Oreolalax yanyuanensis, Hou & Zheng & Yu & Wang & Chen & Xie, 2024

Hou, Yin Meng, Zheng, Pu Yang, Yu, Hao Qi, Wang, Bin, Chen, Xiao Hong & Xie, Feng, 2024, A new toad of Oreolalax Myers & Leviton, 1962 (Anura, Megophryidae) from Sichuan Province, southwest China, ZooKeys 1212, pp. 109-127 : 109-127

Oreolalax yanyuanensis sp. nov.

Figs 3 , 4 , 5 , 6

Type material.

Holotype. • CIBSH 20230603020 (Fig. 3 ), adult male, collected by F. Xie from Shuhe town , Yanyuan county, Sichuan Province (27.473443 ° N, 101.789624 ° E, 3108 m a. s. l.) China . Paratypes. • Seven adult males collected from a small stream of Shuhe town (27.475205 ° N, 101.789108 ° E, 3127 m a. s. l.); on June 3, 2023 ( CIBSH 20230603016–19 , CIBSH 20230603021 , CIBSH 20230603023–24 ) by P. Y. Zheng, H. Q. Yu and F. Xie .

Other specimens.

• Seven tadpoles ( CIBSH 20230603 kd 01–07) collected from a small stream of Shuhe town (27.466241 ° N, 101.786933 ° E, 3032 m a. s. l.); on June 3, 2023; by P. Y. Zheng, H. Q. Yu and F. Xie .

Diagnosis.

The new species is assigned to genus Oreolalax based on following characters: maxillary teeth prominent; back rough, scattered with large warts, covered with oval black spots; pupil vertical; tongue moderately broad, notched behind; femoral glands prominent; pectoral and axillary gland present in males.

The new species differs from its congeners by a combination of the following characters: body size moderate 39.8–52.8 mm in male; head broad; tympanum hidden; distinct black spots present on flanks; toes 1 / 3 webbed, with broad lateral fringes; dorsal body deep brown or yellowish-brown; belly smooth, middle yellow, scattered fine mottling, abdominal margin more spotted; skin on dorsum rough with dense and varied size granules, warts are covered with dark spots or no spots; iris light orange or light yellow above, creamy silver white bellow; and middle pectoral glands are evident in males.

Holotype description

(Fig. 3 ). Body size moderate ( SVL 47.4 mm). Head width greater than length ( HW 17.6 mm, HL 16.2 mm); maxillary teeth developed, without vomerine teeth or acoustic sac; snout bluntly rounded in dorsal view, slightly projecting over lower jaw, longer than eye diameter (SL 6.3 mm, ED 5.9 mm); canthus rostralis indistinct, interorbital distance ( IOD 5.0 mm) wider than internarial distance ( IND 3.5 mm), distinctly larger than upper eyelid ( UEW 3.0 mm); nostrils oval, closer to tip of snout than eyes ( EN 3.1 mm, NS 3.0 mm); no tympanic membrane; supratympanic fold broad; tongue moderately broad, notched behind; pupil vertical.

Fingers moderate, relative finger lengths: I <II <IV < III; finger tips slightly dilated; subarticular tubercles absent; inner palmar tubercle large, nearly rounded, outer palmer tubercle small, oval, completely separated.

Hindlimbs relatively long, length 177 % of body length; shank length subequal to thigh length, slightly shorter than foot length ( THL 23.4 mm, TL 23.8 mm, FL 24.4 mm); heels partially overlap when thighs are positioned at right angles to the body and tibia-tarsal articulation reaches the middle eye when leg stretched; toes 1 / 3 webbed with distinct fringes; inner metatarsal tubercle long oval, small.

In life, dorsal body and head rough, back with moderate sparse granules, relatively small warts on head; with dark-brown triangular between eyes; dorsal arms and hindlimbs with small granules and bumps; distinct warts cover the fold and posterior of snout. Ventral skin smooth; pectoral glands flat; pectoral glands evident, chest spines and finger spines not visible; femoral glands slightly swollen, distinct on posterior thigh. Small verrucous granules around the anus.

