The function of the vertebrate visual system is constrained by eye size, with the width and length of the eye influencing sensitivity and visual acuity, respectively. Thus, eye size can be an important predictor of ecological niche, influencing predatory, defensive, and reproductive strategies and the circumstances under which those behaviors can occur. Watersnakes in the genus Nerodia are semi-aquatic, though there is interspecific variation in diel activity pattern, microhabitat use, and diet. Some species of Nerodia also exhibit an ontogenetic shift in both microhabitat use and prey preference, which may correspond with a similar shift in ocular morphology. We examined the ontogenetic allometry of eye size and shape in two sympatric watersnakes, Nerodia cyclopion and N. fasciata. We found that juveniles of both species have relatively larger eyes than their adult counterparts. Further, the eyes of N. fasciata do not increase significantly in length, but they do become significantly wider, thus potentially increasing the sensitivity of the eye as this species matures. In N. cyclopion, the eye increases in both width and length throughout ontogeny, generating little change in the overall shape, but potentially increasing the resolution of the retinal image. Increased eye length in the more behaviorally aquatic N. cyclopion allows for a greater degree of visual accommodation (via lenticular displacement or deformation), which is potentially beneficial in aquatic foraging. These findings suggest that ontogenetic scaling of eye size in these species corresponds with ontogenetic differences in microhabitat use, foraging behavior, and diet.

Some marine sculpins (Psychrolutidae) exhibit an unusual reproductive mode called internal gametic association (IGA), in which sperm transfer between the sexes occurs during copulation, but fertilization is delayed until the eggs are released in seawater. IGA is suggested in many internally inseminating marine sculpins, but experimental evidence of IGA is limited to a few species. The Fluffy Sculpin (Oligocottus snyderi) and its sister species, the Rosy Sculpin (O. rubellio), occur in sympatry in intertidal zones along the central California coast. Although these species likely exhibit internal insemination, their reproductive strategy is not well understood. Here, we investigate reproductive mode, mating season, egg-laying season, and sperm morphology and activity in Fluffy and Rosy Sculpins near Pillar Point, California. Delayed embryonic development was observed for one clutch of eggs of the Rosy Sculpin after exposure to seawater, indicating IGA in this species. We were unable to demonstrate IGA by initiation of development in the Fluffy Sculpin because we were unable to collect females with ovulated oocytes. Nevertheless, we found that sperm morphology with elongated head and high motility in isotonic solution while immotile in seawater in both species represent characteristics associated with IGA. Seasonal changes in gonadosomatic index (GSI) of both sexes revealed asynchronous gonadal maturation between the sexes in the Fluffy Sculpin and suggest a similar pattern in the Rosy Sculpin; however, the latter was affected by small sample size. These patterns indicate that males copulate with females before egg maturation, and females store sperm for several months. Our study supports the generality of IGA across marine sculpins and provides an understanding of its relationship to asynchrony in GSI between the sexes. Further, while Fluffy and Rosy Sculpins are similar in body morphology, habitat, and reproductive mode, the slight difference in mating season (pre-mating isolation) and sperm head and flagellum length (post-mating isolation) may have contributed to divergence in sympatry with reduced probability of hybridization.

Thermal traits, or how an animal responds to changing temperatures, impacts species persistence and thus biodiversity. Trait databases, as repositories of consolidated, measured organismal attributes, allow researchers to link study species with specific trait values, enabling comparisons within and among species. Trait databases also help lay the groundwork to build mechanistic linkages between organisms and the environment. However, missing or hidden physiological trait data preclude building mechanistic estimates of climate change vulnerability for many species. Thus, physiologically focused trait databases present an opportunity to consolidate data and enable species-specific or multispecies, mechanistic evaluations of climate change vulnerability. Here, we present TRAD: thermal traits of anurans database for the southeastern United States, a database of thermal trait values related to physiological thermoregulation (critical thermal minima and maxima, preferred temperature), behavioral thermoregulation (activity period, retreat emergence temperature, basking temperature, minimum and maximum foraging temperatures), and body mass for 37 anuran species found within the southeastern United States. In total, TRAD contains 858 reported trait values for 37 of 40 species found in the region from 267 peer-reviewed papers, dissertations, or theses and is easily linked with trait data available in ATraiU, an ecological trait database for anurans in the United States. TRAD contains trait values for multiple life stages and a summarization of interspecific adult trait values. Availability of trait data varied widely among traits and species. Estimates of mass were the most common trait values reported, with values available for 32 species. Behavioral trait values comprised 23% of our database, with activity period available for 34 species. We found the most trait values for Cope's Gray Treefrog (Dryophytes chrysoscelis), with at least one trait value for eight traits in the database. Conversely, species in the genus Pseudacris generally had the fewest trait values available. Species with the largest geographic range sizes also had the greatest coverage of data across traits (rho 5 0.75, P , 0.001). TRAD can aid studies of anuran response to changing temperatures, physiological niche space and limitations, and potential drivers of anuran geographic range limits, influencing our understanding of other ecological and evolutionary patterns and processes and enabling multispecies comparisons of potential risk and resilience in the face of climate change.

