New records of megophryids (Amphibia: Anura: Megophryidae) from Son La Province, Vietnam

Abstract Background The family Megophryidae is one of the most poorly known groups of amphibians in Son La Province, Vietnam. In the herpetofaunal list of Vietnam in 2009 only two species of megophryids were recorded from this province and recent studies have documented five additional species of Megophryidae from Son La Province. New information Based on recent field work in northern Vietnam, we report six new provincial records of the family Megophryidae from Son La Province, namely Leptobrachium ailaonicum, Leptobrachella sungi, Megophrys feae, M. jingdongensis, M. microstoma and M. parva. In addition, morphological data were provided for each species, based on newly collected specimens. Our findings bring the species number of the family Megophryidae to 13 in Son La Province.

In Son La Province, Nguyen et al. (2009) recorded only two species of the family Megophryidae, namely Leptobrachium chapaense (Bourret) and Megophrys major Pham et al. (2014b) recorded three additional species, namely M. pachyproctus Huang, M. palpebralespinosa Bourret, and Leptobrachella ventripunctata (Fei, Ye & Li).  reported two species for the first time from this province, viz. Leptobrachium masatakasatoi Matsui and Leptobrachella minima (Taylor). Based on our recent field work in Son La Province between 2014 and 2017, we herein report six new provincial records of the family Megophryidae.

Sampling
Field surveys were conducted in Son La Province from 18 to 22 June 2014 in Copia Nature Reserve (NR); from 27 to 29 April 2015 in Sop Cop NR; from 28 August to 4 September 2015 and from 26 to 30 October 2016 in Phu Yen District; from 14 to 17 April 2017 in Muong La NR; and from 28 April to 3 May 2017 in Bac Yen District (Fig. 1).
Specimens were collected by hand between 19:00-22:00 h. After taking photographs, specimens were euthanised in a closed vessel with a piece of cotton wool containing ethyl acetate (Simmons 2002), fixed in 80% ethanol for five hours and then transferred to 70% ethanol for permanent storage. Voucher specimens were subsequently deposited in the collections of the Institute of Ecology and Biological Resources (IEBR), Hanoi and the Tay Bac University (TBU), Son La Province, Vietnam.

Morphological characters
Measurements were taken with a digital caliper to the nearest 0.1 mm. Abbreviations are as follows: SVL: snout-vent length; HL: head length from posterior corner of mandible to tip of snout; HW: maximum head width, at the angle of jaws; IN: internarial distance; SL: distance from anterior corner of eye to tip of snout; NS: distance from anterior edge of nostril to tip of snout; EN: distance from anterior corner of eye to posterior edge of nostril; EL: eye length, from anterior corner to posterior corner of eye; IOD: minimum distance between upper eyelids; UEW: maximum width of upper eyelid; TD: maximum tympanum diameter; FLL: forelimb length, from axilla to tip of third finger; HLL: hind limb length, from vent to tip of fourth toe; FL: thigh length, from vent to knee; TL shank length. For webbing formula, we followed Glaw and Vences (2007). Sex was determined by gonadal inspection. Map showing the sampling sites in Son La Province, northwestern Vietnam New records of megophryids (Amphibia: Anura: Megophryidae) from Son La ...
Skin. Dorsal surface with fine network of ridges, tubercles present in the posterior region of tympanum; upper lip with 46-78 keratinised spines; supratympanic fold present, from posterior edge of eye to axilla; flanks, belly, chest, throat, underside of forelimbs and thighs with small white pustules.
Colouration in life. Dorsal surface of the head light brown or reddish-brown, with dark brown spots on medial side of upper eyelid; back with irregularly dark brown spots; ventral surface with light brown pustules, more concentrated in chest area (Fig. 2).

Distribution
In Vietnam, this species was recorded from Lao Cai Province (Nguyen et al. 2009). Our new record is approximately 70 km distant from Lao Cai Province. Elsewhere, this species is known from China (Frost 2019).

Ecology
The specimens of L. ailaonicum were found on the edge of small streams and on forest paths between 20:00 and 21:00 h. The surrounding habitat was mixed secondary forest of large hardwood and shrub.

Taxon discussion
The male specimens from Son La have more keratinied spines than those in the previous studies: 46-78 versus 20-48 (Yang et al. 1983) and 50-59 (Ho et al. 1999).
Forelimbs. Forearm robust; relative finger lengths I = II = IV < III, tips of fingers not enlarged into discs; webbing absent; subarticular tubercles indistinct; palmar tubercles round, in contact, inner one very large.
Skin. Dorsal surface of head and body, upper part of flanks with tubercles; upper eyelid granular; supratympanic fold distinct, extending from posterior corner of eye to a point behind articulation of jaw; dorsolateral fold absent; ventral surface smooth.
Colouration in life. Dorsal surface of head brown grey with a dark brown marking between eyes; canthus and supratympanic fold dark brown; upper lip with dark brown bars; limbs with dark brown transverse bars; ventral surface orange (Fig. 3).

