Nidirana guangxiensis Mo, Lyu, Huang, Liao & Wang, 2021

Lyu, Zhi-Tong, Huang *, Zhong, Liao, Xiao-Wen, Lin, Li, Huang, Yong, Wang, Ying-Yong & Mo, Yun-Ming, 2021, A new species of Music frog (Anura, Ranidae, Nidirana) from Mt Daming, Guangxi, China, ZooKeys 1059, pp. 35-56 : 35

Nidirana guangxiensis Mo, Lyu, Huang, Liao & Wang sp. nov.

Chresonymy.

Hylarana (Hylarana) adenopleura - Zhang and Wen 2000 (Mt. Daming, Guangxi)

Nidirana adenopleura - Mo et al. 2014 (Wuming and Shanglin, Guangxi)

Holotype.

NHMG 202007003 (Figs 6 , 7A, B ), adult male, collected by Zhong Huang and Xiao-Wen Liao on 7 July 2020 from Mt Daming (23.5156°N, 108.4370°E; ca 1260 m a.s.l.), Wuming District, Nanning City, Guangxi Zhuang Autonomous Region, China.

Paratypes.

Eighteen specimens. Female NHMG 202007001 (Fig. 7C ), and males NHMG 202007002 (Fig. 7D ), NHMG 202007004-005, 202007007-015, 202007019-020, collected at the same time with the holotype. Female SYS a008811/ NHMG 202008003 and males SYS a008812-8813/ NHMG 202008004-005, collected by Yun-Ming Mo, Zhong Huang, and Xiao-Wen Liao on 18 August 2020 from the same locality with the holotype.

Etymology.

The specific name Nidirana guangxiensis refers to the type locality of the new species in Guangxi Zhuang Autonomous Region. The Zhuang language, one of the official languages of Guangxi Zhuang Autonomous Region, is based on the dialect of Wuming, from where the new species was collected.

Common name.

"Guangxi Music Frog" in English and "广西琴蛙 (guǎng xī qín wā)” in Chinese.

Diagnosis.

Nidirana guangxiensis sp. nov. is placed in the genus Nidirana based on the morphological characteristics of the absence of the thumb-like structure on finger I, presence of well-developed dorsolateral folds, and the presence of suprabrachial glands in breeding males ( Lyu et al. 2017). It is further assigned to the N. adenopleura group by the presence of lateroventral grooves on all toes ( Dubois 1992; Lyu et al. 2019).

Nidirana guangxiensis sp. nov. is distinguished from its congeners by the following combination of the morphological characteristics: (1) body medium sized, with SVL 40.2-47.6 mm (43.8 ± 2.2, N = 17) in adult males and 49.9-51.0 mm (N = 2) in adult females; (2) disks of digits dilated, pointed; (3) lateroventral grooves present on fingers III and IV, and each toe; (4) relative finger length II <I <IV <III; (5) lateral fringes wide on inner sides of fingers II, III and IV but absent on finger I; (6) webbing formula on toes I 2-2⅔ II 2-3 III 2½ -3⅔ IV 3⅔- 2½ V; (7) tibio-tarsal articulation reaching at the nostril; (8) dorsal skin rough with dense granules, several tubercles on the posterior part, flanks, and dorsal hindlimbs, without spinules on the skin; (9) distinct supernumerary tubercles below the base of fingers III and IV, palmar tubercles prominent and distinct; (10) a pair of subgular vocal sacs present; (11) a single nuptial pad on the first finger, nuptial spinules invisible; (12) suprabrachial gland large; (13) nest construction behavior present; (14) calling consisting of 6-11 rapidly repeated regular notes.

Comparison.

Nidirana guangxiensis sp. nov. can be significantly distinguished from all other recognized congeners by the combination of the following characteristics: (1) body medium-sized, SVL 40.2-47.6 mm (N = 17) in adult males and 49.9-51.0 mm (N = 2) in adult females [vs SVL <38 mm in adult male N. nankunensis ; SVL> 50 mm in adult male N. guangdongensis , N. mangveni , and N. xiangica ; SVL <45 mm in adult female N. yeae and N. nankunensis ; SVL> 53 mm in adult female N. guangdongensis , N. lini , N. mangveni , N. occidentalis , and N. xiangica ]; (2) relative fingers length II <I <IV <III [vs II <IV <I <III in N. yeae and N. leishanensis ; II <I = IV <III in N. chapaensis ; I <II <IV <III in N. mangveni ]; (3) lateroventral grooves present on fingers III and IV [vs absent on all fingers in N. yeae , N. occidentalis , and N. pleuraden ; present on all fingers in N. yaoica , N. hainanensis , N. leishanensis , and N. xiangica ; present on all fingers except finger I in N. chapaensis , N. adenopleura , N. guangdongensis , N. lini , N. nankunensis , and N. okinavana (Boettger, 1895)]; (4) lateroventral grooves present on all toes [vs absent on all toes in N. occidentalis and N. pleuraden ]; (5) tibio-tarsal articulation reaches the nostril [vs beyond the snout tip in N. lini ; at the eye in N. yeae and N. occidentalis ]; (6) a single nuptial pad present on finger I [vs nuptial pad absent in N. hainanensis ; nuptial pad divided into two parts on finger I in N. chapaensis ; two nuptial pads respectively on fingers I and II in N. leishanensis ]; (7) a pair of subgular vocal sacs present in males [vs absent in N. okinavana ]; (8) spinules on posterior dorsal skin absent [vs present in N. adenopleura , N. lini , N. mangveni , N. occidentalis , N. pleuraden , and N. xiangica ].