Survival rates are known to vary over the course of an individual's lifetime and among individuals within a population. Quantifying the natural variability in survival rates is crucial when scaling up to infer the dynamics of populations. Using ten years of mark–recapture data from two adjacent wetlands on the Florida Panhandle, we investigated individual and temporal variability in survival rates of Reticulated Flatwoods Salamanders (Ambystoma bishopi). Our objectives were to 1) provide the first estimates of survival for the species, 2) evaluate the relationship between body size and mortality risk, 3) quantify the degree of variability in survival rates across the study period, and 4) discern whether variability in survival or detection correlates with environmental conditions. To address these objectives, we constructed a modified Cormack-Jolly-Seber model that includes body size and year as covariates. Mean annual survival was estimated to be 0.72 and was strongly correlated with body size; survival rates of the smallest individuals in the study were 0.5 and those of the largest individuals were 0.85. Survival also varied considerably across years, but it did not correlate with temperature extremes or rainfall. Therefore, a key priority for future research should be to identify the ecological correlates of mortality risk in A. bishopi. Our results can be integrated into demographic projections for Reticulated Flatwoods Salamanders and will help managers to discern population viability, evaluate alternative management strategies (e.g., habitat restoration), or buffer the impacts of climate change. More broadly, our work highlights the need for more long-term studies that will garner accurate estimates of vital rates to aid ongoing recovery efforts for endangered and at-risk species.

Rovers, rubyfishes, and bonnetmouths (Emmelichthyidae) comprise a small family of fishes that can be distinguished from other perch-like fishes by their generally red, fusiform bodies, highly protrusible mouths, and large rostral cartilage. Their highly protrusible upper jaws have led ichthyologists to group morphologically similar but distantly related taxa within the Emmelichthyidae and is one of the stunning examples of morphological convergence within perch-like fishes. In 2014, the first and only emmelichthyid from the Red Sea, Emmelichthys marisrubri, was described. This species is diagnosed by 80–83 lateral-line scales, 8 dorsal-fin rays, and 4–5 isolated dorsal spines that are separated from membrane-bound dorsal-fin elements, among other features. While examining the osteology of E. marisrubri, I discovered several differences in the oral jaws, suspensorium, neurocranium, and dorsal fin when compared to other species of rovers. Based on these differences and the results of a phylogenetic analysis, I transfer this taxon to the genus Dipterygonotus within the Lutjanidae and among the fusiliers (formerly Caesionidae), an Indo-Pacific group of fishes that also have highly protrusible upper jaws.

Besides studies on mental glands, research regarding cranial integumentary glands potentially involved in courtship of plethodontid salamanders is scarce. In this study, we examined the cranial glands of Eurycea chamberlaini. Scattered amongst typical mucous and serous glands of the integument, we found simple alveolar glands that reacted positively with the periodic acid-Schiff procedure along the lateral sides of the heads of only male E. chamberlaini during the putative mating season. These glands were identical to the lateral head courtship glands previously described in E. bislineata. External nasal glands of E. chamberlaini were also identical in morphology and histology to those previously described in E. bislineata, with the bulk of the secretory terminals residing behind the orbital cavities and extending anteriorly to where their excretory ducts empty through the integument dorsal to the external nares. We measured external nasal gland length, width, height, and volume and found that the means were greater in males when compared to females except for width, which was not sexually dimorphic. We compared external nasal gland tubular diameter to mental gland tubular diameter (a known secondary sexual structure) throughout the year and found a direct correlation that was significant in males but not for females; thus, hypertrophy of external nasal glands occurs at the same time pheromone production increases in mental glands, supporting a previously proposed hypothesis that external nasal glands are also secondary sexual structures in Eurycea. In culmination, Eurycea from two different complexes possess the same suite of cranial integumentary glands that may be involved in courtship, providing evidence that these glands are possibly ubiquitous across Eurycea.

