Leptobrachella phiadenensis, Luong & Hoang & Pham & Ziegler & Nguyen, 2023

Luong, Anh Mai, Hoang, Chung Van, Pham, Cuong The, Ziegler, Thomas & Nguyen, Truong Quang, 2023, Two new species of Leptobrachella Smith 1925 (Amphibia: Megophryidae) from Cao Bang Province, Vietnam, Zootaxa 5369 (3), pp. 301-335 : 312-330

Leptobrachella phiadenensis sp. nov.

(Figs. 5, 6 ; Tables 2–4 )

Holotype. Adult female IEBR A.5205 (field number: PhiaOac2018.40), VIETNAM: Cao Bang Province, Nguyen Binh District, Phia Oac-Phia Den National Park (22°35'41.8"N 105°53'16.7"E, 1,320 m a.s.l.), collected by Hoang et al. on 10 November 2018.

Paratype (n = 1). One adult female IEBR A.5206 (field number: PhiaOac2018.41); the same collection data as for the holotype .

Diagnosis. Leptobrachella phiadenensis sp. nov. is distinguished from its congeners by a combination of the following morphological characters: size medium (27.6–28.6 mm in 2 adult females); head wider than long; tympanum distinct; skin on dorsal head and body rough with warts, tubercles and dermal ridges; toes webbing rudimentary, with narrow dermal fringes; supratympanic fold orange; dorsal surface of head and body with some large dark brown markings, a dark brown triangle in interorbital region, edged in white; flank light brown with some dark flecks; belly white with dark specking on outer margins; iris bicolored, copper in upper part, fading to silvery grey in lower part.

Description of holotype. Habitus stocky, size medium, head wider than long (HDL/HDW 0.97); snout obtusely pointed in dorsal view, slightly projecting beyond margin of lower jaw; nostril round, located closer to the tip of snout than to eye; canthus rostralis round; loreal region sloping; pupil vertical; eye diameter equal to snout length (EYE/SNT 0.91); tympanum distinct, round, tympanum diameter smaller than that of eye (TMP/EYE 0.61); tympanic rim not elevated relative to skin of temporal region; vomerine teeth absent; pineal ocellus absent; tongue large, broad, with small notch posteriorly; supratympanic fold forming a distinct ridge, running from posterior corner of eye towards axillary gland, with few nodules.

Forelimbs thin, slender; finger tips round, equal to phalange width; relative finger lengths: I<II<IV<III; nuptial pad absent; subarticular tubercles absent; a large, round inner palmar tubercle, distinctly separated from small, laterally compressed outer palmar tubercle; finger webbing absent and without lateral fringes.

Hindlimbs slender, tibia nearly half of snout-vent length (TIB/SVL 0.48); heels meeting when thighs adpressed at right angles to the body; tips of toes like those of fingers; relative toe lengths: I<II<V<III<IV; subarticular tubercles absent, replaced by distinct dermal ridges; inner metatarsal tubercle small, oval, pronounced, outer metatarsal tubercle absent; toes webbing rudimentary; toes with very narrow lateral fringes.

Skin texture in life. Skin on dorsal head and body rough with warts, tubercles and dermal ridges; dorsal surface of thighs, upper arms and upper eyelid covered by tubercles and dermal ridges; ventral skin smooth; pectoral gland laterally compressed, 0.5 mm in diameter; femoral glands small, oval, approximately 1.0 mm in diameter, located on posterior ventral surfaces of thighs, closer to knee than to vent; supra-axillary gland raised, 0.9 mm in diameter; ventrolateral glands present, dorsolaterally compressed, forming an incomplete line.

Color in life. Dorsal surface of head and body light brown with some large dark brown markings; a dark brown triangle in interorbital region, edged in white; dorsum with some large dark brown markings, edged in white; supratympanic fold orange; tubercles on dorsum and limbs orange, flank and heel light brown with some dark flecks; upper lip with dark brown bars; loreal and tympanic region with distinct brown markings, a dark brown stripe below supratympanic ridge, running from posterior corner of eye towards shoulder; dorsal surface of limbs with diffuse, transverse dark brown bars; fingers and toes with faint transverse bars; throat, chest and belly white with dark specking on outer margins; outer edges of chin, thighs, arms and tibiotarsus light brown with small whitish spots; supra-axillary gland cream; femoral, pectoral and dorsolateral glands white; iris bicolored, copper in upper half, fading to silvery grey in lower half.

Color in preservative. Dorsal surface brown; throat, chest and belly cream; ventrolateral margins of throat and belly with brown specking; ventral surface of thighs and arms pale brown with white specking; cream pectoral glands became indistinct in preservative.

Variation. Measurements of the type series are shown in Table 2 and photograph of the paratype in life is shown in Fig. 6 . In the paratype, interorbital dark marking is smaller and not connecting with two other dark markings in scapular region. Glands around cloacal opening vary in size and number.

Etymology. Specific epithet is in reference to the type locality of the Phia Den mountain peak (at an elevation of 1,520 m a.s.l.) is one of the two highest peaks in the Phia Oac-Phia Den National Park. We recommend “Phia Den Litter Frog” as the common English name and “Cóc mày phia đén” as the Vietnamese name.

