Congo River basin catfishes previously identified as Doumea alula (Amphiliidae, Doumeinae) were found to include three species that belong not to the genus Doumea but are, instead, the sister-group to a clade formed by all remaining Doumeinae. The species are assigned to a new genus, Congoglanis. Characters delimiting the Doumeinae and the clade consisting of all members of the subfamily except Congoglanis are detailed. Congoglanis alula is distributed throughout much of the Congo River basin; C. inga, new species, is known only from the lower Congo River in the vicinity of Inga Rapids; and C. sagitta, new species, occurs in the Lualaba River basin of Zambia in the southeastern portion of the Congo River system.

A new species of the deep-sea ceratioid anglerfish genus Himantolophus, long hidden within material identified as H. appelii Clarke, 1878, is described based on 43 female specimens collected in southern waters of all three major oceans of the world. A member of the H. appelii group, it differs from its sister-species, H. appelii, the only other member of the group, in details of escal morphology. The two species are geographically sympatric over much of their range.

Etsaputu relictum, a new genus and species sister to all other Ancistrini, is described from the upper Marañon River in Northern Peru. Etsaputu relictum can be diagnosed from all other Hypostominae by having a coracoid with a serrated posterior margin of the posterior process, an opercle with a process extending ventrolaterally from the ventral margin, and branchiostegals one and two fused. Etsaputu relictum is further distinguished by having cheek plates evertible to less than 45° from the sagittal plane, by having fewer than ten (typically zero or six) enlarged cheek-plate odontodes, by having enlarged cheek-plate odontodes straight and no longer than 15 times length of odontodes on lateral body plates, by having large eyes (mean 24.0% of head length, range 21.7–27.6% HL), and by having uniformly gold-brown to bronze base color with golden sheen when alive.

The genus Chaetostoma is a species-rich group of armored catfishes that inhabits rivers and streams in montane forests of South America. Most species of Chaetostoma have been described based on only one or a few specimens from a single river system. Our aim was to determine if the lifting of the Fitzcarrald Arch, 4 Ma, triggered speciation between the disjunct populations of Chaetostoma lineopunctatum in two isolated river drainages: the Río Ucayali and the Río Madre de Dios. We addressed this question by quantifying morphological and molecular divergence among samples of C. lineopunctatum from four river systems, three of which drain into the Río Ucayali drainage, including the type locality for the species, and one river system which drains into the Río Madre de Dios drainage. Morphological divergence, based on measurements, was statistically significant in the MANOVAs for the samples grouped by locality (P < 0.025) and by river system (P < 0.025). However, neighbor-joining trees of specimens grouped by locality (based on Mahalanobis distances) did not show group patterns according to river system. Morphologically, the specimens can be discriminated by river system with up to 88.7% confidence based on size-free discriminant analysis. Furthermore, the divergence values among haplotypes from the Río Ucayali and the Río Madre de Dios drainages, based on partial cytochrome b sequences (801 bp), ranged from 1.1% to 1.5%, which overlaps the 1.2% divergence between haplotypes from the Río Ucayali drainage. Based on the available morphological and molecular data, we conclude that there are not significant differences among populations of C. lineopunctatum from the Río Ucayali and the Río Madre de Dios drainages, and thus the Fitzcarrald Arch uplift did not cause speciation in this taxon. Alternatively, we suggest that isochronous tectonic events prior to the uplift of the Fitzcarrald Arch could have triggered genetic isolation of populations of C. lineopunctatum.

Eupemphix fuscomaculatus Steindachner, 1864 was described on the basis of a single specimen collected at Caiçara, Mato Grosso, Brazil. This species, currently included in the genus Pleurodema, experienced a confusing taxonomic history and is supposedly known only from the holotype and seven specimens from Río Apa, Paraguay, collected by Alfredo Borelli in 1893–1894. Examination of Steindachner's holotype and Borelli's specimens revealed that they are not conspecific, E. fuscomaculatus is a junior synonym of Physalaemus biligonigerus (Cope, 1861 “1860”), and the specimens from Río Apa, Paraguay, could not be distinguished by their morphology or ploidy either from Pleurodema bibroni or P. kriegi, and are referred here as Pleurodema bibroni based on ecological considerations. Contrary to a recent proposal, the presence of vomerine teeth is not considered diagnostic for the genus Pleurodema, as they are absent in seven of the 13 species of Pleurodema examined. In addition, we propose to amend the type locality of P. biligonigerus to the surroundings of La Paz, Entre Ríos Province, Argentina.