A new species of Curculionichthys is described from the Saramacca and Marowijne (=Maroni) River basins in Suriname and French Guiana, eastern Guiana Shield. The new species possesses five of the seven diagnostic characteristics of the genus with the most remarkable morphological trait that distinguishes it from congeners being the presence of a single rostral plate. A genetic comparison with C. karipuna, the geographically closest species, showed a minimal distance of 5% in gene coI between individuals of the two species. The geographic distribution further extends the distribution of the genus across the Guiana Shield and represents the first species of the genus described from outside Brazil.

Uma nova espécie de Curculionichthys é descrita das bacias dos rios Saramacca e Marowijne (=Maroni), no leste do Escudo das Guianas, no Suriname e Guiana Francesa. A nova espécie possui cinco das sete características diagnosticas do gênero, sendo a característica morfológica mais marcante que a distingue das demais congêneres a presença de placa rostral única. A comparação genética com C. karipuna, a espécie geograficamente mais próxima, mostrou uma distância mínima de 5% entre os indivíduos das duas espécies. A distribuição geográfica da espécie estende a ocorrência do gênero no Escudo das Guianas e representa a primeira espécie descrita de fora do Brasil.

We report the first record of a species of Pareiorhaphis in the Manhuaçu River basin, an affluent to the right bank of the middle Doce River drainage in eastern Brazil. The description is based on a series of specimens recently collected and also on historical samples. All specimens were obtained from habitats with very strong water current running over flat bedrock. The new species is readily diagnosed from congeners by features related to the distinct morphology of lower lip papillae, unique pattern of plates covering the pectoral girdle between insertions of pectoral fins, and the lack of a maxillary barbel. In addition, the combination of longer snout, smaller orbital diameter, shape of the pectoral-fin spine, low number of dentary teeth, and lack of a dorsal-fin spinelet also distinguishes the new species from all species of Pareiorhaphis. The new species is further compared to Pareiorhaphis nasuta, P. scutula, P. proskynita, and P. vetula, congeners from the Doce River basin, and hypothesized to have traits that represent important adaptations for living in torrential habitats.

Apresentamos o primeiro registro de uma espécie de Pareiorhaphis na bacia do rio Manhuaçu, afluente da margem direita do médio Rio Doce, no leste do Brasil. A descrição baseia-se numa série de espécimes recentemente recolhidos e também em amostras antigas. Ambas as amostras foram obtidas de habitats com correntes de água muito fortes correndo sobre leito rochoso plano e sem pedras soltas. A nova espécie é prontamente diagnosticada de seus congêneres por características relacionadas à morfologia distinta das papilas do lábio inferior, padrão único de placas cobrindo a cintura peitoral entre as inserções das nadadeiras peitorais e a ausência de um barbilhão maxilar. Além disso, a combinação de focinho mais longo, diâmetro orbital menor, forma do espinho da nadadeira peitoral, baixo número de dentes no dentário e ausência de spinelet da nadadeira dorsal também distingue a nova espécie de todas as outras espécies de Pareiorhaphis. A nova espécie é ainda comparada com Pareiorhaphis nasuta, P. scutula, P. proskynita e P. vetula, congêneres da bacia do Rio Doce, e supostamente possui caracteres que representam adaptação importante para viver em habitats torrenciais.

The Australian banjo frogs are a distinctive group of medium to large, terrestrial, and burrowing limnodynastid frogs known for their conspicuous, single-note advertisement calls which are often likened to the pluck of a banjo string. Preliminary analyses of mitochondrial DNA sequences had previously indicated that the present taxonomy of the group, based primarily on morphology and advertisement calls, may not best reflect the true evolutionary relationships among taxa. In this study, we use comprehensive geographic sampling and integrative analyses of mitochondrial DNA sequences, nuclear single-nucleotide polymorphisms, adult morphology, and advertisement call data to re-evaluate the systematics and taxonomy of the Northern Banjo Frog (Limnodynastes terraereginae) and allied taxa. Our study reveals the presence of three evolutionarily distinct, morphologically divergent, and narrowly allopatric lineages that replace each other in a north–south series from the tip of Cape York Peninsula to the Sydney Basin in the south. Our findings demonstrate that our understanding of the systematics and taxonomy of Australian frogs remains incomplete, even for large and apparently “well-known” species that live in densely populated areas.

