Parotocinclus adamanteus, new species, is described from a series of specimens collected in the upper portion of the Rio Paraguaçu basin, a coastal river within the Chapada Diamantina domain, a large plateau on the State of Bahia in northeastern Brazil. The description of this new species represents the first record of a member of the Hypoptopomatinae from this relictual area. The new species is diagnosed from other Parotocinclus by having a distinct rostral border forming a fleshy intumescence on the lateral portion of head ornamented with moderately hypertrophied odontodes in adult males. It is also diagnosed from congeners by a remarkable secondary sexual dimorphism in the shape of the pelvic fin, in which the branched rays of males decrease in size, resulting in a pointed posterior fin margin (branched pelvic-fin rays in females have approximately the same size, producing a round posterior fin margin). In addition, the new species can be further distinguished from other species of Parotocinclus by lacking a rostral plate covering the tip of the mesethmoid anteriorly, by lacking abdominal plates between the pectoral girdle and the anus, by having numerous premaxillary teeth (45–61), and by having a short and mesially expanded ventral portion of the cheek canal plate. Recent phylogenetic analysis indicates that Parotocinclus adamanteus, new species, is closely related to P. jequi, P. prata, and P. robustus.

Invasive species represent a major threat for biodiversity. The numbers of independent introductions, introduced propagules, and introduction episodes are critical aspects for invasion success. Here, we traced the source(s) of introduction and determined the historical route of invasion in order to understand the main stages of the invasion process. However, we often must rely on indirect information when studying invasive species (i.e., not knowing where the invasive population originated), hence requiring robust analytical methods to solve those questions. The invasive population of the snake Boa constrictor in the Mexican Caribbean (Cozumel Island) has been studied ecologically and genetically, but, despite several lines of evidence suggesting its invasive nature, a full account of its invasive history is lacking. Here, we aimed to reconstruct the boa's invasion history by deciphering the original source(s) of the Cozumel population, routes of invasion, likely number of propagules, and estimation of historical genetic and demographic parameters, based on a comprehensive set of analytical tools including tree topology-based methods and Approximate Bayesian Computational algorithms. The phylogenetic relationship of the Cozumel boa within the Boa constrictor complex was unknown; hence, to identify the source populations, we first needed to clarify its genealogical relationships. We used mitochondrial and nuclear sequences and nuclear microsatellites, together with the widest geographic sampling along the species' entire continental distribution. With our genetic approach, we demonstrate that the Cozumel population was derived from an admixture of individuals from different geographic localities. Moreover, our demography results allowed us to successfully confirm both anecdotal and previous genetic information, concordant with a scenario in which a likely small number of propagules were released on the island about 50 years ago. Notably, national law hinders the possibility of performing any control protocols for the boa, hence our results highlight a rather unique conservation paradox, where the Cozumel boa has a novel endangered protected species status as B. imperator, but it is also an invasive exotic predator threatening the critically endangered endemic and native biota of Cozumel. Therefore, any conservation decisions should consider that boas in Cozumel are invasive, opening the possibility to legally allow implementing control or eradication programs.

Amphibian life history strategies can vary across broad geographic patterns, which have been explained, at least in part, by how development, growth, maintenance, and reproduction respond to temperature. However, there is a dearth of information regarding life history traits and their variation among populations for many amphibian species, which prevents assessment of these broad patterns among species. Therefore, we used museum specimens to assess the variation in reproductive condition of Plethodon montanus across its range and used skeletochronology at five populations along an elevational gradient to determine the elevational variation in age, growth rate, and asymptotic size. We found that body size and temperature seasonality best explained the variation in the presence of eggs and a mental gland, whereas body size alone best explained the presence of enlarged pigmented testes. We also found that longevity in P. montanus is at least 12 years with higher elevations having a higher proportion of older individuals compared to lower elevations and that size was a better explanation of reproductive condition than age across the elevation. Our results further demonstrate the importance of body size for amphibian life history traits and the utility of museum specimens to estimate these traits. Variation in reproductive condition across the range of P. montanus is likely the result of variation in growing season length. Lastly, we found evidence suggesting asymptotic size and growth rates may have changed over the last half century, which would ultimately affect fertility and other life history traits and warrants future studies.

