Lizards of the gonochoristic Aspidoscelis inornata (Little Striped Whiptail) complex are ubiquitous components of vertebrate faunas in diverse habitats in the southwestern United States and northern Mexico. One of these, Aspidoscelis arizonae ( = A. inornata arizonae, Arizona Striped Whiptail), is extant at only a few grassland areas in southeastern Arizona, but nonetheless played an important evolutionary role in the hybrid origins of seven obligatory parthenogenetic species. Although recognized as a distinct species by many, A. arizonae lacks a valid species description and only anecdotal data argue for its recognition. We were unable to separate it from geographically proximate A. inornata in southwestern New Mexico, using diagnostic morphological features (i.e., number of stripes, dark field coloration, sky blue ventral suffusion) previously used to delineate aspidoscelids. Furthermore, we evaluated additional diagnostic characters (i.e., body size plus ten meristic characters) in samples of A. arizonae and A. i. llanuras from three adjacent counties, and found no significant size or meristic differences (P > 0.05). A canonical variate analysis of A. arizonae (n  =  30), A. pai (40), A. inornata spp. (18), and A. i. llanuras (32) across seven meristic characters revealed A. arizonae as indistinguishable from A. i. llanuras (i.e., 30% misclassifications). Apart from formal nomenclature, there are only two morphological groups among the foregoing samples, A. pai and a pooling of the other three. Data from all analyses in this study suggest that either A. arizonae is a cryptic species or a peripheral isolate unworthy of species status.

Las lagartijas de reproducción sexual del complejo Aspidoscelis inornata (Huico Liso) son componentes importantes de la fauna de vertebrados en diversos hábitats en el suroeste de los Estados Unidos y norte México. Una de estas, Aspidoscelis arizonae ( = A. inornata arizonae, Huico Liso de Arizona), está limitada a unas cuantas áreas en el suroeste de Arizona, sin embargo, tuvo un papel evolutivo importante en los orígenes híbridos de siete especies partenogenéticas obligadas. Aunque es reconocida como una especie distinta, A. arizonae carece de una descripción válida para la especie y únicamente datos anecdóticos han sido argumentados para su reconocimiento. En una re-evaluación taxonómica, no pudimos separar a esta especie de poblaciones geográficamente cercanas de A. inornata en el suroeste de Nuevo México, utilizando características morfológicas diagnósticas (esto es, número de rayas, coloración oscura de interespacios entre rayas dorsales, sufusión ventral azul cielo), previamente utilizadas para delimitar aspidoscelidos. Además, evaluamos caracteres diagnósticos adicionales (esto es, tamaño corporal más 10 caracteres merísticos) en muestras de A. arizonae y A. i. llanuras de tres condados adyacentes, y no encontramos diferencias significativas en tamaño o caracteres merísticos (P > 0.05). Un análisis de variables canónicas de A. arizonae (n  =  30), A. pai (40), A. inornata spp. (18), y A. i. llanuras (32) a través de siete caracteres merísticos reveló que A. arizonae es indistinguible de A. i. llanuras (esto es, 30% de clasificación incorrecta). Aparte de la nomenclatura formal, únicamente hay dos grupos estadísticamente válidos entre las muestras anteriores, A. pai y un grupo de otras tres. Datos de todos los análisis en este estudio cuestionan el reconocimiento de A. arizonae como una población aislada que merezca el estatus de especie.

Adult chondrocranial morphology is poorly documented in modern lamniform sharks. Here it is described for the two extant species of Lamna, L. nasus and L. ditropis. Several features are noted and discussed, including hypercalcification of the rostral cartilages, the ethmoidal region associated with ligamentous jaw attachments, and the configuration of the postorbital region. The small polygonal blocks of calcified cartilage (tesserae) that typically line the chondrichthyan endoskeleton are greatly thickened in the rostral bars of Lamna, forming radial columns; furthermore, concentric banding of the columnar calcification in the rostrum of L. ditropis suggests periodic accretion of new calcified tissue below the perichondrium.

