Nidirana shyhhuangi, Lin & Chang & Matsui & Shen & Tominaga & Lin, 2025

Nidirana shyhhuangi sp. nov.

Figs 7 View Figure 7 , 8 View Figure 8 , 9 View Figure 9

Chresonymy.

Rana psaltes View in CoL — Chou 1994; Lue et al. 1999: 80–81; Pan 2000: 114–115; Lue et al. 2002: 80–81; Yang 2002: 50–51; Chen 2003: 46–47; Chen 2006: 48–49. Rana okinavana View in CoL — Matsui 2007; Yang et al. 2008: 68–69; Shang et al. 2009: 96–97; Yang 2009: 300–303. Hylarana (Nidirana) psaltes — Fei et al. 2010: 310. Nidirana psaltes — Fei et al. 2012: 349. Nidirana okinavana View in CoL — Yang and Lee 2019: 92–95.

Type material.

Holotype. NTNUB 149805 (Fig. 8 View Figure 8 ), preserved in National Taiwan Normal University, Taipei, Taiwan. Adult male in a good state of preservation, collected by Shyh-Huang Chen on 11 July 1984 from Lienhuachih (23.92082 ° N, 120.88585 ° E), Yuchi Township, Nantou County, Taiwan. The environment of the type locality (Fig. 10 A View Figure 10 ), at an elevation of ~ 670 m a. s. l., is characterized by small freshwater wetland areas surrounded by patchy bamboo forests and subtropical Ficus - Machilus hardwood forests, featuring a humid microhabitat in the understory GoogleMaps . Paratypes (n = 8). NTNUB 149801 ♀, 149802 ♂, 148803 ♂, 149804 ♀, 149806 ♂ collected on 11 July 1984 GoogleMaps ; and NTNUB E 861 ♂, E 862 ♂, E 863 ♀ collected on 11 October 1986 GoogleMaps . All the above-mentioned specimens, in a good state of preservation, were collected from Lienhuachih   GoogleMaps by Shyh-Huang Chen and preserved in National Taiwan Normal University, Taipei, Taiwan (Table 2 View Table 2 ).

Other material examined

(n = 10). NTNUB 166201 ♂, 166202 ♂, 166203 ♂, 166204 ♂, 166205 ♀ collected on 28 August 1989 by Shyh-Huang Chen GoogleMaps ; NMNS 2377-3588 ♂, 2377-3589 ♂, 2377-3590 ♂ collected on 19 August 1993 by Wen-Hao Chou GoogleMaps ; NMNS LW-W-01 ♂ and an unnumbered specimen (♂) collected by Wen-Hao Chou with the collection date unknown GoogleMaps . All of the above specimens were collected from Lienhuachih (Table 2 View Table 2 ).

Etymology.

The specific epithet of the new species shyhhuangi is a Latinized patronymic noun in genitive case. It is dedicated to Prof. Shyh-Huang Chen, a herpetologist and arachnologist who first discovered this species in the early 1980 s. We propose the common name “ Yuchi music frog ” in English to demonstrate the only two sampling sites of the species in Yuchi (meaning the “ fish pond ”) Township, or “ 魚池琴蛙 ” (pronounced as Yú-Chí-Qín-Wā) in Mandarin for this species.

Diagnosis.

Nidirana shyhhuangi sp. nov. is characterized by a combination of the following characters: (1) a small-sized ranid, body moderately slender; (2) SVL of preserved specimens in adult males 31.6–36.5 mm (mean ± SD = 33.8 ± 1.2 mm, n = 15), females 33.7–38.3 mm (35.9 ± 1.9 mm, n = 4); (3) head triangular, slightly longer than wide; (4) snout comparatively long, triangular in dorsal view with a slightly obtuse tip, moderately pointed in profile; (5) canthus rostralis distinct, contacting with the upper margin of nostril; (6) loreal region dark brown, extending posteriorly over eye and beyond tympanum; (7) upper lip pale white, white line extending posteriorly, forming a white stripe from below nostril to base of forelimb; (8) iris golden above canthus rostralis, dark brown below; (9) tympanum dark brown and conspicuous, dark zone extending posteriorly forming a trapezoid shape; (10) males with a single subgular vocal sac; (11) dorsum brown or yellowish-brown, sometimes gray; distinct vertebral stripe present; spinules on dorsal skin absent; (12) dorsolateral fold prominent, forming a distinct color boundary between dorsum and lateral body; (13) upper half of lateral body dark brown, lower half light brown; (14) jaw, throat, chest, and abdomen uniformly pale creamy yellow, generally lacking spots or patterns; (15) forelimb moderately long, pale brown; upper arm usually with one dark band at the base, forearm with one thin transverse band at the middle; (16) fingers slender, relative finger lengths II <IV <I <III; tips weakly dilated into discs, lateroventral groove absent on all fingers; free of webbing; (17) hindlimb relatively long, brown in color; thigh with two or three transverse dark bands, shank with two; (18) toes long and thin, relative toe lengths I <II <V <III <IV; tips weakly dilated into discs, lateroventral groove present on all toes; webbing partial, webbing formula I 1–1 II 1–1 III 2–2 IV 2–2 V.

