Rana zhijinensis Luo, Xiao & Zhou, 2022

Yan, Shasha, He, Qingqing, Luo, Tao, Xu, Cheng, Deng, Huaiqing, Xiao, Ning & Zhou, Jiang, 2022, Description of a new species of the genus Rana (Anura: Ranidae) from western Guizhou, China, integrating morphological and molecular genetic data, Zoological Systematics 47 (4), pp. 275-292 : 282-289

Rana zhijinensis Luo, Xiao & Zhou , sp. nov. ( Figs 5–6 , Table 5)

Holotype. ♂, adult, GZNU2018081606 ( Fig. 5 ), Guiguo Town (26°33'12.75"N, 105°50'26.90"E; elev. 1525 m), Zhijin County, Guizhou Province, China, 16 August 2018, coll. Tao Luo.

Paratypes. 6♂ 1♀, adult, GZNU2018081601–1605 , GZNU2018081607–1608 , same data as holotype, coll. Tao Luo, Kai Gao and Huan He ; 3♂ 3♀, adult, GZNU2019080401–0402 , GZNU2019080501–0504 , same locality as holotype, 4 August 2019, coll. Tao Luo.

Etymology. The specific epithet “ zhijinensis ” is in reference to the type locality, Zhijin County, Guizhou, China. For the common name, we suggest “Zhijin Brown Frog”, and for the Chinese name “Zhi Jin Lin Wa (ḬḔflḧ)”.

Diagnosis. The new species is assigned to the genus Rana based on the morphological characteristics typical for this genus, including the possession of a prominent dorsolateral fold, a dark temporal mask, and a body that is counter-shaded in various shades of brown.

The species can be distinguished from its congeners by the following combination of morphological characteristics: (1) body medium-sized, SVL = 46.1–53.7mm in adult males (n =8), 54.5–58.6 mm in adult females (n =4); (2) head length equal to head width, HL/HW 1.01 in males and 1.00 in females; (3) internarial distance equal to interorbital distance, HL/HW 1.04 in males females; (4) supratympanic fold present; (5) dorsolateral fold present and thin, extending straight from posterior margin of the upper eyelid to above the groin; (6) tympanum diameter significantly smaller than eye diameter, ED/TD = 0.64 in males and 0.71 in females; (7) fingers circummarginal grooves and webbed absent, relative finger lengths I < II < IV < III; (8) toes circummarginal grooves absent, toe webbing present, toe webbing formula I 1½–2 II 1⅓–2⅔ III 2–2⅔ IV 2⅔–1 V, relative toe lengths I < II < III < V < IV; (9) supernumerary tubercles present only below the base of fingers III and IV; (10) breeding males possess dark gray-blackish nuptial pad separated into three parts with tiny dark gray-blackish tiny spines on finger I; (11) tibiotarsal articulation reaching far forward beyond tip of the snout.

Description (holotype, GZNU 2018081606). Body size large (SVL 53.4mm); head length slightly larger than head width (HL/HW = 1.02); snout short, slightly protruding, and projecting beyond lower jaw in dorsal view, significantly larger than diameter of eye (SL/ED = 1.25); nostril rounded, distinct, slightly closer to snout tip than eye ( NEL / NSL = 1.05); canthus rostralis distinct; internasal distance slightly larger than interorbital distance (IND/ IOD = 1.06) and equal to upper eyelid width (IND/ UEW = 1.00); tympanum rounded, tympanic rim slightly elevated relative to tympanum, tympanum diameter significantly less than diameter of eye (TD/ ED= 0.63); vomerine teeth present, moderately developed, on two oblique ridges; tongue cordiform, deeply notched posteriorly; vocal sacs absent; eyes large, slightly protuberant in dorsal view, eye diameter significantly less than head length (ED/HL = 0.32); dorsolateral fold present and thin, extending straight from posterior margin of upper eyelid to above groin, not curved outward above tympanum supratympanic fold distinct and connected to maxillary gland.

