Nayana Wijayathilaka

A new species of Microhyla (Anura: Microhylidae) from Sri Lanka: an integrative taxonomic approach

Species boundaries of Microhyla rubra of India and Sri Lanka were assessed using the following criteria: genetic barcoding, morphology, and vocalization. We use a ca. 500 bp fragment of the 16S rRNA mitochondrial gene and show that there is an uncorrected pairwise distance of 2.7-3.2% between the Indian and Sri Lankan populations of M. rubra. We show that they are different in several call characteristics such as, dominant frequency, call duration, call rise time and pulse rate. Morphologically, the Sri Lankan population can be distinguished from the typical M. rubra described from southern India, by a combination of characters: body size, skin texture, and feet dimensions. We recognize the population from Sri Lanka as a new species, Microhyla mihintalei sp. nov., a widely distributed lowland species with an elevational distribution of up to 500 m a.s.l.

Conservation in a changing landscape: habitat occupancy of the critically endangered Tennent's leaf-nosed lizard (Ceratophora tennentii) in Sri Lanka

Landscape modification is a key driver of global species extinction. Thus, understanding how species react to changes is essential for effective conservation management in modified landscapes. We examined the impact of selected land use patterns on the critically endangered Ceratophora tennentii in the Knuckles mountain range of Sri Lanka where lizards occupy patches of both natural undisturbed forests and modified plantations – evidently, those with a forest canopy. We tested three potential explanations for non-random habitat selection: availability of suitable microhabitat pockets, availability of prey and direct threats from humans. The microhabitat pockets occupied by the lizards were characterised by shade, humidity and the density of perches. Most lizards were found in mixed cardamom forests followed by natural forests and cardamom plantations, but none were observed in the pine plantations. Food availability showed similar patterns among habitats. Direct mortality by humans did not influence the distribution of this species. Our work indicates that habitat modifications that retain the structural complexity of the vegetation would still permit the existence of the species in densities equal to or greater than that of undisturbed forest patches. It adds to a growing body of literature that signifies the importance of disturbed habitats (intermediate disturbance hypothesis) in protecting threatened species of fauna. It is highly unlikely that some disturbed habitats will be ever be returned to their former pristine state in time frames that are important for species’ conservation. Hence, attention is needed in developing suitable approaches to manage and conserve species across disturbed habitats.

An Acoustic Analysis of the Genus Microhyla (Anura: Microhylidae) of Sri Lanka

Vocalizing behavior of frogs and toads, once quantified, is useful for systematics, rapid species identification, behavioral experimentation and conservation monitoring. But yet, for many lineages vocalizations remain unknown or poorly quantified, especially in diversity rich tropical regions. Here we provide a quantitative acoustical analysis for all four Sri Lankan congeners of the genus Microhyla. Three of these species are endemic to the island, but Microhyla ornata is regionally widespread. Two of these endemics, M. karunaratnei (Critically Endangered) and M. zeylanica (Endangered), are highly threatened montane isolates; the other, M. mihintalei, is relatively common across the dry lowlands. We recorded and analyzed 100 advertisement calls from five calling males for each species, except for M. zeylanica, which only had 53 calls from three males suitable for analyses. All four species call in choruses and their vocal repertoires are simple compared to most frogs. Their calls contain multiple pulses and no frequency modulation. We quantified eight call characters. Call duration and number of pulses were higher for the two montane isolates (inhabiting cooler habitats at higher altitudes) compared to their lowland congeners. Microhyla zeylanica has the longest call duration (of 1.8 ± 0.12 s) and the highest number of pulses (of 61–92 pulses). The smallest of the species, Microhyla karunaratnei (16.2–18.3 mm), has the highest mean dominant frequency (3.3 ± 0.14 kHz) and pulse rate (77 ± 5.8 pulses per second). The calls separate well in the Principal Component space: PC1 axis is mostly explained by the number of pulses per call and call duration; PC2 is mostly explained by the pulse rate. A canonical means plot of a Discriminant Function analysis shows non-overlapping 95% confidence ellipses. This suggests that some call parameters can be used to distinguish these species effectively. We provide detailed descriptions for eight call properties and compare these with congeners for which data is available. This work provides a foundation for comparative bioacoustic analyses and species monitoring while facilitating the systematics of Microhyla across its range.

A new frog species from rapidly dwindling cloud forest streams of Sri Lanka— Lankanectes pera (Anura, Nyctibatrachidae)

The monotypic genus Lankanectes, considered an evolutionary long branch with Indias Nyctibatrachus as its sister lineage, is represented by L. corrugatus, a species widely distributed within the wet zone of Sri Lanka up to 1500 m asl, where it inhabits a variety of lotic and lentic habitats. Here, following an integrative taxonomic approach using DNA-based phylogenies, morphology, morphometry, and ecological niche models, we describe a new species-Lankanectes pera sp. nov. The new species is distinguished from its sister species mainly by its tuberculated throat and absence of dark patches on venter, throat, manus and pes. The uncorrected genetic distances between the two Lankanectes species for a fragment of the non-coding mitochondrial 16S rRNA gene is 3.5-3.7%. The new species has a very restricted climatic distribution with a total predicted area of only 360 km2 (vs. 14,120 km2 for L. corrugatus). Unlike L. corrugatus, which prefers muddy substrates and marshy areas, the new species is observed inhabiting only pristine streams flowing through canopy covered montane forests in the highest reaches of the Knuckles Mountain range. The specialized new species will need immediate conservation attention due to its restricted distribution (montane isolate), specialized habit of inhabiting clear mountain streams, and small population size.

An integrative taxonomic review of the South Asian microhylid genus Uperodon

Based on a recent molecular phylogenetic study, the South Asian microhylid genus Uperodon (subfamily Microhylinae) currently comprises of 12 valid species that are largely restricted to India and Sri Lanka. Considering the revised generic-level status of its various members, here we review the taxonomy of all known species in this genus and clarify their nomenclatural status and geographical distribution, by integrating evidence from genetics, adult and tadpole morphology, breeding ecology, and bioacoustics. Our molecular analyses of a mitochondrial 16S rRNA gene fragment combined with external and internal morphological studies also revealed a distinct new species in the genus. This species, formally described as Uperodon rohani sp. nov., is endemic to Sri Lanka and widely distributed at lower elevations in the island. For nomenclatural stability of various previously known members, the following actions are also undertaken: (1) redescription of the poorly-defined species Ramanella anamalaiensis Rao (= Uperodon anamalaiensis) and Hylaedactylus montanus Jerdon (= Uperodon montanus); (2) neotype designation for Ramanella anamalaiensis Rao (= Uperodon anamalaiensis), Ramanella minor Rao, Ramanella mormorata Rao (= Uperodon mormorata), and Ramanella triangularis rufeventris Rao; (3) lectotype designation for Callula variegata Stoliczka (= Uperodon variegatus); and (4) synonymization of Ramanella minor Rao with Uperodon anamalaiensis.