Ophryophryne synoria Stuart, Sok & Neang, 2006

Jr., Nikolay A. Poyarkov, Duong, Tang Van, Orlov, Nikolai L., Gogoleva, Svetlana S., Vassilieva, Anna B., Nguyen, Luan Thanh, Nguyen, Vu Dang Hoang, Nguyen, Sang Ngoc, Che, Jing & Mahony, Stephen, 2017, Molecular, morphological and acoustic assessment of the genus Ophryophryne (Anura, Megophryidae) from Langbian Plateau, southern Vietnam, with description of a new species, ZooKeys 672, pp. 49-120 : 60-61

New records and range extension for Ophryophryne synoria Stuart, Sok & Neang, 2006

Chresonymy:

Ophryophryne synoria Stuart et al. 2006:135, fig. 5.

" Ophryophryne sp. 3" - Orlov et al. 2008:82 (Chu Yang Sin N.P., Dak Lak Prov., Vietnam; ZISP 12811-12833).

[?] Ophryophryne sp. cf. poilani - Poyarkov [Paiarkov] and Vassilieva 2011:202 (Bidoup Mt., Bidoup–Nui Ba N.P., Lam Dong Prov., Vietnam; ZMMU A-4713).

Ophryophryne synoria - Vassilieva et al. 2016:54-56, figs. 44-47 (Binh Phuoc Prov. and Dong Nai Prov., Vietnam; ZMMU A-4516, ZMMU A-5003).

Holotype.

FMNH 262779, adult male from "O Chung Chry Stream, near 12°17'30"N, 107°03'06"E, 500 m elev., Seima Biodiversity Conservation Area, O’Rang District, Mondolkiri Province, Cambodia", collected by Bryan Lynn Stuart, Sok Ko and Neang Thy ( Stuart et al. 2006; FMNH specimen catalogue). Re-examined by SM.

Paratype.

FMNH 262778, adult male, collected with the holotype ( Stuart et al. 2006).

Measurements of the holotype

(all in mm, taken by SM).SVL 48.8; HW 14.2; HL 13.1; IFE 6.1; IBE 10.8; ED 4.7; TYD 3.0; TYE 3.1; SL 4.3; EN 2.5; NS 1.9; IUE 3.5; IN 3.4; UEW 4.1; FAL 12.0; HAL 13.0; FIL 5.1; FIIL 5.1; FIIIL 8.4; FIVL 5.5; SHL 21.8; TL 21.2; FOL 20.0; TFOL 29.4; IMT 2.2.

Distribution and remarks.

Stuart et al. (2006) described a large-sized Ophryophryne from O’Rang (also spelled as “O’Reang”) District in eastern Cambodia, close to the Vietnamese border, as O. synoria (Loc. 1, Fig. 1). Subsequently, during field surveys in 2009-2011, the species was reported in southern Vietnam from Bu Gia Map N.P., Binh Phuoc Prov. (Loc. 2, Fig. 1) and Cat Tien N.P. in Dong Nai Prov. (Loc. 3, Fig. 1) based on morphological evidence ( Vassilieva et al. 2016). Herein, we confirm the identity of these specimens based on morphological and molecular genetic evidence, and further expand its distribution in southern Vietnam to include medium and low elevation localities in the central and western parts of the Langbian Plateau (Dak Lak, Lam Dong, Dong Nai and Binh Phuoc provinces between 200 and 1500 m a.s.l.; its presence in Dak Nong Prov. is anticipated). We also identify two mtDNA lineages within O. synoria with a moderate level of sequence divergence (p = 2.6%: Table 2, Fig. 2): Subclade B inhabits mountain areas in Lam Dong and Dak Lak provinces and was also recorded for the lowland habitat in Dong Nai Prov. (Locs. 3-4, 6 and 11, Fig. 1) whereas Subclade C is only found in Mondolkiri Prov. of Cambodia and adjacent Binh Phuoc Prov. of Vietnam (Fig. 1, Locs 1-2) and corresponds to O. synoria s. stricto.

Variation.

The studied specimens of O. synoria showed substantial variation in morphological characters, including SVL (Fig. 3) and other morphometric characters (Fig. 4), coloration, and degree of development of palpebral projection (Fig. 6D, E and F). Overall morphology, coloration, and skin glands of the newly discovered populations of O. synoria are in general agreement with the description of the holotype by Stuart et al. (2006). Young specimens from Bidoup–Nui Ba N.P. in life often have reddish or orange coloration of thighs and groin, which was not observed in the type specimens from Cambodia ( Stuart et al. 2006), nor in the Bu Gia Map population. The degree of development of short dorsolateral glandular folds varied among specimens, but they were always distinct (Fig. 6D, E and F). The holotype and the Bu Gia Map population (Subclade C) have the finger length formula F1 = F2 <F4 <F3, while in populations from Bidoup–Nui Ba N.P. and Chu Yang Sin N.P. (Subclade B), the finger length formula is F1 = F4 <F2 <F3. Subclade B populations also tend to have a slightly larger tympanum (TYD/ED 68.4%-80.1%; TYE/TD 73.3%-80.6%) than the nominative O. synoria (TYD/ED 62.0%-71.9%; TYE/TD 83.9%-103.3%). Though the taxonomic status of the two revealed lineages is not completely clear, herein we tentatively regard them as deep intraspecific mtDNA lineages based on observed genetic differentiation and overall morphological similarity.

Vernacular name.

English: “O’Reang Mountain Toad" (this paper); “O’Reang horned frog" ( Vassilieva et al. 2016); Vietnamese: “Cóc Núi O-Reng" ( Vassilieva et al. 2016).