Climate change is affecting rainfall patterns and increasing dry spells in the tropics. Although many environmental conditions can affect the hatching timing and survival of amphibian embryos, increased variation in rainfall and humidity can have particularly strong effects on species facing higher risk from dehydration, such as those with terrestrial eggs. Thus, it is important to understand how these environmental changes may affect the development, behavior, and immediate and long-term survival of amphibian embryos. We investigated whether Gliding Treefrog embryos (Agalychnis spurrelli) adaptively shift their hatching timing in response to dehydration risk, at the cost of smaller hatchling size. We raised embryos under three humidity levels and assessed egg and clutch hydration, hatching timing, and egg mortality. Mean humidity of 92% in Experiment I led to over 98% egg mortality by dehydration. A decrease from over 99 to 96% mean relative humidity in Experiment II induced premature hatching and reduced hatchling size across ages. Both clutch thickness and egg size increased at 99% and decreased at 96% humidity. Our results suggest that embryos of A. spurrelli are extremely dependent on consistent precipitation and particularly vulnerable to climate change. Although we did not directly measure differences in hatchling fitness, our results and previous findings suggest that small, premature hatchlings of A. spurrelli from dehydrated eggs would suffer higher mortality as tadpoles, thus embryos' self-defense against dehydration likely carries a delayed cost. These findings add to our understanding of how predicted climate changes may impact anuran early life stages.

The lateral line system and its innervation were examined in the Nurseryfish Kurtus gulliveri (family Kurtidae). The system is characterized by ca. 373,000 superficial neuromasts (SNs; at 152 mm standard length) occurring over one side of the entire body surface, including the dorsal, anal, and caudal fins. A fine-grid pattern of SNs is spread regularly over the surface, comprising many longitudinal and transverse SN rows, with the axis of best physiological sensibility perpendicular to the long axis of the neuromasts. On the head, rami of the anterior lateral line nerve are similar to those in typical percomorphs, each innervating numerous SNs by extensive ramification. On the trunk, 22 elongated dorsal ramules of the lateral ramus (of the posterior lateral line nerve) supply SNs on the dorsal half of the trunk and dorsal fin, and the dorsal longitudinal collector nerve innervates 22 canal neuromasts along the short (incomplete) trunk lateral line canal. Sixteen ventral ramules arise from the lateral ramus to supply SNs on the ventral half of the trunk and anal fin, which is similar to the pattern of the dorsal ramules. Innervation of the trunk and fins is distinctive, differing from all percomorphs known thus far.

The Australian Tawny Dragon lizard (Ctenophorus decresii), as currently recognized, comprises two genetically divergent lineages, northern and southern, that differ notably in male coloration. A narrow contact zone exists between the lineages with asymmetric and limited hybridization, indicating incompatibility and highlighting the need for further taxonomic assessment. Here, we evaluate morphological variation in C. decresii and elevate the lineages to separate species. The southern lineage retains the name C. decresii (Duméril and Bibron, 1837), and we formally reinstate C. modestus for the northern lineage, which was previously a synonym of C. decresii (Amphibolurus modestus,Ahl, 1926). We redescribe C. modestus and C. decresii and highlight important considerations for reevaluation of their conservation statuses. Recognition of C. modestus represents another species that may have differentiated in relatively mesic mountainous refugia during Pleistocene glacial-interglacial cycles, and underscores the importance of divergence in male coloration as a driver of speciation in the rock dragon species group.

