Megophrys xianjuensis, Wang & Wu & Peng & Shi & Lu & Wu, 2020

Wang, Bin, Wu, Yan-Qing, Peng, Jun-Wei, Shi, Sheng-Chao, Lu, Ning-Ning & Wu, Jun, 2020, A new Megophrys Kuhl & Van Hasselt (Amphibia, Megophryidae) from southeastern China, ZooKeys 904, pp. 35-62 : 35

Megophrys xianjuensis sp. nov. Figures 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9

Type material.

Holotype. CIBXJ190503 (Fig. 4A, B, E, G, I ), adult male, from Shenxianju scenic area, Danzhu Township, Xianju County, Zhejiang Province, China (28.677483N, 120.594888E, 350 m a. s. l.), collected by Bin Wang on 7 May 2019.

Paratype. One adult male CIB20180514007 and one adult female CIB20180514008 collected from the type locality of the new species by Bin Wang on 14 May 2018; one adult male CIBXJ190501 and one adult female CIBXJ190505 collected from the type locality by Bin Wang on 7 May 2019; five adult males CIBXJ20190801, CIBXJ20190802, CIBXJ20190803, CIBXJ20190804 and CIBXJ20190805 collected from the type locality by Bin Wang on 28 August 2019.

Diagnosis.

Megophrys xianjuensis sp. nov. is assigned to the genus Megophrys based on molecular phylogenetic analyses and the following generic diagnostic characters: snout shield-like; projecting beyond the lower jaw; canthus rostralis distinct; chest gland small and round, closer to the axilla than to midventral line; femoral gland on rear of thigh; vertical pupils.

The new species could be identified from its congeners by a combination of the following morphological characters: (1) small size (SVL 31.0-36.3 mm in males and 41.6 mm in female); (2) vomerine ridge present and vomerine teeth absent; (3) tongue not notched behind; (4) a small horn-like tubercle at the edge of each upper eyelid; (5) tympanum distinctly visible, rounded; (6) two metacarpal tubercles in hand; (7) relative finger lengths: II <I <IV <III; (8) toes with rudimentary webbing at bases; (9) heels overlapping when thighs are positioned at right angles to the body; (10) tibiotarsal articulation reaching tympanum to eye when leg stretched forward; (11) an internal single subgular vocal sac in male; (12) in breeding male, the nuptial pads with black nuptial spines on the dorsal bases of the first and second fingers.

Description of holotype.

SVL 34.4 mm; head wider than long (HDW/HDL ratio 1.2); snout obtusely pointed, protruding well beyond the margin of the lower jaw in ventral view; loreal region vertical and concave; canthus rostralis well developed; top of head flat on in dorsal view; an small horn-like tubercle at the edge of the upper eyelid; eye large and convex, eye diameter 40.4% of head length; pupils vertical; nostril orientated laterally, closer to snout than eye; tympanum distinct, TYP/EYE ratio 0.56; vomerine ridges present and vomerine teeth absent; margin of tongue smooth, not notched behind (Fig. 4A, B, E ).

Forelimbs slender, the length of lower arm and hand 44.9% of SVL; fingers slender, relative finger lengths: II <I <IV <III; tips of digits globular, without lateral fringes; subarticular tubercle distinct at the base of each fingers; two metacarpal tubercles, prominent, oval-shaped, the inner one bigger than the outer (Fig. 4G ).

Hindlimbs slender, heels overlapping when thighs are positioned at right angles to the body, tibiotarsal articulation reaching tympanum to eye when leg stretched forward; tibia length slightly longer than thigh length; relative toe lengths I <II <V <III <IV; tips of toes round, slightly dilated; subarticular tubercle absent; toes with rudimentary webbing at bases; lateral fringe narrow; inner metatarsal tubercle oval-shaped; outer metatarsal tubercle absent (Fig. 4I ).

Dorsal rough, with numerous granules; several large warts scattered on flanks; an small horn-like tubercle at the edge of each upper eyelid; a dark brown inverted triangular pattern between anterior corner of eyes, tubercles on the dorsum forming a weak X-shaped ridge and two discontinuous dorsolateral parallel ridges on either side of the X-shaped ridge; several tubercles on the flanks and dorsal surface of thighs and tibias, and limbs barred with dark brown forming four transverse rows; supratympanic fold distinct (Fig. 4A ).

Ventral surface with numerous white granules; chest gland distinct and round, closer to the axilla than to midventral line; femoral gland on rear of thigh; posterior end of the body protrudes distinct and appears as an arc-shaped swelling, upper the anal region (Fig. 4B ).

Colouration of holotype in life.