Large brown markings on dorsum, dark brown triangular pattern between eyes; large markings dorsum brown; ventral skin medium yellow, with scattered little dark speckling; supratympanic fold dark brown; lateral head and flanks brown with dark patches; throat mixed pink and orange yellow, margin with small beige warts; chest pink and the pectoral glands medium yellow; forelimbs covered with black irregular spots; dorsal limbs yellowish-brown, the spots and stripes of dorsal upper arms and tibiotarsal articulation black; ventral arms, thigh, tibia medium yellow with flesh marking; upper iris light orange yellow, lower iris creamy white, both parts embedded black mesh lines.

In preservative (75 % ethanol), dorsal body and head dark grey; irregular spots in forelimbs, black longitudinal stripes on hindlimbs; ventral surface beige, throat and arms beige white; with grayish-brown speckling; mandibular margin warts white; pectoral glands and ventral of the hindlimb beige yellow, scattered black spots; hand and feet dark grey, finger tips and palms grayish-white, inner metatarsal tubercle grey; lateral grey on snout and undereye, patches black; skins beneath supratympanic fold dark grey, flanks grey, covered with creamy white warts, black spots around the edges of warts. Perianal warts and femoral gland creamy-white (Fig. 4 ).

Tadpoles.

Measurements see Suppl. material 4. Description based on preserved tadpole CIBSH 20230603 kd 01 at Gosner stage 37 ( TOL 62.3 mm, BL 20.6 mm) (Fig. 5 ). The mouth is located below the rostral end; labial tooth row formula I: (5 + 5) / (5 + 5): I; the upper lip papillae is large, the central missing length is close to 3 papillae position, the lower lip papillae is small and pointed; and there are small teeth on the auxiliary processes of the oral corner; jaw sheaths strong, serrated, the lip teeth are daggerlike; body elliptical in dorsal view, body width is 113 % of height; snout rounded, eye positioned dorsolateral; SL 29 % of BL; eyes relatively small, ED 8.3 % of BL; nostrils near oval; tail long and muscled, TAL 210 % of BL; TAH 113 % of BH; TBW 44 % of BW; SS 53 % of BL. Body dark brown in the back and lateral view, creamy yellow in the ventral; tail brown; the single opening of the spiracle lateral, without a free distal tube; tail end blunt; faint brown cloud spots faintly visible on upper caudal fin, caudal fin light and broad.

Variation.

Measurements variation of specimens see Suppl. material 1 (unit in mm). Half of the individuals had faint markings on the abdomen ( CIBSH 20230603016, CIBSH 20230603018, CIBSH 20230603021, CIBSH 20230603023), and half had more markings on the abdomen ( CIBSH 20230603017, CIBSH 20230603019, CIBSH 20230603020, CIBSH 20230603022). Color of each specimen was brownish-yellow ( CIBSH 20230603018, CIBSH 20230603023), medium brown ( CIBSH 20230603016, CIBSH 20230603019, CIBSH 20230603021, CIBSH 20230603022), or dark brown ( CIBSH 20230603017, CIBSH 20230603020). Dorsal markings are obvious in most individuals ( CIBSH 20230603016–22), except one ( CIBSH 20230603023). Lateral markings are obvious in most individuals ( CIBSH 20230603016–21, CIBSH 20230603023), except one ( CIBSH 20230603022). Color of warts covering the back was yellowish-brown ( CIBSH 20230603022), light brown ( CIBSH 20230603023), brown ( CIBSH 20230603016, CIBSH 20230603020), dark brown ( CIBSH 20230603018, CIBSH 20230603019), black ( CIBSH 20230603017, CIBSH 20230603021). Wart size was relatively small in some individuals ( CIBSH 20230603017, CIBSH 20230603020, CIBSH 20230603021, CIBSH 20230603023) and relatively large in others ( CIBSH 20230603016, CIBSH 20230603018, CIBSH 20230603022, CIBSH 20230603023). Half of the specimens had dark temporal folds ( CIBSH 20230603017, CIBSH 20230603018, CIBSH 20230603020, CIBSH 20230603021), in others the folds were generally lighter ( CIBSH 20230603016, CIBSH 20230603019, CIBSH 20230603022, CIBSH 20230603023).

