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Coralsnakes of the genus Micrurus are a diverse group of venomous snakes ranging from the southern United States to southern South America. Much uncertainty remains over the genus diversity, and understanding Micrurus systematics is of medical importance. In particular, the widespread Micrurus nigrocinctus spans from Mexico throughout Central America and into Colombia, with a number of described subspecies. This study provides new insights into the phylogenetic relationships within M. nigrocinctus by examining sequence data from a broad sampling of specimens from Mexico, Guatemala, Honduras, Nicaragua, Costa Rica, and Panama. The recovered phylogenetic relationships suggest that M. nigrocinctus is a species complex originating in the Pliocene and composed of at least three distinct species-level lineages. In addition, recovery of highly divergent clades supports the elevation of some currently recognized subspecies to the full species rank while others may require synonymization. [ABSTRACT FROM AUTHOR]

Rivers are known to act as biogeographic barriers in several strictly terrestrial taxa, while possibly serving as conduits of dispersal for freshwater-tolerant or -dependent species. However, the influence of river systems on genetic diversity depends on taxa-specific life history traits as well as other geographic factors. In amphibians, several studies have demonstrated that river systems have only minor influence on their divergence. Here, we assess the role of the paleodrainage systems of the Sunda region (with a focus on the island of Sumatra) in shaping the evolutionary history of two genera of frogs (Sumaterana and Wijayarana) whose tadpoles are highly dependent on cascading stream habitats. Our phylogenetic results show no clear association between the genetic diversification patterns of both anurans genera and the existence of paleodrainage systems. Time-calibrated phylogenies and biogeographical models suggest that these frogs colonized Sumatra and diversified on the island before the occurrence of the Pleistocene drainage systems. Both genera demonstrate phylogenetic structuring along a north–south geographic axis, the temporal dynamics of which coincide with the geological chronology of proto Sumatran and -Javan volcanic islands. Our results also highlight the chronic underestimation of Sumatran biodiversity and call for more intense sampling efforts on the island. [ABSTRACT FROM AUTHOR]

While species boundaries between conspicuously divergent populations of the medically important snake genus Sinomicrurus are well established, instances of erratic chromatic and meristic variation continue to confound taxonomists, since the mid‐1800s. This predicament can be attributed to an inadequate molecular phylogenetic framework and the lack of a comprehensive taxonomic representation of geographic variants. Here, we revisit lineage delineation in this genus, drawing cohesive evidence from a plurality of data and analysis types, including a promising, yet taxonomically under‐utilized, supervised machine learning algorithm (random forest). Overall, this study incorporates data generated by molecular analyses as well as morphometrics and comparative anatomy based on 236 specimens from 28 different natural history collections examined by us, and an additional 161 records from 47 other sources. Our results indicate several very divergent evolutionary lineages concealed as subspecies. Thus, to better reflect this phylogenetic diversity, we raise S. macclellandi iwasakii from the southern Ryukyus and S. m. swinhoei from Taiwan to full species, and resurrect S. annularis. We highlight the need to distinguish at species level the current subspecies of S. japonicus, namely as, S. japonicus and S. boettgeri, and provide diagnostic characters to that end. On the other hand, given unpersuasive support of lineage independence, we sink Taiwanese S. hatori into S. sauteri and S. nigriventer into S. macclellandi. We also meticulously redescribe S. peinani from mainland China and Vietnam based on a substantial number of additional specimens, while synonymizing the recently described S. houi under S. kelloggi. We conclude with a discussion on the role of regional biogeography as a primary driver of cladogenesis in the genus. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Sumatran and Javan bent-toed geckos are most closely related to species from the Thai-Malay Peninsula. • Cyrtodactylus most likely dispersed to Sumatra three times during the late Oligocene and early Miocene. • Cyrtodactylus invaded west Java from the Sumatra once in the early Miocene. • Data support lowland connections over highland land bridges as dispersal pathways. Abstract Complex geological processes often drive biotic diversification on islands. The islands of Sumatra and Java have experienced dramatic historical changes, including isolation by marine incursions followed by periodic connectivity with the rest of Sundaland across highland connections. To determine how this geological history influenced island invasions, we investigated the colonization history and diversification of bent-toed geckos (genus Cyrtodactylus) on Sumatra and west Java. We used mitochondrial and nuclear sequence data to explore species boundaries, estimate phylogenetic relationships and divergence times, and to reconstruct ancestral range evolution. We found that Sumatran and Javan Cyrtodactylus were closely related to species from the Thai-Malay Peninsula, rather than from Borneo, and that Cyrtodactylus most likely dispersed to Sumatra three times during the late Oligocene and early Miocene. Similarly, Cyrtodactylus invaded west Java from Sumatra once in the early Miocene. Our results suggest that despite isolation by marine incursions during much of the Miocene, Cyrtodactylus dispersed to and from Sumatra and west Java likely via land bridges, and that in situ diversification occurred several times on Sumatra. [ABSTRACT FROM AUTHOR]

