A recent study reported widespread hybridization between the Eastern Red-backed Salamander (Plethodon cinereus) and the Northern Ravine Salamander (P. electromorphus) in northern Ohio. In this study, DNA sequence data were obtained from three nuclear loci and 20 single nucleotide polymorphisms (SNPs) were identified from the sequences. They found that 48 out of 90 individuals from 13 populations were hybrids, and in some localities every individual possessed an admixed genotype. As these results contradict our observations, and because levels of hybridization impact our interpretation of past and ongoing studies, we revisited the data. First we reanalyzed the original SNPs using STRUCTURE, then we repeated the analysis using haplotypes instead of SNPs. We found that K = 2 was best supported by both analyses, and they agree in recovering lower levels of hybridization than originally reported. For example, five populations in the original study identified as highly admixed or composed entirely of admixed genotypes we found to be pure P. cinereus or to lack evidence of extensive admixture. Similar results were obtained using NEWHYBRIDS and analyses based on gene trees. We conclude that while hybridization between P. cinereus and P. electromorphus occurs, it is much more restricted than originally reported.

In the present report, I evaluate life history and demography for two populations of the Black-bellied Salamander, Desmognathus quadramaculatus, in the Cowee and Nantahala Mountains, North Carolina, using published data on growth of females, fecundity, and larval growth and development to generate life tables and metabolic life histories for each population. I assumed that females in these populations reproduce biennially, beginning at ages 7–8 years and 8–10 years in Cowee and Nantahala populations, respectively. In deriving life tables, I posited stationary populations wherein net reproductive rate (R₀) equaled 1.0 and population growth rate (r) equaled 0. Fecundity (m_x column of the life table) was based on counts of ovarian follicles in gravid females. Survival values (l_x column of the life table) were generated by an iterative process that yielded a value of R₀ = 1.0. I projected the life spans in each population to 25 years. The demographic models developed by the procedure allowed comparison with those reported earlier for D. monticola and D. ocoee. Age at first reproduction and generation time are key contributors to variation in body size and life history in Desmognathus.

Advances in both morphological and molecular techniques have uncovered many lineages across the tree of life, and Neotropical vertebrates are no exception. Sphaerodactylus geckos (Sphaerodactylidae) are abundant and important components of the Neotropical herpetofauna, but few studies have thoroughly investigated them using a combination of morphology and modern molecular genetic methods. Here, we combine morphological and genetic data to describe a new species of Sphaerodactylus from the northwestern karst region of Puerto Rico. The new species is compared to other closely related and sympatric species of Sphaerodactylus. Morphological analysis shows that the combination of small body size (median SVL = 21.5 mm), lepidosis, skull morphology, and coloration of the head differentiates the new species from its closest relatives, including the related species, Sphaerodactylus klauberi. Comparing sequences of the mitochondrial 16S rRNA gene showed a genetic distance between S. klauberi and the new species of 5.1–5.6%, which is similar to genetic distances among other recognized gecko species. This is the first new species of Sphaerodactylus to be described from Puerto Rico in nearly a century, highlighting the continued need to evaluate and chronicle biological diversity even in well-studied regions.

Las filogenias moleculares han elucidado múltiples linajes en el árbol de la vida, incluyendo varios vertebrados neotropicales. Las salamanquitas del género Sphaerodactylus (Sphaerodactylidae) son abundantes y forman una parte importante de la herpetofauna neotropical. Este género ha sido investigado recientemente utilizando métodos moleculares modernos. En este artículo se describe una nueva especie del género Sphaerodactylus, procedente de la región kárstica del noroeste de Puerto Rico. Los individuos de la nueva especie fueron comparados con especies afines y simpátricas. El análisis morfológico muestra que la combinación entre el tamaño corporal, escamación, morfología del cráneo y coloración cefálica, distinguen a la especie nueva de otras especies cercanas filogenéticamente, incluyendo su especie hermana Sphaerodactylus klauberi. Al comparar secuencias del gen mitocondrial 16S rRNA se observó una distancia genética de 5.1–5.6% entre la especie nueva y S. klauberi, dicha distancia es similar a la que existe entre otras especies descritas de salamaquitas. Ha pasado casi un siglo desde que la última especie de Sphaerodactylus de Puerto Rico fue descrita, ésto resalta la necesidad de seguir evaluando y catalogando la biodiversidad, inclusive en áreas que han sido investigadas a profundidad.

