RESUMO
Recent higher-level frog phylogenetic analyses have included a few members of the endemic Philippine frog genus Sanguirana. Although the monophyly of the group has never been disputed, the recent phylogenetically-supported inclusion of the Palawan Wood Frog (Sanguirana sanguinea) in this clade was highly unexpected. In addition, species boundaries and relationships remain unclear and new species continue to be discovered. We estimate the phylogeny for this endemic Philippine genus using two mitochondrial gene regions and six nuclear loci and complete sampling for all known species. We use a time-calibrated Bayesian estimate of phylogeny and model-testing approach to biogeographic inference to infer ancestral areas and probable means of diversification. These analyses identify Sanguirana as an additional clade for which the 'Out-of-Palawan' biogeographic scenario is unambiguously preferred. This study lends additional support to recent work suggesting that a substantial portion of Philippine vertebrate megadiversity originated via colonization of the archipelago from the Palawan microcontinent, with subsequent invasion of oceanic islands (e.g., range expansion over Huxley's Modification of Wallace's Line), numerous instances of overwater dispersal, and geographic radiation across the archipelago.
Assuntos
Anuros/classificação , Animais , Anuros/genética , Teorema de Bayes , Genes Mitocondriais , Ilhas , Filipinas , Filogenia , Ranidae/genética , Análise de Sequência de DNARESUMO
Widespread, co-distributed species with limited relative dispersal abilities represent compelling focal taxa for comparative phylogeography. Forest vertebrates in island archipelagos often exhibit pronounced population structure resulting from limited dispersal abilities or capacity to overcome marine barriers to dispersal. The exceptionally diverse Old World tree frogs of the family Rhacophoridae have colonized the forested island archipelagos of Southeast Asia on multiple occasions, entering the islands of Indonesia and the Philippines via a "stepping stone" mode of dispersal along elongate island chains, separated by a series of marine channels. Here we evaluate the prediction that two tightly co-distributed Philippine rhacophorids colonized the archipelago during concomitant timescales and in the same, linear, "island-hopping" progression. We use a new multilocus dataset, utilize dense genetic sampling from the eastern arc of the Philippines, and we take a model-based phylogeographic approach to examining the two species for similar topological patterns of diversification, genetic structure, and timescales of diversification. Our results support some common mechanistic predictions (a general south-to-north polarity of colonization) but not others (timescale for colonization and manner and degree of lineage diversification), suggesting differing biogeographic scenarios of geographical diffusion through the archipelago and unique and idiosyncratic ecological capacities and evolutionary histories of each species.
Assuntos
Anuros/genética , Animais , Ecossistema , Filipinas , Filogenia , Filogeografia , Análise de Sequência de DNARESUMO
Cryptic ecologies, the Wallacean Shortfall of undocumented species' geographical ranges and the Linnaean Shortfall of undescribed diversity, are all major barriers to conservation assessment. When these factors overlap with drivers of extinction risk, such as insular distributions, the number of threatened species in a region or clade may be underestimated, a situation we term 'cryptic extinction risk'. The genus Lepidodactylus is a diverse radiation of insular and arboreal geckos that occurs across the western Pacific. Previous work on Lepidodactylus showed evidence of evolutionary displacement around continental fringes, suggesting an inherent vulnerability to extinction from factors such as competition and predation. We sought to (1) comprehensively review status and threats, (2) estimate the number of undescribed species, and (3) estimate extinction risk in data deficient and candidate species, in Lepidodactylus. From our updated IUCN Red List assessment, 60% of the 58 recognized species are threatened (n = 15) or Data Deficient (n = 21), which is higher than reported for most other lizard groups. Species from the smaller and isolated Pacific islands are of greatest conservation concern, with most either threatened or Data Deficient, and all particularly vulnerable to invasive species. We estimated 32 undescribed candidate species and linear modelling predicted that an additional 18 species, among these and the data deficient species, are threatened with extinction. Focusing efforts to resolve the taxonomy and conservation status of key taxa, especially on small islands in the Pacific, is a high priority for conserving this remarkably diverse, yet poorly understood, lizard fauna. Our data highlight how cryptic ecologies and cryptic diversity combine and lead to significant underestimation of extinction risk. Supplementary Information: The online version contains supplementary material available at 10.1007/s10531-022-02412-x.
