Odorrana heatwolei ( Stuart & Bain, 2005 )

Kilunda, Felista Kasyoka, Yang, Shen-Pin, Nguyen, Luan Thanh, Le, Manh Van, Suwannapoom, Chatmongkon, Stuart, Bryan L., Nguyen, Sang Ngoc, Zuo, An-Ru, Zhang, Ding-Can, Duan, Zheng-Pan, Duan, Pei-Wen, Yu, Zhong-Bin, Wu, Yun-He & Che, Jing, 2025, Unveiling hidden diversity in Odorrana (Anura, Ranidae) with description of a new species from Yingjiang, China and the first national records of Odorrana heatwolei in Thailand and Vietnam, Zoosystematics and Evolution 101 (4), pp. 2337-2356 : 2337-2356

Odorrana heatwolei ( Stuart & Bain, 2005)

Figs 6 , 7

Chresonymy.

Rana heatwolei Stuart & Bain, 2005 .

Rana tiannanensis — Ohler 2007 (part).

Odorrana heatwolei — Poyarkov et al. 2021; Liu et al. 2023; Stuart, Seateun, Sivongxay & Phimmachak, 2024.

Common name.

Heatwole’s Odorous Frog ( Stuart et al. 2024)

Type specimens of O. heatwolei .

Holotype: Adult male, Voucher number FMNH 258134 , based on the original description ( Stuart and Bain 2005) and an updated diagnosis ( Liu et al. 2023).

Specimen examined.

Adult male ITBCZ 3660 , collected from Loi 1 Village , Muong Loi Commune, Dien Bien Province, Vietnam by Luan Thanh Nguyen and Hung Van Lo on 6 January 2019 ( 20°56.2431'N, 103°14.55882'E; 700 m a. s. l) .

Morphological diagnosis.

Species measurements are provided in Table 4 . ITBCZ 3660 , adult male; body relatively robust ( SVL 50.8 mm); head length slightly longer than wide ( HL / HW 1.06); dorsum shagreened with skin smooth on limbs and venter, skin on flanks heavily granular; snout pointed in dorsal view and rounded in profile, projecting beyond the lower jaw; canthus rostralis distinctly visible; loreal region concave; nostrils lateral, closer to the tip of the snout than to eye ( SND / NED 0.66); pineal body distinct; eye large and prominent ( ED 7.2 mm) with a golden iris; upper eyelid width greater than interorbital distance ( UEW / IOD 1.23); internasal distance greater than interorbital distance ( IOD / IND 0.94); snout length greater than the eye diameter ( SL / ED 1.14); tympanum large, round and distinct ( TD / ED 0.66), tympanic rim round and distinct, supratympanic fold curving slightly above and behind the tympanum; dorsolateral folds distinct extending close to vent; vomerine teeth distinct in two oblique ridges between choanae; tongue cordiform, deeply notched posteriorly with the anterior portion attached to the floor of the mouth; vocal sac opening at corner of mouth, external vocal sacs present.

Fore-limbs robust; fingers long and slender; no webbing on fingers; tips of all four fingers expanded into discs with circum-marginal grooves, relative length of fingers III> IV> I> II; inner and outer metarcarpal tubercles present; nuptial pad on the base of the first finger present; subarticular tubercles well developed, supernumerary tubercles at the base of fingers II, III and IV. Hind-limbs long and moderately muscular; toes long and slender; tips of toes slightly expanded into discs; toes fully webbed to the base of disc; relative toe lengths IV> V> III> II> I; subarticular tubercles oval and prominent; inner metatarsal tubercle oval and prominent, outer metatarsal tubercle absent; heels perpendicular to the body axis when hind-limbs are adpressed. Dorsal skin surface shagreened, flanks granular; ventral skin smooth.

Colouration in life.

Dorsum brown with distinct, small, darker brown spots; upper and lower lip creamy-white; limbs brown with distinct dark crossbars; iris golden; ventral skin creamy-white, with fine brown mottling concentrated along the throat, chest and lateral margins.

Colouration in preservative.

The dorsum darkened with the small darker brown spots turning black, but still visible across the dorsal surface; dorsal surfaces of limbs darkened to black, with the original limb crossbars becoming indistinct; the ventral surfaces of the head, fore-limbs, chest, belly and hind-limbs faded to a fleshy creamy-white colour.

Comparative remarks.

