Moxostoma lacerum was the first member of the North American ichthyofauna to be documented as extinct. The unique oral morphology of the species has been of interest, as has its unusual diet of small snails. Because of the rarity of specimens, and the disarticulated condition of available skeletons, we take this opportunity to describe the oral skeletal morphology, using the HRXCT technology to reconstruct the skeleton digitally. We find that the premaxillary bones lie posteromedial to the maxillae and that maxilla shape is asymmetrical; it is likely that the animal sucked snails from their shells while holding the shells with a keratinized mandibular shelf.

The endocranial space, nerve pattern, and inner ear of a specimen of Uropeltis woodmasoni are described from digital endocasts rendered from high-resolution X-ray computed tomography scans. The cast of the endocranial space reveals short, stout olfactory bulbs as well as general shortening of the brain along the longitudinal axis. The pattern of innervation agrees with descriptions reported for other uropeltid snakes, although this individual exhibits skull asymmetry in the pathway of the glossopharyngeal nerve and the bifurcation of the jugular canal. There are no internal connections between the perilymphatic canal leading to the foramen pseudorotundum, the recessus scala tympani, and the jugular canal, a situation that differs from those of other alethinophidian snakes. The inner ear is compactly packaged with smoothly curved semicircular canals located in close proximity to the vestibule. Semicircular canal size is comparable to those of larger snakes, and the small size of the skull (9.4 mm) coupled with relative enlargement of the sensory regions of the brain and otic capsule is consistent with the morphological pattern of miniaturized vertebrates, although compounding factors, including phylogeny, ontogeny, and variation, are currently not well understood.

Secretory activity of serous (poison) cutaneous glands was studied with light and transmission electron microscopy over the ontogenetic cycle of the Black-legged Dart Frog Phyllobates bicolor. Serous gland activity includes two steps: biosynthesis and maturation. Biosynthesis is performed by the rough endoplasmic reticulum, smooth endoplasmic reticulum, and Golgi apparatus, and follows the usual pathways of exocrine secretory processes. Maturation is typical of anuran serous glands, which accumulate their products in syncytial secretory units. Maturation involves merging processes between secretory deposits (vesicles and/or granules) distally from the Golgi stacks, as well as an increase in the surface area between the syncytial cytoplasm and the secretory vesicles/granules. In P. bicolor, this interface area increases through the formation of peculiar cytoplasmic outgrowths. These outgrowths allow transport processes involved in maturational changes of secretory product. During maturational storage, the secretory products of P. bicolor acquire a repeating substructure of spherical to short tubular subunits. This recurrent pattern is seen in cutaneous poisons of several anuran species, regardless of their phylogenetic relationships. Among anurans, condensing serous cutaneous products into repeating aggregations of subunits appears to be a successful strategy, which allows intracytoplasmic accumulation of pharmacologically active and/or toxic molecules through various post-Golgian processes. The present findings provide evidence of a novel repertory of cytological activities that stress the large diversity of the maturational pathways leading to the peculiar repeating arrangement of secretory subunits.

Analysis of skeletochronological variation in fibulae of the threatened Florida Sand Skink, Plestiodon (Neoseps) reynoldsi, found numbers of growth marks that almost always exceeded the maximum life span predicted by mark–recaptures studies. We propose that the large number of growth marks observed in the Florida Sand Skink reflect variation in food availability.

A large spawning aggregation of Polymixia lowei, Beardfish, was documented via video and specimen collection in a deep-water (413 m) sinkhole off Key West, Florida on 5 June 2007. The use of the human-occupied submersible, Johnson-Sea-Link II, allowed for in situ observations, video documentation, and specimen collection. The maximum density (117 fish m⁻²), average abundance (56 fish m⁻²), and average standard length (152.1 mm) were estimated from video transects. Ovarian histology of the fish collected indicated recent spawning activity. Observations of a deep scattering layer above the sinkhole by echo sounder suggested that P. lowei were in the water column during the pre-dawn hours. This represents the first report of aggregating behavior for reproduction in P. lowei.

We collected fishes at 28 sites of the middle Wabash River, Indiana, using a boat electrofisher and at ten additional sites using a 10-m beach seine. We used Canonical Correspondence Analysis to test for fish assemblage variation that was explained by variation in water depth and substrate frequency. The multivariate analyses resulted in a longitudinal gradient in water depth and frequency of occurrence of substrate size categories that explained a large component of variation among fish assemblages for both sampling regimes. Our results illustrate that substrate composition and water depth variation are significant environmental predictors of fish assemblage composition for a large river such as the Wabash River.