Female fitness is often influenced by trade-offs in energy allocated to reproduction or self-maintenance that is dependent upon the life history of the organism. Maternal body size and condition are factors that are often positively correlated with clutch size and offspring size. We investigated whether maternal body size (snout–vent length, SVL) and condition (residual of mass on SVL) could predict measures of reproductive success including clutch size, offspring body size (SVL), and offspring survival in the territorial Eastern Red-backed Salamander (Plethodon cinereus). Brooding females and their eggs were collected and then housed in a controlled laboratory setting. We recorded the number of eggs found with each female and separated offspring from females once hatched. At 40 d after hatching, we measured the SVL and mass of females and juveniles. Maternal SVL, but not condition, was positively related to clutch size and offspring SVL; however, there was no significant relationship between clutch size and offspring SVL, indicating no trade-off between number and body size of offspring. In the laboratory, survival of the offspring to 185 d post-hatching was positively related to maternal SVL and negatively related to maternal condition. Also, the mean SVL, measured on day 40, of the offspring that survived to 185 d was significantly greater than the SVL of the offspring that did not survive, indicating a benefit of larger offspring body size. Finally, subsequent egg production (number of new oocytes produced by females following the current reproductive bout) was positively related to maternal SVL and condition (measured 185 d after hatching their previous clutches). These results suggest that larger maternal body size and condition of Eastern Red-backed Salamanders provide increased reproductive success through the number and body size of offspring produced in current or subsequent reproductive bouts and in offspring survival. Large body size in territorial animals like P. cinereus provides benefits for holding high quality territories as well as for increased reproductive success.

Avoiding thermal stress by using hibernacula is fundamental to survival of snakes in temperate environments. Snakes may overwinter alone or aggregate in communal hibernacula to avoid temperature extremes. Limited information is available regarding the overwintering ecology of rattlesnakes, and basic demographic information is necessary for understanding population dynamics, habitat requirements, and management of rattlesnakes. Even less is known about the demographics of species and populations utilizing artificial hibernacula, which may become increasingly important as habitat is lost and/or becomes more fragmented. We used seven years of mark–recapture data of the Western Rattlesnake (Crotalus viridis) at an artificial hibernaculum to estimate annual apparent survival, encounter rates, and transition rates between life stages (mature vs. immature) to investigate how these rates vary over time and in response to drought conditions. Further, we described trends in body condition and age structure, as well as trends in the proportion of reproductive females. Apparent survival rates were consistent and high across the study period for all snakes (including immature and mature females and all males; 0.66). The probability of an immature female surviving and transitioning to a mature adult was high and consistent across the study period (0.73). The stable survival and transition rates observed in this study may indicate other demographic rates, such as reproductive output, may be important drivers of population dynamics. This study contributes basic knowledge about population dynamics of communally overwintering rattlesnakes and suggests survival rates were relatively stable for snakes regularly utilizing this artificial hibernaculum.

Interactions between pathogens and the symbiotic microbial communities that reside in hosts can impact disease processes. Symbiotic microbial communities can act to prevent pathogen infection in some instances, while in other instances, pathogens can disrupt these symbiotic communities. We sought to address these interactions between the fungal skin pathogen Batrachochytrium dendrobatidis (Bd) and the skin bacterial communities of adult Spring Peepers (Pseudacris crucifer). In the laboratory, frogs were exposed to Bd zoospores for a 12-hour period and then monitored for five days. Bacterial community composition on the skin was assessed upon initial collection, 24 hours post-exposure, and at the conclusion of the experiment using 16S rRNA gene amplicon sequencing. Little impact on the bacterial community was observed as a result of Bd exposure, suggesting that the timeline was either too short to observe the effects of Bd, or that the skin communities are resilient in the face of such short exposure periods. In contrast, laboratory housing was associated with changes in skin bacterial community composition, in terms of both relative abundances and bacterial taxa that were present. These findings suggest that even a short time away from their natural environment can have strong effects on the composition of amphibian skin communities and that Bd exposure may not always disrupt these skin communities.

Variation among desmognathan salamanders in the timing of the female reproductive cycle is poorly understood. Although nesting tends to be seasonal, in the warmer months, females may not reproduce on a strictly annual cycle, but on a biennial or irregular schedule. In the present report, I examine the ramifications of annual and biennial female reproductive schedules on demography in two populations of Desmognathus monticola in the southern Blue Ridge Mountains of southwestern North Carolina. Provisional demographic models for each are developed based on published data on age structure, growth and developmental rates, and fecundity in the populations in question. The models indicate that biennial reproduction would require higher first-year survival than annual reproduction, at levels that appear tenable given our understanding of the ecology of nesting females and larvae of this species.