The postorbital region in Lamna is notable for lacking a postorbital process, and in having the supraorbital shelf continuing posteriorly as a supra-otical shelf, which extends as far as the hyomandibular fossa. The orbit in Lamna is apparently not drained in the usual elasmobranch manner (i.e., via a lateral head vein, located lateral and dorsal to the hyomandibula). Instead, the vein passes ventral and medial to the hyomandibula, via a large suborbital fenestra which also houses the orbital artery. This arrangement may be phylogenetically informative because it also occurs in other lamnids, although its wider distribution among lamniforms has yet to be determined.

Otoliths (lapilli) were used to age two catostomid fishes, black redhorse (Moxostoma duquesnei) and golden redhorse (Moxostoma erythrurum), from three White River and one Arkansas River tributary in southwest Missouri. Populations in the James River (White River system) were sampled monthly for one year, and edge analysis was used to determine timing of otolith annulus formation. Both species formed a single opaque annulus in otoliths during May and June. Maximum ages estimated from otolith annulus counts were 11 years for black redhorse and 12 years for golden redhorse. Age classes 2 and 3 dominated populations for both species. Fish length at age was modeled with von Bertalanffy growth models; parameters were k  =  0.39 and L_∞  =  385 for black redhorse and k  =  0.31 and L_∞  =  377 for golden redhorse in James River populations.

Analysis of samples of the auchenipterid catfish genus Tatia collected during a recent ichthyological survey in the Cuyuni River basin in Guyana revealed them to be an undescribed species. Comparative studies associated with the evaluation of that new species demonstrated that a sample of the genus from a right bank tributary of the Río Orinoco in Venezuela, also on the Guiana Shield, represents a second species unknown to science. The placement of Tatia musaica, previously considered incertae sedis in the Centromochlinae, is evaluated and the species is reassigned to Tatia.

Oryzias asinua and O. wolasi are two new species of ricefishes described from several disjunct inland freshwater habitats in the Indonesian province of Sulawesi Tenggara or southeastern Sulawesi. With O. woworae, the first described endemic ricefish of Sulawesi Tenggara, they comprise a group of small, colorful species characterized by orange to deep red dorsal and ventral margins of the caudal fin and the ventral margin of the caudal peduncle and at least the posterior portion of the base of the anal fin, and a bluish sheen on the body in both sexes that is most pronounced in live adult males. The two new species are distinguished from O. woworae by elongate middle dorsal-fin rays in adult males that reach the posterior extent of the first principal caudal-fin ray and by an orange-colored olfactory epithelium that marks each nasal organ in females. Oryzias asinua is relatively slender compared to O. wolasi and O. woworae: the body is narrow (21–25% SL, with a mean 22.9, in O. asinua versus 23–32% SL, mean 25.3 in O. wolasi and 22–30% SL, mean 26 in O. woworae). Oryzias asinua has fewer procurrent caudal-fin rays in the lower lobe (4–5 versus 5–7 in O. wolasi and 5–6 in O. woworae). Oryzias wolasi is golden in life in both sexes and relatively deep-bodied, reaching 32% SL, and has a deeper caudal peduncle (11–12% SL, mean 11.2, versus 9–11, mean 10, in O. asinua and 8–11, mean 9.2, in O. woworae). Maximum parsimony and Bayesian inference analyses of the mitochondrial cytochrome c oxidase subunit 1 (COI) sequence, the DNA barcode, support our hypothesis that we sequenced representatives of three species. All species are allopatric. Description of O. asinua and O. wolasi brings the number of valid species in the beloniform family Adrianichthyidae to 35, 17 of which are endemic to Sulawesi. The two new species are just the second and third ricefishes described from the province of Sulawesi Tenggara, a neglected region in exploration and discovery of the freshwater fish fauna of the Indonesian islands of Sulawesi.

