Nidirana chapaensis ( Bourret, 1937 )

Yuan, Zhiyong, Liu, Xiaolong, Wang, Kai, Wang, Jian, Chen, Jinmin, Jin, Jieqiong, Wei, Pingfan, Zhou, Jiajun & Che, Jing, 2019, Nidirana chapaensis (Bourret, 1937), one additional anuran species for the amphibian fauna of China, Zootaxa 4571 (4), pp. 580-588 : 583-585

Nidirana chapaensis ( Bourret, 1937)

( Figs. 3 and 4 )

Description. Males: SVL 43.0– 47.3mm; head longer than width (HL 14.9–15.4 mm, HW 14.2–14.9 mm); snout obtusely pointed in dorsal view, projecting beyond lower jaw; canthus rostralis distinct; nostril dorsolaterally oriented, close to tip of snout; loreal region concave, sloping; tympanum distinct, rounded, smaller than eye diameter (TMP = 58.2–69.6% EYE); supratympanic fold absent; pineal body distinct; internarial distance relatively greater than interorbital distance (IOD = 86.4–96.5% IND). Two short rows of vomerine teeth present; tongue notched posteriorly; a pair of internal vocal sacs present in males. Skin smooth, except small granular tubercles present on posterior dorsum, near cloacae and hindlimbs; rictal glands distinct; dorsolateral fold distinct.

Relative finger length II <I <IV<III; fingers webbing absent; lateral fringes absent; finger tips expanded with circummarginal grooves without discs; subarticular tubercles distinct; supernumerary tubercle indistinct; three oval palmar tubercles present. Nuptial pad absent in males. Hind limbs long, tibia longer than thigh (TIB =87.1–96.2% TFL); toes long and thin, relative lengths I<II<III<V<IV ( Fig. 4 ); webbing present on toes, webbing formula: I 1–2 II 1–2 III 1–2 IV 2–1 V; narrowly lateral fringes distinct on toes; subarticular tubercles distinct; oval inner metatarsal tubercle distinct; outer metatarsal tubercle indistinct; supernumerary tubercles absent on toes.

Coloration. In life, dorsal coloration of the adults ranges from orange to dark brown, with a narrow white stripe running from pine body to vent, and a pattern of irregular black spots covering the dorsum. The loreal region is blackish, and rictal glands are white. The region around tympanum is usually black, but can be creamy yellow instead. The upper flank is blackish, with spots close to the dorsolateral fold. The remaining parts of flank are mostly creamy yellow, sometimes with black spots scattered across. The iris is bronze. Dark bars are present on the dorsal surface of the limbs. Ventral throat and chest are gray, covered densely with black spots; the belly is yellowish or white. Ventral surfaces of the limbs are creamy-yellow or white with gray spots. The fingers have dark gray spots; subarticular tubercles on the fingers and toes are pale gray and dark brown respectively, and the inner metatarsal tubercle is creamy-yellow.

Distribution. The currently known ranges include northern Vietnam, Laos, Thailand, and south-eastern Yunnan Province of China ( Nguyen et al. 2009; Stuart 2005).

Natural history notes. Specimens were collected in small ponds adjacent to a stream ( Fig. 5 ) between 19:00 and 23:30. The surrounding habitat was coniferous mixed forest at an elevation of ca. 1300 m a.s.l. Call of males were heard at an air temperature of 24°C–28°C and a relative humidity of 53%–85% during April, June and August, 2016. Many individuals were fund in April, but very few were found in June and August. Other frog species observed at the same locality included Microhyla heymonsi , Limnonectes bannaensis , Fejervarya multistriata , Sylvirana maosonensis .

On the distribution of herpetofauna across the China-Vietnam border. Our new record presented here adds to the list of amphibian species which have recently been found to occur on both sides of the China-Vietnam border, such as Limnonectes bannaensis ( Suwannapoom et al. 2016) , Paramesotriton deloustali ( Zhang et al. 2017) , and Tylototriton ziegleri ( Jiang et al. 2017) . Given that the area surrounding the China-Vietnam border is located in the same zoogeographic region ( Holt et al. 2013), and since habitats on both sides of the border are

continuous without any known biogeographic barriers, it is highly possible that species many previously believed endemic to either side of the border are found on the other side, and their distributions are much wider than previously believed. Future collaborative research between herpetologists from both countries are needed in order to obtain a better understanding of the biodiversity in this region.

Figures

FIGURE 3. Color variations of Nidirana chapaensis from the Yunnan population in China: (A–D) dorsolateral, dorsal (E), and ventral (F) views of Nidirana chapaensis in life from China.

FIGURE 4. (A) Dorsal and (B) ventral views of the hand, and (C) dorsal and (D) ventral views of the foot of Nidirana chapaensis in life from China.

FIGURE 5. (A) Habitat of Nidirana chapaensis in Xichou, Wenshan Prefecture, Yunnan Province, China.