A new species of Steindachnerina, family Curimatidae, is described from the headwaters of the Rio Jamanxim in the central portion of the Rio Tapajós basin of the Brazilian Amazon. The species is distinguished from its congeners on the basis of pigmentation and various meristic and morphometric features. The phylogenetic placement of the new species within Steindachnerina is investigated, and notwithstanding the similarities in pigmentation patterns between that species and S. fasciata, those forms were not found to be closely related. The new species represents the first reported occurrence of a species of Steindachnerina within the Rio Tapajós, the fifth largest component of the Amazon. The occurrence of a second species of the genus, S. fasciata, in the Rio Teles Pires, another tributary of the Rio Tapajós basin is also documented. Steindachnerina brevipinna, a species widespread through major portions of the Río de La Plata system, is confirmed to occur in the Rio Xingu of the Amazon basin.

Studies of a few “model” amphibians continue to advance our mechanistic understanding of the endocrine control of larval amphibian development and metamorphosis, but there are few studies examining steroid profiles across species during larval amphibian development. We used censored regression analysis to address our primary objective, which was to examine baseline corticosterone level changes and responses to a standardized stressor throughout larval development in two amphibian species: one anuran (Wood Frogs, Rana sylvatica) and one caudate (Jefferson Salamanders, Ambystoma jeffersonianum). In addition, we looked at two additional factors that could influence the study of corticosterone during larval development, namely the rearing location of the animals (free-living, mesocosm-held, or laboratory-held) and for A. jeffersonianum, the method of induction of the stress response (ACTH injection or a confinement-agitation [CA] protocol). As has been documented for other anurans, baseline corticosterone content of R. sylvatica increased close to metamorphic climax in all rearing locations, although the absolute level varied with rearing location. Baseline corticosterone content of A. jeffersonianum increased gradually over development, and the increase in corticosterone content following CA mirrored the increase in baseline levels, although the absolute magnitude of the increase with CA varied based on rearing location. In larvae of A. jeffersonianum, both the CA method and ACTH injection significantly increased corticosterone content, with 30 min eliciting the maximum hormonal response level. Our results suggest that rearing location can influence corticosterone levels and the response to a standardized CA protocol, and that care should be taken in extrapolating results from laboratory studies to free-living amphibian populations.

Polyandry has been demonstrated in a number of shark species. Studies based on a small number of loci typically estimate the minimum number of sires, which may be much lower than the actual number of sires due to the sharing of alleles by parents. We genotyped three litters of Nurse Shark (Ginglymostoma cirratum) ranging in size from 29 to 39 pups at 12 DNA microsatellite loci to determine the number of sires for each litter. We analyzed the genotypes using two analytical methods, both of which indicated that each litter had five to seven sires with one to 17 pups per sire. Previous analyses of these litters based on MHC loci indicated a minimum of four sires. Because G. cirratum are not capable of long-term sperm storage and ovulate over several weeks, they may require multiple inseminations to fertilize an entire litter. The varying levels of developmental stage among embryos found within a single litter may reflect multiple fertilizations over a prolonged period. Exact enumeration of sires as demonstrated here can provide valuable information for understanding reproductive ecology of live-bearing vertebrates.

Differences in ecological conditions can result in the evolution of dramatic inter-population shifts in whole suites of traits. We studied variation in reproductive output in three lizard populations of the Skyros Wall Lizard (Podarcis gaigeae, Lacertidae) endemic to the Skyros Archipelago (Greece), which live under similar climatic conditions but differ in predation pressure and food availability. Based on the “island syndrome” hypothesis, we predicted that females from island populations would produce larger, but fewer offspring. The study populations differ conspicuously in average body size, with males from the satellite Lakonissi and Diavates islets being respectively 20% and 39% larger than males from the main Skyros Island. Lizards from these predator-free islets produced eggs of larger size than the main Skyros population; however, they also produced significantly larger clutches than the Skyros population (2.31±0.83 and 2.73±1.0 vs. 1.97±0.58 eggs). All inter-population differences in clutch size, clutch volume, and egg size were explained by corresponding differences in average body size of the dams, revealing that across all populations, reproductive effort scaled similarly with maternal body size. There was no evidence of trade-offs between egg size and clutch size as generally encountered in many reptile taxa. The occurrence of this unusual pattern of reproductive investment among islet populations of giants is probably best explained by the occurrence of two underlying drivers: first, the substantial marine subsidies by resident seabird colonies and second, the existence of intense cannibalistic behaviors in the form of attacks to the tail and severe intraspecific predation on juveniles. This suggests that subsidies-driven gigantism in island endemics may free species from such trade-offs and allow a population to maximize reproductive output in multiple, normally conflicting dimensions.

