The labrid fish Cirrhilabrus solorensis was first described in 1853 by Bleeker, based on specimens collected from the Indonesian island of Solor, off the eastern tip of Flores in the Lesser Sunda Islands. Although sufficient at the time, Bleeker's description of the species was brief, resulting in subsequent taxonomic confusion concerning the true identity of this taxon. Presently, the name has been applied to several fishes with notable differences in coloration, particularly in the terminal males. On the basis of additional non-type material and photographic examination of Bleeker's holotype, we redescribe Cirrhilabrus solorensis and resolve the long-standing contention regarding its taxonomic identity. In doing so, we describe two species as new, Cirrhilabrus aquamarinus, new species, on the basis of the holotype and eight paratypes from Sulawesi and the surrounding islands of Banggai and Wakatobi, Indonesia, and Cirrhilabrus chaliasi, new species, described on the basis of the holotype and nine paratypes from Bali, Indonesia. These three species are closely related and, together with C. aurantidorsalis, C. cyanopleura, C. luteovittatus, C. randalli, and C. ryukyuensis, form a complex of species that differ from congeners in having the following combination of characters: caudal fin in males weakly rhomboidal; median fins hyaline with sinuous filigree in both sexes; body with scales edged in inky blue to indigo, their margins often patterned in an argyle motif; and osseus elements that preserve blue to blue-green in alcohol. We briefly discuss the phylogenetic relationships of species in this complex based on results of a companion study detailed elsewhere.

There is very little information of the foraging ecology and parasite infections of many snake species. Here, we used opportunistically collected roadkill to assess diet and parasite prevalence in two snake species in The Bahamas, the Bahamian Racer (Cubophis vudii vudii) and the Bahamian Boa (Chilabothrus strigilatus strigilatus). Over eight months, we conducted up to four daily routine road surveys along a 10 km stretch of highway, as well as opportunistic surveys elsewhere on the island of Eleuthera. Overall, we collected 270 roadkilled snakes of which less than half (39%) were intact and suitable for analyses. Lizards were the most prevalent prey items, although we also found rodents and other snakes. We report on new prey items for the Bahamian Racer, including two snakes and a case of oophagy. Endoparasites, which appeared to be all nematodes, were present only in Bahamian Racers, with 74% of all individuals infected. Parasite infection rates and loads were higher in females than in males. We show that using roadkilled snakes is an effective method for studying the diet and endoparasite prevalence in snakes on a Bahamian island.

Squamate reptiles rely on the vomeronasal organ for chemoperception of their environment. This organ functionally associates with several structures, such as the nasolacrimal duct and choanal groove, which are morphologically diverse among species. In this study, we investigated the morphological characteristics and embryogenesis of the vomeronasal organ and its associated structures in the Japanese Grass Lizard (Takydromus tachydromoides). Separation of the complex of the nasolacrimal duct from the vomeronasal organ was observed in this species, a characteristic morphological feature among squamates. Additionally, we integrated the morphological characteristics of the vomeronasal organ and associated structures among squamates, focusing on topological relationships among the structures. The parsimony and likelihood methods for ancestral state reconstruction suggested the parallelism of several morphological characteristics during the evolutionary history of squamates: loss or reduction of the choanal groove, fusion between the nasolacrimal duct and choanal groove, and separation of the nasolacrimal duct from the vomeronasal organ.

Femoral gland secretions in lizards convey chemical information about the health and social status of the depositing individual. These secretions influence behaviors related to female mate choice and male–male competition, but little is known about how they are first located by lizards in the environment. Secretions are visually conspicuous and can be sighted from a distance by visually adept lizards, but the specificity of secretion reflectance to the depositing species remains unknown. We examined the reflectance spectra of femoral gland secretions from two sympatric lizard species, Aspidoscelis tigris and Gambelia wislizenii, to determine whether secretions could be visually distinguished. Mean reflectance did not differ between species, but A. tigris had higher reflectance in ultraviolet wavelengths. For both species, lizards in better body condition, as determined by the residuals of the relationship between snout–vent length and body mass, had higher ultraviolet reflectance. In summary, our results indicate that femoral gland secretions can be visually discriminated between species if the discriminating lizard is ultraviolet sensitive.