Oryzias asinua dan O. wolasi adalah dua jenis ikan padi yang dideskripsi dari beberapa, habitat air tawar di Provinsi Sulawesi Tenggara, Indonesia. Bersama O. woworae, ikan padi pertama dari Sulawesi Tenggara yang telah dideskripsi, ketiganya merupakan kelompok jenis berukuran kecil, berpola warna menarik, jingga hingga merah tua pada sirip punggung, tepi sirip ekor bagian bawah, tepi bawah batang ekor dan pada sedikit bagian belakang dari pangkal sirip anal, semburat sinar kebiruan terlihat pada tubuh ikan jantan dan betina, yang tampak jelas terlihat pada pada ikan jantan dewasa yang masih hidup. Ke dua spesies baru tersebut dapat dibedakan dari O. woworae dari jari-jari lemah sirip punggung bagian tengah pada ikan jantan dewasa, yang memanjang dan mencapai bagian posterior sirip ekor pertama, juga dari warna jingga pada epithelium olfactory yang menandai setiap organ nasal pada betina. Oryzias asinua tinggi tubuhnya relatif lebih kecil dibandingkan O. wolasi dan O. woworae: tubuhnya pendek (21–25% SL, rata-rata 22.9% pada O. asinua vs 23–32% SL, rata-rata pada O. wolasi dan 22–30% SL, rata-rata 26% pada O. woworae). Oryzias asinua memiliki lebih sedikit jari lemah tambahan pada cuping ekor bagian bawah (4–5 vs 5–7 pada O. wolasi dan 5–6 pada O. woworae). Pada saat masih hidup Oryzias wolasi berwarna keemasan baik pada jantan dan betina, tubuhnya relatif tinggi, mencapai 32% SL, dan batang ekor lebih tinggi (11–12% SL, rata-rata 11.2 vs 9–11, rata-rata 10, pada O. asinua dan 8–11, rata-rata 9.2, pada O. woworae).Maksimum parsimony dan analisa Bayesian inference pada sekuens mitochondrial cytochrome c o

The family Caristiidae, commonly known as manefishes or veilfins, includes several species of mesopelagic, oceanic fishes found throughout the major ocean basins of the world. We present herein the second part of our revision of the family, including all of the “large-mouth” species, which are distinguished from other members of the family by having a narrow suborbital space and a long upper jaw that extends to mid-orbit or beyond and which is visible externally, not covered by the thin bones of the suborbital series. This group, which is comprised of the genera Platyberyx and Caristius, is described in full, including descriptions of five new species. The genus Platyberyx, which includes six species, three of which are newly described, is distinguished from all other caristiid genera by the presence of a conspicuous lateral line with large scales. The genus Caristius, with four species, two of which are newly described, is distinguished from Platyberyx by the absence of a conspicuous lateral line and by the presence of serrated ventral caudal-fin rays. Species in both genera are distinguished from each other on the basis of meristics, morphometrics, dentition, and gill-raker morphology. Most of the species described here are relatively widespread; species of Platyberyx appear to be more common in the Atlantic basin, while Caristius is more common in the Pacific.

A new species of the hypoptopomatine loricariid genus Parotocinclus is described based on material from the headwaters of the Rio Jequitinhonha, Minas Gerais State, eastern Brazil. The new species is distinguished from all congeners, except P. prata and P. robustus, by the absence of abdominal plates between the pectoral girdle and the anus. It differs from P. prata and P. robustus by having a smaller cleithral width (16.7–20.7 vs. 20.8–27.6% SL in P. prata and 25.9–28.8% SL in P. robustus) in addition to other morphological features.

Uma nova espécie de loricarídeo hypoptomatíneo do gênero Parotocinclus é descrita com base em material das cabeceiras do Rio Jequitinhonha, no estado de Minas Gerais, leste do Brasil. A nova espécie é diferenciada de todos os seus congêneres, exceto P. prata e P. robustus, pela ausência de placas no abdômen entre a cintura peitoral e o ânus. Se distingue das espécies acima pela menor largura cleitral (16.7–20.7 vs. 20.8–27.6% do Comprimento Padrão em P. prata e 25.9–28.8% do Comprimento Padrão em P. robustus), além de outros caracteres morfológicos.

