Abstract
The gekkonid lizard genus Hemidactylus Oken is the second most species-rich genus of geckos with greatest diversity in the tropical regions of the world. Some species of the genus are commensal and widespread; however, there are several endemic lineages with restricted distribution. India is home to at least 35 species, with 20 endemic species and the number is steadily increasing with exploration of new habitats and integrated taxonomic approach including molecular data. We made investigations into the molecular and morphological variation throughout the distribution of Hemidactylus triedrus Daudin, 1802 based on fresh specimens, literature review, museum material and molecular data. Results from morphological, molecular and micro-CT based anatomical data are unequivocal and show that H. triedrus is a species complex represented by three species, H. triedrus sensu stricto and two undescribed taxa. H. subtriedrus Jerdon, 1854 syn. nov. was found to be morphologically similar to the type specimen of H. triedrus, and genetically embedded in a clade containing H. triedrus sensu stricto and is here treated as a junior synonym of H. triedrus, whereas H. lankae Deraniyagala is referred to as nomen dubium given that the types are presently not traceable and the original description is inadequate in diagnosing the taxon. The populations from western-central India and parts of Pakistan, and from southern Karnataka are distinct and diagnosable, and are herein described as two new species, respectively. Morphological and molecular data support the distinctiveness of the new species. The present work resolves a taxonomic turmoil that lasted over two centuries highlighting the need for studies that integrate morphological and molecular data.
Highlights
Cryptic species are considered to be the worst-case scenario of taxonomic incompleteness
A sequence from Pakistan, one from an unknown locality from India, and another sequence from the Deccan Traps region was recovered as a single haplotype, Hap_1, which here represents H. sahgali sp. nov
The H. prashadi clade (Agarwal, Giri & Bauer, 2011; Mirza, Bhosale & Patil, 2017) contains several large members of the genus which are endemic to India and Sri Lanka which bear large keeled tubercles
Summary
Cryptic species are considered to be the worst-case scenario of taxonomic incompleteness. These are discrete species that are difficult, or sometimes impossible, to distinguish. A substantial portion of biodiversity is made up of cryptic species (Pfenninger & Schwenk, 2007) and disentangling cryptic species is imperative for assessing biodiversity and its conservation (Murthy et al, 2015). Many of these species are morphologically identical to the nominate form and an integration of multiple lines of evidence, such as molecular data, is necessary in differentiating them. Over the past five years, numerous new species of reptiles have been described from across the globe and in particular, from India and neighboring regions, using an integrated approach (Zug et al, 2006; Agarwal et al, 2016; Deepak et al, 2016; Mirza et al, 2016; Giri et al, 2017; Mirza, Bhosale & Patil, 2017)
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