Observed morphological characters for this specimen align closely with the male holotype description of O. heatwolei from Phongsaly, Laos and male specimens from Yunnan, China, in all the key adult diagnostic traits ( Stuart and Bain 2005; Liu et al. 2023). The measured morphological characters (e. g. SVL, HL, HW, TD, ED, dorsal skin texture, tympanum visibility and presence of dorsolateral folds in males) of the male specimen described herein are within the variation reported for the Lao’s type series ( Stuart and Bain 2005; Liu et al. 2023), including the finger and toe lengths and overall morphology. However, the slight differences in body size variation and dorsal colouration, including less contrasting blotches, may reflect age, regional or habitat-related variation rather than taxonomic distinction.

Natural history.

This species inhabits forest streams and river banks between 600 m and 1200 m a. s. l. It was reported in secondary growth disturbed forest, in approximately 8 m wide rocky forest streams in north-western Vietnam ( Dien Bien Province) near the Laos border ( Stuart and Bain 2005) (Figs 1 , 8 B ). Additionally, it was collected in nature trails at 1161 m a. s. l. in Phu Hin Rong Kla National Park, Phitsanulok Province, Thailand. The low-gradient rocky streams bordered by dense broadleaf forest and shrub cover with slow to moderately flowing water and vegetation along the banks seem to be an ideal habitat offering both terrestrial and aquatic microhabitats for this species. Specimens collected during nocturnal surveys were found either on low vegetation or rocks near flowing water, suggesting a strong association with riparian zones.

Distribution.

The species was only known from its type locality in Phou Dendin National Biodiversity Conservation Area, Phongsaly Province, Laos and the Xishuangbanna Prefecture, Yunnan Province, China. This study constitutes the first confirmed records of O. heatwolei in Vietnam and northern Thailand, extending the species’ known range eastwards to Vietnam and south-westwards into Thailand from the type locality in northern Laos (Fig. 1 ).

Remarks.

Odorrana heatwolei was originally described from the Nam Ou River in the Phou Dendin National Biodiversity Conservation Area, Phongsaly District, Phongsaly Province, Laos ( 22°5.63333'N, 102°12.83333'E) at an elevation of 600 m. Its known distribution includes Laos and parts of China, where it is a natural resident. However, Ohler (2007) placed O. heatwolei under the synonymy of O. tiannanensis . This synonymisation was later challenged by Liu et al. (2023), who re-instated O. heatwolei as a distinct species based on molecular data, identifying it as the sister taxon to O. tiannanensis . Additionally, Poyarkov et al. (2021) expressed doubt about the proposed synonymy, recommending further evidence to clarify the taxonomic status of the species. Our molecular analyses, based on 16 S sequence data, recovered samples collected from Thailand and Vietnam as O. heatwolei after strongly clustering with the topotypic sequences of O. heatwolei ( BPP = 1; BS = 100). This finding establishes the first record of O. heatwolei in both Thailand and Vietnam, specifically from northern Thailand (Tambol Don Paya, Ban Sapan, Amphoe Bo Kluea), near the Laos border, Phitsanulok Province, Thailand and Dien Bien Province in Vietnam, extending its currently known distribution further from Laos and China. Genetic distance analyses further supported its distinction from O. tiannanensis and confirmed its taxonomic identity as O. heatwolei as discussed in detail in the results section.

Figures

Figure 1. Map showing the type locality of Odorrana sudianensis sp. nov. (red triangle) and the type locality of Odorrana heatwolei in Laos (red circle); (green circles) indicate other collection locations of Odorrana heatwolei in China, Thailand and Vietnam.

Figure 6. Adult male Odorrana heatwolei (ITBCZ 3660) from Muong Loi Commune, Dien Bien Province, Vietnam in life. A. Dorsolateral view; B. Lateral view of the head region; C. Dorsal view; D. Dorsal view of fore-limb; photos by Luan Thanh Nguyen.

Figure 7. Photos of Odorrana heatwolei specimen (ITBCZ 3660) before preservation. A. Ventral view; B. Dorsolateral view; C. Dorsal view; after preservation; D. Ventral view; E. Ventral view of hind-limb; F. Ventral view of head and fore-limb; G. Lateral view; H. Ventral view of fore-limbs and the oral cavity; I. Dorsal view. Photos by Luan Thanh Nguyen. Scale bars: 10 mm.

Figure 8. A. Habitat of Odorrana sudianensis sp. nov. from the type locality in Yingjiang, Yunnan, China; photo by Zhong-Bin Yu; B. Habitat of Odorrana heatwolei in Muong Loi Commune, Dien Bien, Vietnam; photo by Luan Thanh Nguyen.