Description of holotype.

Adult male in a good state of preservation (Fig. 8 View Figure 8 ). Measurements of the holotype (left / right, all in mm): SVL 33.0; SFL 14.9 / 14.2; AGL 14.0 / 13.1; DW 9.1; UaL 8.9 / 8.5, LaL 7.2 / 7.8, HdL 7.9 / 8.1, leading to FLL 23.9 / 24.4; ThL 16.1 / 16.5, ShL 17.8 / 17.9, FtL 24.8 / 25.2, leading to HLL 58.7 / 59.5; HL 12.1 / 12.3; HW 11.2; SNT 6.2 / 6.1; ED 3.4 / 3.7; SND 2.9 / 2.9; STD 9.8 / 9.9; TD 2.9 / 2.8; IND 3.9; IOD 3.3.

Body moderately slender and elongated. Head triangular, as wide as body; slightly longer (HL / HW = 110.0 %). Snout comparatively long (50.3 % HL), triangular and slightly obtuse in dorsal view, moderately pointed in profile. Canthus rostralis distinct; loreal region flat; nostril round, lateral, upper margin in contact with canthus rostralis, closer to tip of snout (23.7 % HL) than to eye (50.3 % HL). Eye moderate sized, diameter 28.9 % of HL, slightly larger than eye-nostril distance (26.3 % HL); interorbital space flat, width 26.9 % of HL and 29.5 % of HW. Tympanum readily visible, rounded; diameter 23.3 % HL and 80.7 % of eye diameter; tympanic annulus conspicuous. Supratympanic fold absent.

Forelimb moderately long; UaL 26.3 % SVL; LaL 22.7 % SVL, HdL 24.1 % SVL. Fingers slender, free of webbing, rounded in cross-section, no skin fringes on fingers. First finger well-developed, tip of all fingers slightly expended, width of finger tips ~ 110 % of the thinnest diameter of phalanx, lateroventral groove absent on all fingers. Relative finger lengths: II <IV <I <III; length of finger II (3.42) 69.2 % of finger III (4.94). Inner metatarsal tubercle prominent and outer metatarsal tubercle obscure; subarticular tubercles present, rounded. Hindlimb relatively long; FmL 49.4 % SVL, TbL 54.0 % SVL, FtL 75.6 % SVL. Toes long, thin, tips of toes slightly flattened, width of toe tips ~ 120 % of thinnest diameter of phalanx, lateroventral groove present on all toes. Relative toe lengths: I <II <V <III <IV; length of toe I (4.6) 29.0 % of finger IV (16.0). Webbing partial, webbing formula I 1–1 II 1–1 III 2–2 IV 2–2 V. Inner metatarsal tubercle ovoid-shaped, present at base of first toe at preaxial side; outer metatarsal tubercle absent; subarticular tubercles prominent, rounded.

Color in life. Dorsum yellowish brown, darker near the midline and paler towards lateral edges; a thin but distinct pale vertebral stripe present (Fig. 7 View Figure 7 ). Canthus rostralis and dorsolateral fold prominent, forming a distinct color boundary between dorsum and lateral body. Loreal region dark brown, extending posteriorly over eye and beyond tympanum. Upper lip pale white, white line extending posteriorly, forming a white stripe from below nostril to base of forelimb. Pupil deep black, iris golden above level of canthus rostralis, dark brown below, matching color of the loreal region. Tympanum dark brown, conspicuous, slightly translucent; dark zone extending posteriorly by approximately same width of tympanum diameter, forming a trapezoid shape. Dorsolateral fold darker than dorsum and flanks, displaying a fine but occasionally interrupted black line along fold. Upper half of lateral body similar to mid-dorsal coloration, dark brown; lower half paler, similar to lateral dorsum, pale brown. A slightly raised glandular ridge, pale yellowish brown in color, appearing as a mild swelling of skin, located behind base of forelimb. Jaw, chest, and abdomen uniformly pale creamy yellow, lacking spots or patterns. Forelimb pale brown; upper arm with one dark band at base, forearm with one thin transverse band at middle. Hindlimb brown, thigh with three transverse dark bands on both legs, shank with two; foot and toes with three bands on the left and four on the right.