The psammophilic trichomycterid genus Typhlobelus is rediagnosed on the basis of additional synapomorphic characters, including: 1) the premaxilla displaced posteriorly, and connected to shaft of the mesethmoid rather than to its anterior tip; 2) the premaxilla with complex tridimensional shape, with a large dorsal process directed mesially and bearing teeth (when present) on the lateral end only; 3) the dentary portion of the coronoid process expanded into a broad plate; 4) the palatine club-shaped and oriented obliquely relative to the longitudinal axis of the skull; 5) the semi-discoidal anterior portion of the mesethmoid; 6) the laminar anterior ascending process of the quadrate lacking a cartilaginous tip; 7) hyomandibula with a long posterior process; 8) the neural arch of the Weberian complex ring-like and forming two large dorsal foramina at its border with the supraoccipital; and 9) the basibranchials and hypobranchials poorly differentiated or absent. Additional diagnostic characters are presented for the species currently included in Typhlobelus. A new species of the genus, Typhlobelus auriculatus, from the Rio Xingu in northern Brazil, is uniquely diagnosed from all other trichomycterids, and probably from all other catfishes, by the presence of a well-defined lateral pit immediately posterior to the head, representing a modified pseudotympanus connected by a superficial groove to a pit entering the skull. The species is also unique in the lack of any laterosensory pores on the body or head. The new species is further distinguished from its congeners by the absence of an anal fin and by the presence of opercular odontodes, in addition to other characters of internal and external anatomy.

Characidium amaila, new species, is described from rapids of the upper Kuribrong River (Potaro–Essequibo drainage) upstream of Amaila Falls. It is diagnosed from most other species of Characidium by lacking scales on the isthmus and chest, and by having 8–13 premaxillary teeth, the first four pectoral-fin rays noticeably thickened, 34–36 lateral line scales, and branchiostegal membranes that are free from each other across the isthmus. Characidium amaila is further distinguished by its large adult body size (max.  =  85.5 mm SL), and by having a tan body base color with a dark midlateral stripe that originates on the upper lip and continues posteriorly to the base of the middle caudal-fin rays, a gray to dark-black dorsum with two horizontal rows of small light spots formed by aligned light-colored scale centers, a dark humeral spot, up to 15 irregular black bars that extend from dorsum to lower sides, a light opercular margin, and fins that are uniformly dusky. Several cranial, vertebral, and swim bladder characteristics also support distinctiveness of the new species.

Characidium amaila es descrita de los rápidos de el alto río Kuribrong (cuenca del Potaro–Essequibo) aguas arriba de las Cascadas de Amaila. Se distingue de la mayoría de las otras especies de Characidium por la ausencia de escamas en el istmo y el pecho, y por tener 8–13 dientes premaxilares, por poseer los primeros cuatro radios de la aleta pectoral notablemente ensanchados, 34–36 escamas en la línea lateral, y por tener las membranas de los radios branquiostegales separadas del istmo. Characidium amaila se distingue además por el gran tamaño del adulto (max.  =  85.5 mm SL) y por tener el cuerpo de color base café claro con una banda medio lateral que se origina en el labio superior y continúa posteriormente hasta la base de los radios medios de la aleta caudal; el dorso gris a negro con dos hileras horizontales de pequeños puntos claros formados por la alineación de los centros más claros de las escamas; una mancha humeral oscura; hasta quince barras negras irregulares que se extienden del dorso a la parte inferior de los flancos; el margen del opérculo de color más claro y aletas uniformemente grisáceas. Varios caracteres craneales, de las vertebras y de la vejiga natatoria apoyan el diagnostico de esta especie nueva.

A new species of the genus Hypomasticus is described from tributaries of the left margin of the lower Rio Amazonas, Brazil. The new species is diagnosed from other anostomids by having a dark midlateral stripe from the head to the caudal-fin base and two rows of longitudinally aligned dark blotches on the body, subinferior mouth, three teeth on the premaxilla and four on the dentary, 34 or 35 scales in the lateral line, and 16 scale rows around the caudal peduncle. The new species is hypothesized to be closely related to Hypomasticus despaxi, a species widely distributed in the coastal rivers of French Guiana. The adjacent distribution of the new species relative to Hypomasticus despaxi may be associated with occasional events of river captures in the Serra do Tumucumaque.

