Nidirana xiangica Lyu & YY Wang, 2020

Lyu, Zhi-Tong, Dai, Ke-Yuan, Li, Yao, Wan, Han, Liu, Zhe-Yi, Qi, Shuo, Lin, Si-Min, Wang, Jian, Li, Yu-Long, Zeng, Yang-Jin, Li, Pi-Peng, Pang, Hong & Wang, Ying-Yong, 2020, Comprehensive approaches reveal three cryptic species of genus Nidirana (Anura, Ranidae) from China, ZooKeys 914, pp. 127-159 : 127

Nidirana xiangica Lyu & YY Wang sp. nov. Figures 11 , 12 , 13

Chresonymy.

Nidirana adenopleura : Fei et al. 2009, 2012; Mo et al. 2014.

Holotype.

SYS a006492 (Figs 11 , 12 ), adult male, collected by Zhi-Tong Lyu on 6 August 2018 from Mt Dawei (28.4237°N, 114.0793°E; ca 820 m a.s.l.), Liuyang City, Hunan Province, China.

Paratypes.

Nine adult specimens. Male SYS a006493/ CIB 107276 and female SYS a006491, collected by Zhi-Tong Lyu and Zheng-Jiao Liu at the same time from the same locality as the holotype; male SYS a002591 and female SYS a002590, collected by Jian Zhao on 8 May 2014 from Mt Wugong (27.4079°N, 114.1671°E; ca 800 m a.s.l.), Anfu County, Jiangxi Province, China; Males SYS a 007269-7271, and females SYS a007272-7273, collected by Zhi-Tong Lyu, Yu-Long Li, and Yao Li on 21 June 2018 from Mt Yangming (26.1155°N, 111.9591°E; ca 1150 m a.s.l.), Shuangpai County, Hunan Province, China.

Etymology.

The specific name xiangica is an adjective derived from Xiang (湘), referring to Xiangjiang River (湘江), the major drainage basin within the distribution of the new species.

Differential diagnosis.

Nidirana xiangica sp. nov. is distinguished from its congeners by the following combination of the morphological characteristics: (1) body large and elongated, with SVL 56.3-62.3 (58.0 ± 2.2, N = 6) mm in adult males, and SVL 53.5-62.6 (58.3 ± 4.0, N = 4) mm in adult females; (2) disks of digits dilated, rounded; (3) lateroventral grooves present on all digits; (4) heels just meeting; (5) tibio-tarsal articulation reaching between eye to snout; (6) mid-dorsal stripe absent; (7) dorsal surface and flanks extremely rough with dense tubercles; (8) developed supernumerary tubercles below the base of each finger, palmar tubercles prominent and distinct; (9) supratympanic fold absent; (10) white horny spinules on the entirely dorsum, dorsolateral folds, flanks, dorsal limbs, loreal region, and temporal region including tympanum in males; (11) a pair of subgular vocal sacs present; (12) one single nuptial pad on the finger I, nuptial spinules invisible; (13) suprabrachial gland large, rough and well developed, distinctly prominent; (14) calling: 2-3 notes containing a specific first note.

Comparison.

Morphologically, Nidirana xiangica sp. nov. is unique when compared with all known congeners by the combination of the following characteristics: (1) large body size, SVL 56.3-62.3 mm in males and 53.5-62.6 mm in females vs. <53.0 mm in males or females in N. nankunensis , N. okinavana , N. daunchina , N. yaoica , N. chapaensis , and N. hainanensis ; (2) relative finger lengths II <I <IV <III vs. II <I = IV <III in N. chapaensis ; vs. II <IV <I <III in N. leishanensis ; (3) presence of lateroventral groove on every digit vs. absent on fingers and toes in N. pleuraden ; vs. absent or barely visible on fingers in N. daunchina ; vs. absent on finger I in N. guangdongensis , N. mangveni , N. adenopleura , N. nankunensis , N. okinavana , N. chapaensis , and N. lini ; (4) tibio-tarsal articulation reaches between eye to snout vs. beyond the snout tip in N. lini ; (5) heels just meeting vs. overlapping in N. guangdongensis , N. mangveni , N. adenopleura , N. nankunensis , N. yaoica , N. leishanensis , N. okinavana and N. lini ; (6) white horny spinules on the entirely dorsum, flanks, loreal region, and temporal region including tympanum in males vs. absent on dorsum and flanks or few above vent in N. nankunensis , N. okinavana , N. daunchina , N. yaoica , N. chapaensis , N. leishanensis and N. hainanensis ; vs. present on dorsum while absent on flanks in N. mangveni , N. adenopleura , N. lini and N. pleuraden ; vs. present on dorsum and flanks while absent on temporal regions in N. guangdongensis ; (7) the presence of a single nuptial pad on finger I vs. absent in N. hainanensis ; vs. divided into two parts in N. chapaensis ; vs. two nuptial pads on fingers I and II respectively; (8) the presence of a pair of subgular vocal sacs vs. absent in N. okinavana .

Description of holotype.

SYS a006492 (Figs 11 , 12 ), adult male. Body large and elongated, SVL 56.3 mm; head slightly longer than wide (HDW/HDL 0.99), flat above; snout rounded in dorsal and lateral views, slightly protruding beyond lower jaw, longer than horizontal diameter of eye (SNT/ED 1.27); canthus rostralis distinct; loreal region concave, bearing horny spinules; nostril round, directed laterally, 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, forming a maxillary gland and shoulder gland; supratympanic fold absent; interorbital space flat, narrower than internasal distance (IND/IOD 1.27); pupil elliptical, horizontal; temporal region including tympanum with horny spinules, tympanum distinct, round, TD/ED 0.81, and close to eye, TED/TD 0.29; pineal ocellus distinct; vomerine ridge present, bearing small teeth; tongue large, cordiform, notched behind; a pair of subgular vocal sacs present.