Night frogs of the genus Nyctibatrachus are endemic to the Western Ghats of southern India, and these frogs exhibit unique courtship and spawning behavior. Herein, we studied the breeding biology of Nyctibatrachus humayuni and describe its tadpole. Our results show that N. humayuni is a terrestrial breeder that reproduces during the southwestern monsoon. Adults of N. humayuni are sexually dimorphic: females are larger, and males have femoral glands on the ventral surface of their thighs. The operational sex ratio is highly skewed in favor of males during the breeding season, while it is close to 1:1 during the rest of the year. Males choose suitable spawning sites, establish territories, and initiate calling, whereas females approach the vocalizing males and, following a brief courtship, deposit eggs at the sites chosen by males. Males produce amplitude-modulated advertisement calls consisting of single or multiple notes depending on the social situation. Unlike most frogs, females of N. humayuni do not spawn while in amplexus. Instead, spawning occurs after separation of the pair following a brief ‘abbreviated amplexus.’ Eggs are deposited on the moist rocks, boulders, and muddy surfaces in the middle and along the sides of montane streams. Clutch size is larger during the early breeding season, while it decreases with the season's progression. Interestingly, egg size is comparable among the breeding season phases, suggesting the absence of a trade-off between egg size and clutch size. Tadpoles are moderately oval and dorsoventrally flattened with a blunt snout. The mouth is ventral; the oral disc consists of upper and lower labia and jaw sheaths. Teeth are completely absent; the jaw sheaths are keratinized and serrated. The upper and lower labia are surrounded by a single row of marginal papillae and 2–3 rows of sub-marginal papillae.

A new species of scaleless black dragonfish, Photonectes klepadloae, new species, is described on the basis of a single specimen collected in the central north Pacific Ocean off the Hawaiian Islands. The new species is readily distinguished from all congeners by the postorbital organ shifted forward to below eye, by the presence of the blue luminous tissue on the body arranged in two widely spaced interrupted lines between IV photophores and a streak-like patch on each side above 10^th to 12^th PV photophores, and by the structure of the mental barbel lacking a bulb, but having the long unpigmented distal appendage without a terminal swelling, and a pair of enlarged stalked photophore-like structures on the distal extremity of the stem. A revised key of the known species of Photonectes is presented.

The African anuran genus Cardioglossa contains 19 described species, most of which are distinguished from one another by striking patterns and colors. We present a well-resolved phylogeny based on analyses of mitochondrial and nuclear loci for 18 species of Cardioglossa. This provides the basis for species-delimitation analyses and interpreting historical biogeography in the genus. Whereas much of the diversification within the genus occurred among Central African lineages during the Miocene following the origin of Cardioglossa in the latest Oligocene or earliest Miocene, most species-pairs in the genus diverged more recently during the Plio-Pleistocene. The two most geographically peripheral species—C. cyaneospila in the Albertine Rift Mountains and C. occidentalis in the Upper Guinean Forests of West Africa—both diverged from other lineages during the mid-late Miocene. Because our analyses do not support C. manengouba and C. oreas as distinct species, we recognize these geographically separate and phenotypically distinct populations as subspecies of C. oreas that diverged subsequent to the origin of Mount Manengouba during the past 1.5 million years. In contrast, we find that C. leucomystax likely represents two species found in the Lower Guinean and Congolian forests, respectively. We find recent divergences between several allopatric lineages (either species or populations) that differ in coloration and pattern, including in C. nigromaculata which varies in color across its range in Central Africa and Bioko Island. These recent divergences among allopatric lineages with distinctive coloration and pattern raise new questions about the significance of these traits in this genus for which little is known of its natural history and biology.