Radiotelemetry and genetic markers have enabled herpetologists to test the hypothesis that gene flow is restricted among snake dens (a.k.a. “hibernacula”). In the present study, observations of movement and mating were compared to indirect inferences of gene flow based on genetic data (microsatellite DNA loci) for six neighboring hibernacula of the Timber Rattlesnake (Crotalus horridus) in western St. Louis County, Missouri. Behavioral results were consistent with previous findings for this species, with most individuals exhibiting high fidelity to hibernacula, and males exhibiting larger activity areas than females. Behavioral results also supported several long-standing assumptions: males tended to mate at longer distances from hibernacula than females and random pairing between males and females from different hibernacula could not be rejected. Some gravid females moved considerable distances between locations, but most returned to an area near their own hibernaculum to give birth, and birth distances tended to be shorter than the nearest-neighbor distance between hibernacula. Genetic results indicated that the observed number of heterozygotes did not deviate from Hardy-Weinberg expectations at the level of total sample population, but that a significant heterozygote excess was found within hibernacula. A small but significant proportion of the genetic variance in the total population was due to differences among hibernacula; however, Bayesian clustering algorithms could not sort individuals (or groups of hibernacula) into discrete demes. Results suggest that patterns of genetic differentiation observed among hibernacula of the Timber Rattlesnake are better explained by behavioral and demographic factors resulting in natal philopatry, sex-biased dispersal, and/or a limited number of breeding adults, than by the balance of gene flow and drift, per se.

The relationship between dispersal and predator–prey interactions in heterogeneous landscapes is an underappreciated factor influencing species persistence. This relationship, however, is critical for understanding population dynamics and for implementing management strategies for species. We investigated the influence of habitat heterogeneity and dispersal patterns on neonate survival for the iguana Cyclura cychlura cychlura inhabiting Andros Island in the Bahamas. Contrary to our hypothesis, there was a clear survival advantage for neonates that spent more time in open mangrove habitat than relatively more closed-canopy habitats, most likely because of fewer primary predators in mangroves relative to other habitats. Snake predation was the most significant cause of mortality for neonates dispersing away from nest sites and was highest during the first week after release. The probability of survival to 28 days ranged from 16.7 to 28.4%. Most neonates displayed rapid, nearly linear movements away from nests for a minimum of 14 to 21 days. Mean straight-line distance away from nest sites for surviving neonates was 601 m. There was a significant positive relationship between mean daily movement rates away from nests and days survived. We suspect that the initial and rapid movements away from nests reduce relative predation by dispersing neonates from a zone where predators learn to exploit them. Our results have implications for translocation programs targeting endangered insular iguanas throughout the Neotropics because historically only the presence of non-native mammalian predators was used as a metric to evaluate potential translocation sites.

Bagrus meridionalis (Bagridae; locally called Kampango) is a large substrate-spawning catfish endemic to Lake Malaŵi that exhibits bi-parental care and spawns primarily in the wet season from January to March. The female feeds her young trophic (unfertilized) eggs; the male orally collects offsite benthic organisms, which he brings back to feed the brood. While doing underwater videography in the lake, we observed evidence for brood parasitism of four Kampango nests by the most common clariid catfish in Lake Malaŵi, the endemic Bathyclarias nyasensis (locally called Bombe). Parasitized Kampango nests held Bombe young almost exclusively, and these were protected by Kampango adults until they exceeded 100 mm SL. We found that female and male Kampango fed the Bombe juveniles with trophic eggs and macroinvertebrates, respectively, as they do their own young. These observations represent a sophisticated example of cuckoo behavior in fishes.

Spatial patterns of animals have important implications for population dynamics and can reveal other key aspects of a species' ecology. Movements and the resulting spatial arrangements have fitness and genetic consequences for both individuals and populations. We studied the spatial and dispersal patterns of the Oregon Gartersnake, Thamnophis atratus hydrophilus, using capture–recapture techniques. Snakes showed aggregated dispersion. Frequency distributions of movement distances were leptokurtic; the degree of kurtosis was highest for juvenile males and lowest for adult females. Males were more frequently recaptured at locations different from their initial capture sites, regardless of age class. Dispersal of neonates was not biased, whereas juvenile and adult dispersal were male-biased, indicating that the mechanisms that motivate individual movements differed by both age class and sex. Males were recaptured within shorter time intervals than females, and juveniles were recaptured within shorter time intervals than adults. We attribute differences in capture intervals to higher detectability of males and juveniles, a likely consequence of their greater mobility. The aggregated dispersion appears to be the result of multi-scale habitat selection, and is consistent with the prey choices and related foraging strategies exhibited by the different age classes. Inbreeding avoidance in juveniles and mate-searching behavior in adults may explain the observed male-biased dispersal patterns.

