Scutiger luozhaensis, Shi & Sui & Ma & Ji & Bu-Dian & Jiang, 2023

Shi, Sheng-Chao, Sui, Lu-Lu, Ma, Shun, Ji, Fei-Rong, Bu-Dian, A-Yi & Jiang, Jian-Ping, 2023, A new Asian lazy toad of the genus Scutiger Theobald, 1868 (Anura, Megophryidae) from southern Tibet, China, ZooKeys 1187, pp. 31-62 : 31

Scutiger luozhaensis sp. nov.

Figs 4 , 5 , 6 , 7 , 8

Type material.

Holotype: CIB 119115, adult male, collected from Gari Village, Se Town, Luozha County, Tibet, China (28.2413°N, 90.7842°E, 4150 m a.s.l.) by Sheng-Chao Shi, Peng Yan and Shun Ma on August 3rd, 2021. The holotype was found on alpine meadow aside a stream at night.

Paratypes: 8 specimens: CIB 119116, adult male, collected at the same date and location as holotype; CIB 119117-119118, two adult males, and CIB 119122-119123, two adult females collected at Gari village, Se Town (28.2209°N, 90.8290°E, 3970 m a.s.l.); CIB 119119, adult female, collected adjacent to holotype at Gari village, Se Town (28.2216°N, 90.8283°E, 3795 m a.s.l.); CIB 119120, adult female, collected adjacent to holotype at Gari village, Se Town (28.2459°N, 90.7772°E, 4228 m a.s.l.); CIB 119121, adult female, collected at Quzangbu valley, Lakang Town (28.1189°N, 91.1862° E, 3667 m a.s.l.).

Diagnosis.

Scutiger luozhaensis sp. nov. is assigned to the genus Scutiger by the followings: (1) maxillary teeth absent or indistinct; (2) vomerine teeth absent; (3) tympanum and tympanic ring entirely absent; (4) pupil vertical, (5) femoral glands indistinct; (6) pectoral and axillary gland present in males, and covered by black spines in males in breeding condition; (7) inner three fingers with black nuptial spines in males in breeding condition ( Fei et al. 2009; Fei and Ye 2016).

Scutiger luozhaensis sp. nov. is diagnosed from its congeners by a combination of the following characters: (1) body moderate, male body length 47.0-67.2 mm (n = 13), female body length 49.8-66.2 mm (n = 8); (2) maxillary teeth and budding absent; (3) numerous tiny dense nuptial spines present on dorsal surface of fingers I, II and inner surface of finger III of males in breeding condition with similar size; (4) spine patches on belly of males in breeding condition absent; (5) spines on inner surface of forearm and upper arm of males in breeding condition absent; (6) small patches of black spines present near armpit of males in breeding condition absent; (7) adult males without vocal sac; (8) some large warts and tubercles on dorsum gathered into short skin ridges with several spines present on top; (9) space between upper eyelids wider than upper eyelids; (10) spots or irregular cross bands on limbs absent; (11) webbing between toes rudimentary; (12) coloration of dorsal body olive brown to bronze.

Description of holotype.

Adult male, body moderate (SVL 56.4, body weighted 12.5 g in life, all morphometric measurements in mm).

Head small (HW 17.2, HL 16.6, HH 9.4, ACED 8.0, PCED 13.7), nearly wide as long (HW/HL 1.04), relatedly flat (HH/HW 0.55); snout short (SL 6.5), rounded, slightly protruding beyond jaw, rostral appendage absent, canthus rostralis obtuse, loreal region oblique and concave; nostril oval, closer to tip of snout than eyes (SND 3.3, END 4.1); internarial distance larger than distance from anterior margin of eye to nostril (IND/END 1.22); eyes moderate in size (ED 5.9, ED/HL 0.36); pupil narrow and vertical; distance between upper eyelids smaller than distance between nostrils, but larger than upper eyelids width (IOS 4.5, IND 5.0, UEW 3.8), interorbital space flat; tympanum absent; supratympanic ridge thick, from posterior part of upper eyelids to shoulder; pineal ocellus not present; maxillary teeth and budding absent; tongue oval, not emarginate behind, without papillae and medial lingual sulcus; choanae oval, located against anterior border of palate, widely separated; vomerine ridges and vomerine teeth absent; choana small and oval, widely apart from each other; vocal sac and openings absent.