The value of clearing and staining whole organisms to study vertebrate anatomy is unquestionable. These methods have been developed for over a century leading to protocols to prepare triple-stained specimens to differentiate between bones, cartilage, and nerves. Despite their potential to advance the field of comparative anatomy, nerve-staining methods have been used by a small number of vertebrate systematists in part because of the inconsistently successful preparations. Here, we report on several modifications to the current Sudan black B protocols and propose a new acid-free protocol to differentiate among bone, cartilage, and nerves in whole small vertebrates. This method may also be used to stain solely bone and cartilage by eliminating the nerve-staining steps. The technique herein described is successful for preparing juveniles and adults (including miniatures).

Exposure to ultraviolet (UV) light has both physiological benefits as well as costs. Many lepidosaur reptiles can behaviorally self-regulate their exposure to UV light in order to take advantage of the benefits of UV light while minimizing the costs. Furthermore, lepidosaur scales have been conceptualized by some as a barrier to the penetration of UV light. Here we examine regulation of self-exposure to UV light in three different phenotypes of Bearded Dragon (Pogona vitticeps): wild type, animals exhibiting scales of reduced prominence (‘Leatherback’), and scaleless animals (‘Silkback’). Silkbacks on average chose to expose themselves to lower levels of UV light irradiation than Leatherbacks or wild types did. Bearded Dragons of all scalation phenotypes on average received higher UV irradiation when they were in the cold section of a UV gradient apparatus compared to when they were in the hot section of the apparatus. This either demonstrates that Bearded Dragons under higher UV irradiances choose cooler temperatures or demonstrates that Bearded Dragons at cooler temperatures choose higher UV irradiances. The relationship between chosen temperature and chosen UV light irradiance was not affected by scalation phenotype. This study highlights external influences on the mechanism that regulates UV self-exposure behavior in lepidosaur reptiles.

Malaclemys terrapin is a species of turtle that lives in brackish waters along the eastern coast of the United States from Cape Cod to Texas. We documented distinctive underwater postures during surfacing in hatchlings versus individuals after one year (yearlings). Hatchlings approach the water's surface in horizontal postures, while yearlings approach in a more vertical posture. Because cloacal bursae play a role in controlling buoyancy in freshwater turtles, we investigated their potential role in determining surface postures. We discovered that cloacal bursae are absent in M. terrapin, and we attribute this absence to the osmoregulatory challenges presented by the brackish habitats of this species. We posit that the horizontal postures in the hatchlings create a broader visual target to both aerial and aquatic predators and that the younger turtles likely do not have the strength, muscle mass, lung-volume coordination, or sufficient bone density in the shell to adopt the more visually streamlined vertical posture at the surface.

Mink Frogs (Rana septentrionalis) are a unique ranid species restricted to Canada and the northern edge of the United States, from northern Minnesota to northern Maine. They are a member of the Aquarana clade that includes Green Frogs (R. clamitans), American Bullfrogs (R. catesbeiana), and four other species. Despite being relatively common where present, the biology of this species has been poorly studied and little in particular is known about its breeding and development from fertilization through overwintering as larvae. Critically, the species' representation in museum collections is limited in general, but particularly at early life stages. Here we report on our initial efforts to describe larval Mink Frog development by inducing breeding of wild-caught adults in the laboratory, then sampling tadpoles from fertilization until the subsequent spring. Specimens, including tissue samples, adult specimens of both sexes, an entire laboratory-induced egg mass, and a captive-bred larval series are available in the Yale Peabody Museum of Natural History. Our approach here demonstrates that Mink Frogs can be captive bred for use in laboratory experiments, and our work provides a novel larval series from egg mass to metamorphosis for this secretive, understudied species.

The sole wild population of the endangered Devils Hole Pupfish, Cyprinodon diabolis, has declined to fewer than 40 individuals twice since 2006, prompting increased recovery efforts. The U.S. Fish and Wildlife Service's Devils Hole Pupfish recovery plan stipulates two reproducing captive populations, though, historically, propagation efforts have yielded little success. To address information deficits in reproductive behavior and ecology, from February–December 2010 we investigated environmental factors associated with spawning activity of C. diabolis in Devils Hole, Nevada, USA. An underwater camera continuously monitored a portion of a shallow, submerged rock shelf used for spawning. Select biotic, abiotic, and physico-chemical parameters were monitored continuously throughout the year. Water level and precipitation data provided by the U.S. National Park Service identified disturbances from earthquake-induced seiches and storm-induced flash floods. Zero-inflated Poisson regression provided a model with 28% predictive power with algal cover, light energy, and seiches as the three strongest predictors among tested factors in spawning behavior of C. diabolis in the wild.