Lamniformes (Chondrichthyes: Elasmobranchii) is a group of sharks that consists of 15 extant species with a wide range of morphological diversity. The most rarely captured lamniform is Odontaspis noronhai, and many aspects of its biology remain unknown to date. In this study, the skeletal anatomy of a previously described specimen of O. noronhai was examined using computed tomography. The new skeletal data were then added to a previously published morphology-based character matrix to conduct a new phylogenetic analysis of the Lamniformes. Our phylogenetic study strongly suggests non-monophyly of Odontaspididae, that traditionally consisted of Carcharias taurus, O. ferox, and O. noronhai. Thus, the family Carchariidae is formally resurrected for the genus Carcharias to separate it from the family Odontaspididae sensu stricto for Odontaspis. The overall topology of our phylogenetic trees is similar to that of previously published morphology-based trees and drastically different from the tree topology generally attained by molecular data that cluster Alopias, Megachasma, Odontaspis, and Pseudocarcharias together as a separate clade. The major topological discrepancy between molecular and morphological trees may be attributed to unconventionally asynchronous rates between morphological and molecular evolution, at least in certain species within the Lamniformes, along with likely manifestation of mosaic evolution. The recognition of the family Carchariidae is important to conservation biology, because the extinction of C. taurus would not only mean the elimination of the genus Carcharias, but also the entire family Carchariidae. Our study demonstrates the importance of the integration of both morphological and molecular information to understand organismal evolution.

Agonistic encounters necessary for territory establishment and maintenance can be stressful for those involved. Stress responsiveness associated with territorial behavior can occur on both acute and chronic temporal scales contingent upon social status. Social interactions that recur for territory maintenance pose periodic stressors that incur variable physiological costs across social ranks. Adult males of the Green Anole, Anolis carolinensis, experience stressful social encounters during territorial disputes as individuals contest status within a dominance hierarchy. Dominant males in stable territories are known to exhibit greener body coloration and lower levels of stress hormone, corticosterone, relative to their subordinate counterparts. Periodic interactions with novel competitors, however, may induce comparable levels of cumulative glucocorticoid secretion regardless of social status. Glucocorticoid metabolites excreted in feces can be quantified to assess the chronic hypothalamic–pituitary–adrenal (HPA) axis response to periodic social stressors. Fecal glucocorticoid metabolite (FGM) levels in male A. carolinensis were hypothesized to increase in response to novel social encounters that simulated territory establishment and maintenance. Adrenocortical response to recurring episodes of territoriality was predicted to generate similar longitudinal FGM levels across social ranks. FGM analysis was combined with behavioral assessment of body coloration to further contextualize measured stress levels of dominant and subordinate anoles. Prolonged social interaction led to similarly increased levels of fecal glucocorticoid metabolites in both dominant and subordinate anoles relative to those that were solitary. This study provides an alternative perspective on the activity of the HPA axis in dominant–subordinate relationships of A. carolinensis over prolonged periods of territoriality.

The Sierra Nevada Yellow-Legged Frog (Rana sierrae) has generally been viewed as a lake species, but it has increasingly been found in streams, including in the northern part of its range where it is particularly at risk. Developing effective conservation strategies has been hindered by a lack of knowledge of its basic ecological requirements in stream habitats. To address this information gap, we investigated the demography, habitat use, and movements of stream populations of this federally endangered species. We conducted capture–mark–recapture of adults, quantitatively described stream channel and riparian vegetation characteristics, and collected habitat use data at four northern Sierra Nevada mountain streams, counted egg masses at three central Sierra Nevada streams, and radio-tracked individuals at three central and southern Sierra Nevada streams. Stream populations in the northern range were very small with maximum abundances of <15 individuals, and apparent survival probability ranged from 0.57–0.81. In contrast, one southern Sierra Nevada stream had a large count of 547 adults. Egg mass counts ranged from 22–104 per stream. We found frogs in diverse headwater streams ranging from perennial to intermittent flow regimes, pool versus riffle dominated, and low to high channel gradient, and they used diverse microhabitats within these streams. In these stream habitats, frogs moved little over four-day survey periods but were capable of moving longer distances of up to 1248 m over the summer. Conservation and management of the at-risk R. sierrae are most likely to be effective when built on comprehensive quantitative information on basic ecological requirements in all habitats used by the species.

