Wangyal's Torrent Frog, Amolops wangyali - Species New to Science

[Herpetology 2022] A Review of Torrent frogs (Amolops: Ranidae) from Bhutan, the Description of a New Species, and Reassessment of the Taxonomic Validity of some A. viridimaculatus Group Species aided by Archival DNA Sequences of Century-old Type Specimens.

Stephen Mahony, Tshering Nidup, Jeffrey W. Streicher, Emma C. Teeling and Rachunliu G. Kamei

In: The Herpetological Journal. 32(3); 142-175. DOI: 10.33256/32.3.142175

                                                                                Amolops wangyali species novel

Abstract                   

Seven species of the Asian torrent frogs (genus Amolops) have previously been reported from the eastern Himalayan country of Bhutan. Species identifications from the region have been largely Seven species of the Asian torrent frogs (genus Amolops) have previously been reported from the eastern Himalayan country of Bhutan. Species identifications from the region have been largely based on photographed animals with few voucher specimens available and no molecular sampling. Understanding the taxonomic status of Bhutan’s torrent frogs has also been hampered by the poorly understood distributional limits of species from surrounding regions. Herein we utilised molecular phylogenetic and morphological data for vouchered specimens from Bhutan and provide a complete literature review of all Amolops populations reported from the country. Phylogenetic relationships were estimated by combining available sequence data (from GenBank) with newly generated sequences from recently collected Bhutanese Amolops populations. We also obtained archival DNA sequences from the type specimens of Amolops formosus, A. himalayanus, and A. kaulbacki, collected between 82 and 151 years ago. Our comparative analyses revealed a large, new (to science) species of the Amolops viridimaculatus group from eastern Bhutan. Morphological examinations of related taxa revealed that A. senchalensis from India is not a synonym of A. marmoratus. Molecular phylogenetic results supplemented by morphological data unambiguously demonstrate i) that A. himalayanus is present in eastern Nepal, ii) the presence of a previously undocumented population of A. nepalicus in eastern Nepal, iii) a 200 km range extention for A. kaulbacki into Yunnan, China, iv) that A. gyirongensis should be considered a junior subjective synonym of A. formosus, and v) that A. splendissimus from Vietnam should be considered a junior subjective synonym of A. viridimaculatus. Based on our results, we expand the Amolops viridimaculatus group to include nine species, including A. formosus, A. himalayanus, A. kaulbacki, and the new species described herein. We provisionally include a further three species in the viridimaculatus group based on morphology, A. longimanus, A. nidorbellus, and A. senchalensis. Combining our data with the literature review allowed us to identify several unidentified Amolops species from recent phylogenetic studies and remove nine frog species (including Hyla, Sylvirana, and seven Amolops species) from Bhutan’s amphibian checklist. We recognise four species of Amolops in Bhutan, three of which cannot be confidently identified to the species level based on currently available data.

Keywords: Anura, taxonomy, Himalayas, conservation, vouchered-specimens

Amolops wangyali sp. nov.

 adult male holotype (SCZM 2019.07.18.1) in life (A & B: images taken ex-situ) and immediately after euthanisation, prior to fixation (C–G): A. dorsolateral view; B. lateral view of head, red arrow shows the shoulder gland; C. dorsolateral view; D. ventral view; E. posterior view of thighs; F. palmar view of left hand; G. plantar view of left foot. Scale bars represent 10 mm.