An inverted triangular brown speckle between the eyes; an X-shaped ridges on the dorsum of body, four transverse bands on the dorsal surface of the hindlimb; several dark brown and white vertical bars on the lower and upper lip; the venter purple and the colour of throat is deeper than belly, flank and middle of throat with black brown spots, numerous white granules on the ventral surface and limbs; palms and soles purple and the metacarpal tubercles are orange, tip of digits greyish white; pectoral and femoral glands white (Fig. 5 ).

Preserved holotype colouration.

Dorsal surface fade to olive; the inverted triangular brown speckle between the eyes, X-shaped ridges on dorsum and transverse bands on limbs and digits and brown spots on flank and middle throat are more distinct; ventral surface greyish white; creamy-white substitutes the orange in metacarpal tubercles; the posterior of ventral surface of body, inner of thigh and upper of tibia creamy-white (Fig. 4 ).

Variation.

In some adult individuals a brown Y-shaped marking on the dorsum of head and disconnected with a X-shaped marking on back (Fig. 6A ); an inverted triangular brown speckle between two upper eyelids with Y-shaped marking on back of trunk, the colouration of dorsum is brown with brick-red and the caudal vertebra is pointed in the adult female (Fig. 6B ); in some adult individuals the metacarpal tubercles in palm is grey-white but the tip of fingers is orange and the black spots in flank is smaller (Fig. 6C ); in some adult individuals the white granules in ventral surface are more intensive (Fig. 6D ).

Advertisement calls.

Ten advertisement calls from two individuals of the new species were recorded in the Xianju County, Zhejiang Province, China between 21:00-23:00 on 7 May 2019. The call description is based on recordings of the holotype CIBXJ090503 (Fig. 7 ) from the stone near the streamlet, and the ambient air temperature was 24.5 °C. Each call consists of 22-62 (mean 49.33 ± 14.50, N = 6) notes. Call duration was 4.90-14.22 second (mean10.95 ± 3.42, N = 6). Call interval was 4.12-7.64 second (mean 6.23 ± 1.56, N = 5). Each note had a duration of 0.06- 0.90 second (mean 0.10 ± 0.05, N = 290) and the intervals between notes 0.07-0.88 second (mean 0.13 ± 0.05, N = 284). Amplitude modulation within note was apparent, beginning with lower energy pulses, increasing slightly to a maximum by approximately mid note, and then decreasing towards the end of each note. The average dominant frequency was 6400 ± 465.79 (5520-6840 Hz, N = 6).

Secondary sexual characteristics.

Adult females with SVL 41.6 mm, larger than adult males with 31.0-36.3 mm. Adult males have a single subgular vocal sac (Fig. 5E ). In breeding males, the brownish red nuptial pads on the dorsal bases of the first finger and second fingers with black nuptial spines under microscope.

Tadpole description.

The tadpole was confirmed as Megophrys xianjuensis sp. nov. by molecular phylogenetic analyses. The following tadpole description is based on the specimen CIBXJT19050704 at Stage 31 (Fig. 8 ). Body slender, body and tail yellow-brown in life and fade to light brown and creamy-white of body and tail respectively in preserved specimens; two dotted lines on flank of dorsal from mouth to fin; tail height greater than body height; dorsal fin arising, behind the origin of the tail, height near mid-length, tapering gradually to narrow, tip pointed; tail approximately 1.9 times as long as snout-vent length; tail height 19.9% of tail length; body width slightly longer than body height (BW/BH = 1.1); tail fins lightly coloured, tail muscles with small black spots; eyes large, lateral, nostril near eyes; spiracle on the left side of the body and distinct; oral disk terminal, lips expanded and directed upwardly into a umbelliform oral disk; transverse width of expanded funnel 18.1% of snout-vent length.

Morphological comparisons.

By having small size body, Megophrys xianjuensis sp. nov. differs from M. aceras , M. auralensis , M. binlingensis , M. carinense , M. caudoprocta , M. chuannanensis , M. damrei , M. edwardinae (in female), M. feae , M. flavipunctata , M. gigantica , M. glandulosa , M. himalayana , M. intermedia , M. jingdongensis , M. kobayashii , M. kalimantanensis , M. lekaguli , M. liboensis , M. ligayae , M. longipes , M. major , M. mangshanensis , M. maosonensis , M. medogensis , M. omeimontis , M. oreocrypta , M. periosa , M. popei , M. robusta , M. spinata , M. sangzhiensis , M. shapingensis and M. shuichengensis and M. takensis (maximum SVL <42.0 mm in the new species vs. minimum SVL> 45 mm in the latter).