Ecology of the Sierra Nevada Yellow-Legged Frog (Rana sierrae) is well understood in high elevation lakes, but data on habitat preferences in stream-dwelling populations are lacking. We sought to expand understanding of stream habitat use by R. sierrae by investigating habitat suitability at the microhabitat and reach scales. We collected habitat availability and use data during 2016–2017 at five stream sites representative of geomorphic diversity in the northern Sierra Nevada mountains of California. At each frog use and availability location, we collected data on geomorphic unit type (e.g., riffles, pools), water depth, water velocity, substrate (e.g., gravel, cobble), and percent cover, including herbaceous, canopy, and total cover. Bootstrapped logistic regression models for all study sites combined indicated water depth and velocity were the strongest predictors of post-metamorphic (adult and subadult) use by R. sierrae, while substrate and total cover provided moderate improvement in microhabitat use predictions. Specifically, adults had the highest probability of use in microhabitats with <0.3 m depth and <0.1 m s^–1 velocity. For tadpoles, we found velocity was the strongest microhabitat predictor for all study sites combined, with the highest probability of use in habitats with <0.01 m s^–1. Site-level models highlighted the relative importance of non-hydraulic habitat variables, such as cover, when suitable depth and velocity conditions occurred. At the reach scale, we found hydraulic conditions varied widely in geomorphic units over time, but suitable microhabitat conditions emerged in differing geomorphic units as flows changed over the season. These data indicate that R. sierrae, like other ranid species, may be limited by hydraulically suitable habitat availability, but habitat preferences can be met in a variety of stream reaches when variations in flow conditions over time and space are considered.

Taxonomists currently recognize 16 cryptic species within the Plethodon glutinosus complex revealed by allozyme analysis but that typically do not differ in morphology or color pattern. Two putative species, P. grobmani and P. mississippi, are distributed across the Gulf Coastal Plain, with geographic ranges that are separated by Mobile Bay and the Alabama River. Character divergence is thought to distinguish the two species, with P. grobmani (east of Mobile Bay) having a short snout and extensive patches of white coloration, and P. mississippi (west of Mobile Bay) having an elongate snout and lacking extensive patches of white coloration. However, specimens used to characterize these two species were examined in life, were collected mainly from areas adjacent to Mobile Bay, and were evaluated by a single investigator. Additionally, the two traits (snout shape and color) were combined into a single variable, masking the contribution of each trait to individuating the two species. To test the utility of these characters, we applied identical measurements of the two traits to preserved specimens representing an east–west transect across the geographic ranges of the two putative species. Data were generated by three investigators who measured each specimen twice, a design that allowed examination of reproducibility within and among investigators. Traits were evaluated separately and as a combined score. Both snout shape and color were found to be traits that are reproducible for measurements within individual investigators and the measurement of these traits did not differ among investigators. Specimens from east of Mobile Bay had more extensive white coloration and higher total scores than those west of Mobile Bay; snout shape did not differ across Mobile Bay. Longitude was a significant correlate of color and total score, with the slope of the relationship differing on each side of Mobile Bay. Color and total score of specimens west of Mobile Bay had a positive association with longitude, while scores of specimens east of Mobile Bay had a negative association. Thus, rather than exhibiting character divergence across Mobile Bay, slimy salamanders converge on a phenotype with extensive white coloration at Mobile Bay. We find no color or morphological feature that distinguishes putative P. grobmani from putative P. mississippi, a line of evidence suggesting that those populations are a single species with regional change in color.

