Megophrys damrei, 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 : 25-30

Megophrys damrei sp. nov.

( Figures 1 , 2 & 4 )

Holotype. Adult female (NHM 1972.1524), "Bockor [=Bokor] Plateau, 1000m, Elephant Mts., [Kampot] Cambodia ", collector Malcolm A. Smith, March to April, 1914.

Paratype. Adult male (NHM 1972.1523), from same locality, collector Malcolm A. Smith, March to April, 1914.

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%); 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 damrei 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, adult male SVL 57.1, adult female SVL 69.1; head considerably wider than long, HW/HL 110–113%; temporal region strongly oblique from the edge of the mandible to the supratympanic fold; tympanum visible, oval and oblique; palpebral horn absent; vomerine ridge and teeth present; tongue notched posteriorly; finger length formula IV<I<II<III or IV<II<I<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 male, a few asperities positioned ventrally at rear of jaw only.

Comparisons. Megophrys damrei sp. nov. is here compared to all twelve congeners extant in Cambodia and the neighbouring Southeast Asian countries of Myanmar, Thailand, Laos and Vietnam; M. aceras (Boulenger) , M. auralensis , M. brachykolos , M. jingdongensis Fei & Ye , M. kuatunensis , M. lekaguli , M. longipes (Boulenger) , M. major , M. minor , M. nasuta , M. pachyproctus Huang , M. palpebralspinosa and M. parva . Megophrys damrei sp. nov. (characters in parentheses) differs from the following small bodied species with adult male SVL <50 mm (vs. male SVL 57.1 mm): M. brachykolos , M. kuatunensis , M. minor , M. pachyproctus , M. palpebralspinosa and M. parva ; from M. jingdongensis which possess extensive (vs. rudimentary) webbing between the toes; from M. aceras , M. longipes and M. nasuta by the presence (vs. absence) of a palpebral horn. From M. major by its presence (vs. absence) of a continuous white upper lip stripe and wide lateral fringes on toes, entire upper eyelid dark (vs. dark upper eyelid with two large light patches), HW/HL 97.6–102.1% (vs. HW/HL 110–113%) and presence of a wide band of asperities ventrally on the lower jaw (vs. a few asperities positioned ventrally at rear of jaw only).

In the mountains of southwestern Cambodia and adjoining southeastern Thailand, two medium to large endemic species of Megophrys occur ( M. auralensis and M. lekaguli , respectively), which are most similar to Megophrys damrei sp. nov.; M. auralensis differs by its larger male adult size, SVL 71–76.9 mm (vs. male SVL 57.1 mm), presence (vs. absence) of lateral fringes on the fingers and toes, absence (vs. presence) of vomerine teeth, and finger II<IV (vs. IV<II); from M. lekaguli by its narrower head HW:SVL 35.2–39% (vs. HW:SVL 41.5– 42.6%), temporal region almost vertical when viewed from directly above (vs. strongly oblique from the edge of the mandible to the supratympanic fold [ Figure 2 ])––this character is stable on all larger specimen series of other Megophrys species examined in this study, there also appears to be negligible seasonal variation or variation between sexes in the aforementioned specimen series, FOL:SVL 39.8–45.4% (vs. FOL:SVL 48%), tongue not notched (vs. notched) posteriorly, visible portion of the oval tympanum orientated vertically with ~30% of the upper portion concealed by the supratympanic ridge (vs. oval tympanum obliquely orientated with ~5–10% of the upper border of tympanum concealed by supratympanic ridge), presence of a narrow row of asperities ventrally on the lower jaw (vs. a few asperities positioned ventrally at rear of jaw only).