Abstract: Aim: This study seeks to understand the geological and climatological processes that have promoted biodiversity on the Sunda Shelf in Southeast Asia. Using the parachuting frog genus Rhacophorus, we estimate divergence times and quantify the respective contributions of between and within‐island diversification to species richness and endemism. Location: East and Southeast Asia, the Sunda Shelf. Methods: We generated a concatenated mitochondrial and nuclear DNA sequence alignment for 40 species of Rhacophorus. We estimated phylogenetic relationships and divergence times, constructed lineage‐through‐time (LTT) plots and reconstructed ancestral ranges. Results: We found that Rhacophorus originated 33.0 Ma (95% HPD 27.0–38.0 Ma), and that the diversification rate slowed towards the present. Dispersal was important in early Rhacophorus evolution, but subsequent in situ diversification produced most species diversity on Sumatra and Borneo. Clades that diversified via in situ processes contained higher proportions of endemic species. Main conclusions: Species diversification on the Sunda Shelf is ancient and has occurred slowly. Both dispersal and in situ diversification have promoted Sundaland species accumulation, but within‐island phylogenesis has produced a greater proportion of endemic species on Sumatra and Borneo. Species richness and endemism are most influenced by the size of an island, rather than connectivity. [ABSTRACT FROM AUTHOR]

We describe a new species of coralsnake from northern Dinagat Island, southeastern Philippines. The discovery of this new species comes as a surprise because it is phenotypically distinct from all other Philippine coralsnakes and has a close phylogenetic affinity to the blue coralsnakes of the Sunda Shelf. The new species is distinguished from all Philippine and other Southeast Asian taxa by its large body size and ventral scale counts; its black head and neck; an alternating, broadly banded color pattern of black and off-white; and a bright orange tail. We use DNA sequence data to investigate the phylogenetic placement of the new species and that of several other populations of Philippine coralsnakes with respect to other Southeast Asian and Australasian elapids. Our results corroborate the uniqueness of the new species with respect to all other Philippine and Sundaic taxa, including the species most closely related to it: Calliophis bivirgatus, C. bilineatus, C. philippinus, and C. suluensis. We summarize phylogenetic, biogeographic, and phenotypic character data that substantiate the elevation of Philippine species of Calliophis (formerly considered subspecies of C. intestinalis: C. bilineatus, C. philippinus, and C. suluensis) and Hemibungarus (formerly subspecies of H. calligaster: H. calligaster, H. gemianulis, and H. mcclungi) to the level of full species. The allopatric distributions of these taxa emphasize the systematic and biogeographical significance of the newly discovered taxon: a poorly understood and independent colonization of the Philippine Archipelago by elapid snakes. [ABSTRACT FROM AUTHOR]

We describe a new genus and two new species of toads from the Sumatran volcanoes Gunung Sorikmarapi and G. Kunyit, in the provinces of Sumatera Utara and Jambi, respectively. The new taxa can be distinguished from other genera, and each other, based on genetic differentiation, morphology, and advertisement call structure. We employ both nuclear and mitochondrial data to provide a phylogenetic hypothesis of relationships for the bufonid genera of the Sunda Shelf. While broadly corroborating previous studies, our results also shed light on the phylogenetic position of Pseudobufo. The new genus, Duttaphrynus, and Pseudobufo are basal to other Sunda Shelf genera in our phylogenies. [ABSTRACT FROM AUTHOR]