Forelimbs short and robust, lower-arm 0.20 of SVL and hand 0.25 of SVL; fingers slender, webbing and lateral fringes absent; tip of fingers rounded, not expanded, circummarginal grooves absent; relative finger lengths: I < II < IV < III; subarticular tubercles slightly prominent, rounded: 1, 1, 2, 2; distinct, small, rounded supernumerary tubercles present only below base of fingers III and IV; inner metacarpal tubercle indistinct, ovoid, mostly covered by nuptial pad; two outer metacarpal tubercles distinctly separated and small; nuptial pad with tiny dark gray-blackish spines on finger I, divided into three parts, prior two parts completely joined together.

Hindlimbs long and slender, tibia 0.64 of SVL and foot 0.63 of SVL; heels overlapping when hindlimbs flexed at right angles to axis of body; tibiotarsal articulation reaching forward far beyond tip of snout when hindlimb stretched forward alongside of body; foot length slightly less than tibia length (FL/ TIB = 0.98); circummarginal grooves absent; subarticular tubercles prominent 1, 1, 2, 3, 2; toes one and two webbed, toes webbing formula I 1½–2 II 1⅓–2⅔ III 2–2⅔ IV 2⅔–1 V; relative toe lengths I < II < III < V < IV; absence of lateral fringes on lateral edges of toes I and V; two metatarsal tubercles, inner metatarsal tubercle large, ovoid; outer metatarsal tubercle small.

Dorsal skin smooth, with sparse tiny granules; several small granules on flank; maxillary glands relatively developed; ventral surface smooth; tiny granules on lateral body, dorsal surface of limbs, upper edge of eyelid, temporal region, and anterior and posterior edges of tympanum; throat, chest, and belly of thighs being smooth.

Coloration ( Fig. 5 ). In life, dorsal parts of head and dorsum, flank, forelimb, thigh, tibia, and foot brownish with a few and larger irregular black patches laterally; black speckles forming an indistinct linear stripe between eyelids; black edge intermittently present on anterior two-thirds of both sides of dorsolateral fold; loreal region brownish; canthus rostralis below brownish-black; maxillary gland brownish-black; tympanic rim light purple, central light yellow-brown; forelimbs dorsally same color as dorsal surface of body, with four brown-black transverse bars in forearm; dorsum of thigh and tibia present a grayish brown, with 12 distinct dark brown-black transverse bars; an distinct inverted V-shaped black glandular ridge in scapular region and extending backward to middle of dorsal surface of body to form a distinct inverted V-shaped black glandular ridge at posterior end; throat creamy white; chest and anterior third of belly yellowish; ventral surfaces of forelimbs, inner surface of tarsals, inner surface of thighs, and inner surface of shanks red-orange; nuptial pad dark gray-blackish; tubercles around vent yellowish-white. After preservation in 75% ethanol, dorsal surface of body coloration changed to light grey patches; transverse bands on limbs and digits distinct, and coloration changed to lighter colors. Ventral surface white, with greyish-white on chest and throat; ventral surfaces of forelimbs and hindlimbs creamy yellow with brown mottling; hands and toe webs dark grey.

Measurements (in mm). SVL 53.4, HL 18.7, HW 18.3, SL 7.4, IND 3.8, IOD 3.6, UEW 3.8, ED 5.9, TD 3.7, LAHL 24.1, HAL 13.6, HLL 103.9, TIB 34.0, TFL 44.6, FL 33.2, TW 7.6, NED 3.9, NSD 3.7, TED 1.1, IMTL 2.6.

Variations. The basic statistics for measurements present as in Table 2. Females (SVL 56.8± 1.8 mm, n = 4) have slightly larger body size than males (SVL 50.4 ± 2.9 mm, n = 10). Some individual have smaller irregular black patches on the flank, dorsum of the thigh and tibia has seven brown transverse bars, some of which are indistinct ( Fig. 6 ). Adult males lack vocal sacs. In breeding, dark gray-blackish nuptial pads are present on finger I in males.

Comparisons. The new species is assigned to the R. japonica group based on the following morphological characteristics, i.e., digits without circummarginal grooves, and dorsolateral fold distinct, extending straight from the posterior margin of the upper eyelid to above the groin ( Wan et al., 2020). Here, the morphology of the new species with 11 species of the R. japonica group were compared.

