Megophrys takensis, Mahony, Stephen, 2011

Mahony, Stephen, 2011, Two new species of Megophrys Kuhl & van Hasselt (Amphibia: Megophryidae), from western Thailand and southern Cambodia, Zootaxa 2734, pp. 23-39 : 30-36

Megophrys takensis sp. nov.

( Figures 3–5 )

Holotype. Adult female (NHM 1972.1519), “ 2500ft, Ban Pa Che, N.W. of Tak [Tak Province], N.W. Thailand ”, collector Malcolm A. Smith.

Paratypes. Immature female (NHM 1972.1516) and three adult males (NHM 1972.1517, NHM 1972.1518, NHM 1972.1520); from the same locality, collector Malcolm A. Smith.

Diagnosis. This species is placed in the genus Megophrys as discussed above through morphological exclusion from Brachytarsophrys and Ophryophryne as defined by Delorme et al. (2006). Megophrys damrei sp. nov. differs from Ophryophryne based on the following characters: presence (vs. absent) of vomerine ridges, HW:SVL 41.5– 42.6% (vs. HW:SVL <25%), pupil vertical (vs. horizontal); from Brachytarsophrys by hind legs slender (vs. very large and fleshy), projection of the snout beyond the jaw present (vs. absent), fold of skin on the back of the skull absent (vs. present), single palpebral projection (vs. 3–5 small tubercles), glandular growth shaped spines absent (vs. present).

Megophrys takensis sp. nov. can be diagnosed from all congeners currently referable to the genus Megophrys by the combination of the following characters; a medium sized species, male SVL 47.4–53 mm, female SVL 72.9 mm; tympanum mostly visible, oval and orientated almost vertically, ~5–10% of the upper portion concealed by the supratympanic ridge; posterior end of supratympanic ridge angles horizontally above the shoulder; palpebral horn absent; vomerine ridges form round elongated stalks with vomerine teeth; tongue oval, not notched posteriorly; finger length formula usually IV≤II<I<III or IV=I<II<III, webbing absent; toes with rudimentary webbing, relative length V≤III; subarticular tubercles and lateroventral grooves absent on all digits; nuptial pads present on fingers I and II of males; asperities may be completely absent on mature females and present on males as a patch at the front and rear of lower mandible, side of snout, along ridges and granules dorsally and on tubercles laterally, also present but sparse on outer surfaces of fore and hind limbs.

Comparisons. Megophrys takensis sp. nov. is here compared to all thirty-three congeners extant in Thailand and the neighbouring Asian countries of Myanmar, Laos, Cambodia and China; M. aceras , M. auralensis , M. binchuanensis Ye & Fei , M. boettgeri , M. damrei sp. nov., M. brachykolos , M. caudoprocta , M. daweimontis , M. gigantica Liu, Hu & Yang , M. glandulosa , M. huangshanensis Fei &Ye , M. jingdongensis , M. kuatunensis , M. lekaguli , M. longipes , M. major , M. mangshanensis Fei &Ye , M. medogensis Fei & Ye , M. minor , M. nankiangensis Liu & Hu , M. nasuta , M. omeimontis , M. pachyproctus , M. palpebralspinosa , M. parva , M. sangzhiensis Jiang, Ye & Fei , M. shapingensis , M. shuichengensis Tian, Gu & Sun , M. spinata Liu & Hu , M. tuberogranulatus Mo, Shen, Li & Wu , M. wawuensis Fei, Jiang & Zheng , M. wuliangshanensis Ye & Fei , M. wushanensis Ye & Fei and M. zhangi Ye & Fei.

