Larval morphology and natural history in two Minervarya species from Andaman Islands, with comments on a new phytotelmonous larval morphotype for the genus.

We studied the larval morphology and natural history of two species of Minervarya from the Andaman Islands of India. A recent assignment of Charles Darwins frog to the genus Minervarya opened up new questions on the systematic affinities and natural history of its enigmatic tadpoles. Originally described as Rana charlesdarwini Das, 1998, and long considered as Ingerana charlesdarwini, the tadpoles of this species were poorly understood and incomparable to those of other presumed close relatives based on an original brief description of its phytotelmonous tadpoles. Here we present a detailed redescription of the larval morphology of M. charlesdarwini based on genetically confirmed tadpoles. At the same time, we compared the external morphology of M. charlesdarwini tadpoles to that of its closest phylogenetic and sympatric congener, M. andamanensis, consequently reporting the first-ever larval description for M. andamanensis. For the first time also for minervaryan frogs, we record that M. charlesdarwini lays eggs on the inner walls of tree holes, and the tadpoles possess morphological adaptations for a phytotelmonous life. Their unique features, such as tail-to-body ratio >2.2, reduced labial tooth rows (LTRF 1/1), acutely pointed serrations in the jaw sheath, and the medial portion of the upper sheath broadly arched and that of the lower sheath U-shaped, justify adding a new larval morphotype to the genus Minervarya. In contrast, M. andamanensis breeds and undergoes development in ground water puddles and ponds, a common trait for other known minervaryan species. Furthermore, our study generates new knowledge on the amplexus, oviposition site, and early embryonic development in these species. The deeper understanding of the biology and habitat requirements contributes additional traits for future systematic and evolutionary studies, and helps guide conservation assessments for these two species endemic to a handful of islands in the Andaman Archipelago.

Hiding in Plain Sight: Rain Water Puddles in Nicobar Islands of India Reveal Abundance of a New Frog Species of the Genus Microhyla Tschudi, 1838 (Anura: Microhylidae).

Recent studies on frogs of the Microhyla heymonsi species complex have demonstrated that high genetic variation exists among its various known populations from regions across Asia. We assessed the taxonomic identity of the Nicobar population of Microhyla cf. heymonsi and compared it to the typical Microhyla heymonsi from Taiwan and the two recently described species in this complex from Vietnam. Our study demonstrates that the Nicobar population is both genetically and morphologically divergent and warrants recognition as a new species, which we formally describe here as Microhyla nakkavaram sp. nov. The new species is closely related to M. daklakensis, M. heymonsi, and M. ninhthuanensis, but diagnosable from all three species by a suite of morphological characters, such as the presence of two small tubercles at mid-dorsum along with ( )-shaped markings, length of finger I longer than half the length of finger II, presence of three distinct metacarpal tubercles on hand, rudimentary foot webbing, as well as its slender body shape, granular dorsal skin texture, and other colour characters and body markings. Statistical analyses based on multiple morphometric characters also clearly separate our new taxon from M. heymonsi, with which it was previously confused. Our phylogenetic analyses based on the mitochondrial 16S rRNA locus find Microhyla nakkavaram sp. nov. to be nested in the Microhyla achatina species group, where it is delimited as a distinct species. This lineage shows genetic distances of ≥ 3.5% from all the other known congeners. Currently, the known distribution of the new taxon is restricted to the southernmost group of Nicobar Islands-Great Nicobar, Kondul, and Little Nicobar-where it is found in abundance across a wide range of habitats during the monsoon season. Our study underlines the need to reassess the identity of all the known populations of M. 'heymonsi' from other regions in Southeast and East Asia. To facilitate future taxonomic work in the light of our and other recent findings, we also provide a detailed redescription and revised diagnosis for M. heymonsi based on morphological examination of its century-old type material originating from Taiwan.

Discovery of a new mammal species (Soricidae: Eulipotyphla) from Narcondam volcanic island, India.

We discovered a new Crocidura species of shrew (Soricidae: Eulipotyphla) from Narcondam Island, India by using both morphological and molecular approaches. The new species, Crocidura narcondamica sp. nov. is of medium size (head and body lengths) and has a distinct external morphology (darker grey dense fur with a thick, darker tail) and craniodental characters (braincase is rounded and elevated with weak lambdoidal ridges) in comparison to other close congeners. This is the first discovery of a shrew from this volcanic island and increases the total number of Crocidura species catalogued in the Indian checklist of mammals to 12. The newly discovered species shows substantial genetic distances (12.02% to 16.61%) to other Crocidura species known from the Indian mainland, the Andaman and Nicobar Archipelago, Myanmar, and from Sumatra. Both Maximum-Likelihood and Bayesian phylogenetic inferences, based on mitochondrial (cytochrome b) gene sequences showed distinct clustering of all included soricid species and exhibit congruence with the previous evolutionary hypothesis on this mammalian group. The present phylogenetic analyses also furnished the evolutionary placement of the newly discovered species within the genus Crocidura.