Uma nova espécie do gênero Hypomasticus é descrita dos tributários da margem esquerda do baixo rio Amazonas, Brasil. A espécie nova se diferencia dos demais anostomídeos por ter uma faixa lateral escura da cabeça até a base da nadadeira caudal e duas fileiras longitudinais de manchas escuras ao longo do corpo, boca subinferior, três dentes no pré-maxilar e quarto no dentário, 34 ou 35 escamas perfuradas na linha lateral e 16 séries de escamas ao redor do pedúnculo caudal. A espécie nova é considerada proximamente relacionada a Hypomasticus despaxi, uma espécie amplamente distribuída nos rios costeiros da Guiana Francesa. A distribuição adjacente da espécie nova, em relação a Hypomasticus despaxi, pode estar associada a eventos de captura de rios na Serra do Tumucumaque.

A new species of Arapaima has been discovered from the central Amazon of Brazil. This new taxon is readily distinguished from all other Arapaima by the following three characters: 1) dorsalmost lateralis sensory cavity on preopercle extremely slender (vs. broadly oval or nearly rectangular in other nominal taxa); 2) ventrolateral margin of head where third infraorbital meets anterior limb of preopercle strongly angled such that ventral surface of head is almost flat (vs. ventrolateral margin of head relatively rounded); and 3) anterior third of dorsal-fin base covered with an enlarged, thickened sheath that hides anterior dorsal-fin rays when adpressed (vs. no thickened sheath on anterior base of dorsal fin and anterior dorsal-fin rays visible when adpressed). Distinguished from all other Arapaima except A. agassizii by having extremely long fourth infraorbital. Distinguished from A. arapaima and all other examined non-type specimens by notably slender body (the holotypes of A. gigas, A. mapae, and A. agassizii also have slender bodies). Further distinguished from A. mapae and A. agassizii by having relatively deep caudal peduncle (6.0% SL, vs. ∼4.0% in latter two taxa), and from A. gigas by having dentary teeth in a single row (vs. dentary teeth in 2–2.5 irregular rows). This species was collected near the confluence of the Solimões and Purus rivers in Amazonas State, Brazil. It is the first new species of Arapaima to be described since 1847, and comparisons with Arapaima from Mamirauá Reserve demonstrate that there are at least two species of Arapaima present in Amazonas State.

Alterations of flow regimen, pollution, and introductions of exotic species have significantly altered the composition of invertebrates in many river systems throughout the world. How these alterations affect the diet of higher level predators is not well understood. We studied the diet of the Northern Map Turtle (Graptemys geographica) in the dam-regulated Susquehanna River in north-central Maryland. Northern Map Turtles are a relatively large, top-order predator that is legally endangered in the state and is impacted by commercial collecting elsewhere. Gastropods, trichopteran larvae, and invasive Corbicula sp. predominated across diet samples. Marked sexual and size-related differences occurred. Adult male G. geographica fed primarily on a group of small gastropod species (Planorbidae, Hydrobiidae, Physidae), trichopterans, and Corbicula, while adult females fed primarily on pleurocerid snails. There was virtually no overlap in the diets of the two sexes of G. geographica. This is of special conservation concern because two different groups of prey are needed in order to support this population of Northern Map Turtles, and many North American pleurocerid gastropod species are highly endangered and also threatened by hydroelectric activity. Our results are consistent with reports of other Map Turtle populations before the invasion of Zebra Mussels (Dreissena sp.), which often result in a sharp change in diet. Zebra Mussels have already been documented immediately upstream of our study site, so impacts from this invasive species may become apparent in the near future.

The spatial ecology of animals is influenced by a combination of factors. Spatial ecology parameters are commonly calculated for rattlesnakes of the genus Crotalus, but they are highly variable within and among populations and species. Rattlesnake movements can be influenced by sex, body size, season, and abiotic factors, but the relative importance of each still remains unknown. We quantified aspects of the spatial ecology of a population of Northern Pacific Rattlesnake (Crotalus oreganus oreganus) in the southern part of its range in order to determine the factors that influence its spatial ecology. We found that males had larger home range sizes than females for the entire 14-month study. However, sex differences in movements were present during the spring mating season but not the summer post-mating season, suggesting that male mate searching causes males to have larger overall home ranges than females. We also found that body size was not related to home range size, but this effect was sensitive to the inclusion of two outlier males. Our seasonal analyses revealed that outside the mating season, male body size was negatively related to mean daily movement, while female body size was positively related to mean daily movement. In the spring, larger males made their first long distance movement earlier than smaller males, suggesting that body size may influence the timing of mate searching activity. Our study shows that sex and season, which are influenced by the mating system, are important factors that determine the spatial ecology of C. o. oreganus.