The Plethodon glutinosus complex is composed of 16 lineages that are thought to have conserved morphological characteristics and rapid rates of diversification. Typically, these lineages are recognized as species, but the monophyly of some has been questioned. Three lineages have distributions that converge in the state of Alabama: Plethodon glutinosus, P. grobmani, and P. mississippi. If these species are present in the state and are reproductively isolated, then we expected to recover three monophyletic lineages. If these species are present in the state, but exhibit extensive introgression, then we expected to recover sets of private haplotypes associated with each species and sets of shared haplotypes among species. We sampled 40 specimens of slimy salamanders from throughout the state. Samples were analyzed using two genes, cytochrome b (n = 38) and RPL12 (n = 17). Additionally, we added 47 cytochrome b sequences for Alabama specimens of the three species available on GenBank to examine relationships of this larger sample. We failed to recover three monophyletic lineages within any estimated gene tree and failed to recover sets of private haplotypes. Instead, haplotype-network structure revealed a single metapopulation. We conclude that Alabama contains a single species of slimy salamander, Plethodon glutinosus, with complex genetic connectivity throughout the state.

Adenomera andreae and A. hylaedactyla are two widespread Amazonian frogs that have been traditionally distinguished from each other by the use of different habitats, toe tip development, and more recently through advertisement calls. Yet, taxonomic identification of these species has always been challenging. Herein we undertake a review of type specimens and include new phenotypic (morphology and vocalization) and mitochondrial DNA information for an updated diagnosis of both species. Our morphological analysis indicates that the single type (holotype) of A. hylaedactyla could either belong to lineages associated with Amazonian forest-dwelling species (A. andreae clade) or to the open-formation morphotype (A. hylaedactyla clade). Given the holotype's poor preservation, leading to the ambiguous assignment of character states for toe tip development, as well as a vague type locality encompassing a vast area in eastern Ecuador and northern Peru, the identity of this specimen is uncertain. Morphology of toe tip fragments and the original species description suggest that A. hylaedactyla could correspond to at least two described species (A. andreae or A. simonstuarti) or additional unnamed genetic lineages of the A. andreae clade, all bearing toe tips expanded into discs. Analysis of morphometric data, however, clustered the holotype with the Amazonian open-formation morphotype (toe tips unexpanded). While additional data can be obtained from the holotype of A. hylaedactyla, at this time this type cannot be unequivocally assigned to any species of Adenomera distributed across eastern Ecuador and Peru's northernmost region of Loreto. For the time being, the name A. hylaedactyla still accommodates the only Amazonian open-habitat species. As to the type series of Adenomera andreae, a forest-associated species with toe tips fully expanded (developed into small discs) from eastern Brazilian Amazonia, we found that one of its paratypes shares a morphotype with the open-habitat species and is reassigned to A. hylaedactyla. With the taxonomic identity of A. hylaedactyla unresolved, formal descriptions of cryptic species complexes within the A. andreae clade distributed across the type locality of A. hylaedactyla run the risk of a possible future synonymization with A. hylaedactyla. Yet, not naming more circumscribed and potentially threatened cryptic species puts them at risk, as they would probably not qualify for conservation funding. Given the current fire crisis in the Amazon Basin, the risk of losing species before they are described far outweighs the risk of synonymization. We recommend that researchers prioritize descriptions based on the potential extinction risk of new species.

Stream fish assemblages in small streams are often less diverse than those in larger streams. Two models to explain this have emerged, one which focuses on local habitat conditions derived from processes related to discharge, and the other which links patterns of network connectivity to dispersal ability and network position in the watershed. Both models now have some support in stream fishes, but how they might interact is not well studied. We draw on observations from stream invertebrates to propose that stream size will affect niche specialization and network position will affect functional trait-based diversity. We test this hypothesis using data from the Interior Highlands, USA. Diversity of upland-adapted groups and trait-based assemblage metrics tied to strategies dependent on depth, flow, and stream width showed strong relationships to stream size. Diversity of lowland-adapted groups and metrics of assemblage morphological diversity showed strong relationships to network position. Examination of patterns of spatial b-diversity supports the idea that dispersal of lowland-adapted groups is linked to network connectivity. Responses to both network position and stream size included longer, later reproductive seasons with more species exhibiting parental care. We support that both stream size and network position interact to lower fish diversity in small streams, but that they do so in different manners. We further discuss the ecological uniqueness and need for research and conservation efforts of small streams low in watershed networks.