Habitat selection is important for a species' survival, and its identification represents a crucial component in the development of conservation strategies. Habitat selection occurs when habitats are used disproportionately to their availability, and what constitutes available habitat will depend on the biology of the species under investigation. Habitat selection and movement patterns of Spotted Turtles (Clemmys guttata) in a population near Lake Huron, Ontario, were studied over two consecutive years using radio telemetry. Selection was assessed at two spatial scales (second order, home range from population range; and third order, locations from home range) using compositional analyses. Spotted Turtles shift macrohabitat use throughout the annual cycle, therefore seasonal habitat selection was also analyzed. Selection occurred at both scales tested, and the ranking of preferred habitats differed based on the scale of analysis. Selection differed across seasons (emergence, nesting, post-nesting), but was similar between the sexes. Despite seasonal shifts in macrohabitat selection, microhabitat used did not differ seasonally, but females were more likely to choose locations with cover in the late summer compared to males. Individuals selected overwintering sites that afforded structural protection and a temperature near 0°C. Movements were similar between the sexes, with a reduction in activity in July and August. The seasonal variability in habitat selection supports the need for surveys at multiple time-points within the year to fully document the critical habitat requirements of Spotted Turtles.

A new species of the Scinax perpusillus group is described from southern Espírito Santo, Brazil. It differs from the other ten species of the group in having the dorsum of body and limbs densely covered by prominent granules (smooth or with scattered irregular warts in all other species of the group) and in lacking any trace of markings on dorsum, inguinal region, and hidden surfaces of hindlimbs (present in all other species of the group). The new species is known only from the type locality. Unpigmented nuptial pads, never previously reported for the group, are present in all studied species (nine of eleven included in the group). Inguinal glands are easily visible in the new species, S. alcatraz, and S. littoreus.

The Waccamaw Darter Etheostoma perlongum is one of three teleost fish species and several molluscs endemic to Lake Waccamaw, a large Carolina Bay in southeastern North Carolina. We assessed species status by sequencing most of the mitochondrial cytochrome b (cyt b) gene in E. perlongum and its putative sister species, E. olmstedi, from the adjoining Waccamaw River and streams in the nearby Pee Dee and Cape Fear Drainages. Phylogeographic analysis shows strongly supported river- and drainage-specific clades with divergence times dating to the Pleistocene. Haplotypes of Etheostoma perlongum are very similar and not phylogenetically distinct from sequences from the Waccamaw River population of E. olmstedi. However, strong haplotype frequency differentiation shows that free genetic exchange does not occur between the river and lake, and along with life history distinctiveness, suggests reproductive isolation despite contact between these populations. Coalescent simulations showed that incomplete lineage sorting between reproductively isolated populations is a plausible explanation for the failure of cyt b sequences to have achieved reciprocal monophyly. Gene tree/species tree discord equal to that seen in our cyt b data was produced in ≥ 5% of coalescent trees, using lake-river divergence times of T  =  5–10 thousand years ago (kya), no gene flow and N_e  =  10⁵; simulations with more realistic values of N_e  =  10⁴ and T  =  10–20 kya required recurrent lake-river migration to generate comparable levels of incomplete sorting of haplotypes. Studies of behavioral reproductive isolation and multilocus studies of nuclear DNA should be used to distinguish these scenarios and to further evaluate the species status of the endemic Waccamaw Darter.

A new limbless species of scincid lizard of the genus Brachymeles is described from Mt. Labo, Bicol Peninsula, Luzon Island, Philippines. The species was encountered only on this isolated volcanic peak and is conspicuously absent from surrounding, well-surveyed regions of the Bicol Peninsula. The new species is the fourth known limbless species of Brachymeles and the third to be discovered in the Philippines. It is the second longest limbless species of Brachymeles, and, aside from size, can be distinguished from all congeners by features of its external morphology, including both color and scalation. The discovery brings the total number of known Brachymeles species in the Luzon Faunal Region to eleven, including two limbless forms.