Holotype description. A medium sized, heavily built species, mature female, SVL 69.1. Head large (HW 28.7, HL 25.4, HL:SVL 36.8%, IFE 11.4, IBE 19.4), wider than long (HW:HL 113%), snout rounded dorsally, obtuse laterally, protruding beyond the mandible, without rostral appendage, lores acute and concave with well developed canthus rostralis, dorsal region of snout concave. Eye (EL 7.3) larger than tympanum ( TYD 4.2, TYD:EL 57.5%), shorter than snout (SL 8.3, EL:SL 88%). Eye-tympanum distance (TYE 4.4) slightly longer than tympanum diameter. Tympanum distinctly oval, obliquely orientated with the upper ~5 % concealed by supratympanic ridge. Pupil indistinct. Nostril positioned laterally, circular with a raised posterior rim, closer to eye than snout (EN 4.0, SN 4.3), internarial distance (IN 7.8) wider than the narrowest point of the frontal (IUE 7.0), both considerably wider than the eyelids (UEW 6.0). Pineal ocellus absent. Vomerine ridges of medium size, rounded, with ca. five distinct blunt vomerine teeth, vomerine ridges equidistant from choanae and each other, positioned slightly posterior to the choanae. Tongue large, a small notch posteriorly with no medial lingual process. Supratympanic fold narrow with minimal widening posteriorly, extends from the orbit and curves down along the upper and posterior border of the tympanum terminating above the shoulder.

Arms moderately long and thin, forearm (FAL 17.5, FAL:SVL 25.3%) not enlarged relative to the upper arm, slightly shorter than hand length ( HAL 17.9). Fingers long and narrow, finger length formula IV<I<II<III (FIL 9.4, FIIL 9.9, FIIIL 12.8, FIVL 7.2). Interdigital webbing, lateral fringes and subarticular and supernumerary tubercles absent, prepollox barely distinguishable, palmer tubercles absent. Digit tips slightly expanded and flattened without disks or terminal grooves.

Hind limbs relatively long and thin, tibia overlap slightly when legs are held at right angles to the body, thigh length (TL 34.4) slightly shorter than shank (SHL 35.0, SHL:SVL 50.7%), longer than the foot (FOL 33.2). Toes long and thin, relative toe lengths I<II<V<III<IV, toe V reaches the base of the distal phalange on toe III. 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 present.

Skin of the dorsal snout, head, back, throat, chest and limbs smooth. Flanks weakly granular with a few sparsely arranged, small tubercles. Dorsal surface of thighs with five short, evenly spaced ridges. Entire abdomen, posterior thigh and cloacal region finely granular. Tympanum smooth, borders slightly raised, area posterior to the rear axis of mandibles granular. Palpebral horn absent, replaced by a short, raised fleshy ridge, remaining dorsal surface of the eyelid finely granular. A narrow, raised dorsolateral fold extends from posterior to the curved portion of the supratympanic fold (but not in contact) to above the groin. A fine posteriorly oriented “V” shaped ridge extends across the parietal from approximately the mid eyelids to the level of the anterior border of the tympanum. A weak, “Y” shaped parietoscapular ridge present extending posteriorly from the temporal region, approximately level mid way between the eye and tympanum, meeting medially beyond the level of the insertion of the forelimbs, continuing medially as a row on fine granules before bifurcating on the middorsum, extending posterolaterally towards, but not meeting, the dorsolateral folds. Pectoral glands raised, positioned on the chest at the level of the axilla, femoral glands not distinctly raised, positioned closer to knee than to cloaca. A small patch of white asperities present on each side, ventrally at the rear of the jaw. Asperities absent elsewhere on the body.