Color in preservative. Patterns in alcohol-preserved specimens show minimal change (Figs 4 View Figure 4 , 8 View Figure 8 ). However, coloration fades slightly. Most brown tones become slightly paler, the yellow component of yellowish brown fades, and the white line on the upper lip becomes less distinct compared to live specimens.

Variation. Some individuals are gray, a coloration that may be more common in females (Fig. 7 B View Figure 7 ). The lower half of the iris in one-year juveniles is red or reddish brown (Fig. 7 C View Figure 7 ). The number of transverse bands on the limbs varies: a majority of individuals (85.7 %) have one transverse band on the forearm, while a minority (14.3 %) has two. The number of bands on the thigh ranges from two (39.3 %) to three (60.7 %) (Fig. 5 C View Figure 5 ), and on the shank, the bands are mostly two (85.7 %), occasionally three (14.3 %) (Fig. 5 D View Figure 5 ). The number of bands on the foot is typically three (85.7 %), occasionally four (14.3 %).

Sexual dimorphism. Sexual dimorphism within species of Nidirana shyhhuangi sp. nov. is recognized for glandular ridges and vocal sacs, both of which are present exclusively in males. Adult males can be distinguished from females by the presence of a pale yellowish-brown glandular ridge behind the base of the forelimbs, which is especially prominent during the breeding season (Fig. 7 A View Figure 7 ). Compared to males, females tend to have a paler and more grayish coloration (Fig. 7 B View Figure 7 ), while males typically have a darker body color. The males of Nidirana shyhhuangi sp. nov. have a single subgular vocal sac (Fig. 7 D View Figure 7 ). A pair of vocal slits, located between the lower jaw musculature and epidermis, is present only in mature males and is absent in females. Additionally, males exhibit slightly raised nuptial pads, although they are not particularly prominent, and these pads are entirely absent in females.

Body size of both sexes overlap, but females are usually larger than males in both snout – vent length and body mass. SVL of preserved specimens in adult males 31.6–36.5 mm (mean ± SD = 33.8 ± 1.2 mm, n = 15), females 33.7–38.3 mm (35.9 ± 1.9 mm, n = 4). SVL of live individuals (C. Chang, unpublished data) in adult males 32.0– 40.1 mm (35.5 ± 1.3 mm, n = 49), females 35.2–40.8 mm (38.3 ± 1.5 mm, n = 16). Body mass of live individuals (CC, unpublished data) in adult males 3.60–5.25 g (4.38 ± 0.42 g, n = 49), females 4.75–6.70 g (5.52 ± 0.51 g, n = 16).

Comparisons. Nidirana shyhhuangi sp. nov. could be distinguished from its most closely related congener, N. okinavana , by its significantly smaller and non-overlapping adult body size (Fig. 4 View Figure 4 ). Nidirana okinavana always exceeds 40 mm (n = 18 adults), whereas Nidirana shyhhuangi sp. nov. never exceeds 38.3 mm (n = 19 adults). Nidirana okinavana usually has two transverse bands on the thigh and one on the shank; whereas Nidirana shyhhuangi sp. nov. typically has three bands on thigh and two on the shank (Fig. 5 View Figure 5 ). Nidirana shyhhuangi sp. nov. could be further distinguished by a relatively longer snout – forelimb length (SFL / SVL), upper arm length (UaL / SVL), lower arm length (LaL / SVL), forelimb length (FLL / SVL), shank length (ShL / SVL), foot length (FtL / SVL), and hindlimb length (HLL / SVL) (Suppl. material 1: fig. S 1). Additionally, Nidirana shyhhuangi sp. nov. has relatively larger tympanum (TD / HL), shorter internostril distance (IND / HL), and shorter interorbital distance (IOD / HL) for characters at head (Suppl. material 1: fig. S 1).

The smaller body size of Nidirana shyhhuangi sp. nov. also leads to differences in behavioral traits compared to N. okinavana . The new species is in the nest building group of the genus; the mud nest opening (Figs 7 D View Figure 7 , 10 B View Figure 10 ) measures approximately 2 cm in diameter in the new species, while that of N. okinavana can reach up to 5–6 cm. The mean clutch size of Nidirana shyhhuangi sp. nov. is 39 eggs (maximum 51), whereas N. okinavana can have up to 65 eggs ( Kuramoto 1985) or even 80 eggs ( Utsunomiya and Utsunomiya 1983; Maeda and Matsui 1990; Matsui and Maeda 2018).

