Megophrys obesa Wang, Li and Zhao

Li, Yu-Long, Jin, Meng-Jie, Zhao, Jian, Liu, Zu-Yao, Wang, Ying-Yong & Pang, Hong, 2014, Description of two new species of the genus Megophrys (Amphibia: Anura: Megophryidae) from Heishiding Nature Reserve, Fengkai, Guangdong, China, based on molecular and morphological data, Zootaxa 3795 (4), pp. 449-471 : 463-468

Megophrys obesa Wang, Li and Zhao sp. nov.

Holotype. SYS a002275, adult male, collected on 20 August 2013 by ZYL and YYW from Heishiding Nature Reserve (23°28'27" N, 111°53'53" E; 399.2 m a.s.l.), Fengkai County, Guangdong Province, China. ( Figure 6 ).

Paratypes. Six adult female specimens, from HNR at elevations between 399.2–433.6 m. SYS a002270–2272, collected on 16 August 2013 by YLL, KC and YYW; SYS a001956, collected on 12 November, 2012 by RLL; SYS a000164, 0 178, collected on 2 May, 2008 by JHY and YYW.

Diagnosis. Megophrys obesa sp. nov. is characterized by the combination of following characters: (1) A stout and slightly small-sized species measuring 37.5–41.2 mm in SVL in adult females, 35.6 mm in SVL in adult male; (2) head width slightly larger than head length, HDW/HDL ratio 1.03–1.12; (3) snout round in dorsal view, slightly projecting, sloping backward to mouth in profile, protruding well beyond margin of lower jaw; (4) canthus rostralis developed; (5) tympanum moderate, TMP/EYE ratio 0.51–0.66; (6) two vomerine ridges moderately developed, no vomerine teeth; (7) margin of tongue smooth, not notched behind; (8) the heels not meeting; (9) tibio-tarsal articulation reaches forward the posterior margin of eye; (10) tibia relatively short, 0.41–0.47 of SVL; (11) relative finger length I <II ≤ IV <III; (12) toes with weak fleshy webs at their bases; (13) subarticular tubercle distinct at the base of each digit; (14) dorsal skin smooth scattered granules and tubercles, usually several large tubercles as pustule-like on flanks of trunk; (15) a triangle ridge with granules between eyes, apex of triangle usually reaches the occiput; (16) an X-shaped or Y-shaped dorsal ridge with granules on back of trunk; (17) usually presence of two discontinuous dorsolateral ridges on either side of the dorsal ridge; (18) a horn-like tubercle at the edge of the eyelid small, distinct; (19) dorsal surface brown, with an complete or incomplete dark interorbital triangle with a brown center, usually an X-shaped dark marking on the back of trunk; (20) gravid females bear pure yellowish oocytes.

Comparisons. Megophrys obesa sp. nov. is here compared with above 46 recognised species of genus Megophrys and M. acuta sp. nov.. Comparative data are shown in Table 3 .

M. obesa sp. nov. can be steadily distinguished from sympatric species M. acuta sp. nov. (in parenthesis) by its body short and stout (vs. slender), minimum SVL 37.5 mm in adult females (vs. maximum SVL 33.6 mm), snout rounded (vs. pointed), horn-like tubercles small (vs. slightly large), lateral fringes on toes absent (vs. present), subarticular tubercles of toes present (vs. absent), ventral surface grey black, dotted orange spots, spotted white (vs. reddish brown mottled black and white), hindlimbs with broad complete black transverse bands (vs. broken transverse bands or complete thin bands).

M. obesa sp. nov. is a sister taxon to M. cheni in our phylogenetic tree, and differs from latter (in parenthesis) by its body short and stout (vs. slender); minimum SVL 35.6 mm in adult male, 37.5 mm in adult females (vs. maximum SVL 29.5 mm in adult males, 34.1 mm in adult females); shank short, TIB / SVL ratio 0.41–0.47 (vs. 0.50–0.54), and heels not meeting when the hindlimbs are flexed and thighs are held at right angles to the body axis (vs. the heels overlapping); tibio-tarsal articulation reaches forward the posterior margin of eye, when hindlimbs are stretched along the side of the body (vs. reaches the anterior region of eye); margin of tongue not notched (vs. notched); lateral fringes on toes absent (vs. present).