The new species is phylogenetically closest to R. chaochiaoensis , but can be morphologically distinguished from the latter by combining the following morphological characteristics: head length equal to head width, HW/HL 1.01 in males and 1.00 in females (vs. smaller, HW/HL 0.96 in males and females); internarial distances equal to interorbital distances, IND/ IOD 1.04 in males and females (vs. significantly smaller, IND/ IOD 0.55 in males and females); relative finger lengths I < II < IV < III (vs. II < IV <I < III); relative toe lengths I < II < III < V < IV (vs. I < II < V = III < IV), toe webbing formula I 1½– 2 II 1⅓–2⅔ III 2–2⅔ IV 2⅔–1 V (vs. I 1–1⅔ II 1⅓–2 III 1½–2½ IV 2⅔–1 V); presence of lateral fringes on the inner and outer edges of toes II, III and IV (vs. absence of all toes); tibiotarsal articulation reaching forward far beyond the tip of the snout (vs. beyond nostrils); inverted V-shaped black glandular ridge in the scapular region and body dorsal mid-side (vs. only in the scapular region), nuptial pad dark gray-blackish divided into three parts in breeding males (vs. gray, divided into four parts).

Compared to the ten remaining species in the R. japonica group, the new species differs from R. hanluica as follows: head length equal to width, HL/HW 1.01 in males and 1.00 in females (vs. larger, HL/HW 1.11 in males and 1.13 in females), relative finger lengths I < II < IV < III (vs. II <I < IV < III), toe webbing formula I 1½–2 II 1⅓–2⅔ III 2–2⅔ IV 2⅔–1 V (vs. I 1⅓–1⅔ II 1–2 III 1⅓–2½ IV 2⅓–1 V), supernumerary tubercles present only below the base of fingers III and IV (vs. each finger), nuptial pad dark gray-blackish and divided into three parts (vs. nuptial pad gray and divided into two parts); from R. omeimontis by having a relatively medium body size, SVL = 46.1–53.7 mm in adult males, 54.5–58.6 mm in adult females (vs. 56.7–63.7 mm in males, 61.7–70.3 mm in females), one inverted V-shaped markings on the dorsal surface (vs. absent), head length equal to width, HL/HW 1.01 in males and 1.00 in females (vs. slightly smaller, 0.98 in males and females), supratympanic fold present (vs. absent), relative finger lengths I < II < IV < III (vs. II < IV <I < III), relative toe lengths I < II < III < V < IV (vs. I < II < V = III < IV), supernumerary tubercles present only below the base of finger IV (vs. absent), tibiotarsal articulation reaching forward far beyond tip of the snout (vs. reaching the front of nostrils); from R. jiulingensis by head length equal to width, HL/HW 1.01 in males and 1.00 in females (vs. significantly smaller, HW/HL 0.82 in males and 0.85 in females), internarial distances equal to interorbital distances, IND/ IOD 1.04 in males and females (vs. significantly larger, IND/ IOD 1.20 in males and 1.22 females), supratympanic fold present (vs. absent), one inverted V-shaped markings on the dorsal surface (vs. absent), supernumerary tubercles present only below the base of fingers III and IV (vs. each finger), toe webbing formula I 1½–2 II 1⅓–2⅔ III 2–2⅔ IV 2⅔–1 V (vs. I 1⅓–2 II 1⅓–2⅓ III 1 ½–2⅔ IV 3–1⅓ V), nuptial pad dark gray-blackish (vs. creamy white); from R. japonica by two outer metacarpal tubercles distinctly separated (vs. absent), inverted V-shaped black glandular ridge in the scapular region and body dorsal mid-side (vs. only in the scapular region), tibiotarsal articulation reaching forward far beyond tip of the snout (vs. reaching or beyond tip of the snout in males, reaching the center of the eye or beyond the nostril in females), nuptial pad dark gray-blackish and divided into three parts (vs. nuptial pad grayish brown or yellowish brown and divided into two parts); from R. dabieshanensis by supratympanic fold present (vs. absent), relative finger lengths I < II < IV < III (vs. II < IV <I < III), relative toe lengths I < II < III < V < IV (vs. I < II < V < III < IV), one inverted V-shaped markings on the dorsal surface (vs. absent), supernumerary tubercles present only below the base of fingers III and IV (vs. absent), toe webbing formula I 1½–2 II 1⅓–2⅔ III 2–2⅔ IV 2⅔–1 V (vs. I 2–1 II 2 + –1 + III 3– 2 IV 2–2 + V), black edge intermittently present on