Forelimbs long (LAL 14.6, LAW 5.6, HAL 12.6, LAW/LAL 0.38); fingers slender, without web and lateral dermal fringes, relative length of fingers: I<II<IV<III; fingertips rounded, not dilated; subarticular tubercles and supernumerary tubercles below the base of finger absent; inner metacarpal tubercles distinct and flat, positioned at the base of finger I, slightly smaller than outer metacarpal tubercles; nuptial pad present on dorsal surface of finger I, II and inner surface of finger III, nuptial spines on finger I and II numerous dense and tiny, but faded on finger III.

Hindlimbs moderately short (TL 21.0, TL/SVL 0.37); tibiotarsal articulation reaching the shoulder when hindlimbs stretching forward; heels widely separated when hind limbs are flexed and held perpendicular to body; thighs slightly longer to tibia but shorter than feet (THL 21.4, TL 21.0, FL 25.0, TFL 36.0); tibia moderate (TW 5.9, TW/THL 0.28); toes slender, relatively lengths I<II<V<III<IV, rudimentary webbed, webbing formula: I ½-1II½-2III1½-2½IV2½ -2V, with narrow lateral fringes, tips rounded and not dilated; subarticular tubercles indistinct; dermal ridges continuous on under toes; inner metatarsal tubercle elliptical and prominent (IMTL 4.1), outer metatarsal tubercle absent; tarsal fold thick.

Skins rather rough on dorsal surface; large warts and tubercles scattered on dorsal body, some arranged in rows, some gathered into short skin ridges; keratinized spines on warts and tubercles not observed, but there are one to six separated pale colored tiny granules on top of each dorsal tubercle (Fig. 4C ), presumedly to be remains of faded keratinized spines; skins on head between and before eyes relatively smooth; tiny pale-colored granules also present along supratympanic ridge and on upper eyelids; temporal region with several small granules, loreal region relatively smooth; upper and lower lips without spines present but also has tiny pale-colored granules, spines presumedly to be faded with the ending of breeding season; skins on dorsal limbs thick, scattered with small granules; skin on dorsal tibiotarsal region with developed dermal glands; dorsolateral skin folds absent; ventral body, flanks and ventral limbs smooth; ventral hands and feet smooth; dozens of fine rounded tubercles scattered around cloaca; a pair of pectoral spine patches faded but with a pair of pectoral skin pads left on chest; axillary glands present and relatively smaller, spines on axillary glands had faded; femoral glands absent.

Coloration.

In life (Fig. 4 ), skin on dorsal surface of body and limbs basically deep olive brown; anterior head pale brown; granules on top of warts and tubercles of dorsal body, limbs, supratympanic ridge and upper eyelids pale yellowish; tubercles around cloaca yellow; ventral surface generally olive grey, more purplish on chest and throat; ventral hands and feet olive yellow; nuptial spines on fingers black; iris basically dark, with numerous bronze pigments and irregular dark gaps; tongue flesh colored. In preservative (Fig. 5 ), dorsal body mostly black-brown, tubercles on flanks nearly black with yellowish white point, dorsal surface of finger I, II and inner surface of finger III pale yellowish; ventral belly pale grayish brown; ventral limbs, ventral chest and ventral head yellowish brown; granules on lips, metacarpal tubercles, tubercles around cloaca and axillary glands grey; iris dark with uniformly distributed bronze pigments, upper and lower half not bicolored.

Variation

Morphological measurements of the adult type series are summarized in Table 4 (see detailed measurements in Suppl. material 5). The other specimens generally exhibit morphological consistency with the holotype, albeit with some variations. The arrangement and shape of large spiny tubercles on the dorsal surface of body vary among individuals, but all have large longitudinal tubercles; warts and tubercles on dorsum are larger and fewer on some females (Fig. 6C, D ), and smaller on juvenile (Fig. 6G ). Dorsal coloration varies from olive brown to bronze in adults (Fig. 6A, C, E, F ), while darker in some juveniles (Fig. 6G, H ). Ventral coloration varies from olive grey to immaculate yellowish (Fig. 6B ). Keratinized spines on warts and tubercles did not fade on a male from Lakang Town in early August (Fig. 6A ).

Sexual dimorphism.

Males are averagely smaller than females, have relatively longer limbs and wider lower arms (Table 4 ). In adult males, a pair of pectoral glands and a pair of slightly larger axillary glands present on chest, all of them covered by tiny dense black spines in breeding season (Fig. 7 ). Dorsal surface of first and second fingers, and inner surface of third finger with tiny dense black nuptial spines on adult males in breeding season. Females with a pair of axillary glands, but no spines covered. No observable lineae masculinae present from ventral view of body in males. Tubercles around cloaca on females (e.g., Fig. 6D ) fewer and less distinct compared with those on males. Vocal sac and opening absent in both gender.