Distribution
In Vietnam, this species has been recorded from Lao Cai, Dien Bien, Yen Bai, and Vinh Phuc provinces (Nguyen et al. 2009). Our new record in Son La Province filled the distribution gap of the species in northwestern Vietnam. Elsewhere, this species is known from China (Frost 2019).

Ecology
The specimens were found at night, between 19:00 and 22:00 h, on the side of the streams in the secondary forest.
Skin. Dorsal surface smooth with some small warts; upper eyelid with tubercles, one of which being larger; supratympanic fold present, from posterior edge of eye to axilla; ventral surface smooth.
Colouration in life. Dorsal surface brown olive; supratympanic fold edged in dark brown below; upper lip light brown; ventral surface dark brown with some whitish dots (Fig. 4).

Distribution
In Vietnam, this species has been recorded from Lao Cai, Yen Bai, Ha Giang, Cao Bang, Lang Son, Vinh Phuc and Bac Giang provinces (Nguyen et al. 2009). Our new record in Son La Province filled the distribution gap of the species in northwestern Vietnam. Elsewhere, this species has been recorded from southern China, Myanmar and Thailand (Frost 2019).
Skin. Dorsal surface of head and body smooth; supratympanic fold extending from posterior edge of eye to axilla; upper lips, around tympanum and upper eyelid with small spines; flanks with some tubercles; surrounding of cloaca with tubercles; dorsolateral folds present; and ventral surface smooth.
Colouration in life. Dorsal surface brown to light yellowish-brown; a darker brown triangular marking with a yellow central blotch between eyes; chin, chest and anterior part of belly dark brown in males or light brown with erratic dark brown blotches in females, a round white spot on each side of the chest present; posterior part of belly and ventral surface of thighs cream to dirty white; posterior part of thighs dark brown with some light blotches (Fig. 5).

Distribution
In Vietnam, this species has been recorded from Lao Cai and Ha Giang provinces (Nguyen et al. 2009). Our new record in Son La Province is approximately 70 km and 150 km distant from Lao Cai and Ha Giang provinces, respectively. Elsewhere, this species is known from China (Frost 2019).

Ecology
The specimens were found on the edge of streams, between 19:00 and 21:30. The surrounding habitat was secondary forest, composed of larger hardwoods and shrubs. Megophrys microstoma (Boulenger, 1903
Colouration in life. Dorsum greyish or light brown, upper surface of limbs with transverse dark brown bars; flanks with some small black spots; ventral surface cream with dark brown marbling (Fig. 6).

Distribution
In Vietnam, this species has been recorded from Lao Cai and Ha Giang in the North southwards to Dak Lak and Lam Dong provinces (Nguyen et al. 2009, Hecht et al. 2013). Our new record in Son La Province filled the distribution gap of the species in northwestern Vietnam. Elsewhere, the species is known from China, Laos, Thailand and Cambodia (Frost 2019).

Ecology
The specimens were found between 19:30 and 22:00 h on branches or stones near rocky streams. The surrounding habitat was secondary forest composed of medium hardwoods and shrubs. ( Skin. Dorsal surface smooth; flanks with small glandular warts; supratympanic fold present, from posterior edge of eye to axilla; around cloaca with small tubercles; ventral surface smooth.

Megophrys parva
Colouration in life. Dorsal surface light yellowish-brown; a darker brown triangular marking between eyes; upper lips with vertical dark brown bars; ventral surface whitish, a round white spot on each side of the chest present; ventral surface of limbs reddish (Fig. 7).

Distribution
In Vietnam, this species has been recorded from Lao Cai, Lai Chau, Dien Bien, and Ha Giang provinces (Nguyen et al. 2009, Orlov et al. 2015, Luong et al. 2019. Our record in Son La Province is the southernmost record of this species in Vietnam. Elsewhere, this species is known from Nepal, India, Bangladesh, Myanmar, Thailand, China, and Laos (Nguyen et al. 2009, Frost 2019).

Ecology
The specimens were found on the edge of streams, between 19:00 and 22:00 h. The surrounding habitat was mixed secondary forest of medium hardwoods and shrubs.

Discussion
The  (Le et al. 2014, Pham et al. 2014a, Pham et al. 2014b, Le et al. 2015a, Le et al. 2015b. Amongst six newly recorded species from Son La Province, three species were found in the protected areas (i.e. Copia, Sop Cop and Muong La nature reserves) and three other species were recorded in Phu Yen District. Our new findings bring the total species number of the family Megophryidae to 13 in Son La Province (after Nguyen et al. 2009, Pham et al. 2014b. Further field surveys are likely to reveal a much greater diversity of amphibians from Son La Province, particularly in poorly explored forests of Muong La, Ta Xua, and Xuan Nha nature reserves.