Lizards, as predators, can use different prey foraging strategies that are expected to influence daily movement behavior and home range use. Variation in lizard movement behavior can be achieved via frequency changes in movement step lengths and turning angles that can facilitate distinctive prey-searching and foraging strategies. Komodo Dragons (Varanus komodoensis) exhibit a distinct dietary transition at ∼18 kg, where lizards switch from consuming small-bodied and abundant prey species to highly dispersed adult ungulate prey. Our study examined competing models for the relative effects of ontogenetic dietary shift, body mass, sex, time of day, and arboreal habitat use on Komodo Dragon movement behavior (i.e., the proportional use of Lévy flight movement steps) and home range area (i.e., 50 and 95% utilization distributions). Model ranking indicated that two models incorporating the proportion of adult ungulates and body mass best explained the increased use of Lévy flight movement behavior of Komodo Dragons. Body mass also best explained the increase in the 50 and 95% utilization distribution Kernel home range areas. However, the slope of this relationship was less steep than that predicted by metabolic scaling theory and suggested that attributes specific to Komodo Dragons, or their environment, may attenuate their spatial requirements. This study demonstrates that because of distinct shifts in diet and other activities associated with large body size, Komodo Dragons alter movement behavior and increase their home range area to optimize environmental resource use.

Based on collections made in the western Guiana Shield over the last 21 years, Characidium crandellii and C. declivirostre are redescribed and two similar species are described from Guyana. These species all have enlarged paired fins with three to four rays thickened ventrally on the pectoral fin and two rays thickened on the pelvic fin. The species can be separated from all other Characidium and Melanocharacidium by having the venter unscaled from the isthmus to the pelvic origin. Characidium crandellii is found in the Essequibo and Takutu River systems and in an isolated population above Tencua Falls in the Ventuari River and the upper Paragua River (Orinoco River basin). Characidium declivirostre is found throughout the right-bank, shield tributaries of the Orinoco River system and in the upper Negro River. Characidium duplicatum, new species, appears to be rare but widely distributed in the Essequibo River system. Characidium wangyapoik, new species, is only known from the upper Ireng River, Branco River basin, along the border between Brazil and Guyana.

The “Lacustricola” hutereaui species complex is herein defined by the possession of banded dorsal, anal, and caudal fins in males and also by the pointed premaxilla ascending process, in which the premaxilla medial surface is slightly convex. “Lacustricola” pygmaeus, new species, known from the Okavango, Cuando, and upper Zambezi Rivers, is distinguished from the other species belonging to the “L.” hutereaui species complex by the following exclusive character states: an inconspicuous reticulate pattern on scale margins (vs. conspicuous); banded anal, dorsal, and caudal fin in females (vs. hyaline); faint bands in the middle rays of caudal fin in males (vs. conspicuous bands); rounded caudal fin in males (vs. slender); bright green-blue color in some of the flank scales (vs. absent); quadrate posterior margin with a deep concavity (vs. convex or about straight); and first dorsal-fin ray inserted in a vertical to second and third anal-fin ray (vs. fourth to eighth). Additionally, other morphometric, meristic, and osteological characters in combination proved to be useful in distinguishing the new species. Through the analysis of type material and recently collected specimens, the little known species “L.” chobensis is considered as a valid species and redescribed. It is easily distinguished from the other species belonging to the “L.” hutereaui species complex by a combination of external morphology, osteology, and coloration pattern characters. Comprehensive information on the osteology and external morphology of topotypes of “L.” hutereaui are presented, and description of coloration in life is provided for specimens from the Ubangui River, in the Central African Republic.

“Blackwater diving,” or nighttime SCUBA diving in epipelagic environments, has become highly popular in recent years because lay participants encounter animals that are difficult and expensive to observe through other methods. These same observations can be priceless for researchers working with these species, so an interface between the scientific communities and recreational divers would be mutually beneficial. In this paper, we describe one such interface through the photography, collection, and DNA barcoding of larval fishes from the island of Hawaii. The images and videos from this activity provide an exciting window into the epipelagic environment and the way larval fishes appear and swim within it. Blackwater diving allows us to see the often-elaborate appendages and other specializations of these larvae as they appear in situ, prior to extensive net and fixation damage. However, blackwater diving remains an almost exclusively recreational pursuit, particularly popular among underwater photographers, who have little interest in (or object to) collecting specimens for scientists. Nonetheless, a logical next step is careful hand collection of specimens for scientific study. Growing numbers of recreational divers around the world have access to an otherwise expensive-to-research habitat. Here we present, for the first time, in situ and post-fixation photos of larval fishes that were hand collected and fixed in 95% ethanol by blackwater divers operating out of Kona, Hawaii, with DNA barcode identifications congruent with morphology and pigmentation where possible. With the right motivation, blackwater diving could augment research in the pelagic ocean and significantly enhance natural history collections and our knowledge of the larvae of marine fishes.

