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| Protoblepharus apatani Mirza, Bragin, Bhosale, Gowande, Patel & Poyarkov, 2022 DOI: 10.7717/peerj.12800 |
Abstract
The Himalayas represent a renowned biodiversity hotspot and an important biogeographic realm that has influenced origin and diversification of multiple taxa. A recent herpetological investigation of the eastern Himalayas of the Indian state of Arunachal Pradesh led to the discovery of a unique lineage of ablepharine skink, which is herein described as a new genus along with a new species. The findings are based an integrated taxonomic approach incorporating data from external morphology, microCT scans of the skull and molecular data. The molecular phylogeny of ablepharine skinks is also presented that suggests taxonomic amendments. Discovery of this unique lineage of skinks further highlights the biogeographic importance of the eastern Himalayas as a source for origin of several relic biota.
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| Protoblepharus apatani gen. et sp. nov. holotype male (BNHS 2853) in life. Photo by: Zeeshan A. Mirza. |
Protoblepharus gen. nov.
Types species: Protoblepharus apatani sp. nov. [described below].
Species included: Protoblepharus apatani sp. nov.; Protoblepharus medogensis comb. nov. Jiang, Wu, Guo, Li and Che, 2020; Protoblepharus nyingchiensis comb. nov. Jiang, Wu, Wang, Ding and Che, 2020.
Phylogenetic definition: Protoblepharus is a maximum crown-clade name referring to the clade originating with the most recent common ancestor of Protoblepharus apatani sp. nov. and Protoblepharus nyingchiensis comb. nov., and includes all extant species that share a more recent common ancestor with these taxa than with Ablepharus pannonicus.
Etymology: The proposed generic epithet is a Latinized combination of the Greek words ‘proto’ (πρωτό), meaning ‘primitive’ or ‘first’, and ‘blepharo’ (βλέφαρο) meaning ‘eyelid’ referring to the ablepharine skinks. The proposed name highlights the distinct phylogenetic position of the new genus with reference to Ablepharus skinks.
Recommended English name: East-Himalayan Skinks.
Diagnosis: Ablepharine skinks with a small to medium sized body (SVL up to 63 mm) with a subtle posterior palatine process. The pterygoid lacking process at the palatine-pterygoid junction and furthermore, pterygoid bordering the suborbital fossa. Postorbital bone present. The pterygoid lacking a recurved posterior process. Supranasal bone absent. Lower eyelid scaly and movable, lacking a transparent “window”. Body scales glossy, smooth or striated, lacking keels in 23–26 rows around the midbody. Scales on dorsum and body flanks with or without apical pits. Tympanum with or without small lobules. No reduction of digits (pentadactyle). Paravertebral scales 53–64. Lamellae on fourth finger 7–10 and 11–15 (rarely 16) on fourth toe. A single large scale covering the dorsal surfaces of each digit. Medial pair of precloacal scales enlarged.
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Comparisons: The new genus is compared to members of the clade that include the following genera: Ablepharus, Scincella, Isopachys, Sphenomorphus and Tropidophorus (see Fig. 1). The new genus, Protoblepharus gen. nov. differs from the genus Ablepharus and Scincella in bearing a subtle posterior palatine process (vs posterior palatine process absent in Ablepharus and Scincella), lower eyelid movable (vs fused in some species of Ablepharus) lacking the transparent “window” (vs present in some species of Ablepharus and Scincella). The new genus further differs from Tropidophorus in bearing a sunken tympanum (vs tympanum exposed and superficial in Tropidophorus), in dorsal scales smooth and feebly striated and glossy (vs heavily keeled in Tropidophorus). The new genus further differs from Isopachys in having well-developed limbs (vs absent in Isopachys). The new genus differs from the members of the genus Sphenomorphus having pterygoid bones widely separated, not in contact (vs in contact in Sphenomorphus), it further differs from some members of the genus Sphenomorphus in lacking supranasal bone (vs present in a few species of Sphenomorphus).
Distribution: The new genus inhabits montane forests of Eastern Himalaya from Arunachal Pradesh State of India eastwards along the Brahmaputra River valley to Medog County of Tibet (Xizang) in China (Fig. 2).
Protoblepharus apatani gen. et. sp. nov.
Diagnosis: A small-sized member of the genus Protoblepharus gen. nov. with adult body size measuring SVL = 40.0–55.1 mm. Dorsal scales striated with apical pits, in 26 rows around the midbody; apical pits present on scales on dorsal surfaces of forelimbs and hindlimbs. Three to four pairs of nuchals. Tympanum lacking lobules. Six supralabial scales; 12–13 subdigital lamellae on fourth toe.
Etymology: The specific epithet is given as a noun in apposition honouring the Apatani tribe of Ziro Valley in Arunachal Pradesh; we would like to express our gratitude to the members of the local Apatani community for their help and assistance during our fieldwork in Arunachal Pradesh.
Recommended English name: Apatani East-Himalayan Skink.
Conclusions:
In this study, we present an updated multilocus phylogeny for the ablepharine skinks, which allow us to revise the taxonomy of the group and provide new insights on its origin and evolution. We report on a previously unknown deeply divergent clade of ablepharine skinks, inhabiting the Eastern Himalayan region, which we describe as a new genus; we further describe a new species of this clade from the Arunachal Pradesh State of India. The East Himalayan clade, described as Protoblepharus gen. nov., forms a sister lineage with respect to all other ablepharine skinks, suggesting that the Eastern Himalaya might be the possible area of origin for the whole group. Within the remaining ablepharine skinks, we report that the presently adopted taxonomy, recognizing two genera with a complete fusion of eyelids (Ablepharus sensu stricto) and partial fusion of eyelids (Asymblepharus syn. nov.), is inaccurate and misleading, as the species with the completely fused eyelids are nested within the radiation of taxa with free or partially fused eyelids thus rendering the genus Asymblepharus syn. nov. paraphyletic. We propose to treat this group as a single genus Ablepharus sensu lato, and regard Asymblepharus syn. nov. and Himalblepharus syn. nov. as its subjective junior synonyms. Further studies on phylogenetic relationships of ablepharine skinks are needed to clarify the spatio-temporal process of their diversification, to test the ‘out of Himalaya’ biogeographic hypothesis, and to provide further insights into morphological evolution of this poorly studied group of lizards.
Zeeshan A. Mirza, Andrey M. Bragin, Harshal Bhosale, Gaurang G. Gowande, Harshil Patel and Nikolay A. Poyarkov. 2022. A New Ancient Lineage of Ablepharine Skinks (Sauria: Scincidae) from eastern Himalayas with Notes on Origin and Systematics of the Group. PeerJ. 10:e12800. DOI: 10.7717/peerj.12800
