Ishan Agarwal

Insights into Himalayan biogeography from geckos: A molecular phylogeny of Cyrtodactylus (Squamata: Gekkonidae)

The India-Asia collision profoundly influenced the climate, topography and biodiversity of Asia, causing the formation of the biodiverse Himalayas. The species-rich gekkonid genus Cyrtodactylus is an ideal clade for exploring the biological impacts of the India-Asia collision, as previous phylogenetic hypotheses suggest basal divergences occurred within the Himalayas and Indo-Burma during the Eocene. To this end, we sampled for Cyrtodactylus across Indian areas of the Himalayas and Indo-Burma Hotspots and used three genes to reconstruct relationships and estimate divergence times. Basal divergences in Cyrtodactylus, Hemidactylus and the Palaearctic naked-toed geckos were simultaneous with or just preceded the start of the India-Asia collision. Diversification within Cyrtodactylus tracks the India-Asia collision and subsequent geological events. A number of geographically concordant clades are resolved within Indo-Burmese Cyrtodactylus. Our study reveals 17 divergent lineages that may represent undescribed species, underscoring the previously undocumented diversity of the region. The importance of rocky habitats for Cyrtodactylus indicates the Indo-Gangetic flood plains and the Garo-Rajmahal Gap are likely to have been important historical barriers for this group.

A phylogeny of the only ground-dwelling radiation of Cyrtodactylus (Squamata, Gekkonidae): diversification of Geckoella across peninsular India and Sri Lanka.

The subgenus Geckoella, the only ground-dwelling radiation within Cyrtodactylus, closely overlaps in distribution with brookii group Hemidactylus in peninsular India and Sri Lanka. Both groups have Oligocene origins, the latter with over thrice as many described species. The striking difference in species richness led us to believe that Geckoella diversity is underestimated, and we sampled for Geckoella across peninsular India. A multi-locus phylogeny reveals Geckoella diversity is hugely underestimated, with at least seven undescribed species, doubling previously known richness. Strikingly, the new species correspond to cryptic lineages within described Indian species (complexes); a number of these endemic lineages from the hills of peninsular India outside the Western Ghats, highlighting the undocumented diversity of the Indian dry zone. The Geckoella phylogeny demonstrates deep splits between the Indian species and Sri Lankan G. triedrus, and between Indian dry and wet zone clades, dating back to the late Oligocene. Geckoella and brookii group Hemidactylus show contrasting diversification patterns. Geckoella shows signals of niche conservatism and appears to have retained its ancestral forest habitat. The late Miocene burst in speciation in Geckoella may be linked to the expansion of rain forests during the mid-Miocene climatic optimum and subsequent fragmentation with increasing late Miocene aridification.

Cryptic species and Miocene diversification of Palaearctic naked-toed geckos (Squamata: Gekkonidae) in the Indian dry zone

We sampled Palaearctic naked‐toed geckos from across their range in India and used two mitochondrial and two nuclear genes to reconstruct relationships within a global phylogeny. Published sequences of Peninsular Indian Hemidactylus allow us to contrast these two groups in dating analyses – providing insights into the history of the Indian dry zone. Palaearctic naked‐toed geckos first moved onto the Indian Plate in the Oligocene, with higher‐level diversification probably linked to collision of the Indian and Eurasian plates, and subsequent dispersal into‐India and diversification with increasing Miocene aridity. An independent gekkonid radiation with species in the dry zone, Hemidactylus diversified during the same period in Peninsular India. Our results demonstrate that dry zone taxa across India may date back to at least the Miocene, with a potential historical climatic barrier between the Indus and Peninsular Indian Divisions. ‘Cyrtopodion’ aravallense is revealed to be a complex with seven genetically and environmentally divergent lineages that began diversifying in the late Miocene, congruent with increased aridity in north‐western India. This discovery of cryptic diversity in the Indian dry zone represents the first terrestrial vertebrate radiation from north‐western central India and highlights how little we understand of the regions’ biodiversity, emphasizing the need for systematic geographic sampling and multiline evidence to reveal true patterns of diversity. The ancestor of ‘Cyrtopodion’ aravallense came into the nascent Indian dry zone in the Miocene and has since diversified, potentially in the absence of any sympatric scansorial rupicolous geckos. Cyrtopodion scabrum represents a unique case of commensalism and shows phylogeographic structure in its presumed native range. The taxonomic implications of our study include a number of undescribed species, recognition of ‘Cyrtopodion’ as a distinct lineage and the non‐monophyly of Altiphylax.

A new rock dwelling Hemidactylus (Squamata: Gekkonidae) from Chhattisgarh, India.