The taxonomy of the Western Indian Ocean species of Acanthopagrus is reviewed. A new species, A. omanensis, is illustrated and described from two specimens. Acanthopagrus vagus (Peters, 1852) is resurrected from the synonymy of Acanthopagrus berda (Forsskål, 1775), redescribed, and compared with A. berda. Acanthopagrus vagus differs from all congeners in the following combination: scale rows between fifth dorsal-fin spine base and lateral line 3; front edge of dorsal scaly area on head with a median W-shaped scaleless area anteriorly; second anal-fin spine longer than third anal-fin spine; ventral edge of first two infraorbitals straight (slightly curved in fish more than 25 cm SL); preopercle flange with 0–6 scales, number increasing with growth, scales obvious on fish more than 20 cm SL; anal fin with pale rays, and a black streak near the base on each inter-radial membrane; molariform teeth well developed on both jaws. Acanthopagrus berda is differentiated from all congeners by the following combination: scale rows between fifth dorsal-fin spine base and lateral line 3; anterior head profile slightly convex, front edge of dorsal scaly area of head convex, with small scales anteriorly; ventral edge of first two infraorbitals with a strongly curved concavity that receives the enlarged tip of the maxilla in fish larger than 13 cm SL; no scales on preopercle flange; second anal-fin spine clearly longer than third anal-fin spine; anal fin almost completely black (no pale rays); molariform teeth well developed, lower jaw teeth rows strongly curved laterally at rear of jaw. Acanthopagrus omanensis, new species, is discernible from all congeners by the following combination: scale rows between fifth dorsal-fin spine base and lateral line 5; front edge of dorsal scaly area on head forming an obtuse angle anteriorly; ventral edge of first two infraorbitals straight; no scales on preopercle flange; second anal-fin spine slender and subequal to third anal-fin spine; dorsal and caudal fins with wide black margins; upper and lower molariform teeth poorly developed. Junior synonyms of A. berda and A. vagus are discussed, with notes on other congeners, including nominal species of Sparidentex, which are sometimes confused with species of Acanthopagrus. A key to species of Acanthopagrus from the Western Indian Ocean is presented.

The genus Lepidocephalichthys is revised and diagnosed as having the seventh and eighth pectoral rays modified in the mature male. Other cobitids have different pectoral rays modified (second ray in Cobitis). The 17 valid species of Lepidocephalichthys are discussed and compared. Fifteen species are redescribed: L. annandalei, L. arunachalensis, L. berdmorei, L. coromandelensis, L. furcatus, L. goalparensis, L. guntea, L. hasselti, L. irrorata, L. jonklaasi, L. lorentzi, L. manipurensis, L. micropogon, L. thermalis, and L. tomaculum; and two new species are described from Thailand, Laos, Vietnam, and Myanmar. Lepidocephalichthys kranos, new species, is distinguished from all other Lepidocephalichthys except L. irrorata by having conspicuous scales on top of the head and from L. irrorata by its more anterior dorsal fin placement and larger size. Lepidocephalichthys alkaia, new species, is distinguished from all other Lepidocephalichthys by a dark stripe extending from the snout, through the orbit, and continuing to the terminus of the caudal fin. Acanthophthalmus sandakanensis is reassigned from Lepidocephalichthys to Pangio based on its modified first and second pectoral rays. Sexual dimorphism in Lepidocephalichthys is discussed, as are the validity and taxonomic history of forked-tailed species. Species are illustrated, and a taxonomic key to species is provided.

Sternarchogiton zuanoni, a new species of electric knifefish, is described from the rapids and waterfalls of Cachoeira de Kaituká along the Rio Xingu at Altamira, Pará, Brazil. The new species is diagnosable from congeners by a unique combination of morphometric and meristic features, details of pigmentation, the pattern of dentition on the dentary, the possession of an edentulous premaxilla, and an unelaborated lower lip. The description of S. zuanoni brings the number of species in the genus to five. The presence of S. labiatus in the Río Orinoco basin is documented and a key to the species of the genus is provided.

The species currently assigned to the South American electric fish genus Porotergus are reviewed. Porotergus duende, a new species, is described from the lowland western Amazon basin in Brazil and Peru. Porotergus gimbeli from the lowland Amazon basin in Brazil and Peru, and P. gymnotus from the Essequibo drainage of Guyana are redescribed. Porotergus duende and P. gimbeli are restricted to deep channel habitats. Porotergus gymnotus occurs in shallow rivers. Notes on the ecology and electric organ discharge of P. duende and P. gimbeli are presented. A key to the members of the genus is provided.

The Bayou Darter, Etheostoma rubrum, is endemic to the Bayou Pierre system of southwestern Mississippi where it occupies swift, shallow riffles with coarse, firm substrata. The Bayou Pierre system has experienced extensive erosion in response to rapid headcutting leading to loss of riffle habitat and degradation of riverine conditions. Due to its high degree of habitat specificity along with ongoing habitat fragmentation and potentially reduced gene flow between isolated populations, the Bayou Darter is vulnerable to severe population declines and possible extinction. Our objectives were to quantify levels of genetic diversity in the mitochondrial control region and infer population structure across the range of the species. Sequencing of 106 sampled individuals revealed only three mtDNA haplotypes with one variable site. Haplotype diversity and nucleotide diversity were low (h ≤ 0.11 and π < 0.001), and there was no structure revealed among the four sampled populations. The low genetic diversity in E. rubrum may best be explained by a small range size and recent genetic bottleneck.