Megophrys takensis sp. nov. (characters in parentheses) differs from the following small bodied species with adult female SVL <50 mm (vs. 72.9 mm): M. binchuanensis , M. boettgeri , M. brachykolos , M. daweimontis , M. kuatunensis , M. minor , M. pachyproctus , M. tuberogranulatus , M. wawuensis , M. wuliangshanensis and M. wushanensis ; from the following known only from males of SVL <45 mm (vs. 47.4–53 mm): M. huangshanensis , M. palpebralspinosa and M. zhangi ; from M. caudoprocta and M. sangzhiensis by presence (vs. absence) of a caudal projection above the vent of males; from M. jingdongensis , M. omeimontis , M. spinata and M. shuichengensis by presence (vs. absence) of extensive webbing between the toes; from M. gigantica , M. nankiangensis and M. shapingensis by absence (vs. presence) of a visible tympanum; from M. aceras , M. longipes and M. nasuta by the presence (vs. absence) of a palpebral horn; from M. auralensis by absence (vs. presence) of vomerine teeth; from M. glandulosa and M. major by larger adult size, male SVL 76.3–81 mm, female SVL 76.5–99.1 mm, and male SVL 65.5–75 mm, females SVL 81.5–93 mm respectively (vs. male SVL 47.4–53 mm, female SVL 72.9 mm), presence (vs. absence) of lateral fringes on toes, and presence (vs. absence) of a yellow or white upper lip stripe; from M. mangshanensis by relative finger lengths of II<I and IV (vs. IV≤II or IV=I), tongue large, pear shaped, posterior slightly notched (vs. small longitudinally oval, without notch posteriorly), dorsal skin smooth (vs. granular).

From M. parva (based on 3 paralectotypes of Leptobrachium parvum ) by absence (vs. presence) of vomerine teeth, vomerine ridges weak when present (vs. round elongated stalks), choanae visible from inside of mouth (vs. choanae not visible from inside of mouth), fingers I<IV (vs. IV≤I); from M. medogensis by larger size of adult, males SVL 63 mm (vs. male SVL 47.4–53 mm) and TYD <TYE (vs. TYD >TYE, n=4, TYD =TYE, n=1); from M. lekaguli by small (vs. round elongated, very prominent) vomerine ridges, dorsal skin smooth (vs. densely granular), larger size of adult males, SVL 56.6–66.6 (vs. male SVL 47.4–53); from M. damrei sp. nov. by small (vs. round elongated, very prominent) vomerine ridges, dorsal skin smooth (vs. densely granular), tongue large and wide with small notch posteriorly (small longitudinally oval, not notched posteriorly), HW:SVL 41.5–42.6% (vs. 33.9– 38.3%) and TYD:EL 57.5–66.7% (vs. 71.1–77.1%).

Holotype description. A medium sized, slender built species, mature female, SVL 72.9. Head small (HW 24.7, HL 22.9, HL:SVL 31.4 %, IFE 10.0, IBE 17.9), wider than long (HW:HL 107.9%), snout rounded dorsally, obtuse, laterally protruding beyond the lower mandible, obtuse surface concave, without rostral appendage, lores acute and concave with well developed canthus rostralis, dorsal snout concave. Eye (EL 7.6) larger than tympanum ( TYD 5.4, TYD:EL 71.1%) and slightly longer than snout (SL 7.1, EL:SL 107.0%). Eye–tympanum distance (TYE 4.6) shorter than tympanum diameter. Tympanum oval, almost vertical with the upper ~5 % concealed by the supratympanic ridge. Pupil indistinct. Nostril is positioned laterally, oval with a raised rim dorsally and posteriorly, half way between eye and snout (EN 3.7, SN 3.7), internarial distance (IN 6.7) wider than the narrowest point of the frontal (IUE 6.2), which is slightly wider than the eyelids (UEW 6.0). Pineal ocellus absent. Vomerine ridges form rounded elongated stalks, extending beyond the level of the inner dermal fringe of the upper mandible with which they are in contact with, seven long vomerine teeth, choanae are not visible from the interior of the mouth as they are obscured by the vomerine ridges and wide dermal fringe of the upper mandible. Tongue small, longitudinally oval with no notch posteriorly, medial lingual process absent. Supratympanic fold narrow along two thirds its length, widening significantly on posterior third, extends from the orbit broadly curving down through the upper portion of the tympanum and terminating above the shoulder with a short horizontal portion.

Arms moderately short and thin, forearm (FAL 16.8, FAL:SVL 23%) not enlarged relative to the upper arm, slightly shorter than hand ( HAL 17.8). Fingers long and narrow, finger length formula IV<II<I<III (FIL 9.2, FIIL 8.6, FIIIL 11.6, FIVL 6.9). Interdigital webbing, lateroventral fringes on digits, subarticular and supernumerary tubercles all absent, prepollox barely distinguishable, palmer tubercles absent. Digit tips slightly expanded and flattened without disks or terminal grooves.