Distribution and ecological notes. Leptobrachella phiadenensis sp. nov. is currently known from Phia Oac-Phia Den National Park in Cao Bang Province, Vietnam. Two specimens of the new species were found, one on a rock and another one on the bank of a small cascade stream, in evergreen forest at an elevation of 1,320 m a.s.l. ( Fig.7A ). The surrounding habitat was secondary forest of medium and small hardwoods mixed with bamboo ( Fig. 7C ). Leptobrachella phiadenensis sp. nov. occurs sympatrically with Leptobrachella phiaoacensis sp. nov., L. ventripunctata and L. nyx . Other amphibian species found at the sites included Quasipaa boulengeri (Günther) , Odorrana nasica (Boulenger) , Boulenophrys caobangensis (Nguyen, Pham, Nguyen, Luong & Ziegler) , and Limnonectes bannanensis Ye, Fei, Xie & Jiang.

Leptobrachella phiaoacensis sp. nov. was collected in a stream on the slope of Phia Oac mountain, whereas Leptobrachella phiadenensis sp. nov. was collected in a stream on the slope of Phia Den mountain.

Comparisons. Comparative morphological data of Leptobrachella phiadenensis sp. nov. and 70 recognized Leptobrachella species occurring north of the of the Isthmus of Kra were listed in Table 3 .

In the phylogenetic tree Leptobrachella phiadenensis sp. nov. is a sister taxon to L. shangsiensis with a high support value (1.0 in BI, 94.3% in ML) ( Fig. 2 ), and it can be distinguished from the later by a genetic divergence of 3.9%. Morphologically, it differs from by L. shangsiensis by having a smaller body size in females (SVL 27.6–28.6 mm vs. 30.8–35.9 mm in L. shangsiensis ), flank light brown with some dark flecks (vs. lateral side of trunk with creamy whitish spots in L. shangsiensis ), and supratympanic fold orange (vs. supratympanic fold black with dark reddish rim in L. shangsiensis ).

Leptobrachella phiadenensis sp. nov. differs from L. pluvialis by having toes with narrow lateral fringes (vs. absent in L. pluvialis ), and skin on dorsal head and body rough with warts, tubercles and dermal ridges (vs. smooth in L. pluvialis ); from L. nyx by having a smaller body size in females (SVL 27.6–28.6 mm vs. 37.0–41.0 mm in L. nyx ), head wider than long (vs. head longer than wide in L. nyx ), and toes with narrow lateral fringes (vs. absent in L. nyx ); from L. ventripunctata by having a smaller body size in females (SVL 27.6–28.6 mm vs. 31.5–35.0 mm in L. ventripunctata ), toes with narrow lateral fringes (vs. absent in L. ventripunctata ), and different ventral color pattern (creamy white with brown dusting on margins vs. chest and belly with dark brown spots in L.ventripunctata ); from L. aerea by having distinct black spots on flanks (vs. absent in L. aerea ), distinct dorsolateral markings (vs. indistinct in L. aerea ), and iris bicolored: copper in upper half, fading to golden in its lower half (vs. iris bronze in L. aerea ); from L. feii by having a larger body size in females (SVL 27.6–28.6 mm vs. 25.67 mm in L. feii ), a smaller ratio EYE/SVL (0.13 vs. 0.15 in L. feii ), and head wider than long (vs. head longer than wide in L. feii ); from L. minima by having a smaller body size in females (SVL 27.6–28.6 mm vs. 31.6–37.3 mm in L. minima ), toes with narrow lateral fringes (vs. absent in L. minima ), and skin on dorsal head and body rough with warts, tubercles and dermal ridges (vs. smooth in L. minima ); from L. nahangensis by having toes with narrow lateral fringes (vs. absent in L. nahangensis ), skin on dorsal head and body rough with warts, tubercles and dermal ridges (vs. smooth with small pustules and minute tubercles uniformly distributed in L. nahangensis ), and iris bicolored: copper in upper half, fading to silvery grey in its lower half (vs. iris gold uniformly distributed with minute black, reticulations in L. nahangensis ); from L. wuhuangmontis by having a smaller body size in females (SVL 27.6–28.6 mm vs. 33.0– 36.3 mm in L. wuhuangmontis ), and different ventral color pattern (creamy white with brown dusting on margins vs. greyish white mixed by tiny white and black dots in L. wuhuangmontis ).

Figures

FIGURE. 6. Paratype of Leptobrachella phiadenensis sp. nov. (IEBR A. 5206) in life. Photo by C.V. Hoang.

FIGURE. 7. A) Habitat of Phia Oac-Phia Den National Park in Cao Bang Province, Vietnam, B) Microhabitat habitat of Leptobrachella phiaoacensis and C) Microhabitat habitat of Leptobrachella phiadenensis. Photos by C.T. Pham and C.V. Hoang.

FIGURE. 2. The Bayesian inference (BI) tree based on the partial 16S rRNA mitochondrial gene. Values at nodes correspond to BI/ML support values, respectively. Leptobrachium cf. chapaense and Xenophrys truongsonensis are used in the outgroup.