It was recently proposed that there are three new species of Salvelinus with microendemic distributions in the Great Smoky Mountains National Park, Tennessee, USA. The three species of Salvelinus were hypothesized to be distinct from their congener Brook Trout S. fontinalis based on three meristic traits—pored lateral-line scales, vertebral counts, and number of basihyal teeth. After analyses that included specimens sampled from a larger portion of the geographic range of S. fontinalis, we conclude that the three populations of Salvelinus recently described as new species are not morphometrically distinct from Brook Trout and consider all three to be synonyms of S. fontinalis. Moreover, the low number of specimens originally examined conflates morphological differences among populations with sexual dimorphism and/or phenotypic plasticity, both of which are documented extensively in Brook Trout but were not controlled for in the species descriptions. While there is currently insufficient phenotypic or genotypic evidence to support the hypothesis of three new species that are distinct from S. fontinalis, we acknowledge the need to understand the unique selection pressures that shape evolutionary trajectories in small, isolated populations of Brook Trout and to conserve evolutionarily significant sources of genotypic and phenotypic diversity. To that end, we provide comments on research opportunities to support Brook Trout conservation, including the importance of collaborative, range-wide phylogenetic studies to identify the most appropriate scales of management efforts.

A new genus and two new species of Indo-Pacific clingfishes are described in this study. The new genus, Flabellicauda, belongs to the Diademichthyinae and can be distinguished from other genera currently placed in this subfamily by the following combination of characters: snout moderate in length and slightly pointed, not extremely long or strongly rounded; oral cleft very small, restricted to anterior tip of snout, posterior portion of both jaws covered by thick skin of snout; gill opening a tiny, narrow slit, dorsalmost point level with base of 9^th to 14^th (usually 12^th, rarely 9^th) pectoral-fin ray in lateral view; gill membrane attached to isthmus; two rows of gill filaments on gill arches 1–3; extremely small “single” adhesive disc, its length 8.1–13.5% SL; center of disc flat, without cavity; disc papillae flattened, similar in size across disc surface; preopercular lateral-line canal and associated pores absent; dorsal, anal, and caudal fins connected via thin membrane, giving appearance of single, continuous median fin around posterior part of body; and upper and lower hypural plates completely fused, forming large fan-like hypural complex. Two new species are described and assigned to Flabellicauda, new genus, including F. alleni, new species (type species of Flabellicauda, new genus), and F. cometes, new species. Two additional species previously assigned to Lepadichthys are transferred to Flabellicauda, new genus, including F. bolini, new combination, and F. akiko, new combination. Among species of Flabellicauda, new genus, F. akiko is unique in having the following characters: head sensory canal pores poorly developed, including 1 nasal and 1 postorbital pore (vs. usually 2 nasal, 2 lacrimal, and 2 postorbital pores in F. alleni, new species, and F. bolini; 2 nasal pores in F. cometes, new species); upper end of gill opening level with base of 9^th or 10^th pectoral-fin ray in lateral view (vs. 12^th to 14^th); disc region A with papillae at center (vs. disc region A without papillae at center); and body background color red in life, with white stripes along body (vs. body background color black or maroon in life, with white stripes along body). Although F. alleni, new species, is very similar to F. bolini, the former differs from the latter in having a higher number of gill rakers (viz., 5–8 [modally 6, rarely 5], 6–8 [6], and 6–8 [7] on the first, second, and third gill arch, respectively, and 18–24 [19] total gill rakers [first + second + third arch] in F. alleni, new species, vs. 4–6 [5] on the first, second, and third arch, respectively, and 12–17 [14] total gill rakers in F. bolini). In addition to the meristic difference, head length, pre-disc length, orbit diameter, and caudal-peduncle length and width proportions further aid to distinguish F. alleni, new species, from F. bolini. Examined specimens of F. alleni, new species, were collected from Sri Lanka and southeast Asia, whereas those of F. bolini were collected from Papua New Guinea, Vanuatu, and Fiji; the range of the two species are not known to overlap. Flabellicauda cometes, new species, can be easily distinguished from F. alleni, new species, and F. bolini in having the following characters: 10–12 dorsal-fin rays (vs. 12–15 [13]); 9–11 anal-fin rays (vs. 10–13 [11], rarely 10); head sensory canal pores poorly developed, including 2 nasal and 1 postorbital pores. Notes on the ecology of each of the four species of Flabellicauda, new genus, are also provided.