Organisms are commonly exposed to numerous stressors that induce behavioral, physiological, or morphological changes in some combination. At northern temperate latitudes, de-icing agents (primarily sodium chloride, NaCl) are a major stressor to species in freshwater ecosystems. Species-specific responses to road salt toxicity range from lethal to sublethal effects, but it remains unclear how these effects interact with biotic stressors. Morphology can be quite sensitive to environmental changes, yet we know little about how it is affected by road salt exposure. We exposed Wood Frog tadpoles (Rana sylvatica) to two road salt formulations (NaCl and a mixture of NaCl, MgCl₂, and KCl), each at three concentrations (200, 600, and 1000 mg Cl^–/L), crossed with three biotic stressor levels (predator cue, competition, and a no-stressor control). We then measured the impacts on relative morphology (snout–vent length, body width, forelimb length, forelimb width, hindlimb length, hindlimb width) of the emerging metamorphs. Salt concentration and biotic stressors both impacted relative morphology, but their effects did not interact. Exposure to road salts increased relative snout–vent length (SVL) and body width. In contrast, competition induced relatively shorter SVL and forelimb length while predator cues induced relatively longer hindlimbs and narrower forelimbs. This is the first discovery that road salts can induce changes in amphibian morphology and that these effects are independent of changes induced by biotic stressors. Future research should examine the effects on overwintering success and future fitness in amphibians as well as the impacts of salt on the morphology of other aquatic taxa that are being exposed to freshwater salinization.

Species of the tubenose poacher genus Pallasina are assessed following examination of over 450 specimens from throughout the Pacific Rim, from the coast of California to the Chukchi Sea and Sea of Japan. The results presented here, including both morphological and mitochondrial DNA datasets, indicate that three species of Pallasina occur in the North Pacific and surrounding seas. Pallasina aix is found in the eastern North Pacific from California to southeast Alaska and in the Salish Sea. It has the shortest barbel of the three species and a unique haplotype in the mitochondrial COI region. Pallasina barbata is the most widespread species, ranging from the Gulf of Alaska to the Chukchi Sea and west to northern Japan. It is distinguished by having a moderate barbel length and can be separated from the other two species using a variety of meristic characters. Pallasina eryngia is found only in the central and northern Japanese Archipelago, and it is a relatively deep-water species. It is distinguished by having a long barbel, as well as relatively high counts of vertebrae and dermal plates. This study presents redescriptions of all three species and a key to their identification.

Sea turtle hatchlings emerge from underground nests at night, rapidly crawling seaward to swim off shore. Once in the water, hatchlings might experience high predation rates while in shallow water before reaching deeper water where encounters with predators, and consequently mortality rates, likely decline. Behavioral studies have described different swimming strategies used by hatchlings to counter nearshore predation. Coastal and oceanographic conditions are also likely to influence dispersal away from near shore to the open ocean. This study assessed predation rates of Hawksbill Turtle (Eretmochelys imbricata) hatchlings as they dispersed from shore at Chagar Hutang Bay, Malaysia and the role surface currents play in the transport of hatchlings off shore in the nearshore environment. An acoustic doppler current profiler was used to measure surface currents, and direct observations of hatchlings swimming off shore were made from a kayak using GPS loggers to track hatchling swimming paths. Six of the 31 hatchlings tracked (19.4%) were predated, most within 50 m of shore, indicating that predators are more abundant in shallower areas of the bay where a coralline-rocky bottom predominates. Survival tended to be greater under dark conditions when moonlight was absent or minimal. We quantified the relative importance of the tidal current in a hatchling's offshore swim, and found that in most cases, tidal surface currents assisted the offshore movement of Hawksbill hatchlings as they dispersed from the beach. These findings provide a better understanding of how sea turtle hatchling dispersal is affected by predation, moonlight, and physical oceanographic conditions at Chagar Hutang Turtle Sanctuary.