By lacking vomerine teeth, Megophrys xianjuensis sp. nov. differs from M. aceras , M. ancrae , M. carinense , M. baluensis , M. caudoprocta , M. chuannanensis , M. damrei , M. daweimontis , M. dongguanensis , M. fansipanensis , M. flavipunctata , M. glandulosa , M. hoanglienensis , M. himalayana , M. insularis , M. intermedia , M. jingdongensis , M. jinggangensis , M. jiulianensis , M. kalimantanensis , M. kobayashii , M. lancip , M. lekaguli , M. liboensis , M. ligayae , M. major , M. mangshanensis , M. maosonensis , M. medogensis , M. megacephala , M. montana , M. nasuta , M. nankunensis , M. nanlingensis , M. omeimontis , M. oropedion , M. oreocrypta , M. palpebralespinosa , M. parallela , M. parva , M. periosa , M. popei , M. robusta , M. rubrimera , M. sangzhiensis , M. stejnegeri , M. takensis , M. zhangi and M. zunhebotoensis (vs. present in the latter).

By having a small horn-like tubercle at the edge of each upper eyelid, Megophrys xianjuensis sp. nov. differs from M. binchuanensis , M. binlingensis , M. damrei , M. gigantica , M. minor , M. nasuta , M. nankiangensis , M. oropedion , M. pachyproctus , M. spinata , M. stejnegeri , M. takensis , M. wuliangshanensis , M. wushanensis , M. zhangi , and M. zunhebotoensis (vs. tubercle lacking in the latter) and differs from M. carinense , M. feae , M. gerti , M. hansi , M. intermedia , M. kalimantanensis , M. koui , M. liboensis , M. microstoma , M. palpebralespinosa , M. popei , M. shuichengensis , and M. synoria (vs. having a prominent and elongated tubercle at the edge of each upper eyelid in the latter).

With its tongue not notched behind, Megophrys xianjuensis sp. nov. differs from M. ancrae , M. baolongensis , M. binlingensis , M. boettgeri , M. carinense , M. cheni , M. chuannanensis , M. damrei , M. dringi , M. fansipanensis , M. feae , M. feii , M. flavipunctata , M. gerti , M. glandulosa , M. hoanglienensis , M. huangshanensis , M. insularis , M. jiulianensis , M. jingdongensis , M. kalimantanensis , M. kuatunensis , M. liboensis , M. mangshanensis , M. maosonensis , M. medogensis , M. minor , M. nankiangensis , M. nanlingensis , M. omeimontis , M. oropedion , M. pachyproctus , M. parallela , M. popei , M. robusta , M. sangzhiensis , M. shapingensis , M. shuichengensis , M. spinata , M. vegrandis , M. wawuensis , M. zhangi , and M. zunhebotoensis (vs. tongue notched behind in the latter).

By toes rudimentary webbing at base, Megophrys xianjuensis sp. nov. differs from M. brachykolos , M. carinense , M. flavipunctata , M. jingdongensis , M. jinggangensis , M. lini , M. major , M. palpebralespinosa , M. popei , M. shuichengensis , and M. spinata (vs. at least one-fourth webbed in the latter).

By heels overlapping when thighs are positioned at right angles to the body, Megophrys xianjuensis sp. nov. differs from M. acuta , M. brachykolos , M. dongguanensis , M. huangshanensis , M. kuatunensis , M. nankunensis , M. obesa , M. ombrophila , and M. wugongensis (vs. heels not meeting when thighs are positioned at right angles to the body in the latter).

By tibiotarsal articulation reaching forward to the region between tympanum and eye when hindlimb is stretched along the side of the body, Megophrys xianjuensis sp. nov. differs from M. baolongensis , M. nankiangensis , M. pachyproctus , M. serchhipii , M. shuichengensis , and M. tuberogranulata (vs. reaching posterior corner of the eye in the latter); differs from M. daweimontis , M. glandulosa , M. lini , M. major , M. medogensis , M. obesa , and M. sangzhiensis (vs. reaching the anterior corner of the eye or beyond eye or nostril and tip of snout in the latter); differs from M. leishanensis (vs. reaching middle part of eye); differs from M. mufumontana (vs. reaching tympanum in males and to the eye in females).

By having an internal single subgular vocal sac in male, Megophrys xianjuensis sp. nov. differs from M. caudoprocta , M. shapingensis , and M. shuichengensis (vs. vocal sac absent in the latter).

By having nuptial pads and nuptial spines on the dorsal base of the first and second fingers in breeding male, Megophrys xianjuensis sp. nov. differs from M. acuta , M. feii , M. shapingensis , and M. shuichengensis (vs. nuptial pads and nuptial spines lacking in the latter); differs from M. boettgeri , and M. elfina (vs. nuptial pads and nuptial spines only on the first finger in the latter).