Measurements variation of tadpoles see Suppl. material 4. The dorsal color of CIBSH 20230606 kd 01, CIBSH 20230606 kd 03–04, CIBSH 20230606 kd 05–06 is nearly black, while numbers CIBSH 20230606 kd 02 and CIBSH 20230606 kd 07 are dark brown. Light brown cloud spots on the upper caudal fin, ranged from faintly visible ( CIBSH 20230606 kd 01, CIBSH 20230606 kd 03) to obvious ( CIBSH 20230606 kd 02, CIBSH 20230606 kd 04–07).

Comparisons.

In Oreolalax , 19 species occur in southwest China and northern Vietnam. Oreolalax yanyuanensis sp. nov. could be easily distinguished from them by several characters (Suppl. material 5). By having moderate body size (39.8–52.8 mm) in males, the new species differs from O. major (vs. 59.2–68.7 mm), O. popei (vs. 60.0–69.0 mm), O. rhodostigmatus (vs. 57.5–73.5 mm), O. sterlingae (vs. 36.8 mm), and O. weigoldi (vs. 58.2 mm).

By having head width> head length, the new species differs from O. chuanbeiensis , O. nanjiangensis (vs. head width ≈ head length), O. weigoldi (vs. head width = head length), O. multipunctatus , O. popei , O. rhodostigmatus , and O. schmidti (vs. head width <head length).

By having no tympanum, the new species differs from O. liangbeiensis , O. major , O. longmenmontis , O. sterlingae , O. chuanbeiensis , O. multipunctatus , O. nanjiangensis , O. pingii , O. popei , O. puxiongensis , O. schmidti , O. weigoldi (vs. hidden), O. lichuanensis , O. omeimontis (vs. concealed or slightly visible), and O. rhodostigmatus (vs. rather visible).

By having 1 / 3 toe webbing, the new species differs from O. puxiongensis , O. schmidti (vs. no webbing), O. longmenmontis , O. sterlingae , O. lichuanensis , O. multipunctatus , O. nanjiangensis , O. omeimontis , O. pingii , O. popei , O. rhodostigmatus (vs. rudimentary), O. xiangchengensis , and O. weigoldi (vs. well webbed).

By having triangular pattern between eyes, the new species differs from O. rugosus , O. liangbeiensis , O. major , O. xiangchengensis , O. sterlingae , O. chuanbeiensis , O. granulosus , O. lichuanensis , O. nanjiangensis , O. pingii , O. popei , O. rhodostigmatus , and O. weigoldi (vs. no triangular pattern).

By having middle spiny patches on the chest, the new species differs from O. liangbeiensis , O. major , O. xiangchengensis , O. chuanbeiensis , O. granulosus , O. weigoldi , O. omeimontis (vs. large patches), O. pingii , O. rhodostigmatus , O. jingdongensis , O. lichuanensis (vs. relatively large patches), O. longmenmontis , O. sterlingae , O. multipunctatus , O. nanjiangensis , and O. popei (vs. small patches).

By having dark bars on the limbs, the new species can differ from O. rugosus (vs. no or irregular), O. xiangchengensis , O. pingii , and O. puxiongensis (vs. no).

By having brown yellow or medium yellow scattered variable brown spots on the belly, the new species can differ from O. rugosus (creamy yellow or yellow, no spots), O. liangbeiensis (creamy white without any spots), O. xiangchengensis (light brown, no spots), O. sterlingae (cream with dark marbling), O. granulosus (yellow-white or with fine light gray veins), O. lichuanensis (purplish with dark brown flecks), O. multipunctatus (grey brown, with few or without spots), O. nanjiangensis (without dark spots), O. pingii (gray-white, no spots), O. popei (brown-red, fully covered with small gray-brown spots), O. puxiongensis (grayish-yellow, no spots), O. rhodostigmatus (grayish-brown, no spots), O. schmidti (entirely purple-yellow, no spots), O. weigoldi (light brown with dark cloudy spots on ventrolateral), and O. longmenmontis (flesh red and greyish-white with some black speckles).