Nidirana shyhhuangi sp. nov. is sympatrically distributed with the much more abundant congener, N. adenopleura . Body size of the latter is significantly larger than both Nidirana shyhhuangi sp. nov. and N. okinavana , with SVL ranging from 45–70 mm in the Taiwanese population ( Lue et al. 1999; Lin and Fu 2022). Nidirana adenopleura usually has one additional (3 or 4) transverse band on the thigh, with more and clearer warts and black spots on its lateral skin. Dorsal coloration of Nidirana shyhhuangi sp. nov. is paler, with dark brown longitudinal stripes on either side of the pale yellow mid-dorsal line. The males of Nidirana shyhhuangi sp. nov. have a single subgular vocal sac (Fig. 7 D View Figure 7 ), whereas that of N. adenopleura has a bilobed subgular sac.

Body size of Nidirana shyhhuangi sp. nov. is smaller than all other congeners, which makes it the smallest Nidirana of all. SVL of Nidirana shyhhuangi sp. nov. does not exceed 36.5 mm in males and 38.3 mm in females. On the other hand, most of the other Nidirana spp. exceeds 40 mm in both sexes, including N. daunchina (40.6–53.0 mm, Lyu et al. 2017), N. guangdongensis (50.0– 59.3 mm, Lyu et al. 2020 b), N. guangxiensis (40.2–51.0 mm, Lyu et al. 2021), N. leishanensis (49.5–56.4 mm, Li et al. 2019), N. lini (44.1–68.6 mm, Chou 1999; Lyu et al. 2017), N. mangveni (53.6–65.1 mm, Lyu et al. 2020 b), N. occidentalis (44.5–61.3 mm, Lyu et al. 2020 a), N. pleuraden (46.2–61.7 mm, Lyu et al. 2017; Lyu et al. 2020 a), N. shiwandashanensis (46.2–50.8 mm, Chen et al. 2022 a), N. xiangica (53.5–62.6 mm, Lyu et al. 2020 b), N. yaoica (42.1–45.6 mm, Lyu et al. 2019), and N. yeae (41.2–44.7 mm, Wei et al. 2020).

SVL of Nidirana shyhhuangi sp. nov. overlaps with N. chapaensis (35.5–51.8 mm, Chuaynkern et al. 2010), N. hainanensis (32.8–44.4 mm, Fei et al. 2007), and N. nankunensis (33.3–39.5 mm, Lyu et al. 2017). However, the lateroventral groove is present on the fingers of N. hainanensis , and also present on all fingers except finger I in N. chapaensis and N. nankunensis . In contrast, the lateroventral groove is absent on the fingers of Nidirana shyhhuangi sp. nov.

In addition to body size, Nidirana shyhhuangi sp. nov. could be distinguished from N. occidentalis and N. pleuraden for dilated finger tips and toe tips; from N. mangveni for relative length of fingers (II <I <IV <III); from N. adenopleura , N. guangdongensis , N. lini , N. mangveni , N. occidentalis , N. pleuraden , and N. xiangica for absence of Spinules on dorsal skin. Comparisons among these species are listed in Table 4 View Table 4 , with updated information of N. okinavana revised from Matsui and Maeda (2018) and this study.

Call properties. Mating calls of Nidirana shyhhuangi sp. nov. comprises quick, continuous, and regular pulses lasting 1.5–2.7 sec (1.808 ± 0.285 sec; n = 8) (Table 3 View Table 3 , Fig. 6 View Figure 6 ; Suppl. materials S 2 – S 4). The majority (> 85 %) of a single call comprises 16–30 pulses, with some cases reaching 32 pulses. The dominant frequency of the calls usually ranges between 800–900 Hz (840.5 ± 24.7). Compared to the closely related N. okinavana , Nidirana shyhhuangi sp. nov. is characterized for its higher pulse number (19.7 ± 5.0 vs. 15.8 ± 1.6, P = 0.0561), higher pulse frequency (10.8 ± 1.0 pulses / sec vs. 8.4 ± 0.3 pulses / sec, P <0.01), and higher dominant frequency (840.5 ± 24.7 Hz vs. 723.4 ± 63.7 Hz, P <0.01).

Tadpole description. Measurements at Gosner stage 30 (n = 1, in mm): TOL 41.5, SVL 13.9, BW 8.9, BH 6.2, TAL 26.8, TAH 6.7, TBW 3.6, SNL 3.1, SS 8.2, IOD 3.5.