Hind limbs relatively short and thick, tibia overlap slightly when legs are held at right angles to the body, thigh length (TL 31.9) slightly shorter than shank length (SHL 32.6, SHL:SVL 44.7%) but longer than the foot (FOL 29.5). Toes long and thin, relative toe lengths I<II<V<III<IV. Digit tips slightly dilated and flattened but without disks, base of digits with a thick rudimentary webbing. Lateral fringes, outer metatarsal tubercle, subarticular and supernumerary tubercles all absent. Inner metatarsal tubercle present but barely distinguishable and ridge of thickened skin on the ventral surface of digits not well developed.

Skin of the dorsal snout, head, back, flanks and upper surfaces of thigh and shank weakly granular with a few sparsely arranged, small weakly raised tubercles on the flanks. Throat, chest, abdomen, forelimbs and remaining surfaces of the hind limbs, smooth. Dorsal surface of thighs with five evenly spaced dermal ridges. Lores and lateral surfaces of the head covered in small and medium sized granules, tympanum slightly concave and minutely granular. Palpebral horn and short raised fleshy ridge on upper eyelid absent, but slightly thickened medially. A narrow, raised dorsolateral fold extends from posterior to the upper curved portion of the supratympanic fold (but not in contact), to approximately two thirds distance to groin. A weak posteriorly oriented “V” shaped ridge extends across the parietal region from inner edge of eyelids to the level of the anterior border of tympanum. A more pronounced “Y” shaped parietoscapular ridge extending posteriorly from the temporal region approximately level mid way between the eye and tympanum, meeting medially beyond the level of the insertion of forelimbs, continuing medially before bifurcating (to form an inverted “V”) on the middorsum, extending posterolaterally to join the dorsolateral folds. Pectoral glands weakly raised, positioned on the chest at the level of the axilla, femoral glands not distinctly raised, positioned half way between knee and cloaca.

Colouration in alcohol. Dorsal surface of head, back and limbs grey-brown. A hollow dark brown triangular marking between the eyes, the posterior border follows the above mentioned “V” shaped ridge, some barely distinguishable darker blotches follow the anterior “Y” shaped portion of the parietoscapular ridge. Flank tubercles appear as light spots, some bordered below with dark brown spots. Rim of lower and upper eyelid dark brown, two light patches on either side of the thickened portion of the eyelid, the anterior patch larger and with a dark central stripe. Lateral surfaces of the snout anterior to the orbit dark brown, a wide vertical dark brown suborbital bar, anterior of which is a second thin dark vertical bar, two feint dark blotches on the upper mandible posterior to the primary suborbital bar. A faintly darker brown patch covers the tympanum. Several small dark spots on the posterior end of the supratympanic fold. Gular region and chest faded greyish-brown with four darker blotches on the edges of the lower mandible, a short longitudinal dark brown bar extends from mid gular to the anterior chest, small dark spots and blotches on the lateral and posterior chest. Gray-brown of the chest blends to a mottled yellow-brown of the abdomen, with several large brown blotches laterally. Ventral thighs and shank mottled with faded light and dark blotches. Several dark brown blotches on the anterior thigh and shank, outer tarsus with a continuous dark brown patch from the foot to the base of the shank. Area surrounding the vent dark brown fading distally on the posterior thigh. Forelimbs brown above with two dark brown transverse stripes from the inner to anterior surface of the forearm, ventrally light brown with dark brown patches on the posterior surface of the forearm. Ventral surface of hands and feet faded grey-brown. Pectoral and femoral glands white, pectoral gland surrounded by a dark ring.