Despite the benefits of quantitative data generated by massively parallel sequencing, resolving mitotypes from mixtures occurring in certain ratios remains challenging. In this study, a bioinformatic mixture deconvolution method centered on population-based phasing was developed and validated. The method was first tested on 270 in silico two-person mixtures varying in mixture proportions. An assortment of external reference panels containing information on haplotypic variation (from similar and different haplogroups) was leveraged to assess the effect of panel composition on phasing accuracy. Building on these simulations, mitochondrial genomes from the Human Mitochondrial DataBase were sourced to populate the panels and key parameter values were identified by deconvolving an additional 7290 in silico two-person mixtures. Finally, employing an optimized reference panel and phasing parameters, the approach was validated with in vitro two-person mixtures with differing proportions. Deconvolution was most accurate when the haplotypes in the mixture were similar to haplotypes present in the reference panel and when the mixture ratios were neither highly imbalanced nor subequal (e.g., 4:1). Overall, errors in haplotype estimation were largely bounded by the accuracy of the mixture's genotype results. The proposed framework is the first available approach that automates the reconstruction of complete individual mitotypes from mixtures, even in ratios that have traditionally been considered problematic. [ABSTRACT FROM AUTHOR]

Despite a considerable amount of research, the systematics of the ranid genus Huia have remained unresolved, mostly owing to insufficient sampling and morphological similarities. As currently circumscribed, Huia consists of five species, but multiple studies have consistently demonstrated that it is not a monophyletic genus. However, no study has approached the problem with adequate data and provided a systematically sound solution, leaving the genus to languish in a classification that is phylogenetically incoherent. We generated the most comprehensive sampling of Huia to date, based on extensive fieldwork in Java and Sumatra. Using an integrative taxonomy framework, we analysed four mitochondrial and two nuclear markers and, in conjunction with tadpole morphology, investigated the phylogenetics of Huia and its congeners. Corroborating previous studies, Huia is recovered as a paraphyletic group. Huia cavitympanum emerges as the sister taxon to Meristogenys. The remaining members of Huia form a monophyletic group, sister to the H. cavitympanum + Meristogenys clade. Our extensive geographical sampling in Sumatra and Java reveals multiple highly divergent lineages that potentially represent undescribed species. Using our expanded molecular and morphological dataset, we resolve the paraphyly of Huia by restricting the genus to its type species and propose a new genus to accommodate the strongly supported clade of Sumatran and Javan populations previously belonging to Huia. [ABSTRACT FROM AUTHOR]

We describe a new species of Pulchrana from the island of Sumatra, in western Indonesia. Pulchrana fantastica, new species, is currently only known from Aceh and Sumatera Utara provinces. It is related to P. siberu and P. centropeninsularis as inferred from morphological similarity and phylogenetic relationships, estimated from DNA sequences. It can be diagnosed by the following unique combination of characters: (1) SVL adult males 40.32-45.19 mm; (2) males have large humeral glands on the anteroventral surface of brachium, nuptial pads absent; (3) dorsal skin finely granular to granulated, with or without asperities at the tip of granules; (4) webbing formula: I(1 - 1-11/2)II(1/2 - 2)III(1 - 2-21/3)IV(2-21/3 - 1)V; (5) straight dorsolateral stripes, thin, continuous, anteriorly confluent at snout, posteriorly interconnected by a series of spots; (6) middorsum in adults black with light medial line or combination of spots and line, black without marking in juveniles; (7) dense cream or yellow to orange spots on flanks, and dorsal side of limbs, spots non-uniform in shape; (8) venter greyish or brown, with small light dots on throat and chest, sometimes reaching abdomen; (9) iris background black, lower part with dense orange stippling, upper region with orange reticulation with gold in the middle, pupil encircled with solid orangegolden line; (10) upper and lower lip grey or brown with cream or yellow spots. We also report the presence of P. centropeninsularis from Sumatra; a species previously known only from a single locality in the Malay Peninsula; and discuss the biogeographic implications of this significant range extension. [ABSTRACT FROM AUTHOR]

Motivation Assays in mitochondrial genomics rely on accurate read mapping and variant calling. However, there are known and unknown nuclear paralogs that have fundamentally different genetic properties than that of the mitochondrial genome. Such paralogs complicate the interpretation of mitochondrial genome data and confound variant calling. Results Remove the Numts! (RtN!) was developed to categorize reads from massively parallel sequencing data not based on the expected properties and sequence identities of paralogous nuclear encoded mitochondrial sequences, but instead using sequence similarity to a large database of publicly available mitochondrial genomes. RtN! removes low-level sequencing noise and mitochondrial paralogs while not impacting variant calling, while competing methods were shown to remove true variants from mitochondrial mixtures. Availability and implementation https://github.com/Ahhgust/RtN Supplementary information Supplementary data are available at Bioinformatics online. [ABSTRACT FROM AUTHOR]