Oreolalax yanyuanensis is genetically closest to O. rugosus , O. liangbeiensis and O. major . In addition to the morphological differences (Fig. 6 ; Suppl. material 5), the new species distinctly differs from these three in measurement proportions. The new species can differ from O. rugosus by having larger LFT, TL, and smaller IN, IOD, UEW, TW. The new species distinctly differs from O. liangbeiensis by having larger HL, HW, ED, LAHL, TL, LFT and smaller SL, IOD. The new species distinctly differs from O. major by having larger HW, ED, TL, LFT and smaller SL, IN, IOD (Table 2 ).

In elevational distribution, the new species (occurring between 3000–3200 m) can be distinguished from some Oreolalax species occurring below 3000 m (a. s. l.) as follows: O. major (vs. 1600–2000 m), O. longmenmontis (vs. 1300–1450 m), O. chuanbeiensis (vs. 2000–2200 m), O. granulosus (vs. 2300–2450 m), O. jingdongensis (vs. 2300–2450 m), O. lichuanensis (vs. 1790–1840 m), O. multipunctatus (vs. 1800–1920 m), O. nanjiangensis (vs. 1600–1856 m), O. omeimontis (vs. 1050–1800 m), O. popei (vs. 1000–2000 m), O. puxiongensis (vs. 2600–2900 m), O. rhodostigmatus (vs. 700–1790 m), O. schmidti (vs. 1700–2400 m), and O. sterlingae (vs. 2900 m).

Etymology.

The specific epithet “ yanyuan ” refers to the type locality of the species, Yanyuan County, Sichuan Province. We suggested the common name as “ Yanyuan toothed toad ”, and the Chinese name as “ Yan Yuan Chi Chan (盐源齿蟾) ”.

Distribution and ecology.

Oreolalax yanyuanensis sp. nov. is currently only known from the type locality, Shuhe town, Yanyuan county, Sichuan Prov., China at elevations of 3000–3200 m. The new species inhabits subtropical alpine scrub and swamp, and was found in small montane streams (Fig. 7 ). The breeding season is currently uncertain; it is speculated that it breeds in April or May based on the tadpole development stage. Four sympatric amphibian species ( Bombina maxima Boulenger, 1905 ( Boulenger 1905), Rana chaochiaoensis Liu, 1946 ( Liu 1946), Panophrys binchuanensis Ye & Fei, 1995 ( Ye and Fei 1995) and Nanorana sichuanensis Dubois, 1987 ( Dubois 1987 “ 1986 ” )) were found in the same habitat.

Figures

Figure 3. Photos of the holotype CIBSH 20230603020 of Oreolalax yanyuanensis sp. nov. A dorsal view B ventral view; the white arrow indicates the position of the pectoral gland C lateral view D ventral view of hand E ventral view of foot.

Figure 4. The holotype CIBSH 20230603020 of Oreolalax yanyuanensis sp. nov. in preservative A dorsal view B ventral view C lateral view D dorsal view of the left hand E ventral view of the left foot.

Figure 5. Photos for the tadpole CIBSH 20230603 kd 01 in preservative of Oreolalax yanyuanensis sp. nov. A dorsal view B ventral view C lateral view D ventral view of head.

Figure 6. Specimen photos of Oreolalax yanyuanensis sp. nov. and its relative species A, B dorsal and ventral view of the holotype CIB 25333 of O. rugosus C, D dorsal and ventral view of the topotype CIB 24678 of O. liangbeiensis E, F dorsal and ventral view of the topotype CIB 24695 of O. major G, H dorsal and ventral view of the topotype CIBSH 20230603020 of Oreolalax yanyuanensis sp. nov. Scale bar: equal to 10 mm.

Figure 7. Habitats of Oreolalax yanyuanensis sp. nov. in southeastern Hengduan Mountains region, Sichuan Province, China A, B, C adults’ habitats D tadpoles’ habitat.