M. obesa sp. nov. is a slightly small-sized species with SVL 35.6 mm in adult male, SVL 37.5–41.2 mm in adult females, and can be readily distinguished from following 21 congeners with SVL longer than 45 mm in adult males, SVL longer than 50 mm in adult females: M. aceras , M. auralensis , M. binlingensis , M. caudoprocta , M. damrei , M. gigantica , M. glandulosa , M. jingdongensis , M. lekaguli , M. longipes , M. major , M. mangshanensis , M. medogensis , M. megacephala , M. omeimontis , M. robusta , M. sangzhiensis , M. shapingensis , M. shuichengensis , M. spinata and M. takensis .

M. obesa sp. nov. can be visibly distinguished from the remaining recognised 24 congeners by its body remarkably short and stout. Further, it steadily differs from them by the combination of following characters: hindlimbs relatively short, its heels not meeting when the hindlimbs are flexed and thighs are held at right angles to the body axis vs. relatively long, heels meeting or overlapping in M. ancrae , M. baolongensis , M. binchuanensis , M. boettgeri , M. daweimontis , M. huangshanensis , M. jinggangensis , M. lini , M. minor , M. nankiangensis , M. oropedion , M. pachyproctus , M. palpebralespinosa , M. parva , M. tuberogranulatus , M. vegrandis , M. wawuensis , M. wuliangshanensis , M. wushanensis , M. zhangi ; horn-like tubercles at edge of upper eyelids small and distinct vs. slightly large in M. jinggangensis , M. palpebralespinosa , M. parallela ; horn-like tubercles indistinct or absent in M. binchuanensis , M. nankiangensis , M. oropedion , M. pachyproctus , M. tuberogranulatus , M. wawuensis , M. wuliangshanensis , M. wushanensis , and M. zhangi ; vomerine teeth absent vs. present in M. ancrae , M. daweimontis , M. jinggangensis , M. oropedion , M. pachyproctus , M. palpebralespinosa , M. parva , M. serchhipii , M. zhangi , M. zunhebotoensis ; margin of tongue smooth, not notched vs. notched in M. ancrae , M. baolongensis , M. boettgeri , M. huangshanensis , M. kuatunensis , M. minor , M. nankiangensis , M. oropedion , M. pachyproctus , M. vegrandis , M. wawuensis and M. zhangi ; lateral fringes on toes absent vs. present in M. binchuanensis , M. boettgeri , M. jinggangensis , M. kuatunensis , M. lini , M. nankiangensis , M. palpebralespinosa , M. wushanensis (in males) and M. zhangi ; shank short, TIB / SVL ratio 0.41–0.47 vs. 0.46–0.55 in M. ancrae , 0.54 in M. daweimontis , 0.47–0.50 in M. jinggangensis , 0.46–0.53 in M. lini , 0.49 in M. minor , M. nankiangensis , M. pachyproctus and M. zhangi , 0.55 in M. palpebralespinosa , 0.48–0.53 in M. parva , 0.45–0.51 in M. tuberogranulatus , 0.49–0.54 in M. vegrandis , 0.51–0.59 in M. wawuensis , 0.50–0.51 in M. wuliangshanensis , 0.47–0.48 in M. wushanensis , 0.46–0.50 in M. zunhebotoensis ; tympanum moderate, distinct (TMP/EYE ratio 0.51–0.66) vs. tympanum great in M. jinggangensis (0.73–0.88), tympanum small or indistinct in M. baolongensis (0.41), M. binchuanensis (0.33–0.50), M. cheni (0.41–0.54), M. huangshanensis (<0.5), M. kuatunensis (0.44), M. nankiangensis (hidden), M. pachyproctus (0.29), M. parva (0.4), M. serchhipii (0.39), M. wawuensis (0.33) and M. palpebralespinosa (tympanum small); tibio-tarsal articulation reaches forward the posterior margin of eye, when hindlimbs are stretched along the side of the body vs. reaches the region between shoulder and tympanum in M. brachykolos , reaches the middle of eye in M. zunhebotoensis , reaches the anterior region of eye in M. lini , M. pachyproctus and M. serchhipii , reaches the tip of snout in M. daweimontis . Moreover, M. obesa sp. nov. differs from M. brachykolos from southern China (in parenthesis) by inner metacarpal tubercle, outer metacarpal tubercle and inner metatarsal orange-red, tip of digits pale grey tinged pinkish (vs. all pale grey); subarticular tubercle only at the base of each toe, distinct or indistinct (vs. subarticular tubercles on toes present, basal ones large, distinct); the region around cloaca smooth, with scattered small granules (vs. with heavy tubercles, ones on each side of cloaca large, pointed); differs from M. kuatunensis which were reported to occur in Heishiding Nature Reserve by SVL 35.6 mm in adult male (vs. maximum SVL 29.6 mm); differs from M. minor which were reported to occur in Heishiding Nature Reserve by the groin brown or light brown, ventral surface of thighs black brown with faint white patches (vs. orange).