• New Molecular phylogeny of Sumatra's cloud forest Draconinae lizards. • Sumatra's montane Draconinae lizards have deep divergence and allopatric distributions. • Draconinae lizard diversity arose from in situ diversification. • Distributions and divergence estimates may elucidate history of Pleistocene forests. Biogeographical evidence, both, for and against the "regional endemism paradigm" hypothesis has been uncovered across the Greater Sunda Region (Sundaland) of Southeast Asia. Additionally, there are competing hypotheses regarding how Pleistocene forests may have impacted biological patterns and processes in Sumatra. Using montane agamid lizards from Sumatra, we derived and analyzed a phylogenetic dataset, genetic divergence estimates, and contemporary distributional patterns among species. We tested whether (1) Sumatra's highland Draconinae diversification fits the regional endemism paradigm hypothesis and (2) Draconinae phylogeography provides biological evidence for Pleistocene forest extent at various points in history. Our results suggest in situ diversification was the main driver behind montane Draconinae lizard diversification in Sumatra, rejecting the "regional endemism paradigm". Contemporary distribution of endemic species and their genetic relationships may potentially provide biological evidence for determining more precise elevational lower limits of montane forests during the Pleistocene epoch. Our data suggests montane forests did not retreat more than 700–750 m during glacial maxima because lower retreating forests would have become interconnected, allowing for widespread dispersal, exchange of gene flow and sympatric distributions contemporarily. To the contrary, our divergence estimates show that cloud forest dragons have been isolated for millions of years, suggesting there may have been a continuous disconnect between some areas, predating the Pleistocene. There may also be other ecological and evolutionary factors that impacted Draconinae distributions, such as competition, making this an excellent system for testing questions regarding montane biogeography. Additionally, we provide the first phylogeny for a wide range of Sundaland agamid species and identify some biogeographic pressures that may have triggered montane Draconinae diversification in Sumatra. [ABSTRACT FROM AUTHOR]

Background: Snakes are found on every continent in the world except Antarctica, and on smaller land masses. Being ecologically important, they also cause a large number of bites, leading to millions of deaths. Mitochondrial and nuclear gene sequences are being used to identify, characterize, and infer genetic biodiversity among different snake species. Furthermore, phylogenetics helps in inferring the relationships and evolutionary histories among these species. Black cobra is one of the four most venomous snakes in Pakistan. Four mitochondrial (ND4, Cytochrome b, 12S rRNA, and 16S rRNA) and four nuclear (C-mos, RAG-1, BDNF, and NT3) genes were used to trace diversity and infer the phylogenetic relationship of black cobra in Pakistan. Results: Almost similar phylogenies were obtained through maximum likelihood and Bayesian inference, showing two species of cobra in Pakistan, namely, black cobra (Naja naja) and brown cobra (Naja oxiana). All Naja species were divided into three clades: black cobra (N. naja) and brown cobra (N. oxiana) cladding with different species of Naja; N. naja (Pakistan) cladding with N. naja from Nepal; and N. oxiana showed close relationship with Naja kaouthia from Thailand and Naja siamensis from Thailand. Conclusion: It was confirmed genetically that there are two cobra species in Pakistan, i.e., black and brown cobras. This study will help in not only genetic conservation but also developing anti-venom against snake species. [ABSTRACT FROM AUTHOR]

Strong spatial sorting of genetic variation in contiguous populations is often explained by local adaptation or secondary contact following allopatric divergence. A third explanation, spatial sorting by stochastic effects of range expansion, has been considered less often though theoretical models suggest it should be widespread, if ephemeral. In a study designed to delimit species within a clade of venomous coralsnakes, we identified an unusual pattern within the Texas coral snake ( Micrurus tener): strong spatial sorting of divergent mitochondrial (mtDNA) lineages over a portion of its range, but weak sorting of these lineages elsewhere. We tested three alternative hypotheses to explain this pattern-local adaptation, secondary contact following allopatric divergence, and range expansion. Collectively, near panmixia of nuclear DNA, the signal of range expansion associated sampling drift, expansion origins in the Gulf Coast of Mexico, and species distribution modeling suggest that the spatial sorting of divergent mtDNA lineages within M. tener has resulted from genetic surfing of standing mtDNA variation-not local adaptation or allopatric divergence. Our findings highlight the potential for the stochastic effects of recent range expansion to mislead estimations of population divergence made from mtDNA, which may be exacerbated in systems with low vagility, ancestral mtDNA polymorphism, and male-biased dispersal. [ABSTRACT FROM AUTHOR]