) and are characterized by terrestrial direct development ( Bossuyt and Dubois 2000). Body stout. Head convex in lateral view. Snout rounded in dorsal view, pointed in lateral view. Canthal edges rounded. Loreal region concave. Interorbital space convex. Internasal space concave. Nostrils oval.

Pupil oval, horizontal. Tympanum distinct, oval, oblique, its outer rim indistinct. Pineal ocellus absent. Vomerine ridge absent. Tongue moderate, emarginate, not bearing a lingual papilla. Supratympanic fold distinct. Cephalic ridges absent. Co-ossified skin on head absent. Upper arm short, lower arm short, strong. Fingers thin. Relative length of fingers, 1 <2 <4 <3. Tips of fingers with discs bearing circum-marginal grooves. Fingers without lateral dermal fringe. Outer edge of 4th finger and outer edge of lower arm with tuberculated dermal fold. Webbing on fingers absent. Subarticular tubercles on fingers prominent, oval, single, some absent IV 2 (penultimate subarticular tubercle). Prepollex oval, distinct. Two palmar tubercles, oval, distinct. Supernumerary tubercles present on palm. Thigh slender. Shank slender. Toes strong. Relative length of toes, 1 <2 <3 <5 <4. Tips of toes with discs, with circum marginal groves. Webbing present on toes (absent on toe I). Subarticular tubercles on toes prominent, oval, single, some absent IV 2. Inner metatarsal tubercle distinct, oval. Tarsal fold present. Outer metatarsal tubercle absent. Outer edge of 5th toe and outer edge of foot with a tuberculated dermal fold. Supernumerary tubercles present on foot. Tarsal tubercle present. Dorsal and lateral parts of head and body and upper part of flank with glandular warts bearing horny spinules. Lower part of flank granular. Dorsolateral fold absent. Dorsal and lateral parts of upper arm, lower arm, thigh, shank and foot with glandular warts with horny spinules. Nuptial pad absent, but pale yellow subdermal glands on inner edge of 1st finger and on prepollex. Throat, chest and belly granular. Underside of thigh and shank smooth. Vocal sacs and internal vocal slits present.

Coloration in life. Dorsal and lateral parts of head brown with symmetrical darker brown patches. Upper areas of eyelids and posterior area of interorbital with distinct black patches. Upper flank grayish brown, lower flank pale yellow-gray. Inguinal zone pale yellow with dark-brown patches. Loreal region brown. Tympanic region and tympanum brown with small darker brown patches. Both upper and lower lips pale brown. Dorsal and lateral parts of limbs brown. Lower arm with 2, thigh with 2, shank with 3 and foot with 4 wide, brown patches. Throat, margins of throat, chest and belly pale yellow or white. Underside of thigh and webbing pale yellow. Fingers and toes dorsally light brown.

Coloration in alcohol (based on holotype, WHT6304). Dorsal and lateral parts of head grayish brown with symmetrical brown patches. Upper areas of eyelids and posterior area of interorbital with distinct black patches. Upper part of flank grayish brown, lower part pale gray. Inguinal zone white with dark-brown patches. Loreal region gray. Tympanic region and tympanum grayish brown. Both upper and lower lips pale gray. Dorsal and lateral parts of limbs gray. Lower arm with 2, thigh with 2, shank with 3 and foot with 4 wide brown patches. Throat, margins of throat, chest and belly pale gray or white. Underside of thigh and webbing pale yellow. Fingers and toes dorsally pale gray.

Measurements of holotype (WHT6304, in mm): DBE, 7.4; DFE, 4.6; DL, 0.8; DW, 1.3; ED, 2.7; EN, 2.2; ES, 3.8; FEL, 9.6; FL I, 1.6; FL II, 2.2; FL III, 4.0; FL IV, 3.0; FOL, 13.1; HL, 8.4; HW, 8.5; IML, 0.9; IN, 2.0; IO, 2.1; LAL, 3.9; MBE, 2.8; MFE, 5.2; MN, 7.3; NS, 1.2; PAL, 6.4; SVL, 21.9; TBL, 10.1; TL I, 1.6; TL II, 2.0; TL III, 3.2; TL IV, 4.8; TL V, 3.3; TYD, 0.6; TYE, 1.1; UAW, 4.2; UEW, 1.8.

Etymology. The species name honors the developmental biologist, director of the Museum of Comparative Zoology (Harvard University, USA), and Alexander Agassiz Professor of Zoology, James Hanken. It is Latinized as a noun in the genitive singular case.

Remarks. Pseudophilautus hankeni resembles P. schmarda morphologically, but it can be distinguished from the latter species as follows: canthal edges rounded (vs. sharp in P. schmarda ); toes with (vs. without) a lateral dermal fringe; rudimentary webbing present (vs. absent) on toes; and presence (vs. absence) of a subdermal nuptial pad.

Distribution. Pseudophilautus hankeni shows a very restricted distribution, being known hitherto only from its type locality at Bambarella and Riverston regions in Knuckles. The species seems to be restricted to the highest elevations of the Knuckles mountains (peaks over 1200 m elevation). It was observed on the leaves of shrubs (0.3– 1.0 m above ground) under the cover of the montane cloud forest canopy. Given its restricted, high-elevation habitat, it may be at risk from climate warming, further encroachments into the forest from lower elevations, and agrochemical usage in nearby tea plantations.

Figures

FIGURE 1. PC 1 vs. PC 2 factor scores of the principal components analysis of Pseudophilautus schneideri, n. sp. and P. folicola, show these species to separate well from each other in PC space. Most of the variation is explained by the PC 1 axis, which relates mainly to body size (P. schneideri being smaller). The PC 2 axis is mostly explained by nostril-to-snout length and length of finger 3; here, P. schneideri overlaps completely with P. folicola.

FIGURE 2. PC 1 vs. PC 2 factor scores of the principal components analysis of Pseudophilautus hankeni, n. sp. and P. schmarda, show these species to separate fairly well from each other in PC space. Most of the variation is explained by the PC 1 axis, which relates mainly to body size (P. hankeni being smaller). The PC 2 axis is mostly explained by NS, MBE and MFE (NS loads positively, and the other two negatively); here, P. hankeni overlaps completely with P. schmarda.

FIGURE 7. Distribution of Pseudophilautus schneideri, n. sp. (circles) and Pseudophilautus hankeni, n. sp., (squares), in Sri Lanka.

FIGURE 8. Pseudophilautus hankeni (WHT 6295), in life, Bambarella.

FIGURE 9. Pseudophilautus hankeni n. sp.: a, lateral; b, dorsal; and c, ventral aspects, respectively, of head of holotype, male, WHT 6304, 21.9 mm SVL. Scale bar: 1 mm.

FIGURE 10. Pseudophilautus hankeni n. sp.: 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 6304, 21.9 mm SVL. Scale bar: 1 mm.