Corresponding authors: Jianping Jiang (
Academic editor: J. Penner
The
Hoang CV, Nguyen TT, Ninh HT, Luong AM, Pham CT, Nguyen TQ, Orlov NL, Chen YH, Wang B, Ziegler T, Jiang JP (2021) Two new cryptic species of
The genus
In Vietnam, nine species of
Map showing the type localities of
Heymon’s narrow-mouthed frog,
During our recent field surveys in Kon Tum, Dak Lak, Lam Dong, and Ninh Thuan provinces in central Vietnam between 2016 and 2019, a number of microhylid frog specimens were collected that morphologically resembled
Field surveys were conducted in Kon Tum, Dak Lak, Lam Dong, and Ninh Thuan provinces, Vietnam (Fig.
Extraction of genomic DNA from 41 tissue samples (Suppl. material
In addition to the 41 sequences of the collected samples in this work, we used 76 available sequences of 12S rRNA–16S rRNA from GenBank (Garg et al. 2019) for phylogenetic analyses. Sequences of
Phylogenetic trees were constructed by using Maximum Likelihood (
All measurements were taken from 63 preserved specimens (Suppl. material
Terminology for describing eye coloration in life followed
A total of 45 species (Suppl. material
Measurements were used to compare the morphometric difference between the four males and six females of the population from Dak Lak Province and the nine males and two females of the population from Ninh Thuan Province vs. the eight males and two females of
The final alignment of 12S rRNA–16S rRNA contained 1979 numbers of characters. Of these, 1222 sites were conserved and 731 sites exhibited variation, with 587 characters being parsimony-informative. The transition-transversion bias (R) was estimated as 1.279. Nucleotide frequencies were A = 31.64%, T = 23.96%, C = 23.09%, and G = 21.31% (data for ingroup only).
The genetic divergence of the population from Ninh Thuan Province and its congeners ranged from 3.6% (
The
Bayesian Inference of the matrilineal genealogy of
The two new forms could be assigned to the genus
The two new forms differ from other known species of
The two new forms of
Based upon the phylogenetic analyses of 12S rRNA–16S rRNA sequences, the two populations clearly differ from all other species of
(n = 10) All collected by C.V. Hoang et al. at the same location as the holotype:
Selected diagnostic characters for the comparisons between the species of the
16.5–22.0 | 17.7–20.1 | 17.3–18.8 | |
18.0–26.5 | 22.9–26.8 | 21.6–23.6 | |
Habit | Stocky | Stocky | Stocky |
Snout profile | rounded, obtusely pointed | rounded | rounded |
Dorsal skin | smooth | smooth | smooth |
F1 vs. F2 | F1 ≤ ½ F2 | F1 > ½ F2 | F1 ≤ ½ F2 |
Disks on distal end of fingers | present | present | present |
Dorsal median longitudinal line grooves on finger disks | usually present | present | present |
Disks on distal end of toes | present | present | present |
Dorsal peripheral grooves on toe disks | usually present | present | present |
Presence or absence of superciliary tubercles | absent | absent | absent |
Presence or absence of light dorsomedial (vertebral) line | present | present | present |
Tibiotarsal articulation | shorter than snout | shorter than snout | shorter than snout |
Foot webbing | I2 – 2½II2 – 3III3 – 4IV4⅓ – 3V | I2 – 2½II2 – 3III3 – 4IV4⅓ – 3V | I2 – 2½II2 – 3III3 – 4IV4⅓ – 3V |
Distribution | S China, NE India, SE Asia to Sumatra | Dak Lak | Ninh Thuan |
Dorsolateral and ventral views of the specimens in life: comparative specimen of
Habitus stocky, size medium,
Dorsolateral and ventral views of the specimens in preservative: comparative specimen of
Forelimbs short, about three times shorter than hindlimbs (
Lateral view of the head, right hand and right food of
Hindlimbs slender and slightly short (
Dorsal surface of head and body smooth, flank shagreened, dorsal surface smooth, including fingers and toes, fore and hind limbs; ventral surfaces smooth.
Dorsal surface of head and trunk pinkish brown with a dark brown marking in X-shape between eyes to arm, dorsolateral stripes form wavy dust strip towards the groin; a small dark marking in ‘ ()’-shape in the center of the dorsum and a mid-dorsal line extending from the tip of snout to vent. Flanks and lateral surface of head dark, a dark lateral stripe running from snout tip to nostril, fading towards upper jaw. Chin dark grey; throat white with scattered dark grey dusting; chest and belly creamy white. Limbs dorsally with narrow indistinct dark brown cross-bars; fingers and toes dorsally brown with dark brown cross-bars; forelimbs ventrally creamy white, hindlimbs ventrally with creamy white thigh becoming dark grey toward shank, foot. Iris bicolored, golden in upper one-third, dark copper in its lower two-thirds; pupil oval, horizontal, black.