Forelimbs moderately robust, lower arm 0.20 of SVL and hand 0.26 of SVL; fingers thin, relative finger lengths II <I <IV <III; tip of each finger slightly dilated, forming rounded disks; lateroventral grooves on all fingers, not meeting at the tip of disks; fingers free of webbing; presence of distinct lateral fringes on inner and outer sides of fingers II, III, and IV, and on outer side of finger I; subarticular tubercles prominent and rounded; developed supernumerary tubercles below the base of each finger; three elliptic, large, prominent and very distinct palmar tubercles; a single nuptial pad on the dorsal surface of first finger, nuptial spinules invisible.

Hindlimbs relatively robust, tibia 0.50 of SVL and foot 0.74 of SVL; heels just meeting when hindlimbs flexed at right angles to axis of body; tibio-tarsal articulation reaching the loreal region 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; well-developed lateroventral grooves on toes, not meeting at the tip of disks; webbing moderate, webbing formula: I 1½ - 2 II 1⅓ - 2⅓ III 1⅔ - 3 IV 3⅓ - 1⅔ V; presence of lateral fringes on inner and outer sides of each toes, forming distinct dermal flap on the lateral edges of toes I and V; subarticular tubercles rounded, prominent; inner metatarsal tubercle elliptic, length triple the width; outer metatarsal tubercle indistinct, small and rounded; tarsal folds and tarsal tubercle absent.

Dorsal surface very rough with dese tubercles and dense horny spinules; developed dorsolateral fold with sparse horny spinules from posterior margin of upper eyelid to above groin but intermittent posteriorly; flank very rough with sparse warts, dense tubercles and dense horny spinules; a large and rough suprabrachial gland behind base of forelimb, distinctly prominent; dorsal surface of forelimb rough with dense horny spinules, two weak longitudinal ridges on upper arms and slightly extending to lower arm; the dorsal surfaces of thigh and tibia rough with dese tubercles and dense horny spinules, 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.

Coloration of holotype.

In life (Fig. 11 ), dorsal surface greenish brown; horny spinules on the skin white; pineal ocellus yellowish; absence of mid-dorsal stripe; dorsolateral fold greenish brown; upper flank greenish brown, warts on flank yellowish; lower flank yellowish white with black stripe; suprabrachial gland yellowish white with black stripe. Dorsal limbs brown; two greenish crossbars on the thigh, two on the tibia and three on the tarsus. Loreal and temporal regions greenish brown, tympanum light brown; upper ⅓ iris brownish white and lower ⅔ iris reddish brown; maxillary gland and shoulder gland white. Throat and anterior chest dark purplish brown; ventral surface of body and limbs creamy white; rear thigh tinged with pink; ventral hand white with large brown patches; ventral foot purplish brown.

In preservative (Fig. 12 ), surface of dorsum and dorsal limbs changed as dark brown; white spinules significantly distinct; crossbars on limbs clearer; ventral surface faded, throat and anterior chest dark grey.

Variations.

Measurements of type series are given in Table 8 . All specimens were similar in morphology. Females (58.3 ± 4.0 mm, N = 4) (Fig. 13A, B ) are not significantly larger than males (58.0 ± 2.2 mm, N = 6), but relatively smooth than males, not bearing white horny spinules on the dorsum, dorsolateral folds, flanks, and temporal region. Pineal ocellus invisible in SYS a006493 (Fig. 13C ); dorsal surface reddish brown in SYS a006491 and greenish in SYS a007269 (Fig. 13D ); numerous black spots on dorsum and flanks in SYS a007273; lateroventral grooves poorly developed on fingers I and II in SYS a002591.

Distribution and ecology.

Currently, Nidirana xiangica sp. nov. is known from Mt Dawei and Mt Yangming of Hunan, Mt Wugong of western Jiangxi, and Mt Dupangling of northeastern Guangxi, indicating its potential distribution area is in the Xiangjiang River Basin. The frog inhabits natural or artificial ponds and paddy fields. This species has no behavior of nest construction, and the adult males call at the water surface from May to August. The tadpoles of this species remain unknown.

Vocalization.

The advertisement call (N = 57) of Nidirana xiangica sp. nov. contains 2-3 notes containing a specific first note. The two-note call has a duration of 331.9-427.0 (374.6 ± 23.5, N = 19) ms; the three-note call has a duration of 542.7-624.8 (569.2 ± 20.6, N = 38) ms. The first notes last 148.0-233.0 (170.4 ± 14.5, N = 57) ms with the rise time 89.8-149.1 (126.2 ± 17.5, N = 57) ms; the non-first notes last 60.1-128.0 (74.6 ± 11.8, N = 95) ms with the rise time 2.2-43.0 (27.8 ± 10.2, N = 95), and the intervals last 85.0-195.6 (125.8 ± 17.8, N = 95) ms.

Figures

Figure 11. Morphological features of the adult male holotype SYS a 006492 of Nidirana xiangica sp. nov. in life. (A) dorsolateral view; (B) ventral view; (C) right hand; (D) nuptial pad; (E) left foot; (F) close-up of head showing the dense white horny spinules on dorsum, upper eyelid, loreal region, and temporal region including tympanum.

Figure 12. Morphological features of the adult male holotype SYS a 006492 of Nidirana xiangica sp. nov. in preservative. (A) dorsal view; (B) ventral view; (C) lateral view; (D) left hand; (E) right foot.

Figure 13. (A) adult female paratype SYS a 006491 of Nidirana xiangica sp. nov.; (B) adult female paratype SYS a 007273; (C) adult male paratype SYS a 006493; (D) adult male paratype SYS a 007269.