Breeding organisms rely on numerous environmental cues to determine optimal sites for oviposition. Site selection is often associated with factors that increase fitness, and the identification of these factors can help conservation efforts. For amphibians that breed in wetlands, the quality of terrestrial subsidies (e.g., leaf litter) can strongly influence larval survival and development by altering water chemistry and available nutrients. In this study, we examined the preference of breeding Gray Treefrogs (Hyla versicolor) for wetlands containing litter species of varying chemical quality. Based on previous studies of larval survival, we hypothesized that treefrogs would oviposit more eggs into wetland mesocosms containing litter with high nutrient concentrations and low phenolic concentrations. To test our hypothesis, we counted the number of eggs oviposited by treefrogs in artificial wetland mesocosms containing either Red Maple (Acer rubrum), Black Oak (Quercus velutina), or Eastern Hemlock (Tsuga canadensis) litter. We conducted this study over two breeding seasons. Counter to our hypothesis, we found that treefrogs preferred to oviposit in mesocosms containing maple litter, which contains high levels of both nutrients and phenolic acids. We discuss possible explanations for this result, including the possible anti-parasitic effects of phenolic acids. This is the first study demonstrating that breeding amphibians can differentiate between wetlands containing leaf litter species of differing chemistry. Given global declines in amphibian species concurrent with widespread changes in forest composition, our results emphasize the importance of considering leaf litter quality in wetland management and conservation efforts.

When non-native species are introduced to new areas without their native predators, they may lose their ability to detect and avoid those predators, especially if the behaviors impose some sort of cost. Few studies have investigated whether non-native populations have lost the ability to avoid their native predators. Coquí frogs, which are endemic to Puerto Rico, were introduced to Hawaii in the late 1980s. Our goal was to investigate whether Coquís from Hawaii avoid predators from their native Puerto Rico. To test this, we collected frogs from both ranges and two arthropod predators from Puerto Rico (tailless whip scorpions and tarantulas). We determined experimentally whether frogs from Hawaii and Puerto Rico exhibited the same avoidance behaviors to these predators. We found that frogs from both ranges avoid attack by moving away from predators and that there was no difference in behaviors between the two ranges. Results suggest that, after nearly 20 generations, frogs from Hawaii have not lost their ability to detect and avoid native predators. The antipredator behaviors Coquís exhibit may help them avoid novel predators in their introduced range and may have contributed to their successful invasion.

Redspot Chub (Nocomis asper) are a keystone species in Ozark Highland streams of the Arkansas River drainage because their unique mound-building reproductive behavior facilitates recruitment of nest associates. Data contributing to an increased understanding of Redspot Chub natural history is required for the conservation of this species as it is listed as a species of concern throughout most its range. The findings presented within thoroughly describe Redspot Chub feeding ecology by documenting an ontogenetic diet shift, patterns of seasonal resource use, important prey taxa, estimates of trophic position and dietary niche breadth, as well as documenting feeding strategies at population and individual levels. Diet collections were conducted seasonally in 2018 and 2019 at four sites on Spavinaw Creek in Arkansas and Oklahoma. Logistic regression provided evidence for a previously undescribed ontogenetic diet shift, which split Redspot Chub into two functionally different species from a dietary perspective. Redspot Chub ≥ 162 mm total length (TL, RSCB) occupied a significantly higher trophic level than Redspot Chub < 162 mm TL (RSCS). In terms of caloric contribution, Ringed Crayfish (Faxonius neglectus neglectus) nearly accounted for the entire diet of RSCB, regardless of season. This specialization led to a much lower overall dietary niche breadth when compared to RSCS. Furthermore, Amundsen plots clearly depicted RSCB population specialization on crayfish. Conversely, Trichoptera were the most important prey across seasons for RSCS. Coleoptera, Ringed Crayfish, and Ephemeroptera ranked second in importance at different times seasonally. RSCS also possessed a relatively narrow niche width, but Amundsen plots exhibited a pattern where seasonally the two most important prey types were specialized on by approximately half the population, while smaller proportions of the population specialized on less commonly used prey resources. Species' diets reflect an integration of numerous ecological components; therefore, our aim was to provide a greater understanding of Redspot Chub feeding ecology that may be useful for informing future conservation assessments and management decisions.