While taxonomic research of the genus Diploderma has made considerable progress in the past decade, far less attention was given to the arboreal species in the subtropical areas. Combining mitochondrial genetic and morphological data, we evaluated the current taxonomic hypotheses of one of the subtropical, arboreal species complexes, the D. fasciatum complex, based on examination of the type series and newly collected specimens. Mitochondrial genealogy shows that D. jinggangense, D. fasciatum, and D. szechwanense together form a monophyletic group, and D. jinggangense is paraphyletic to D. szechwanense. Although there are moderate genetic divergences among populations, such divergence differences are gradual geographically. Morphological comparisons of all commonly used diagnostic characters fail to differentiate the three species. In particular, the previously proposed diagnosis, the presence of transverse gular fold, is variable in this species complex. Our data support the previous taxonomic hypothesis that D. szechwanense and D. fasciatum are synonyms, and we also add D. jinggangense as another junior synonym of D. fasciatum. With newly available specimens, we revise the diagnostic characters of D. fasciatum, describe its coloration in life, and expand its distribution in southwestern and southern China. Our discovery of D. fasciatum in Guangdong Province represents a new provincial herpetofauna record. Finally, we highlight the taxonomic uncertainties on the species status of D. grahami with respect to D. fasciatum and discuss the issue on the recent unnecessary changes of the Chinese common names of the genus Diploderma, recommending maintaining stability of Chinese common names and continuous usage of “Long Xi” as the common name for Diploderma.

Taxonomic studies over the past decade of the endemic Night Frog genus Nyctibatrachus (originally described in 1882) from Peninsular India have more than tripled, from 11 at the turn of this century to 36 by 2017. Despite these revisionary contributions, it is still challenging for field biologists to identify night frog species reliably, due to a near-complete absence of diagnostic, discrete character states or trait values. Worse, many questionably diagnosed night frog species' status has ostensibly been “supported” by phylogenies derived from sparsely sampled gene-trees that are based on a single locus or a handful of markers—with topology and arbitrary genetic distance thresholds of 3–6% used to support new species descriptions. We sought to re-evaluate and validate the species boundaries of six currently nominated species of Nyctibatrachus of the aliciae group (N. aliciae, N. periyar, N. deveni, N. pillaii), N. vasanthi, and N. poocha clade using a comprehensive integrative taxonomic approach that integrates classical taxonomy, molecular species delimitation analysis, statistical analysis of morphological characters of adults and larvae, analyses of bioacoustics, and natural history information. Our results indicate that recent descriptions of Nyctibatrachus deveni, N. periyar, and N. pillaii represent cases of taxonomic inflation (over-splitting), because the evidence cited in support of their recognition is irreproducible, subjective, and devoid of strong statistical support. We demonstrate the need for multidimensional species delimitation approaches in the celebrated Western Ghats biodiversity hotspot paleo-endemic genus Nyctibatrachus and suspect that this concerning trend of over-splitting amphibian species based on limited data and untenable support may be applicable to other amphibian groups.

Understanding the relationship between species and the environment is crucial to predicting their responses to human-induced global changes, i.e., habitat conversion, biological invasions, and global warming. Precipitation and river level are relevant factors that regulate the populations of aquatic organisms. We used long-term data to assess the effects of climate on nest number, clutch size (number of eggs per nest), hatching success, and unviable eggs of the Giant South American River Turtle (Podocnemis expansa) in a protected area of Brazilian Amazonia. We found a positive relationship between the number of nests and precipitation on headwaters in May. We also observed that clutch size increased when the local river level rose; hatching success increased with rising local river level, mainly during October and November; and egg failure increased with rising headwater river level. We show how precipitation and river level (at local and headwater) can influence reproductive success in P. expansa, highlighting the perils of human-induced environmental changes.

Mud snakes (Serpentes: Homalopsidae) are a morphologically diverse family of aquatic snakes distributed from eastern Pakistan, eastward through South Asia, mainland and maritime Southeast Asia, and extending to New Guinea and northern Australia. Some species of homalopsids represent the most abundant tetrapods in aquatic systems in tropical Asia, but with few evolutionary studies investigating their diversity with dense geographic and taxonomic sampling. The genus Hypsiscopus includes two named species that inhabit freshwater systems throughout most of Southeast Asia: H. matannensis of Sulawesi, and the widespread H. plumbea found in rivers, lakes, and rice paddies in the remainder of Southeast Asia. We use a multilocus dataset of two mitochondrial and three nuclear genes with dense sampling of H. plumbea to elucidate the evolutionary history of this genus. We find that H. plumbea is paraphyletic with respect to H. matannensis, with populations around and north of Central Thailand's Khorat Plateau phylogenetically outside of a clade containing H. matannensis and H. plumbea south of the Khorat Plateau. This lineage differs morphologically and genetically from H. plumbea sensu stricto (south of the Khorat Plateau) and H. matannensis. We describe this lineage as a third species of Hypsiscopus based on its phylogenetic position and meristic and color pattern data. This study exemplifies the need to investigate widespread, abundant taxa to better understand the evolutionary histories of aquatic snakes in Southeast Asia.