Description of holotype. An adult male individual. Body remarkably stout and short with 35.6 mm in SVL; head length shorter than head width, HDW/HDL ratio 1.1; snout round in dorsal view, slightly projecting, sloping backward to mouth in profile, protruding well beyond margin of lower jaw; top of head flat; eye large, eye diameter 33% of head length, pupil vertical; nostril oblique ovoid with low flap of skin laterally; canthus rostralis developed; loreal region vertical, not concave; internasal distance slightly larger than the interorbital distance; tympanum moderate, distinctly visible, TMP/EYE ratio 0.66; tympanum-eye distance 2.1 mm, TEY/TMP ratio 0.78; choanae large, ovoid at the bases of the maxilla; two vomerine ridges moderately developed, no vomerine teeth; margin of tongue smooth, not notched behind.

Forelimbs robust; radioulna length 25% of SVL, hands without web, moderately longer, 23% of SVL; fingers without lateral fringes, relative finger length I <II <IV <III; tips of digits round, slightly dilated; a distinct subarticular tubercle only at the base of each finger; two metacarpal tubercles well developed, inner ones significantly enlarged. Hindlimbs robust; tibio-tarsal articulation reaches the posterior region of eye, when hindlimb is stretched along the side of the body; the heels not meeting when the flexed hindlimbs are held at right angles to the body axis; tibia length 44% of SVL; foot length 59% of SVL; relative toe lengths I <II <V <III <IV; tips of toes round, slightly dilated; toes with a fleshy web at their bases; indistinct subarticular tubercle only at the base of each toe; lateral fringes lacking; tarsal fold absent; inner metatarsal tubercle long ellipsoid; outer metatarsal tubercle absent.

Skin on all upper surfaces smooth, with scattered granules and a few tubercles; an X-shaped ridge on back and a dorsolateral ridge on either side of the dorsal ridge; the presence of a horn-like, slightly prominent tubercle at the edge of the eyelid; supratympanic fold distinct, narrowed, curving posteroventrally from posterior corner of eye to a level above insertion of arm; several tubercles scattered on flanks and posterior dorsum; ventral surface smooth, with granules; the region around cloaca smooth, with scattered small granules; pectoral gland slightly large, round, prominently elevated relative to ventral surface, closer to axilla than to mid-ventral line; single slightly large femoral gland on rear of thigh; cloacal opening unmodified, directed posteriorly, at upper level of thighs.

Measurements of holotype (in mm). SVL 35.6, HDL 12.6, HDW 13.8, SNT 4.4, IND 3.9, IOD 3.7, EYE 4.1, TMP 2.7, TEY 2.1, HND 8.2, RAD 8.8, FTL 20.9, TIB 15.7.