The bluehead wrasse, Thalassoma bifasciatum (Labridae), a protogynous hermaphrodite common to shallow reefs of the Caribbean, exhibits two color-phases: small, initial phase (IP) individuals may be either male or female, while larger, terminal phase individuals are always male. Among individuals in the initial phase, population sex ratios are generally female biased; however, that bias becomes increasingly pronounced on smaller reefs. We tested the hypothesis that this relationship between population size and IP sex ratio results from sex-specific recruitment strategies. Initial phase males experience very low reproductive success on small reefs, but do well on larger reefs. It would thus be adaptive for IP males to avoid small, patch reefs common in lagoons by preferentially settling on the first reef they encounter: the large, fringing reefs forming the seaward edge of lagoon systems. We used otolith analysis to test the prediction that IP males would exhibit shorter and less variable planktonic larval durations (PLD) relative to IP females. Our data confirm the second of these predictions, IP male PLDs were significantly less variable than those of IP females, but this difference was not strong enough to result in a shift in the mean PLDs of IP males and females.

The competition–predation hypothesis has been widely used for many years to explain the segregation along moisture gradients by species of dusky salamanders (genus Desmognathus) along Appalachian streams. According to this idea, all species originally favored aquatic sites, and large, aggressive species displaced smaller ones to more terrestrial habitats, both ecologically and evolutionarily. We tested this hypothesis by investigating the role of a recently described, previously unsuspected member (D. folkertsi) of this assemblage. This species coexists in widespread sympatry with its larger, cryptic congener, D. quadramaculatus. The competition–predation hypothesis predicts that the smaller D. folkertsi is displaced to more terrestrial habitats by the larger, aggressive D. quadramaculatus. We did not find D. folkertsi farther from water than D. quadramaculatus. However, in streams where they are sympatric, D. folkertsi was more abundant in small tributaries while D. quadramaculatus predominated along the main stem. This pattern is consistent with niche compression associated with interspecific competition. In behavioral trials to test interactions between these two species, neither species from sympatric populations avoided other salamanders or their chemical cues. Salamander–salamander aggression also appeared to be reduced. Each species from allopatric sites avoided other salamanders, regardless of species, and D. quadramaculatus significantly avoided chemical cues of other salamanders. While the general idea of the competition–predation hypothesis held, specific predictions failed. Therefore, we propose the competition–predation hypothesis be modified to account for each species of Desmognathus having a unique fundamental niche that then influences how they interact with sympatric congeners.

Roads can directly impact animal populations by increasing the risk of mortality; however, a more subtle ecological effect may lie in the way roads impede gene flow by creating barriers to animal movement. We investigated the effect a road network, containing both paved and unpaved surfaces, has on the movement patterns of the Eastern Hognose Snake (Heterodon platirhinos) in the Long Point region of Ontario, Canada by radio-tracking 17 adult snakes over two years. We used telemetry data collected in the field to infer the minimum number of road crossings made by snakes, and random walk simulations to estimate the number of road crossings snakes would have made if they moved randomly in relation to roads. Comparing the inferred and expected number of crossings allowed us to test the hypothesis that roads constrain movements because snakes avoid crossing them. Overall, the road network did not impede snake movements. When examined separately, however, we showed that road substrate affected movement: snakes avoided crossing paved roads while they crossed sand roads readily. Male and female snakes crossed roads at the same frequency. While the risk of road mortality is reduced by road avoidance, such avoidance of paved roads may contribute to the genetic isolation and further decline of this species-at-risk.