Colour in preservative. Dorsal surface of head and back, mottled chestnut brown; a solid dark brown triangular marking between the eyes, the posterior border of which follows the V-shaped parietal ridge. An additional dark brown hourglass marking on the dorsum. Larger flank tubercles with light centres, all bordered below by dark brown. Rim of lower and upper eyelid dark brown, a wide light patch with a central narrow dark central stripe positioned anterior to the fleshy palpebral ridge, a second light patch posterior to the palpebral ridge on the upper eyelid. Lateral surfaces of the snout anterior to the orbit dark brown, a wide slightly oblique dark brown bar below the eye, a dark brown patch extends from the posterior border of the eye over the tympanum to the rear of the supratympanic fold. Gular region and chest dark brown with dark and light blotches along the edges of the lower mandible. A short dark brown bar on both sides of the throat and a short longitudinal bar from mid gular to the anterior chest. Dark brown of the chest fades and becomes marbled with light and dark blotches over the abdomen. Ventral thighs and shank primarily light with darker blotches anteriorly, speckled posteriorly. Outer tarsus with a continuous dark brown blotch from the foot to the base of the shank, dorsal surface of the hind limbs are a darker shade of brown to dorsum. Area surrounding the vent dark brown fading distally on the posterior thigh. Forelimbs brown above with two dark brown transverse stripes on the forearm, ventrally light brown with dark brown patches on the forearm. Ventral surface of hands and feet faded grey-brown. Pectoral and femoral glands white, pectoral gland bordered by a dark ring.

Variation. Refer to table 1 for variation in the morphometrics between the male paratype and female holotype. One noticeable difference is the finger length formula of the paratype IV<II<I<III. Further differences include: vomerine teeth present but barely protruding through flesh of vomerine ridge, dorsal markings as described for holotype but hourglass marking reduced to a thin “Y” connecting to an inverted “V” marking, shank with feint dark barring, entire ventral surface of throat, chest and abdomen with very fine pale granules giving a speckled appearance to areas with dark pigment.

Male secondary sexual characters. Two pale, smooth, oval nuptial pads on the dorsal surface of basal phalange of fingers I and II, external vocal sac indistinct and forearm moderately enlarged relative to the upper arm. Caudal projection above vent, absent.

Etymology. The specific epithet is derived from Chuör Phnum Dâmrei the Khmer translation for Elephant Mountains, Dâmrei meaning elephant, a noun referring to the type locality.

Distribution. The collection locality provided for the two known specimens is "Bockor Plateau, 1000m, Elephant Mts., Cambodia " which currently refers to Bokor Plateau (10°37.611’ N, 104° 01.543 E), 1000 m a.s.l., Kampot District, Kampot Province, southeast Cardamom Mountains, southern Cambodia. The habitat on the plateau itself has been described as follows “covered in a mosaic of grassland with heath forest and sandstone outcrops, and the slopes of the plateau are covered in evergreen forest” ( Stuart & Emmett 2006). The transition zone between the plateau and primary evergreen forest of the mid to lower slopes, is covered by a low canopy mixed forest of deciduous, evergreen and sporadic coniferous trees.

Remarks. At the time of the field visit (6–11 July 2010) the monsoon was considered to be late, and no significant rain fell during those days. Tadpoles allocatable to Megophrys were not found in the water bodies searched. Previous surveys of the area made by Stuart and Emmett (2006) and Grismer et al. (2008b) from 5–15 May 2000 and 9–11 July 2007 respectively, also did not yield this species, indicating that it probably does not breed during this time when many of the smaller streams are reduced to pools. The type specimens were collected during March/ April, thus it may be worthwhile for future expeditions to the area to rediscover this species to be made during these months. Despite the location of Bokor plateau in the jurisdiction of Bokor National Park, the mountain is currently under a considerable amount of construction for a casino, large tourist resort and associated infrastructure. Other habitat pressures at Bokor National Park include illegal logging and human encroachment at the boundaries of the forest, primarily at lower to mid elevations.

M. damrei sp. nov. M. takensis sp. nov.

Figures

FIGURE 1. Megophrys damrei sp. nov. holotype female (NHM 1972.1524); A. dorsal, B. ventral, C. foot, D. hand.

FIGURE 2. Comparison of head shape between similar species; A. Megophrys damrei sp. nov. paratype adult male (NHM 1972.1523): note –– temporal region strongly oblique from the edge of the mandible to the supratympanic fold, B. Megophrys lekaguli topotype adult male (NHM 1979.440): note –– temporal region almost vertical from the edge of the mandible to the supratympanic fold.

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).