Many widely distributed lizard species exhibit high intraspecific variation and often harbor cryptic diversity (e.g. Zamudio et al., 1997; Bergmann and Russell, 2007; Linkem et al., 2010; Smith et al., 2011; Ahmadzadeh et al., 2013; Oliver et al., 2014). These findings hint at the underestimated diversity of lizards across the world. The Indian subcontinent, a vast landscape, which is topologically and climatically heterogeneous, provides an ideal setting to further explore this issue. This large swathe of land harbors many widely distributed species and recent molecular studies indicate the presence of cryptic diversity among many lizard groups from India (Bansal and Karanth, 2010; Bauer et al., 2010; Agarwal et al., 2014a, b; Agarwal and Karanth, 2015). In this study, we attempt to better understand the diversity of one such widely distributed agamid genus, Sitana, which is endemic to the Indian subcontinent.
Sitana are small ground dwelling agamid lizards found in diverse sets of habitats like scrublands, plateaus and sandy beaches with sparse vegetation (Pal et al., 2010; Subramanean and Reddy, 2010; Shanbhag et al., 2003; Trivedi, 2011). They primarily feed on insects but are also known to eat mollusks and plant seeds (Pal et al., 2007). In many parts of the country, they breed before the beginning of the south west monsoon (Pal et al., 2010; Subramanean and Reddy, 2010; Shanbhag et al., 2003; Trivedi, 2011). Males possess prominent dewlaps which are used in inter and intra-specific communication during the breeding season. Dewlaps are absent in female.
Cuvier (1829) described Sitana ponticeriana from Puducherry (then Pondicherry) in south India, which is the type species of the genus. Günther (1864) described a second species, Sitana minor. In his description, he mentioned that it is found in and around Madras (now Chennai). Jerdon (1870) described a third species, Sitana deccanensis, from Deccan. Boulenger (1885) synonymized both Sitana minor and Sitana deccanensis with Sitana ponticeriana. Amarasinghe et al. (2015) resurrected Sitana deccanensis, but agreed with Boulenger in considering Sitana minor a junior synonym of Sitana ponticeriana (Cuvier, 1829). Three species of Sitana (Sitana fusca Schleich and Kästle, 1998, Sitana sivalensis Schleich, Kästle and Shah, 1998, Sitana schleichi Anders and Kästle, 2002) were recently described from the Terai of Nepal. These three species are distinct from the Indian species of Sitana in having smaller dewlaps that do not extend beyond the forearm insertion, and no overlapping scales on the dewlaps (Schleich and Kästle, 2002). More recently, two new species of Sitana were described from Sri Lanka, Sitana bahiri Amarsinghe, Ineich, and Karunarathna, 2015 and Sitana devakai Amarsinghe, Ineich, and Karunarathna, 2015. Presently, only two species are known from India, though much of the range of the genus Sitana falls within this country. Given that Sitana is widely distributed in the various biogeographic subregions of India, we suspected that the Indian population might harbor various cryptic species. Furthermore, despite that many new Sitana species have been described in recent years, only one published nucleotide sequence is available in GenBank database (Macey et al., 2000), indicating that molecular data have not been recruited in an effort to identify cryptic lineages. The one available sequence was recently analyzed in the context of a dated phylogeny, suggested that the genus Sitana diverged from the genus Otocryptis (Wagler, 1830) around 12 million years ago in South Asia (Blankers et al., 2010).
Sitana ranges from the foothills of the Himalayas (Terai region of Jammu and Kashmir) in the north, to coastal Sri Lanka in the south, to Pakistan in the west, and into parts of West Bengal in the East. Stoliczka (1872), based on his experience collecting in the subcontinent and museum collections, suggested that Sitana is not found east of Brahmaputra River. However, the results of the German Indian Expedition of 1955-1958 (Hallermann et al., 2001) report a single specimen from Umsaw (Umsning), Mehalaya, West Khasi Hills, India, which is labelled as Sitana ponticeriana. This study aims to contribute to our understanding of Sitana taxonomy using morphology and support it with molecular data. We sampled in five different states in Peninsular India, including the type localities of Sitana ponticeriana and Sitana deccanensis. On the basis of these additional specimens to the museum collections, we describe one new genus and five new species of Fan-throated lizards: Sarada gen. nov., Sarada darwini sp. nov., Sarada superba sp. nov., Sitana visiri sp. nov., Sitana laticeps sp. nov. and Sitana spinaecephalus sp. nov. Additional descriptions are given for Sitana ponticeriana and Sarada deccanensis comb. nov.