Variation. Refer to table 1 for morphometric variation in the type series. The paratypes agree with the holotype in most morphological aspects with some exceptions. The holotype and two paratypes (NHM 1972.1516, NHM 1972.1518) have the finger length formula IV<II<I<III, the remaining two paratypes (NHM 1972.1517 and NHM 1972.1520) have the formula IV=II<I<III and IV=I<II<III respectively. The parietoscapular fold may form a complete or incomplete “V” instead of a “Y” shaped ridge, the inverted “V” ridge of the posterior portion, may or may not join the dorsolateral folds. Granules of the posterior upper eyelids, rear of the head, entire dorsum, flanks, lores, rear of the jaw, dorsal surfaces of thighs and shanks, dorsolateral and parietoscapular folds, have white asperities on all paratypes. A narrow to wide band of both black and white asperities border the lower jaw ventrally on all paratypes. The immature female paratype (NHM 1972.1516) was the only other specimen (with the holotype) that the mouth was not too brittle to open and examine the vomerine ridges which were as described above for the holotype. This suggests that the extreme elongation of the ridges is not dependant on the maturity of individuals in this species. Extent of the upper tympanum concealed by supratympanic fold varies from ~5–10%. All specimens in the type series have a hollow triangle on head, but other dorsal markings may not be visible. The ventral pattern of blotches on the abdomen and thighs varies in density and contrast between all individuals examined.

A live (uncollected) male (SVL 51 mm) was dorsally covered in light asperities, most dense on dorsal folds and tubercles, and agrees exactly with the above diagnosis of external morphological characters. An example of colouration and markings in life are therefore depicted in figure 5, based on this individual. Ventral colouration of the live individual was; throat and chest dark mottled greyish-black with black blotches, abdomen mottled light grey and white with black blotches ventrolaterally, ventral thigh and shank mottled light grey and white, ventral tarsus, feet and hands dark greyish-black. A live (uncollected) recently metamorphosed juvenile had similar dorsal markings to the male, however dorsal ridges and larger tubercles were white, primarily on the posterior back and flanks, hind limbs were mottled grey and white. Iris colouration was dark brown, as opposed to grey brown on the adult. Ventrally, plain translucent grey on the throat, chest and anterior abdomen.

Male secondary sexual characters. Smooth dark nuptial pad covering the proximal half of the dorsal surface of finger I and a smaller oval pad dorsally at the base of finger II, forearms are moderately thickened relative to the females, external vocal sac indistinct and caudal projection above vent, absent.

Etymology. The specific epithet takensis is a toponym referring to the type locality of Tak, Tak province, western Thailand.

Distribution. The collection locality for the five type specimens is provided as “Ban Pa Che, 2500ft, Burma ” on the label within the specimen jar, and “ 2500ft, N.W. of Tak, N.W. Thailand " on the outer label of the jar. The specimen register reads “ 2500ft, Ban Pa Che, N.W. of Tak, N.W. Thailand ”. This locality currently refers to Ban Pa Che (762 m a.s.l.), northwest of Tak town (16°52’16” N, 99°07’30” E), Tak Province, in western Thailand. Live individuals of this species were found on a stream bank in Taksinmaharat National Park, 25 km west of Tak town, which consists of dry deciduous, tropical evergreen and conifer forest to 1000 m a.s.l. The stream is located 2.5 km by road north of the park headquarters (16°46’81” N, 98°55’79” E), next to the landmark “giant” Krabach tree Anisoptera costata (Dipterocarpaceae) (750 m a.s.l.). This portion of the forest is referred to by the local forest department as mature dry evergreen forest.

Remarks. One adult male ( Fig. 5 ) was located by following sporadic mating and territorial calls during a short rain shower at 19:40 h. This individual was calling from the central axis of a “ tree fern ”, one meter above ground level, three meters from the bank of a narrow undulating forest stream (2 m wide, 30 cm deep). One metamorph was found 100 m from the calling male, amongst dense low vegetation, 4 m from the bank of the same stream at 20:20 h. No further adult individuals, or tadpoles allocatable to this species were found within 3 km of stream banks, downstream from the Krabach tree, however, brief sporadic calls were heard from three other unlocated males from within dense bushy vegetation near the banks of the stream.

Figures

FIGURE 3. Megophrys takensis sp. nov. holotype female (NHM 1972.1519); A. dorsal, B. ventral, C. foot, D. hand.

FIGURE 4. Profile view of head; A. Megophrys damrei sp. nov. holotype female (NHM 1972.1524) and B. Megophrys takensis sp. nov. holotype female (NHM 1972.1519).

FIGURE 5. Megophrys takensis sp. nov. adult male in life, not collected, from Taksinmaharat National Park; A. lateral view, B. dorsolateral view, C. stream habitat at observation site, D. view of forest from above the canopy.