Studies of frogs overwintering in ice-covered ponds and lakes have documented large winterkills, suggesting that winter can be a time of great stress and may be a serious threat to rare and endangered frog species that overwinter in these systems. Lotic systems are assumed to be better oxygenated and therefore less subject to overwinter mortality than lentic systems, but few studies of the winter ecology of ranids in stream ecosystems exist. We investigated the habitat use and survival of Columbia Spotted Frogs (Rana luteiventris) overwintering in a stream system in the Toiyabe Mountains of Nevada. We radio-tracked 13 Spotted Frogs from October 2000 to March 2001 to locate hibernacula and document winter habitat use. During the winter, frogs moved up to 191 m under the ice, often upstream against the current. We marked 1,763 frogs from 2000 to 2001 and found evidence of winterkill (population decreases of 66% to 86.5%) at four out of five sites while the fifth site showed no evidence of winterkill. This corresponded to an actual observation of winterkill of 88% of the frogs at one of the sites, making this one of a few studies directly tying observed wintertime mortality to mark–recapture estimates of decreases in ranid populations and the first to do so for amphibians overwintering in a lotic system. Amphibian winter ecology in lotic systems, the severity and frequency of winterkill events in these systems, and their effect on population size and structure is in need of further study over a wide range of species and should be considered in conservation plans for ranids in lotic systems.

Toadlets of the genus Brachycephalus are endemic to the Brazilian Atlantic Rainforest, where they inhabit the forest floor leaf litter. These miniaturized frogs are commonly known as flea-toads or pumpkin toadlets depending on their phenotypic characteristics. Herein, we describe a new species of the genus Brachycephalus from montane forests (970–1200 m a.s.l.) in the Serra dos Órgãos mountain range, in the state of Rio de Janeiro, southeastern Brazil. The new species is characterized by having a small body size within the genus (maximum SVL 9.6 mm in males and 10.9 mm in females), a noticeably granular dorsum with an X-shaped mark and a median row of small yellow tubercles, a yellow background color with red blotches on ventral surfaces, a lateral dark brown stripe, and the absence of hyperossification in the skeleton. Morphological features of the new taxon resemble those of both flea-toads and pumpkin toadlets. Based on our molecular phylogenetic hypothesis, the new species is recovered sister to the clade formed by the monophyletic B. ephippium and B. vertebralis species groups (previously considered as lineages of a more inclusive B. ephippium group). We also reinforce the suggestion of not using the name B. didactylus group because it does not represent a monophyletic taxon. The new species probably has an extremely restricted geographic distribution, and its discovery reinforces the importance of the Serra dos Órgãos mountains for the conservation of the Atlantic Rainforest anuran biodiversity.

Wide-ranging species often span geographic dispersal barriers, providing opportunity for divergence via genetic drift or natural selection. Such conditions can be favorable for speciation, and wide-ranging taxa are frequently subdivided into multiple species by modern molecular studies. However, with wide-ranging species, it is important to explicitly test for isolation-by-distance (IBD), which can produce continuous genetic variation that may be misinterpreted as discrete population structure or even distinct species. Here we examine the Green Frog (Rana clamitans), a wide-ranging species of the Aquarana clade distributed across much of North America. The broader phylogenetic context for R. clamitans within Aquarana is poorly understood, particularly its relationship with the closely related and IUCN Vulnerable Florida Bog Frog (Rana okaloosae). Additionally, although phenotypic variation within Rana clamitans previously merited description of two subspecies, patterns of genetic diversity remain unclear. Using genome-wide ddRAD markers, we largely resolve relationships within Aquarana and unambiguously identify R. okaloosae as the sister lineage to R. clamitans. Despite mtDNA introgression, we find little genomic evidence of hybridization between R. okaloosae and R. clamitans. Within R. clamitans there are two well-supported and geographically divided clades, which are identified as distinct species by a multispecies coalescent-based approach. However, the two clades exhibit low genealogical divergence. Population genetic analyses reveal that genetic variation within R. clamitans is best described by a pattern of IBD rather than independently evolving lineages. We conclude that R. clamitans is indeed a single species and the subspecies concept is of limited use. Our analysis demonstrates the importance of understanding continuous genetic variation when delimiting lineages and highlights the power of combining population genetic and phylogenetic perspectives to describe diversity within wide-ranging taxa.