Geographically widespread species that occupy varied thermal environments provide testable models for understanding the evolution of life-history responses to latitude. Studies that draw range-wide conclusions using descriptive data from populations in the core of a species' distribution can overlook meaningful inter-population variation. The Texas Horned Lizard (Phrynosomatidae: Phrynosoma cornutum) spans an extensive latitudinal distribution in North America and has been well studied in connection with life-history evolution, yet populations occupying the most northern and coldest areas within its range were absent from previous examinations. We tested genus-wide patterns and challenged species-specific findings on the evolution of the life-history strategy of P. cornutum using populations at the northern edge of its geographic range and comparative material from farther south. Traits in populations at the highest latitudes corroborated several patterns for the genus and species, including delayed reproduction and a trend towards smaller adult body size with increasing latitude. Novel in our study, however, was the finding of a comparative increase in clutch size among size-adjusted females in Kansas, indicating a reproductive response for greater fecundity at the northern edge of its geographic range. Furthermore, analyses adjusted for body size revealed that egg dimensions were constant across variation in clutch size, suggesting that there is not a strong relationship between egg size and egg number across latitude. We discuss the selective pressures that may have resulted in the diminution of adult body size coupled with greater fecundity that is unique to the northernmost populations of P. cornutum. Our findings highlight the type of insights into the study of life-history evolution that can be gained across Phrynosomatidae from the inclusion of populations representing latitudinal endpoints.

Green salamanders (Plethodontidae: Aneides aeneus) are rock outcrop habitat specialists, possessing numerous unique morphological adaptations (e.g., prehensile tail and squared toe-pads) for climbing. Some authors believe A. aeneus, which is widely distributed across the Appalachian Mountains of the inland eastern United States, comprises a species complex due to substantial karyotypic variation among populations. We conducted a population genetic and phylogenetic study across the range of A. aeneus and discovered substantial genetic structure, including four distinct lineages, one of which we describe as Aneides caryaensis, new species. Restricted to a narrow geographic distribution in western North Carolina, this species faces pressing conservation threats due to rapid real estate and tourism development in the area. We also recommend the recognition of three geographically distinct and reciprocally monophyletic lineages as evolutionarily significant units due to strong mitochondrial and nuclear differentiation among them. Aneides aeneus has been petitioned for listing under the Endangered Species Act, and our study further highlights the need for conservation management of this complex. Our formal recognition of the extent of genetic and evolutionary diversification of the complex is a critical step in establishing conservation strategies.

A taxonomic revision of Sturisomatichthys is presented. A total of 383 specimens including both type and non-type specimens of all valid species were examined. Sturisomatichthys was found to encompass ten valid species: Sturisomatichthys aureus, S. caquetae, S. citurensis, S. dariensis, S. festivus, S. frenatus, S. kneri, S. leightoni, S. panamensis, and S. tamanae. In addition, three new species are described: Sturisomatichthys reinae, new species, from the Baudó River, in northwestern Colombia, belonging to the Caribbean slope of the continent; Sturisomatichthys guaitipan, new species, from the upper and middle Magdalena River basin, Colombia; and Sturisomatichthys varii, new species, from the San Juan River basin in western Colombia, on the Pacific slope. Sturisomatichthys caquetae, from the Morelia River, upper Amazon, is transferred back from Sturisoma, and S. leightoni was found to be distributed, besides the Magdalena-Cauca basin, in the Orinoco basin; thus, Sturisomatichthys is shown to be distributed in both trans- and cis-Andean drainages. A neotype is designated for S. aureus from the lower Magdalena basin. New records of localities in the northwestern region of South America, as well as the redescription and taxonomic comments on all valid species, are provided. Maps with the species distributions and a key for identification of the species are provided.