After preservation in ethanol, dorsal coloration changed from light brown to greyish pink (Fig.
Specimens vary in body size, dorsal markings, and black scapular spots. Adult males smaller than adult females, adult males with small vocal sac (Suppl. material
Specific epithet is in reference to the type locality, Ninh Thuan Province. We recommend “Ninh Thuan narrow-mouth frog” as the common English name and “Nhái bầu ninh thuận” as the Vietnamese name.
All specimens were collected at night from 19:00 to 23:00 h on the ground near the banks of a small stream in the forest and on the sides of a recently constructed road next to the devastated forests (Fig.
Habitat of
Currently, the evergreen forest in Phuoc Binh National Park is connected with other forests in Tay Nguyen Plateau. Based on its habitat and altitudinal range, the new species is likely to be endemic to Tay Nguyen Plateau. However, the extent of its actual distribution range requires further study. Given the available information, we suggest
Plots of the first principal component (
(n = 9) All collected by C.V. Hoang et al. at the same location as the holotype:
(1)
Habitus stocky, size medium
Forelimbs comparatively short, about three times shorter than hindlimbs (
Hindlimbs slender and slightly short (
Skin: Dorsal surface of head and body smooth, flanks smoothly shagreened, dorsal surface of fore and hind limbs, including fingers and toes, smooth; ventral surfaces smooth (Fig.
Dorsal surface of head and trunk yellowish brown to light brown with a dark brown marking in a V-shape between eyes to insertion of arms. Vertebral and dorsolateral stripes forming a wavy dust stripe towards the groin. A small dark brown marking in ‘ ()’-shape in the center of the dorsum and mid-dorsal line. Flanks and lateral surface of head dark, a darker lateral stripe running from snout tip to nostril, fading towards the upper jaw and the belly, fading into belly as dusting. Chin dark grey; throat white with scattered dark grey dusting; chest and belly creamy white. Limbs dorsally with narrow indistinct dark brown cross-bars; fingers and toes dorsally brown with dark brown cross-bars; forelimbs ventrally creamy white, hindlimbs ventrally with creamy white thigh changing to dark grey toward shank and foot. Iris bicolored, golden in upper one-third, dark copper in lower two-thirds; pupil oval, horizontal, black (Figs
After preservation in ethanol, the dorsal coloration changed from brown to whitish grey (Fig.
(Suppl. material
Specific epithet is in reference to the type locality, Dak Lak Province. We recommend “Dak Lak narrow-mouth frog” as the common English name and “Nhái bầu dak lak” as the Vietnamese name.
All specimens were collected at night from 19:00 to 23:00 h on the ground near the banks of small temporary ponds formed after heavy rain, along the edges of the forest and on the sides of a recently constructed road next to the devastated forests (Fig.
Currently, the evergreen forest in Nam Ka Nature Reserve, Dak Lak Province, is connected with other forests in the Tay Nguyen Plateau. The extent of its actual distribution range requires further study. Given the available information, we suggest
Our matrilineal genealogy is consistent with those of
The discovery of
In terms of conservation concern, habitat loss is one of the greatest threats to amphibians in Southeast Asia, and the amphibians of the region appear to be particularly vulnerable to habitat alterations (
We would like to thank the directorates of the Bi Doup-Nui Ba National Park, Phuoc Binh National Park, Nam Ka Nature Reserve and Forest Protection Department of Kon Tum Province for supporting our work and issuing relevant permits. Many thanks to L. Iogansen, A. Ostroshabov (St. Petersburg), and T. Y. Nguyen (Hanoi) for their assistance. Thanks to E. J. Sterling (New York) and K. Koy (Berkeley) for providing the map. Research of TTN is funded by the Vietnam National Foundation for Science and Technology Development (NAFOSTED, Grant Number 106.05-2019.334). This research is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA23080101), NSFC (31471964), The World Academy of Sciences (TWAS), CAS- TWAS president fellowship program, RFBR 19-54-54003 Vietnam, the State programm AAAA-A19-119082990107-3 and Ideal Wild.
Tables S1–S6
species data