Unlike most terrestrial vertebrates, which use force generated from the hind limbs to jump, salamanders jump by laterally bending and then rapidly straightening the body, using momentum to carry the individual through the air. This movement is strikingly similar to both the terrestrial escape response of mudskippers and terrestrial blennies, and shares a general pattern of movement with the C-start escape response in several aquatic vertebrates. While the axial musculature appears to be responsible for this behavior, it remains to be seen what role the limbs and tail play. Across a two-fold range in body sizes, few kinematic parameters were correlated with size. The lack of strong scaling relationships suggests a spring mechanism that allows performance to be maintained despite a two-fold increase in size.

Long-distance signals such as bellows, roars, headslaps, and infrasound pulses are important components of crocodilian behavioral repertoire, yet there is little or no published information on signaling for many species. Here, original data augmented with a compilation of published and unpublished sources are presented for 24 species of crocodilians. Their analysis shows that crocodilians adapt their signal composition to habitat structure by choosing physically different components. Flexible multi-component composition might partially explain the extraordinary evolutionary longevity of crocodilian signaling. Comparative analysis provides novel evidence for solving the long-standing debate about the phylogeny of the genus Tomistoma, supporting its affinities with crocodiles rather than true gharials. It also suggests that the absence of species with adult male length of less than 120 cm among extant crocodilians might be caused by the necessity of producing infrasound as an honest signal of status.

The common estuarine fish species Fundulus heteroclitus or Mummichog has long been used in ecotoxicological studies; however, their periodic spawning pattern is perceived to limit their use in reproductive bioassays and the availability of sensitive life stages. This study evaluated the lunar periodicity of spawning, egg production, and changes in gonadosomatic index (I_G) in the laboratory using wild and F₁-generation Mummichogs that originated from three different geographic areas: the northern extreme part of their geographic range (New Brunswick, Canada; 45°N), the middle of the northern subspecies range (Massachusetts, USA; 41°N), and within the southern subspecies range (Virginia, USA; 37°N). Unlike some previous studies of wild and laboratory-held fish, Mummichogs from all locations were continuous spawners over a prolonged period of time (8 weeks) under laboratory conditions. However, there was greater variance in egg production in smaller fish (≤70 mm total length) compared to larger fish. Our results demonstrate the potential to use Mummichogs consistently in testing protocols due to the absence of lunar spawning in the laboratory, and further suggest that larger fish should be used to optimize the power to interpret results when conducting reproductive bioassays.

Toe-clipping is a commonly used method to mark reptiles and amphibians, collect genetic information, and collect samples to identify disease. Institutional animal care and use committees impose restrictions on such practices in an effort to mitigate pain inflicted on research animals. However, what is considered “painful” is often based on anthropomorphic intuition rather than scientific evidence. While there is no way to quantify pain, plasma corticosterone levels can provide a measure of the stress caused by procedures. Such data can provide animal care and use committees with the quantitative data they need to make appropriate decisions regarding procedures. We measured and compared plasma corticosterone levels in control, handled, and toe-clipped Cane Toads (Rhinella marina) to determine the extent to which toe-clipping induces stress. While both handling and toe-clipping did significantly increase corticosterone levels when compared with toads that had not been handled, we found no difference in corticosterone levels between Cane Toads that were handled only and Cane Toads that had been handled and had their toes clipped. We therefore conclude that toe-clipping does not cause a greater stress response than does handling.