Tadpoles. Their description is based on two tadpoles preserved in 75% ethanol at stage 32 (CIB 119630-1) and 29 (CIB 119630-2) from Lakang Town, Luozha County (Fig. 8 , Table 5 ). Identification of the tadpoles was confirmed by DNA analyses. TOL 40.9-50.7 mm, BL 17.7-18.6 mm, tails length average 152% of body; body elliptical in dorsal view, snout rounded; eyes moderate, dorso-laterally positioned; nostril oval, located in the middle of tip of snout and eyes; oral disc ventrally located; papillae on lips well developed, larger on upper labium; tooth row formula I:3+3/3+3:I or I:3+3/2+2:I; spiraculum sinistral, extended as a short tube, spiracular opening oval; tail musculature robust and greatly narrowing to tail tip. Coloration in preservative greyish brown on dorsal view; semitransparent pale grey on ventral view; tail uniformly pale brown without distinct dark spots.

Distribution and ecology.

Scutiger luozhaensis sp. nov. is currently only known from Luozha county, Shannan Prefecture, Tibet Autonomous Region, China and expected to be found in adjacent areas of Bhutan (Fig. 9 ). It is a common species in its habitat, which includes mountain streams, moist scrub or forest floors near streams, and ponds of alpine wetlands (Fig. 10 ). The elevation records of the new species range from 3268 m to 4437 m. Tadpoles at stages 29, 39, and 48 were recorded in a slack head stream from late July to middle August and it is thought that the tadpoles overwinter. No calls were heard in the field from late July to middle August. Spines on nuptial pads and chest of most adult males had faded when found during field work; the breeding season for the species is here recorded to include June. Nanorana parkeri (Stejneger, 1927) was found to occur with the new species. Although S. boulengeri was also found in Luozha County, it was found near an alpine lake at elevation 4623 m, not sympatrically with S. luozhaensis sp. nov., which was found restricted to lower elevation.

Etymology.

The specific epithet luozhaensis is named after the type locality, Luozha county. We propose the English common name Luozha lazy toad and the Chinese name common name 洛扎齿突蟾 ( Luò Zhā chǐ Tū Chán).

Figures

Figure 4. Holotype of Scutiger luozhaensis sp. nov. (CIB 119115) in life A dorsolateral body B dorsal body C short skin ridges and tubercles on dorsal body D ventral body E lateral head F ventral feet G ventral hand H ventral view of maxillary showing no vomerine or maxillary teeth. Photographed by SCS.

Figure 5. Holotype of Scutiger luozhaensis sp. nov. (CIB 119115) in preservative A dorsal and B ventral body. Photographed by LLS.

Figure 6. Variations of Scutiger luozhaensis sp. nov. A, B dorsal and ventral view of an adult male from Lakang Town C, D dorsal and ventral view of an adult female from Lakang Town E dorsolateral view of an adult female from Lakang Town F dorsolateral view of adult female CIB 119120 from Se Town G, H dorsolateral and ventral view of juvenile CIB QZ 2021115 from Shengge Town. Photographed by SCS.

Figure 7. Spine patches and nuptial spines of a male Scutiger luozhaensis sp. nov. CIB QZ 2021090 from Shengge Town, Luozha County A outer smaller axillary spine patches and inner larger pectoral spine patches B tiny dense nuptial spines on dorsal surfaces of fingers I, II, and inner surface of finger III. Photographed by SCS.

Figure 8. Tadpole of Scutiger luozhaensis sp. nov. at Gosner stage 29 from Lakang Town, Luozha County A dorsal view B lateral view C ventral view D mouth part of CIB 119630 - 1 E mouth area of CIB 119630 - 2. Photographed by LLS.

Figure 9. Type localities of Scutiger luozhaensis sp. nov. and other species in Clade D.

Figure 10. Habitats of Scutiger luozhaensis sp. nov. in Luozha County, Tibet, China A Qisehai valley in Lakang Town B alpine wetlands in Gari Village, Se Town at elevation 4437 m C moist mixed coniferous and broad-leaved in Lajiao Town at elevation 3700 m D Pugong stream and the Luozha Canyon in Lakang Town at elevation 3268 m. Photographed by SCS.