Diversifying in the mountains: spatiotemporal diversification of frogs in the Western Ghats biodiversity hotspot

Mountain ranges are hotspots of biodiversity. However, the mechanisms that generate biodiversity patterns in different mountainous regions and taxa are not apparent. The Western Ghats (WG) escarpment in India is a globally recognized biodiversity hotspot with high species richness and endemism. Most studies have either invoked paleoclimatic conditions or climatic stability in the southern WG refugium to explain this high diversity and endemism. However, the factors driving macroevolutionary change remain unexplored for most taxa. Here, we generated the most comprehensive dated phylogeny to date for ranoid frogs in the WG and tested the role of paleoclimatic events or climatic stability in influencing frog diversification. We found that the diversity of different ranoid frog clades in the WG either accumulated at a constant rate through time or underwent a decrease in speciation rates around 3-2.5 Ma during the Pleistocene glaciation cycles. We also find no significant difference in diversification rate estimates across elevational gradients and the three broad biogeographic zones in the WG (northern, central, and southern WG). However, time-for-speciation explained regional species richness within clades, wherein older lineages have more extant species diversity. Overall, we find that global paleoclimatic events have had little impact on WG frog diversification throughout most of its early history until the Quaternary and that the WG may have been climatically stable allowing lineages to accumulate and persist over evolutionary time.

70 years of herpetology in India: insights into shifts in focal research areas and gender ratios among authors

Herpetology in India took off during the British colonial rule with the documentation of herpetofauna. Several studies have outlined the early history of Indian herpetology; however, few have traced the growth of this field since India’s independence. We analyse trends in Indian herpetology focusing on taxa, subfields, and authorship over the last 70 years. Of the 1177 published articles we analysed, 64.9% studied reptiles, 26.5% studied amphibians and 8.6% were general herpetofaunal studies. Frogs, lizards, and snakes being the most diverse herpetofauna groups, each accounted for 20-21% of the published articles and significantly outnumber publications on caecilians (2.3%), salamanders (0.4%), chelonians (12.6%), and crocodiles (4.4%). We found a significantly greater number of publications on Diversity & Distribution (34.2%), Taxonomy & Systematics (21.6%) and Ecology (19.4%) compared to other subfields, and detected a decline in Development, Physiology & Cytology and Evolutionary biology studies over the last four decades (1980-2019). The gender ratio among co-authors was dominated by men with only 29.7% of publications containing women authors. The overall proportion of women authors has not changed significantly over decades, but our analyses detected a significant decrease in women first authors and the proportion of women authors when the corresponding authors were men. Women authors were substantially lower in the subfield of Taxonomy & Systematics, and women published significantly more on amphibians compared to reptiles. Overall, we highlight the growth of herpetology in India from two key viewpoints, scientific pursuits, and gender parity among herpetologists.

Dwarfs of the fortress: A new cryptic species of dwarf gecko of the genus Cnemaspis Strauch, 1887 (Squamata, Gekkonidae) from Rajgad fort in the northern Western Ghats of Maharashtra, India

A new species of the genus Cnemaspis Strauch, 1887 is described from the Rajgad fort in the northern Western Ghats of Maharashtra, India. The new species, belonging to the flaviventralis clade, is one of the smallest known Indian Cnemaspis and can be distinguished from other congeners by its genetic distinctiveness and few key morphological characters. The new species can be diagnosed from all other Indian congeners by its small body size (SVL < 27 mm), the absence of conical and spine-like tubercles on flank; heterogeneous dorsal pholidosis; presence of only femoral pores and no precloacal pores in males; weakly keeled scales on the ventral surface of neck, pectoral, abdominal region and limbs; granular scales on the tail with whorls of slightly enlarged, strongly keeled tubercles; and the absence of enlarged median subcaudal scales. The new species is currently known to inhabit the man-made historical structures from a single locality in Rajgad, Maharashtra, where it is presumed to be uncommon.

A new Indian species of Rhinophis Hemprich, 1820 closely related to R. sanguineus Beddome, 1863 (Serpentes: Uropeltidae)

A new species of the uropeltid (shieldtail snake) genus Rhinophis is described based on a type series of seven specimens from the Wayanad region of the Western Ghats of peninsular India. The holotype was collected before 1880 but had been misidentified as the phenotypically similar and parapatric (possibly partly sympatric) R. sanguineus. Rhinophis karinthandani sp. nov. is diagnosed by a combination of 15 dorsal scale rows at midbody, 4-8 pairs of subcaudal scales, colour pattern (uniformly dark above, whitish below with extensive dark mottling), and by its distinct mitochondrial DNA sequences (e.g. 7.6% uncorrected p-distance for nd4). Phylogenetic analysis of mitochondrial DNA sequence data indicates that the new species is most closely related to R. sanguineus among currently recognised species, with this pair most closely related to the partly sympatric R. melanoleucus. The new species description brings the number of currently recognised species in the genus to 24, six of which are endemic to India and 18 endemic to Sri Lanka. A new key to the identification of Indian species of Rhinophis is provided.

Warning signals promote morphological diversification in fossorial uropeltid snakes (Squamata: Uropeltidae)

Many species possess warning colourations that signal unprofitability to predators. Warning colourations are also thought to provide prey with a ‘predator-free space’ and promote niche expansion. However, how such strategies release a species from environmental constraints and facilitate niche expansion is not clearly understood. Fossoriality in reptiles imposes several morphological limits on head and body size to facilitate burrowing underground, but many fossorial snakes live close to the surface and occasionally move above ground, exposing them to predators. In such cases, evolving antipredator defences that reduce predation on the surface could potentially relax the morphological constraints associated with fossoriality and promote morphological diversification. Fossorial uropeltid snakes possess varying degrees of conspicuous warning colourations that reduce avian predation when active above ground. We predicted that species with more conspicuous colourations will exhibit more robust body forms and show faster rates of morphological evolution because constraints imposed by fossoriality are relaxed. Using a comparative phylogenetic approach on the genus Uropeltis, we show that more conspicuous species tend to have more robust morphologies and have faster rates of head-shape evolution. Overall, we find that the evolution of warning colourations in Uropeltis can facilitate niche expansion by influencing rates of morphological diversification.