In life, the body oval and dorsally flattened, with body width exceeding body height (BW / BH = 1.44) (Fig. 9 View Figure 9 ). Both body and tail pale yellowish brown, covered with dense, minute golden dots, with several brown spots on dorsum and tail. Tail fusiform, ~ 1.93 × snout – vent length, with a height comprising 25.0 % of total tail length. Dorsal fin originates before base of tail. Eyes lateral, nostrils situated near snout. Spiracle located on left side of body, directed dorso-posteriorly. Labial tooth row formula 1: 1 + 1 / 1 + 1: 2, with lower lips bearing more labial papillae than upper (Fig. 9 A, B View Figure 9 ).

After 40 days of growth, all tadpoles reached a maximum TOL of 53–54 mm (n = 30). By days 45–49, the tail had fully regressed, and the SVL of froglets measured 17.9–18.1 mm (n = 30). For comparison, N. okinavana tadpoles in Japan undergo metamorphosis at a SVL of ~ 20 mm, with a maximum TOL of ~ 70 mm ( Maeda and Matsui 1990; Matsui and Maeda 2018), and froglets 20.0 ± 0.3 mm (mean ± SD) in SVL immediately after tail absorption ( Kuramoto 1985).

Distribution and natural habitats.

Nidirana shyhhuangi sp. nov. is only known from two sites: Lienhuachih and Xiangshan (Sun Moon Lake). A past report from Jiaoxi Township in Yilan County (e. g., Shang et al. 2009; Fei et al. 2010; Fei et al. 2012; Yang and Li 2019) has been thoroughly investigated by local researchers, but this site could not be confirmed despite multiple surveys (S. - H. Chen, pers. comm., 2 July 2024 to SML).

The habitat of Lienhuachih population (~ 670 m a. s. l.), discovered by Shyh-Huang Chen in 1984, is composed of ponds and patchy bamboo forests surrounded by typical low-elevation Ficus - Machilus forests (Fig. 10 A View Figure 10 ). Water continuously seeps into the pond from the mountain hollow, keeping the pond at a stable water level. The substrate of the habitat remains moist and waterlogged throughout the year due to continuous water flow or hydrostatic pressure, with the soil being soft and highly absorbent. The soil texture in this area is yellow laterite soil with a topsoil of gray-brown sandy loam and subsoil composed of clay mixed with rock fragments ( Koh et al. 1978; Lin and Fu 2022).

The second distribution site of Nidirana shyhhuangi sp. nov. was discovered from Xiangshan (~ 800 m a. s. l.) near the famous landmark Sun Moon Lake in 2005. The macrohabitat of this site comprises a valley terrain consisting of streams, dense forests, slopes, and forest paths ( Lin and Fu 2022). The valley’s soil is interspersed with humus, making it very soft and moist. A subsurface water layer maintains the stream’s flow even during the dry season. Substrate in this area appears similar to reddish yellow earth indicative of laterization, likely consisting of gravelly clay, which is suitable for the nesting and reproduction of the frogs ( Lin and Fu 2022).

Both habitats are situated in mountain hollows, which facilitate the collection of surrounding water sources. Coupled with the inflow of subsurface water, these habitats remain perennially waterlogged and moist even in the dry season, promoting the aggregation of the frogs.

Natural history notes.

Nidirana shyhhuangi sp. nov. is the only mud-nesting species among the ranid family in Taiwan (Figs 7 D View Figure 7 , 10 B View Figure 10 ). Breeding season starts from April and lasts to late September. During the breeding season, male frogs select soil slopes within ~ 20 cm from the water to excavate mud nests, where they call from inside the nest to attract females. Newly built mud nests are shaped like pottery embryos, with an opening diameter of ~ 0.5–2 cm and an internal width of ~ 4 cm, often covered by fallen leaves or twigs. Unlike most frogs that lay eggs directly in water, the nest-building behavior reduces predation risk of the offspring, but requires significant energy expenditure. On average, it takes 2–3 hours for a male complete a nest ( Lin and Fu 2022). The eggs are laid in cluster within the mud nest excavated by the male, with approximately 40 eggs per nest (range 31–51, mean ± SD = 39 ± 7, n = 6).

The eggs of the frog are encased in a transparent gelatinous substance and develop and hatch within the mud nests. The hatched tadpoles usually remain in the nest for a period of time, until heavy rain flushes the nests or water levels rise and allow the tadpoles to be released into adjacent streams or ponds. The tadpoles are brown in color, benthic, and have a larval period of 45–50 days at water temperatures of 26–29 ° C ( Lin and Fu 2022).