Megophrys boettgeri and M. kuatunensis were suggested to be distributed in Zhejiang Province, China and might be sympatric with Megophrys xianjuensis sp. nov. (Fei et al. 2016; Wang et al. 2017b). The new species can be distinguished from these species by a series of morphological characters as follows. The new species vs. M. boettgeri : vomerine ridges present vs. vomerine ridges absent, tibiotarsal articulation reaching forward to the region between tympanum and eye when hindlimb is stretched along the side of the body vs. tibiotarsal articulation reaching forward to eye, having nuptial pads and nuptial spines on the dorsal base of the first and second fingers in breeding male vs. nuptial pads and nuptial spines only on the first finger, heels overlapping when thighs are positioned at right angles to the body vs. heels just meeting, light round patches on the shoulder absent vs. present. The new species vs. M. kuatunensis : heels overlapping when thighs are positioned at right angles to the body vs. heels not meeting, toes with rudimentary webbing at bases vs. toes without webbing.

Molecular phylogenetic analyses revealed that the new species was genetically closer to M. lishuiensis . The new species can be distinguished from M. lishuiensis by a series of morphological characters as follows. Vomerine ridges present vs. vomerine ridges absent; heels overlapping when thighs are positioned at right angles to the body vs. heels just meeting or not meeting; light round patches on the shoulder absent vs. present; having significantly lower ratios of UEW, ED, TYD, LW and TW to SVL in males; and having significantly higher ratios of UEW, ED and HAL to SVL in females (all p -values <0.05; Table 3 ).

Distribution and habitats.

Megophrys xianjuensis sp. nov. is known from the type locality, Xianju County, Zhejiang Province, China at elevations between 320-480 m a.s.l. This new species is frequently found on stones in the streams in the subtropical montane forests (Fig. 5E ; Fig. 9 ). Six sympatric amphibian species, i.e., Amolops wuyiensis , Odorrana tianmuensis , O. graminea , O. tormota , Limnonectes fujianensis , and Quasipaa spinosa , were found.

Etymology.

The specific epithet xianjuensis refers to Xianju County, Zhejiang Province, China, where the type locality of the species is located. We propose the common name "Xianju horned toad" in English and Xian ju Jiao Chan in Chinese.

Figures

Figure 1. Localities for specimens used in this study. 1, the type locality of Megophrys xianjuensis sp. nov., Xianju County, Zhejiang Province, China; 2. the common type locality of M. boettgeri (black) and M. kuatunensis (purple), Wuyi Mountain, Nanping County, Fujian Province, China; 3, the type locality of M. lishuiensis, Lishui City, Zhejiang Province, China.

Figure 2. Maximum Likelihood tree of the genus Megophrys reconstructed based on the 16 S rRNA and COI gene sequences. ML bootstrap support / Bayesian posterior probability was denoted beside each node. Samples 1 - 89 refer to Table 1.

Figure 3. Plots of the first principal component (PC 1) versus the second (PC 2) for Megophrys xianjuensis sp. nov. and M. lishuiensis from principal component analyses A male B female.

Figure 4. Holotype CIBXJ 190503 of Megophrys xianjuensis sp. nov. and holotype CIBWYF 00164 of M. lishuiensis A, B dorsal view and ventral of Megophrys xianjuensis sp. nov., respectively C, D dorsal view and ventral of M. lishuiensis, respectively E oral of Megophrys xianjuensis sp. nov. showing vomerine ridges (red arrows) F oral of M. lishuiensis showing no vomerine ridge G ventral view of hand of Megophrys xianjuensis sp. nov. H ventral view of hand of M. lishuiensis I ventral view of foot of Megophrys xianjuensis sp. nov. J ventral view of foot of M. lishuiensis.

Figure 5. Photos of the holotype CIBXJ 190503 of Megophrys xianjuensis sp. nov. in life A dorsal view B ventral view C ventral view of hand D ventral view of foot E dorsolateral view showing the single external subgular vocal sac (red arrow).

Figure 6. Colour variation in Megophrys xianjuensis sp. nov. in life A, B dorsolateral view of a male (Voucher: CIBXJ 190501) and a female (Voucher: CIBXJ 190505), respectively C, D ventral view of CIBXJ 190501 and CIBXJ 190505, respectively.

Figure 7. Advertisement call of the holotype CIBXJ 190503 of Megophrys xianjuensis sp. nov. A waveform showing one note B waveform showing three notes of one advertisement call C sonogram showing one note D sonogram showing three notes of one call.

Figure 8. Tadpole specimen CIBXJT 19050704 of Megophrys xianjuensis sp. nov. A dorsal view B lateral view C ventral view. Arrows indicate two dotted lines on flank of dorsum from mouth to fin.

Figure 9. Habitats of Megophrys xianjuensis sp. nov. in the type locality, Xianju County, Zhejiang Province, China A landscape showing mountain forests B a mountain stream where toads of the new species occur.