A new species of Rhinophis Hemprich, 1820 (Serpentes: Uropeltidae) from the Wayanad region of peninsular India

A new species of the shieldtail snake genus Rhinophis is described based on a type series of seven recently collected specimens from the Wayanad region of the Western Ghats of peninsular India. Rhinophis melanoleucus sp. nov. is diagnosed based on a combination of 15 dorsal scale rows at (or just behind) midbody, more than 215 ventral scales and a long rostral. The new species also has a distinctive (mostly black and white) colouration. A new key to the identification of Indian species of Rhinophis is provided.

Conspicuous colours reduce predation rates in fossorial uropeltid snakes

Uropeltid snakes (Family Uropeltidae) are non-venomous, fossorial snakes that are found above ground occasionally, during which time they are exposed to predation. Many species are brightly coloured, mostly on the ventral surface, but these colours are expected to have no function below the ground. Observations have shown that the cephalic resemblance (resemblance to heads) of uropeltid tails may direct attacks of predators towards the hardened tails, thereby potentially increasing handling times for predators. Experiments have also shown that predators learn to avoid prey that are non-toxic and palatable but are difficult to capture, hard to process or require long handling time when such prey advertise their unprofitability through conspicuous colours. We here postulate that uropeltid snakes use their bright colours to signal long handling times associated with attack deflection to the tails, thereby securing reduced predation from predators that can learn to associate colour with handling time. Captive chicken experiments with dough models mimicking uropeltids indicate that attacks were more common on the tail than on the head. Field experiments with uropeltid clay models show that the conspicuous colours of these snakes decrease predation rates compared to cryptic models, but a novel conspicuous colour did not confer such a benefit. Overall, our experiments provide support for our hypothesis that the conspicuous colours of these snakes reduce predation, possibly because these colours advertise unprofitability due to long handling times.

Rediscovery of Cnemaspis nilagirica Manamendra-Arachchi, Batuwita and Pethiyagoda, 2007 (Squamata: Gekkonidae) from Kerala, India with notes on morphology and distribution

Cnemaspis nilagirica was described by Manamendra-Arachchi, Batuwita and Pethiyagoda in 2007 based on a single female specimen that was a syntype of Gonatodes kandianus var. tropidogaster described by Boulenger in 1885. However, a living population of this species has not been reported since its original description by Boulenger. Based on fresh material and comparisons with the holotype of C. nilagirica, we here report the collection of this species after over 130 years. We provide the first description of a male specimen and additional information on morphological variation, distribution and natural history.

Description of two new species of Cnemaspis Strauch, 1887 (Squamata: Gekkonidae) from the Western Ghats of Kerala, India

Two new species of geckos of the genus Cnemaspis Strauch, 1887 are described from the southern Western Ghats of Kerala. Both species are medium to large sized Cnemaspis and can be differentiated from all other Indian congeners by a suite of distinct morphological characters. Both species are found in the high elevation forests of the two major massifs-       Anaimalai Hills and Agasthyamalai Hills and are presently known to have very restricted distributional ranges. The discovery of these novel species highlights the understudied diversity of reptiles in the high mountain ranges of the Western Ghats.

Paleoclimate determines diversification patterns in the fossorial snake family Uropeltidae Cuvier, 1829

Understanding how and why diversification rates vary across evolutionary time is central to understanding how biodiversity is generated and maintained. Recent mathematical models that allow estimation of diversification rates across time from reconstructed phylogenies have enabled us to make inferences on how biodiversity copes with environmental change. Here, we explore patterns of temporal diversification in Uropeltidae, a diverse fossorial snake family. We generate a time-calibrated phylogenetic hypothesis for Uropeltidae and show a significant correlation between diversification rate and paleotemperature during the Cenozoic. We show that the temporal diversification pattern of this group is punctuated by one rate shift event with a decrease in diversification and turnover rate between ca. 11Ma to present, but there is no strong support for mass extinction events. The analysis indicates higher turnover during periods of drastic climatic fluctuations and reduced diversification rates associated with contraction and fragmentation of forest habitats during the late Miocene. Our study highlights the influence of environmental fluctuations on diversification rates in fossorial taxa such as uropeltids, and raises conservation concerns related to present rate of climate change.

A reappraisal of the rhacophorid bush frog Raorchestes flaviventris (Boulenger, 1882), with an evaluation of the taxonomic status of R. emeraldi Vijayakumar, Dinesh, Prabhu and Shankar, 2014

Raorchestes flaviventris, a species of rhacophorid bush frog described from the Western Ghats by George Albert Boulenger in 1882, has never been reported from the region since its description. However, we herewith report a record of the species after almost 132 years and redescribe the species and also clarify confusions that prevailed over the taxonomic status of the species and its closely-related congeners, along with shedding light on literature regarding its distribution. Also, the recently described R. emeraldi Vijayakumar et al., 2014, which we suggest to be the same species, becomes a junior subjective synonym of R. flaviventris.

A novel third species of the Western Ghats endemic genus Ghatixalus (Anura: Rhacophoridae), with description of its tadpole

The Western Ghats biodiversity hotspot is a recognized center of rhacophorid diversity as demonstrated by several recent studies. The endemic genus Ghatixalus is represented by two species from two separate high-elevation regions within the Ghats. Here, we describe a third species that can be distinguished by morphological and larval characters, as well as by its phylogenetic placement.