Amolops wangyali sp. nov.

 adult male holotype (SCZM 2019.07.18.1) in life (images taken ex-situ) adult female paratype (SCZM 2019.07.18.2) in life (A & B) 

Amolops wangyali sp. nov.

juveniles in life (A–D) showing ontogenetic variation in colouration and markings: A & B. dorsolateral and profile views of a nearly metamorphosed juvenile (SCZM 2019.07.18.3), from the type locality, images taken ex-situ; C. dorsolateral view of larger juvenile (SCZM 2019.07.20.1), from Rongthong (27.2808, 91.53937, ca. 1,520 m a.s.l.), Trashigang District, Bhutan, image taken ex-situ; D. dorsal view of uncollected halfgrown juvenile, from Jere Chhu/Stream, Khaling Town, Bhutan, image taken in-situ; E. habitat at the type locality, Bodidrang Chhu/ Stream, taken from the Singye Thegchog Bridge two days after the collection of the holotype (20 July 2019); F. adult female paratype (SCZM 2019.08.02.1) from Bodidrang Chhu/Stream, image taken immediately after euthanisation, prior to fixation. Scale bar represents 10 mm.

Etymology: 

The specific epithet is a patronym, named in recognition of Mr. Jigme Tshelthrim Wangyal, a Forest Officer with the Department of Forest and Park Services, Ministry of Agriculture and Forests, Government of Bhutan. Jigme is an accomplished Bhutanese herpetologist and has published many papers on the subject (Wangyal, 2011, 2013, 2014; Wangyal & Gurung, 2012, 2017; Wangyal & Das, 2014; Wangyal et al., 2020). Jigme’s extensive network of Forest Officers, researchers and wildlife enthusiasts have supplemented his extensive personal observations in several of his publications, and as a consequence, many of the species currently on Bhutan’s amphibian and reptile checklist were first documented in the country through his efforts. He continues to support and inspire interest in amphibian and reptile research through seminars and field training workshops and is a vocal proponent for improving standards of herpetological research in Bhutan. 

Suggested common name:  Wangyal’s torrent frog.

CONCLUSIONS

In summary, we identified four species of Amolops from Bhutan: (1) Amolops sp. 1. (viridimaculatus group: from Tshewang & Letro, 2018), (2) A. cf. gerbillus (marmoratus group), (3) A. cf. putaoensis (monticola group), and (4) A. wangyali sp. nov. (viridimaculatus group). Outside of the new species described herein, we were unable to determine species identities for these taxa given the available data. Until such time as vouchered specimens are clearly identified from the country by means of a detailed morphological comparison of vouchered specimens with relevant taxonomic literature, and/or with the aid of DNA sequence data, the following nine species must be formally removed from the amphibian checklist of Bhutan: (1) Amolops formosus, (2) A. gerbillus, (3) A. himalayanus (including A. aff. himalayanus), (4) A. mantzorum, (5) A. marmoratus, (6) A. monticola, (7) A. wenshanensis, (8) Sylvirana cf. guentheri, (9) Hyla annectans (including Hyla cf. annectans). Unintentional misidentifications in the literature can result in significantly overestimated/ erroneous geographic distributions for species, a situation which undermines conservation efforts. Inaccuracies in such assessments could even result in the redirection of conservation resources (funds and efforts) away from vulnerable range restricted species that require urgent attention. For these reasons, we encourage authors not to assign species names to taxa in publications if there is any uncertainty regarding the identification of the species. Many populations of amphibians reported from Bhutan (and elsewhere in Asia) are provided non-specific locality details (e.g. lack GPS coordinates, elevation details), are not represented in museum/university collections by vouchered specimens, and are often published without photographic evidence. Locally abundant species can often be dismissed as “common”, or of little scientific interest, and subsequently ignored by researchers; however, studies on Himalayan amphibians have demonstrated that “common” or widespread species occasionally represent complexes of morphologically similar species (e.g. Dubois, 1975; Kamei et al., 2009; Dever et al., 2012; Khatiwada et al., 2017; Mahony et al., 2013, 2018, 2020), so careful attention to document every species should be made when possible. Our review of Amolops reports in literature demonstrate that some taxonomic information can be obtained from good quality images of uncollected animals, but inevitably an accurate species inventory for Bhutan’s amphibian fauna will not be possible without permanently maintained reference collections of vouchered specimens. Range restricted species may be only one drought, forest fire or hydroelectric dam away from extinction, thus the urgency to catalogue the Himalayan biodiversity has never been more urgent.