Particularly, Nidirana guangxiensis sp. nov. is relatively close in phylogeny to N. yeae from northern Guizhou, but it can be distinguished by: the relative fingers length II <I <IV <III [vs II <IV <I <III in N. yeae ]; lateroventral grooves present on fingers III and IV [vs absent on all fingers]; tibio-tarsal articulation reaches the nostril [vs at the eye]; lateral fringes wide on inner sides of fingers II, III and IV but absent on finger I [vs present only on fingers III and IV]; webbing formula on toes I 2-2⅔ II 2-3 III 2½ -3⅔ IV 3⅔- 2½ V [vs I 2-2 II 1⅔- 3½ III 2½ -3⅔ IV 3⅔-2 V]; in males, head larger, HDL/SVL 0.42 ± 0.02 [vs 0.35 ± 0.03], HDW/SVL 0.38 ± 0.02 [vs 0.35 ± 0.01], radio-ulna length shorter, RAD/SVL 0.17 ± 0.01 [vs 0.20 ± 0.01], and foot length longer, FTL/SVL 0.78 ± 0.03 [vs 0.70 ± 0.05].

Description of holotype.

NHMG 202007003 (Figs 6 , 7A, B ), adult male. Body medium-sized, SVL 43.8 mm; head relatively long and wide (HDL/SVL 0.42, HDW/SVL 0.36), longer than wide (HDW/HDL 0.86), flat above; snout rounded in dorsal and lateral views, slightly protruding beyond lower jaw, longer than horizontal diameter of eye (SNT/ED 1.57); canthus rostralis distinct, slightly curved inwards on the nostril; loreal region concave; nostril round, closer to the snout than to the eye; a longitudinal swollen mandibular ridge extending from below nostril through lower edges of eye and tympanum to above insertion of arm, where the ridge is intermittent, forming a maxillary gland and shoulder gland; supratympanic fold absent; interorbital space flat, narrower than internasal distance (IND/IOD 1.31), pineal ocellus invisible; pupil elliptical, horizontal; tympanum distinct, round, relatively large, TD/ED 0.98; vomerine ridge present, bearing small teeth; tongue cordiform, margin of the tongue notched; a pair of subgular vocal sacs present.

Forelimbs moderately robust, lower arm 0.17 of SVL and hand 0.27 of SVL; fingers thin, relative finger lengths II <I <IV <III; tip of each finger slightly dilated, forming rounded disks; lateroventral grooves on fingers III and IV, not meeting at the tip of disks; fingers free of webbing; lateral fringes present and distinct on inner and outer sides of fingers II, III and IV, but absent on finger I; subarticular tubercles prominent and rounded; supernumerary tubercles present below the base of fingers III and IV; palmar tubercles three, elliptic, large, prominent and distinct; a single nuptial pad on the dorsal surface of finger I, nuptial spinules invisible.

Hindlimbs robust, tibia 0.53 of SVL, and foot 0.76 of SVL; heels overlapping when hindlimbs flexed at right angles to axis of body; tibio-tarsal articulation reaching at the nostril when hindlimb is stretched along the side of the body; toes relatively long and thin, relative lengths I <II <V <III <IV; tip of each toe slightly dilated with remarkable elongated ventral callous pad, forming long and pointed disk; lateroventral grooves well developed on each toe, not meeting at the tip of disks; webbing moderate, formula: I 1⅓-2 II 1⅓-2⅓ III 1⅔-3 IV 3⅓-1⅓ V; lateral fringes present on inner and outer sides of each toe, forming distinct dermal flap on the lateral edges of toes I and V; subarticular tubercles rounded, prominent; inner metatarsal tubercle elliptic, length triple width; outer metatarsal tubercle indistinct, small and rounded; tarsal folds present and tarsal tubercle absent.