We describe a new species of fanged frog (genus Limnonectes) from Mindoro and Semirara Islands, of the Mindoro Pleistocene Aggregate Island Complex, of the central Philippines. Although morphologically indistinguishable from its closest relative, Limnonectes acanthi, of the Palawan faunal region, the two species can be readily diagnosed on the basis of spectral (dominant frequency) and temporal (pulse number and structure) properties of their advertisement calls, and their allopatric insular geographic ranges on permanently separate geological platforms which have not been connected by dry land in the recent geological past—all of which we interpret as congruent and independent lines of evidence supporting our recognition of two independently evolving evolutionary lineages (species). Ribosomal RNA mitochondrial gene sequences were used to provide genetic identification of specimens and estimate phylogenetic relationships; genetic divergences between Palawan and Mindoro faunal regions exceed those estimated among other, uncontroversial, phenotypically distinct Philippine species with equivalent levels of allopatry and biogeographic isolation. The recognition of the new species further emphasizes the degree to which even well-studied Philippine landmasses still harbor unrecognized biodiversity, and suggests that other widespread Philippine fanged frogs should be scrutinized for non-traditional diagnostic character differences (mate-recognition signal divergence, ecological differences, larval characteristics, life-history trait variation), especially when their geographic ranges span the archipelago's permanent, deep-water trenches, which define its well-characterized Pleistocene Aggregate Island Complexes.

Bromeliads are recognized as vital habitats for arboreal amphibians. However, these plants are often not included in traditional amphibian surveys. Furthermore, focused canopy sampling techniques are time-consuming, require specialized equipment and training, and, in the case of bromeliads, sampling is typically destructive. In this study, we developed and tested a new passive sampling technique for amphibians in bromeliads, which can be easily implemented in common amphibian surveys in the Neotropics. Our study was conducted in five different forests along an elevation gradient (0–2,200 m a.s.l.) in the central region of Veracruz, Mexico. In each forest, 15 tank bromeliads were relocated on large trees at 1.5 m above the ground (n = 75) by fastening them onto metal rings attached to the trees. Over a period of one year, these bromeliads were inspected monthly for amphibians. In total, we recorded 34 individuals belonging to eight species, including small and rare species that are normally difficult to find in the field. This technique appears to be effective in detecting frogs and salamanders across a range of ecosystems, especially in the cloud and mangrove forest where they were found more frequently throughout the year. Bromeliad relocation represents an alternative sampling technique for arboreal amphibians, which reduces the number of bromeliads that have to be sacrificed, requires few resources and minimal prior knowledge, and can be implemented effectively in studies that need repeated sampling through time.

Anurans often call in acoustically complex choruses, which can consist of multiple closely related species. Closely related sympatric species often differ in phenology and the acoustic properties of male advertisement calls, which, in some species, are phenotypically plastic. The tetraploid Eastern Gray Treefrog (Hyla versicolor) originates from multiple, separate hybridization events of the diploid Cope's Gray Treefrog (Hyla chrysoscelis) with now-extinct diploid anurans. The two species are visually indistinguishable, exhibit highly similar ecology and behavior, and co-occur frequently across their range. Males of these species can be distinguished from each other by the structure of their advertisement calls. Daily audio recordings and weather data were collected for five consecutive years from eight breeding sites of sympatric H. versicolor and H. chrysoscelis. We examined spatial and temporal patterns in calling phenology and responses of both species to environmental cues. Additionally, we measured three advertisement call properties to evaluate differences in call structure based on community composition. The phenologies of the two gray treefrog species were nearly identical, and the presence of the other species did not significantly affect call pulse rate or dominant frequency in either species. Chorus composition affected call duration in both species, but in H. chrysoscelis, this effect was temperature dependent. Our results indicate that while calling phenology does not contribute to reproductive isolation in sympatric gray treefrogs, modulation of phenotypically plastic call properties could affect male mating success and prezygotic reproductive isolation.