Cylix tupareomanaia, new genus and species, is described from three specimens (35.5–55.5 mm SL), collected from rocky reefs at 12–17 m depth from Taitokerau Northland, New Zealand. The new taxon shares morphological synapomorphies with the superficially similar Australian endemic Idiotropiscis and Indo-Pacific Acentronura, including head angled ventrally approximately 25° from the principal body axis, enclosed brood pouch, brood pouch plates, prehensile tail, and absence of caudal fin. Cylix tupareomanaia, new genus and species, however, is distinguishable from all other members of the Syngnathidae by the following combination of bony autapomorphic characters: a cup-like crest present anterodorsally on the supraoccipital; and large conspicuous midventral conical spines on the cleithral symphysis and first trunk ring between the pectoral-fin bases. The new species can be further differentiated by genetic divergence in the mitochondrial COX1 gene from Acentronura breviperula, A. tentaculata, Idiotropiscis australe, and I. lumnitzeri (estimated uncorrected p-distances of 19.5%, 20.4%, 17.9%, and 18.4%, respectively). A phylogenetic hypothesis from the analysis of two nuclear loci, 18S and TMO-4C4, supports the placement of C. tupareomanaia, new genus and species, as the sister taxon to a clade comprising the genera Acentronura and Idiotropiscis. Cylix tupareomanaia, new genus and species, represents the eighth member within the pygmy pipehorse clade to be described from the Indo-Pacific and the first new genus and species of syngnathid to be reported from New Zealand since 1921.

Among western North American amphibian lineages, the plethodontid salamander genus Batrachoseps has undergone the most extensive radiation. Here we describe a new species in the genus from the vicinity of Point Arguello, central California. This lineage falls within the B. pacificus group, but it is differentiated from other species in the group by both molecular sequence data and morphology. It is geographically disjunct from its close relatives, with a tiny range in unlikely habitat along a narrow strip of the Pacific Coast, where it is entirely surrounded by B. nigriventris, a distant relative. Although intraspecific molecular variation is almost entirely absent, some population structure was detected across the 4 km extent of its range. Because of its tiny range and limited genetic variation, the impacts of any potential modifications to its known habitat should be evaluated to ensure the species' continued conservation.

For species with variable phenology, it is often challenging to produce reliable estimates of population dynamics or changes in occupancy. The Arizona Toad (Anaxyrus microscaphus) is a southwestern USA endemic that has been petitioned for legal protection, but status assessments are limited by a lack of information on population trends. Also, timing and consistency of Arizona Toad breeding varies greatly, making it difficult to predict optimal survey times or effort required for detection. To help fill these information gaps, we conducted breeding season call surveys during 2013–2016 and 2019 at 86 historically occupied sites and 59 control sites across the species' range in New Mexico. We estimated variation in mean dates of arrival and departure from breeding sites, changes in occupancy, and site-level extinction since 1959 with recently developed multi-season staggered-entry models, which relax the within-season closure assumption common to most occupancy models. Optimal timing of surveys in our study areas was approximately 5–30 March. Averaged across years, estimated probability of occupancy was 0.58 (SE = 0.09) for historical sites and 0.19 (SE = 0.08) for control sites. Occupancy increased from 2013 through 2019. Notably, even though observer error was trivial, annual detection probabilities varied from 0.23 to 0.75 and declined during the study; this means naïve occupancy values would have been misleading, indicating apparent declines in toad occupancy. Occupancy was lowest during the first year of the study, possibly due to changes in stream flows and conditions in many waterbodies following extended drought and recent wildfires. Although within-season closure was violated by variable calling phenology, simple multi-season models provided nearly identical estimates as staggered-entry models. Surprisingly, extinction probability was unrelated to the number of years since the first or last record at historically occupied sites. Collectively, our results suggest a lack of large, recent declines in occupancy by Arizona Toads in New Mexico, but we still lack population information from most of the species' range.