Amphibians in freshwater coastal wetlands periodically experience acute exposure to salinity from hurricane-related overwash events, as well as chronic exposure associated with rising sea levels. In a comparative experimental approach, we examined whether seven species of anuran amphibians vary in their tolerance to changes in salinity. In a laboratory study, we exposed larval Hyla cinerea (Green Treefrog), H. squirella (Squirrel Treefrog), Lithobates catesbeianus (American Bullfrog), L. sphenocephalus (Southern Leopard Frog), Anaxyrus terrestris (Southern Toad), and Gastrophryne carolinensis (Eastern Narrow-mouthed Toad) from an inland population in north central Florida, USA, and Osteopilus septentrionalis (Cuban Treefrog) tadpoles from an inland population in southwest Florida, to acute salinity for 72 h. For each species, we replicated trials in which tadpoles were exposed to salinities of 0.2 (control), 5, 10, 12, 14, and 16 ppt. For all species, tadpoles reared in the control and 5 ppt treatments had 96.7–100% survival. No individuals of G. carolinensis survived at salinities exceeding 5 ppt and no individuals of any species survived in the 14 or 16 ppt treatments. For all other native species, survival at 10 ppt ranged from 46.7 to 80%, but declined to 0% at 12 ppt (except for H. cinerea, of which only 3.3% survived at 12 ppt). In contrast, all individuals of the invasive, non-native O. septentrionalis survived exposure to a salinity of 10 ppt, and survival in this species remained relatively high at 12 ppt. Our results illustrate that the non-native O. septentrionalis has a higher salinity tolerance than the native species tested, which may contribute to its invasion potential. Moreover, species commonly associated with coastal freshwater wetlands differ in their salinity tolerances, suggesting that salt water intrusion due to storm surges and sea level rise may affect the species composition of these ecosystems.

Crawfish Frogs (Lithobates areolatus) are a relatively widespread but understudied North American species suspected to be in steep decline. Discussions to petition this species for federal listing have begun and therefore effective techniques to survey and monitor populations must be developed. Crawfish Frogs produce unusually loud breeding calls, making call surveys the most efficient way to assess populations; however, their peak breeding period lasts for only a few nights, sometimes for only one night. We used automated calling survey techniques at two wetlands where the numbers of Crawfish Frog males present were known (±1%) for the entire length of the breeding season to examine detection probabilities in relation to season, time of day, weather variables, survey duration, and the numbers of males present. We then used these data to ask three simple but important questions: 1) When should researchers listen—that is, what times and under what environmental conditions should surveys for Crawfish Frogs take place? 2) How long should surveys last? and 3) What can call surveys tell us about the size of a population? The most supported model for detection included the quadratic relationship of time and date, a positive linear relationship with temperature, and a negative linear relationship with recent rain, while the most supported model for estimating abundance included the quadratic relationship of time and date, and call rate. Five-minute surveys should suffice during peak breeding for known large populations; 15-minute surveys with repeat visits should be used for small populations or when sampling new areas. These findings should improve manually collected (auditory) call survey efficiencies for Crawfish Frogs, surveys that are being organized to provide the first objective data on the status of this species across its range.

Amphibian populations worldwide are experiencing declines and contaminants are hypothesized to be one of the leading contributors to these declines. In particular, the salinization of amphibian habitats is a global issue that has received relatively little attention. Of the recent studies that have emerged, the majority focus on single-species responses, and because these studies often vary in methodology, assessing tolerances across species can be challenging. Thus, one step toward a broader understanding of salt loading is to assess tolerances across multiple species using similar methodologies. Additionally, in nature, amphibians can face low, sublethal concentrations of increased salinity. Though not lethal, these low concentrations can have long-term impacts on amphibian traits such as mass or their responses to future stressors. To address these issues, we first compared relative salinity tolerances of three common frogs in central Texas (Incilius nebulifer, Gulf Coast Toad; Lithobates berlandieri, Rio Grande Leopard Frog; and Acris crepitans, Blanchard's Cricket Frogs). Next, we explored the effect of sublethal salinities on the mass of I. nebulifer. Finally, we investigated the potential for sublethal salinities to increase tolerance of I. nebulifer to a later exposure of lethal salinity concentrations (acclimation). We found that across the three amphibian species, A. crepitans tadpoles were the most tolerant, followed by L. berlandieri tadpoles, and then I. nebulifer tadpoles. Sublethal concentrations of salinity did not affect mass of I. nebulifer tadpoles. Finally, exposure to sublethal levels of salinity did not increase tolerance of I. nebulifer tadpoles to a later exposure of higher salinity concentrations. Instead, tadpoles exposed to sublethal concentrations of salinity died at a faster rate when exposed later to a higher salinity concentration. With the increasing potential for salt loading to amphibian habitats due to anthropogenic influences and global climate change, understanding the consequences of salinity across multiple species as well as the effects of sublethal concentrations has important implications for amphibian conservation.