A new species of frog of the genus Odontophrynus is described from grassland of the subtropical regions of Argentina, Brazil, and Paraguay based on morphological, osteological, bioacoustical, cytogenetic, and molecular evidence. The new species is characterized by having medium size; rostral and eye-nostril glandular warts well developed; several long glandular ridges, longitudinally oriented, on dorsum; several medium-sized, nearly rounded, dark-brown dorsal blotches; light mid-dorsal stripe continuous and well defined or restricted to the head and the urostyle regions; and mid-dorsal stripe, interorbital, and dorsolateral bands with a moderately whitish highlight, light brown, or reddish coloration. Additionally, the new species has a skull with nasals slightly separated both from each other and frontoparietals, and frontoparietal fontanelle not exposed. The advertisement call consists of a single multipulsed note with a dominant frequency of 820–1,121 Hz and a pulse rate of 99.3–140.7 pulses/s. The chromosomal complement is diploid with 2N = 2X = 22 chromosomes and nucleolar organizer regions on the interstitial regions of the short arm of chromosome pair 4. The phylogenetic analysis allowed us to recover the new species belonging to the O. americanus species group with genetic distances from its congeners ranging from 2.11 to 4.82% in a partial sequence of 16S ribosomal RNA gene. The new species is geographically isolated from the other currently known diploid species of the group, but in some localities is found in sympatry or syntopy with the tetraploid O. americanus.

The microhylid genus Micryletta, often called Paddy Frogs, is a taxonomically modest group of frogs currently comprised of eight species distributed across India, China, and Southeast Asia. None of the recent investigations into this group have explicitly focused on the diversity of these frogs in Myanmar, a critically undersampled region previously thought to contain only one species of Micryletta, M. inornata. Recent field expeditions to Myanmar conducted by the authors have resulted in the discovery of numerous populations of Micryletta in the northern and southern portions of the country in Kachin State and Tanintharyi Region, respectively. In this study, we investigate the status of these populations, their taxonomic identities, and broadly assess the diversity of this enigmatic group of frogs in Myanmar. Using comparative morphological and molecular data, we find the diversity of Micryletta in Myanmar has been poorly appreciated, which we demonstrate with the discovery of M. aishani, a species previously only known from neighboring India, and M. lineata, a species originally described from Peninsular Thailand. Our investigation into the taxonomic status of M. lineata demonstrates the validity in the recognition of this species, which is supported with evidence derived from morphology, geography, and molecular data. We additionally provide a detailed re-description of this species based on novel specimens from southern Myanmar. We also document M. inornata sensu stricto in Myanmar, sympatric with M. lineata, bringing the total to three species of Micryletta occurring in Myanmar.

The family Pomacentridae is a species-rich group of primarily marine fishes. The phylogenetic relationships of the damselfishes are examined herein using sequence data from five mitochondrial (12S, 16S, ATP synthase subunits 8/6, cytochrome b, and cytochrome c oxidase I) and three nuclear (histone H3, recombination activating gene 1 exon 3, and Tmo-4C4) loci. A combined data matrix of 6,865 base pairs was compiled for 462 taxa, representing 322 damselfish species, and used to reconstruct the phylogeny of pomacentrids via maximum likelihood. The resulting topology supports the monophyly of the family and some groups within it, corroborating some conclusions drawn by recent studies but contradicting others. We find that the family is composed of four major lineages, recognized herein as the subfamilies Chrominae, Glyphisodontinae, Microspathodontinae, and Pomacentrinae. The subfamily Microspathodontinae is sister to a clade of the other three subfamilies, and the subfamily Glyphisodontinae is sister to a clade of Chrominae and Pomacentrinae. The monotypic subfamily Lepidozyginae is recovered within Microspathodontinae and placed in the synonymy of Microspathodontinae. Species of Plectroglyphidodon and Stegastes are reassigned to maintain the monophyly of both genera. In Chrominae, the generic limits of Azurina and Chromis are revised to reflect monophyletic groups. The genus-group name Pycnochromis is resurrected to accommodate a group of former Chromis sister to Dascyllus. In Pomacentrinae, the genus Premnas is recovered within Amphiprion and placed in the synonymy of Amphiprion. The genus Chrysiptera is broadly polyphyletic within Pomacentrinae. The genus Amblypomacentrus is revised to accommodate some species formerly classified as Chrysiptera.