Dorsal skin rough with dense granules, several tubercles on the posterior part, flanks, and dorsal hindlimbs, not bearing spinules on the skin; developed dorsolateral fold from posterior margin of upper eyelid to above groin but intermittent posteriorly; a large and smooth suprabrachial gland behind base of forelimb, prominent; weak longitudinal ridges on upper arms and slightly extending to lower arm; the dorsal surfaces of thigh and tibia relatively rough with tubercles, forming several longitudinal ridges. Ventral surface of throat, body, and limbs smooth; large flattened tubercles densely arranged on the rear of thigh and around vent.

Color of holotype.

In life (Fig. 7A, B ), dorsal surface of head and body brown; a longitudinal light brown mid-dorsal stripe faintly beginning from interorbital area, extending posteriorly to vent and become more distinct; several black spots on posterior dorsum of body; dorsolateral fold brown; upper flank brown with small black spots; lower flank light brown; suprabrachial gland yellowish brown. Dorsal forelimbs brown; dorsal hindlimbs brown, two olive crossbars on the thigh, three on the tibia, and three on the tarsus; irregular olive marks on dorsal toes. Loreal and temporal regions dark brown, tympanum pink; upper ⅓ iris brownish white and lower ⅔ iris reddish brown; maxillary gland and shoulder gland creamy white. Lips, throat, ventral surface of body and limbs creamy white; rear thigh tinged with pink and pale grey patches; ventral hand and foot pale white.

In preservative (Fig. 6 ), dorsal surface becomes dark brown with the mid-dorsal stripe and black spots more distinct; flank surface and the suprabrachial gland become pale; crossbars and marks on limbs dark brown; loreal and temporal regions dark brown; maxillary gland and shoulder gland more distinct; ventral surface pale grey; rear thigh and ventral foot become dark grey.

Variations.

Measurements of type series are given in Table 4 . All specimens were similar in morphology. Females are significantly larger than males, with relatively smoother skin and fewer tubercles on dorsum and flanks. The colorations vary from pale brown to reddish brown in individuals (Fig. 7C-F ). The patterns of mid-dorsal stripes are also variable but always present.

Male secondary sexual characteristics.

A pair of subgular vocal sacs, a pair of slit-like openings at posterior of jaw; a single light brown nuptial pad on the dorsal surface of finger I, nuptial spinules invisible; suprabrachial gland present.

Tadpole.

Body length 19.1 mm and tail length 43.1 mm in the 37th stage tadpole SYS a008814 (Fig. 8 ); body oval, flattened above; snout rounded in dorsal aspect and profile; eyes lateral; labial tooth row formula: 1:1+1/1+1:2; spiracle on left side of body, directed dorsoposteriorly; tail depth larger than body depth; dorsal fin arising just before origin of tail, maximum depth near mid-length, tapering gradually to narrow pointed tip.

Distribution and ecology.

Currently, Nidirana guangxiensis sp. nov. is known only from the type locality, Mt Daming, which is located between Wuming District and Shanglin County, Nanning, Guangxi (Fig. 1 ). This species of frog can only be found in the alpine swamp and neighboring brushwood on the peak of Mt Daming. The estimated extent of occurrence is less than 500 km2, and the estimated area of occupancy is less than 50 km2. The swamp was surrounded by subtropical evergreen broadleaf forests (Fig. 9A ). Sympatric frog species observed in the swamp are Duttaphrynus melanostictus (Schneider, 1799), Gracixalus jinxiuensis (Hu, 1978), Kurixalus odontotarsus (Ye & Fei, 1993), and Polypedates mutus (Smith, 1940).

Nidirana guangxiensis sp. nov. was observed to have nest construction behavior. The nest is in the form of a mud burrow ca 25-30 mm in diameter and near the roots of plants. The top of the nest is open and may fill with water during the rainy season (Fig. 9B ). From April to August, males call from dusk to midnight in the nest. In late April, tadpoles at the 26th-42nd stages can be observed, with the majority at the 33rd-37th stages.

Figures

Figure 1. Map showing the collected localities for the Nidirana samples of Clade C (see Fig. 2) used in this study.

Figure 6. Morphological features of the adult male holotype NHMG 202007003 of Nidirana guangxiensis sp. nov. in preservative A dorsal view B ventral view C lateral view D right hand E right foot. Photos by Shuo Qi.

Figure 7. Variation and colorations of Nidirana guangxiensis sp. nov. in life A, B male holotype NHMG 202007003 C female paratype NHMG 202007001 D male paratype NHMG 202007002 E, F uncaptured female and male individuals in the wild. Photos by Zhong Huang, Zhi-Tong Lyu, and Yun-Ming Mo.

Figure 8. Tadpole SYS a 008814 of Nidirana guangxiensis sp. nov. Photos by Shuo Qi.

Figure 9. A habitat of Nidirana guangxiensis sp. nov. in the type locality in Mt Daming B a male calling in a nest and two nests filled with half of water. Photos by Yun-Ming Mo and Shuo Qi.