Coloration of holotype in life. Dark brown above; a dark interorbital triangle with a large brown center, apex of triangle reaches the occiput; posteriorly obscure darker markings; forearm with two distinct, oblique dark bands; a large black mark bordered with white edge on the elbow; hindlimbs with broad black transverse bands; tip of snout dark brown; a dark brown vertical band under the eye; supratympanic fold white; horn-like tubercles reddish orange. Lower lip black with white spots. Ventral surface grey black; throat, chest with black spots and scattered orange spots; a longitudinal uniform black streak down the center of the throat and chest; belly mottled with white and dotted with orange red spots on the central region, large black mottling on either side; ventral surface of limbs black brown with faint white patches; rear of forearm with a large black mottling; the palms and soles black brown, inner metatarsal tubercle and outer metacarpal tubercle orange-red, tip of digits pale grey tinged pinkish; pectoral glands white; femoral glands white. The iris light brown with black lines; pupil black.

Coloration of holotype in preservative. Dark brown fades to greyish-brown on dorsal surface; dark interorbital triangle becomes black and more distinct; ventral surface is paled in color: ground color grey-brownish, orange faded, marks and lateral mottlings more distinct.

Variation. Measurements and body proportions of type series are given in Table 4 .

M. obesa sp.nov. does not show significant secondary sexual characteristics. All paratypes (six females) are similar to holotype, but also show variation in morphology. The adult females with SVL 37.5-41.2 mm, slightly larger than adult male. SYS a000164, 0 178 and 2272 with X-shaped ridge and X-shaped dark marking on back of trunk, two longitudinal dorsolateral dark stripes and ridges on either side of the X-shaped marking. Body color of SYS a000164 and 0 178 after being collected for two days was faded to light brown.

Etymology. The specific epithet “ obesa ” is a Latin adjective (stout), referring to the stout body of the species. We propose the standard name “Heishiding’s Horn Toad”, Chinese name “Hei Shi Ding Jiao Chan”.

Distribution and habits. Currently, M. obesa sp. nov. is known only from the type locality, Heishiding Nature Reserve, Fengkai County, Guangdong Province, China ( Figure 7 . A and B). It inhabits lowland forest at elevations between 399.2–433.6 m, and is more frequently found in bamboo forest and encountered along forest paths. Its area of occurrence is estimated to be less than 10 km 2.

Remark. Despite our repeated herpetological surveys from 2008 to 2013, M. obesa sp. nov. was only found and collected in May, August and November, and the male advertisement calls were never heard. All specimens were collected in the rain or just after the rain. Among them, SYS a001956 was found on a leaf of Aloe at height of 10 cm, at a distance of 0.5 m away from small, slow-moving mountainous streams surrounded by moist subtropical evergreen broadleaved forests; SYS a002272 was found on the roadside ferns at height of 10 cm, about 5 m away from the stream; the remaining specimens were found on the paths surrounded by bamboo forest, about 40 m away from the stream. Dissecting specimen SYS a000164, 26 termites were found in its stomach.

The male holotype SYS a002275 with developed testes in the abdominal cavity; the female specimens SYS a000164, 0 178, 2270, 2271 and 2272 with rudimentary ovaries and ovary fat. Gravid female SYS a001956 with pure yellowish mature oocytes measuring 1.7 mm in oviducts.

Figures

FIGURE 7. Habitat of M. obesa sp. nov. at the type locality from Heishiding Nature Reserve. A: The paratype SYS a 002272 was found on roadside next to the stream, at a distance of about 7 m from the stream. B: The paratype SYS a 002271 was found on a path surrounded by bamboo forest at a distance about 40 m from the stream. Photos by YLL.

FIGURE 6. A: Dorsolateral view of the adult male holotype SYS a 002275 of Megophrys obesa sp. nov. in life. B: Ventral view of holotype in life. C: Dorsolateral view of the adult female paratype SYS a 002272 in life. D: Ventral view of paratype SYS a 002272 in life. E: Dorsolateral view of the adult female paratype SYS a 000164 in life. F: Dorsal view of the adult female paratype SYS a 000178 in life. Photos by YYW and YLL.