North American horned lizards of the genus Phrynosoma are largely myrmecophagous and squirt systemic blood from circumocular sinuses during encounters with certain mammalian predators. The predators react with distinct revulsion. Using bioassay-guided fractionation of blood plasma, we endeavored to identify the source and characteristics of the active chemical compound(s) responsible for this negative oral response. Our results of coyote bioassays and a series of novel mouse bioassay experiments were largely concordant. The active compound(s) was likely plasma-borne with a molecular weight (mw) of between 800 and 1,600. To identify the source of the active compound(s), we noted bioassay responses of different species of horned lizards. The active compound(s) was present in plasma fractions of species known to eat Pogonomyrmex and squirt blood, and it was absent in the plasma fractions of species that do not squirt blood and eat other ants or arthropods. Plasma fractions from individuals of P. cornutum, a blood-squirting species, fed Pogonomyrmex had more aversive levels of the active compound(s) compared to those given a cricket diet. In addition, extracts from Pogonomyrmex indicate that the active compound(s) in lizard plasma is associated with the abdomen of these ants, where venom is stored. The toxic enzymes of ant venom may be metabolized by horned lizards resulting in one or more small peptides that act as the active ingredient(s) in the lizard's circulating blood. We suggest that utilization of this widely dispersed, venomous, and abundant diet only became available to stem horned lizards with the evolution of unique prey capture techniques. This broadened diet then led to incorporation of the compound(s) from Pogonomyrmex spp. into their blood plasma, facilitating the evolution of antipredator blood-squirting. These transformative events apparently established an evolutionarily stable configuration that led to or expanded the unique “Phrynosoma suite” of characteristics from which subsequent diverse clades have evolved across arid North America.

Las lagartijas cornudas norteamericanas del género Phrynosoma, son en gran parte mirmecófagos, arrojan sangre de man-era sistémica por los senos circumoculares durante los encuentros con ciertos mamíferos depredadores. Cuando la sangre entra en su cavidad bucal, los depredadores reaccionan con una clara repulsión. Utilizando la fracción del plasma sanguíneo en bioensayos, identificamos las características y el origen de los compuestos químicos activos responsables de esta respuesta oral negativa. Los resultados de una serie de experimentos de bioensayos con coyotes, así como una nueva serie de experimentos de bioensayos con ratones, fueron en gran medida concordantes. Es probable que los compuestos activos sean transportados en el plasma con un peso molecular de entre 800 y 1600 (mw). Para identificar el origen de los compuestos activos, se observaron las respuestas de bioensayos en ratones del plasma de diferentes especies de lagartijas cornudas. Los resultados indican que los compuestos activos están presentes en las fracciones del plasma de especies que son conocidas por comer Pogonomyrmex y su relación con arrojar sangre, y además, que están ausentes en las fracciones del plasma que no arrojan sangre, y que comen otras hormigas y artrópodos. Las fracciones de plasma de individuos de P. cornutum, una especie sanguinolenta, alimentadas con Pogonomyrmex presentó niveles más elevados de compuestos en su plasma en comparación con los alimentados con grillos. Además, fracciones de plasma de Pogonomyrmex indican que el compuesto activo(s) en la plasma está asociado con el abdomen de estas hormigas, que es donde se almacena el veneno. El rol aparente del veneno de la hormiga cosechadora en la bioactividad del plasma en las lagartijass cornudas, puede no deberse a su absorción directa. En cambio, las enzimas tóxicas del veneno de las hormigas pueden ser metabolizadas por estas lagartijas, lo que da como resultado uno a más péptidos pequeños que actúan como ingredientes activos en la sangre circundante de estas. Nuestro estudio abre un campo de investigación para comprender las complejidades de las relaciones evolutivas entre las diversas especies de lagartijas cornudas y Pogonomyrmex spp. Sugerimos que esta dieta abundante, venenosa y ampliamente dispersa, solo estuvo disponible para lagartijas cornudas con la evolución de técnicas únicas de captura de presas. Esta dieta condujo posteriormente a la incorporación de los compuestos de Pogonomyrmex spp. en el plasma sanguíneo, lo que facilitó la evolución de los chorros de sangre con funcionalidad antidepredador. Estos eventos transformadores aparentemente establecieron una configuración evolutiva del “conjunto Phynosoma”, con características únicas, a partir de las cuales los subsiguientes diversos clados han evolucionado a lo largo de la árida América del Norte.