The short larval ontogenetic phase has a large impact on success or failure of fish populations due to naturally high mortality rates. Yet, for the federally endangered fishes Colorado Pikeminnow Ptychocheilus lucius and Razorback Sucker Xyrauchen texanus, information about this sensitive life stage is limited. We determined species-specific age–length functions, spawning periodicity, and environmental factors related to growth and the onset of spawning by these species in the San Juan River of the Colorado River basin. Daily ages were determined from lapillar otoliths, and growth rates were calculated for subsamples of San Juan River larval Colorado Pikeminnows and Razorback Suckers collected from 2009 through 2017 and six candidate age–length functions were fit to evaluate the relationship between age and growth. Spawning periodicity estimates from the best-fit-model and published function were compared to those from observed otolith ages and differences were analyzed. The responses of spawning periodicity and growth to abiotic and temporal conditions were evaluated. For both species, spawning dates produced by otolith ages and best-fit functions were significantly different from those produced by the published functions, but not from each other. Age–length functions determined in this study enable more accurate back-calculation of ages and prediction of spawning periodicity than published functions. The spawning periodicity estimate of San Juan River Colorado Pikeminnow and Razorback Sucker were both impacted by multiple parameterizations of temperature and discharge. For both species, fish age had the biggest influence on growth. Accurate knowledge of spawning periodicity and factors affecting fish growth can improve timing of management activities to maximize benefit to Colorado Pikeminnows and Razorback Suckers in the San Juan River.

Species delimitation is a first step for realizing the extent of biodiversity and is relevant for all downstream applications in biology. The production of large genome-scale datasets for non-model organisms combined with the development of methodological tools have allowed researchers to examine fine-scale processes of speciation such as timing of origin, degree of migration, population-size changes, selection, drift, and recombination. Studies using reptiles and amphibians have, in part, paved the way for the development and use of such methods for exploring speciation and delimitation. While these methodologies have improved our understanding of processes of diversification, researchers are far from agreeing upon a set of criteria to delimit species. In cases where genetic lineages are discovered that are unique to geographic areas, researchers usually agree that two entities exist. Disagreement about taxonomic status often centers on the degree of reproductive isolation between taxa and probability of remaining distinct. However, reproductive isolation is frequently inferred without examining gene flow, understanding the nature of hybrid zones, or determining the amount and type of introgression. Here, we review some of the vexing problems for delimiting reptiles and amphibians, which include isolation by distance, gene flow and differential allelic introgression, hybrid zone dynamics, and the nature of genomic islands of divergence. We also respond to recent literature criticizing model-based species delimitation in North American snakes in the context of these methodological advancements and address how scientists can move forward with studies on speciation.

Over the last two decades, mitochondrial DNA (mtDNA) sequence data, as well as analyses of nuclear DNA based on the multispecies coalescent model, have increasingly been used to delimit species, sometimes based on limited sampling and without other supporting evidence. We have argued elsewhere that the uncritical use of these approaches has resulted in unnecessary and unwarranted taxonomic changes that have real and long-lasting consequences for science and society. Unfortunately, these arguments have been misrepresented by Burbrink and Ruane's Point of View on “contemporary” species delimitation in this issue. Here, we discuss the role of models in species delimitation research, and again argue that careful consideration of model assumptions (and their potential violation) is necessary when inferring population history and delimiting species. We echo recent calls for targeted, thorough geographic sampling across contact zones and into parapatric ranges to test for reproductive isolation and draw inferences about the evolutionary independence (or lack thereof) of populations that exchange genes. Finally, despite our very different views on how best to identify species and when to make taxonomic changes, we end by highlighting areas where we agree with Burbrink and Ruane's Point of View and offer suggestions for future research.