the anterior two-thirds of both sides of the dorsolateral fold (vs. golden), nuptial pad divided into three parts (vs. two parts); from R. jiemuxiensis by head length equal to head width, HL/HW 1.01 in males and 1.00 in females (vs. slightly smaller, HL/HW 0.96 in males and females), one inverted V-shaped markings on the dorsal surface (vs. absent), dorsolateral fold extending straight from posterior margin of the upper eyelid to above the groin (vs. slightly curved above the tympanum), relative finger lengths I < II < IV < III (vs. II < IV <I < III), nuptial pad dark gray-blackish and divided into three parts (vs. gray and divided into two parts), two outer metacarpal tubercles distinctly separated (vs. merged at base); from R. longicrus by head length equal to head width, HL/HW 1.01 in males and 1.00 in females (vs. larger, HL/HW 1.18 in males and 1.07 females), dorsolateral fold extending straight from posterior margin of the upper eyelid to above the groin (vs. slightly curved above the tympanum), relative finger lengths I < II < IV < III (vs. II <I < IV < III), supernumerary tubercles present only below the base of fingers III and IV (vs. absent), toe webbing formula I 1½–2 II 1⅓–2⅔ III 2–2⅔ IV 2⅔–1 V (vs. I 1⅔–2⅓ II 1½–2⅔ III 1⅔–3½ IV 3⅓–1½ V); from R. zhenhaiensis by head length equal to head width, HL/HW 1.01 in males and 1.00 in females (vs. slightly larger, HL/HW 0.98 in males and females), internarial distances equal to interorbital distances, IND/ IOD 1.04 in males and females (vs. significantly smaller, IND/ IOD 0.58 in males and females), dorsolateral fold extending straight from posterior margin of the upper eyelid to above the groin (vs. slightly curved above the tympanum), relative finger lengths I < II < IV < III (vs. II < IV <I < III), relative toe lengths I < II < III < V < IV (vs. I < II < V = III < IV), two outer metacarpal tubercles distinctly separated (vs. merged at the base), tibiotarsal articulation reaching forward beyond tip of the snout (vs. reaching to the nostril); from R. culaiensis by head length equal to head width, HL/HW 1.01 in males and 1.00 in females (vs. larger, HL/HW 1.40 in males), dorsolateral fold extending straight from posterior margin of the upper eyelid to above the groin (vs. slightly curved to temporal fold above tympanum), tibiotarsal articulation reaching forward far beyond tip of the snout (vs. reaching to the nostril), one inverted V-shaped markings on the dorsal surface (vs. absent), nuptial pad dark gray-blackish and divided into three parts (vs. nuptial pad dark brown and divided into two parts); from R. chevronta by head length equal to head width, HL/HW 1.01 in males and 1.00 in females (vs. larger, HL/HW 0.97 in males and 0.96 in females), internarial distances equal to interorbital distances, IND/ IOD 1.04 in males and females (vs. larger, IND/ IOD 1.18 in males and 1.38 females), relative finger lengths I < II < IV < III (vs. II < IV <I < III), relative toe lengths I < II < III < V < IV (vs. I < II < V < III < IV), nuptial pad dark gray-blackish and divided into three parts (vs. nuptial pad purplish gray, undivided, and complete).

Distribution. China (Guizhou).

Ecology. Currently, the new species is known only from the type locality, Guiguo Town, at elev. 645– 728 m. The new species has only been found in or near a pool of water outside a cave in an area located far from the village. After three years of survey data showed that adults and egg ( Fig. 5D ) were collected and discovered only from late July to mid-August each year, we presumed that this was their breeding season. Therefore, we speculated that the breeding period begins in late June and lasts until about mid-August.

Figures

Figure 5. Morphological features of the live adult male holotype GZNU2018081606 of Rana zhijinensis Luo, Xiao & Zhou, sp. nov. A. Dorsolateral view; B. Dorsal view; C. Ventral view; D. Egg cluster; E. Ventral view of hand and dark gray-blackish nuptial pad; F. Ventral view of foot.

Figure 6. Variation of the live adult male paratype GZNU20220705001 of Rana zhijinensis Luo, Xiao & Zhou, sp. nov. A. Dorsolateral view; B. Dorsal view; C. Ventral view.