A distinct new species of gecko of the genus Hemidactylus is described from the Kanker district of Chhattisgarh State, east-central India. This large-sized (SVL average 81.33±13.40 to at least 98.0 mm) Hemidactylus is characterized by a dorsum with small granules, intermixed with 10-12 rows of irregularly arranged, slightly larger, rounded, weakly-keeled tubercles at midbody; 10-12 and 13-15 subdigital lamellae on the first and fourth digits, respectively, of both manus and pes; a single enlarged postcloacal tubercle on either side of the tail; 10-12 femoral pores on each thigh separated by 5-8 poreless scales; 12-14 supralabials and 10-12 infralabials.

A new species of large-bodied, tuberculate Hemidactylus Oken (Squamata: Gekkonidae) from the Eastern Ghats, India

A distinct new gecko of the genus Hemidactylus is described from Andhra Pradesh, India. This large-sized (snout to vent length up to at least 105 mm), scansorial Hemidactylus is characterized by dorsal scalation of small granules intermixed with large, pointed, trihedral tubercles that form 16-17 fairly regularly arranged longitudinal rows at midbody; 9-11 subdigital lamellae below the first and 11-13 below the fourth digit; 6-8 strongly pointed and keeled enlarged tubercles on the original tail; 20-23 femoral pores separated by 4 poreless scales in males; 11-13 supralabials and 9-11 infralabials. This is the third vertebrate endemic to the Mahendragiri Range, highlighting the significance of this topographically complex region.

A new species of the Cyrtodactylus ( Geckoella ) collegalensis (Beddome, 1870) complex (Squamata: Gekkonidae) from Western India

A new species of Cyrtodactylus (Geckoella) from the C. collegalensis complex is described based on a series of specimens from western and central India. Morphological and molecular data support the distinctiveness of the new form, which can be diagnosed from other Cyrtodactylus (including other Geckoella) species by its small body size (snout to vent length to 56 mm), the absence of precloacal and femoral pores, no enlarged preanal or femoral scales, and a dorsal scalation consisting wholly of small, granular scales. The new species is most closely related to C. collegalensis, C. speciosus and C. yakhuna, from which it differs by the presence of a patch of enlarged roughly hexagonal scales on the canthus rostralis and beneath the angle of jaw, its relatively long limbs and narrow body, and a dorsal colour pattern of 4-6 pairs of dark spots.

Two new species of bent toed geckos, Cyrtodactylus Gray, 1827 (Squamata: Gekkonidae) from Northeast India with comments on name-bearing types from the region

Two new species of the genus Cyrtodactylus are described based on collections from Northeast India, and descriptions and diagnoses of previously described species and synonyms from the region are provided. One of the new species from lowland habitats in Tripura is medium sized, with a continuous series of precloacal pores, and is allied to C. ayeyarwadyensis from Myanmar; while the other new species from West Bengal is smaller, with both femoral and precloacal pores, and is related to C. gubernatoris from West Bengal and Sikkim. We designate a lectotype for Cyrtodactylus khasiensis and recognize the C. khasiensis synonym Gymnodactylus himalayicus as a valid species of Cyrtodactylus based on morphological evidence, and suggest the recognition of the last remaining subspecies of C. khasiensis, C. k. cayuensis, as a valid species based on geography and morphology. The stabilization of the taxa Cyrtodactylus khasiensis and C. gubernatoris with a limited subset of characters and specific distributional data, as well as the elevation of Cyrtodactylus himalayicus comb. nov. from synonymy, will allow the descriptions of many more Cyrtodactylus species from the region.

A new earless species of Poyntonophrynus (Anura, Bufonidae) from the Serra da Neve Inselberg, Namibe Province, Angola

Abstract African pygmy toads of the genus Poyntonophrynus are some of the least known species of African toads. The genus comprises ten recognized species endemic to sub-Saharan Africa, five of which are restricted to southwestern Africa. Recent field research in Angola provided new material for three species of Poyntonophrynus, including a morphologically distinctive population from the Serra da Neve Inselberg. Based on a combination of external morphology, high-resolution computed tomography scanning, and molecular phylogenetic analysis, the Serra da Neve population is described as new species that is nested within the genus. The most striking character that differentiates the newly described species from its congeners is the lack of a tympanic middle ear, a condition common in the family Bufonidae, but so far not known for Poyntonophrynus. The description of this new species from southwestern Angola reinforces the biogeographic importance of the region and further suggests that southwestern Africa is the cradle of diversity for this genus.

On the Status of Cyrtodactylus malcolmsmithi (Constable, 1949)

Abstract Cyrtodactylus malcolmsmithi was described by Constable in 1949 in the genus Gymnodactylus on the basis of its apparently undivided subdigital lamellae. The species has not been collected since and only finds mention in some checklists and new Cyrtodactylus descriptions. We recently examined the holotype and paratype of this enigmatic taxon and discovered that the subdigital lamellae are divided. The species is accordingly transferred to the genus Hemidactylus, within which it is a member of the Hemidactylus brookii complex and a valid species, Hemidactylus malcolmsmithi comb. nov. We assign recently sampled populations to this taxon and provide a diagnosis against congeners from the Indian subcontinent and a summary of characters for the species.