RESUMO
In a recent article, Chandramouli et al. (2020) re-assessed the systematic position of the hylaranine frog Indosylvirana nicobariensis and proposed a new monotypic genus, Bijurana, for this species. The authors re-examined the type series of specimens and attempted to justify the recognition of a new genus using morphological and phylogenetic data. They concluded that the taxon's unique phylogenetic position, high genetic divergence (uncorrected p-distance ≥ 13.64% of the 16S rRNA mitochondrial gene), and a unique combination of morphological characters warranted the erection of the new genus.
Assuntos
Anuros , Genes Mitocondriais , Animais , Anuros/genética , Filogenia , RNA Ribossômico 16SRESUMO
We summarize all available amphibian and reptile species distribution data from the northeast Mindanao faunal region, including small islands associated with this subcenter of endemic vertebrate biodiversity. Together with all publicly available historical information from biodiversity repositories, we present new data from several major herpetological surveys, including recently conducted inventories on four major mountains of northeast Mindanao, and adjacent islands of Camiguin Sur, Dinagat, and Siargao. We present species accounts for all taxa, comment on unresolved taxonomic problems, and provide revisions to outdated IUCN conservation status assessments in cases where our new data significantly alter earlier classification status summaries. Together, our comprehensive analysis of this fauna suggests that the greater Mindanao faunal region possesses distinct subcenters of amphibian and reptile species diversity, and that until this area is revisited and its fauna and actually studied, with on-the-ground field work including targeted surveys of species distributions coupled to the study their natural history, our understanding of the diversity and conservation status of southern Philippine herpetological fauna will remain incomplete. Nevertheless, the northeast Mindanao geographical area (Caraga Region) appears to have the highest herpetological species diversity (at least 126 species) of any comparably-sized Philippine faunal subregion.
RESUMO
A new species of slender skink is described from the Philippines. The species is endemic to Lubang Island, and is assigned to the Brachymeles bonitae Complex based on phenotypic and genetic data. Specimens were collected from Lubang Island between 1991 and 2012, and were examined based on morphological data (qualitative traits, meristic counts, and mensural measurements). Published genetic sequence data from phylogenetic studies of the genus reveal the new species to be highly divergent from congeners. Brachymeles ligtas sp. nov. is differentiated from other members of the genus based on a number of distinct morphological features, including small body size (SVL 60.7-79.6 mm), bidactyl fore-limbs, digitless hind limbs, high number of presacral vertebrae (50), and the absence of auricular openings. Additionally, the new species has diagnostic, distinct dorsal head scale patterns. This new species becomes the only member of the genus known to occur on the deep-ocean island of Lubang.
Assuntos
Lagartos/anatomia & histologia , Lagartos/classificação , Distribuição Animal , Animais , Feminino , Lagartos/fisiologia , Masculino , Filipinas , Especificidade da EspécieRESUMO
Studies of the diversity of Philippine amphibians and reptiles have resulted in the continued description of cryptic species. Species formerly thought to range across multiple recognized faunal regions are now considered to be assemblages of multiple unique species, each restricted to a single faunal region. This pattern continues to hold true when considering Philippine skinks of the genus Brachymeles. Recent studies have resulted in the description of numerous unique species with many exhibiting various degrees of digit loss or limb reduction, as well as suggesting that unique lineages are still present in the B. bonitae Complex. In this paper, we describe a new species of fossorial skink within this species complex from Tablas Island based on collections made nearly 50 years ago. Although no genetic data are available for the new species, examinations of morphological data (qualitative traits, meristic counts, and mensural measurements) support its distinction from all other members of the genus. Brachymeles dalawangdaliri sp. nov. is differentiated from other members of the genus based on a suite of unique phenotypic characteristics, including a small body size (SVL 66.0-80.9 mm), bidactyl fore-limbs, digitless, unidactyl, or bidactyl hind limbs, a high number of presacral vertebrae (49), the absence of auricular openings, and distinct dorsal head scale patterns. The description of the new species increases the diversity of endemic vertebrates recognized to occur in the Romblon Island Group in the central Philippines.