Sex ratios at birth or hatching in snake populations are often assumed to be 1∶1 in agreement with Fisherian theory. We evaluated secondary sex ratios (SSRs) in two viperids (Sistrurus catenatus and S. miliarius) and four natricine colubrids (Nerodia rhombifer, Thamnophis proximus, T. radix, and T. sirtalis). We captured 274 gravid females that produced 2443 living offspring. Population-level SSRs in our focal species did not differ significantly from 1∶1. In addition, variation in individual litter SSRs conformed to expectations generated by the binomial distribution with an even sex ratio. Each species showed individual variation in SSRs; however, the majority of variation in litter SSRs was not explained by variation in the maternal or litter characteristics we examined. The three exceptions were a very strong negative association between mean offspring mass and litter SSR in T. radix (r²  =  0.96), a strong positive association between mean offspring mass and litter sex ratio in T. proximus (r²  =  0.40), and a strong positive association between maternal condition and litter SSR in T. proximus (r²  =  0.40). Whether or not these relationships have functional or adaptive significance warrants further study. The majority of our results were unsurprising and not statistically significant. We suggest, however, that the presentation and publication of both non-significant and significant results is exactly what is needed to give an accurate view of SSRs at both the population level and the maternal level in snakes.

Japanese Medaka, Oryzias latipes, is a widely used organism in biological investigations because of its high fecundity, small adult size, and ease of husbandry. However, many aspects of its life history have not been fully described. In this study we determine patterns of somatic growth, frequency of egg production, and competency of eggs. We also describe temporal aspects of reproductive output. We modeled the length-at-age relationship with a von Bertalanffy growth function and found mean parameter values: L_∞  =  49.5 mm TL (total length), k  =  0.010 dph⁻¹ (days post hatch), and t₀  =  3.3 mm TL. These estimates are used to predict longevity of 347 to 485 days. The weight-at-length relationship was described using a power curve and resulted in mean parameter estimates, a  =  2.16 × 10⁻⁵ and b  =  2.79. The mean proportion of eggs that hatched was 73% (95% confidence interval: 53 to 93%). We observed that 50% of larvae emerge from eggs at 3.5 days and 99% of larvae emerge at 7.5 days in incubation. Daily egg production increased to a maximum number (range: 8 to 48) of eggs at 92 days post hatch. Total egg production by individual females ranged from 38 to 141 eggs. We found a significant negative linear relationship (F  =  34.7, P < 0.001, R²  =  0.28) between the number of eggs collected from an individual during a single egg deposition event (n  =  91) and mean egg volume. However, there were large variations in the sizes of individual eggs within a clutch (median CV  =  14.8). Our work provides previously unreported life-history information that can be used to effectively develop experiments in the laboratory and field, and increased understanding of this species.

Leaf-litter geckos of the genus Sphaerodactylus are highly diversified but their small size and secretive habits have made them difficult to study. In 1972–1973, we conducted a demographic study on a population of S. vincenti ronaldi from a xerophytic forest in Martinique, with the prediction that seasonality in local climatic conditions, especially precipitation, should cyclically constrain food consumption, growth, and reproduction. We used a mark–recapture method to get basic data on population structure and density. We sacrificed 62 specimens to determine diet and reproductive conditions. Individual age, growth, and longevity were assessed by skeletochronology. Lizards were ubiquitous in the 900 m² study area, with most found singly under humid rotten logs. Population density averaged 8220 geckos/ha. Individual movements were very limited over a six-month period. We noted a high incidence (62%) of tail autotomy. Diet included a diversity of small invertebrate prey (15 different orders) with collembolans being most abundant. However, food consumption (measured as stomach content and intestine masses) dropped to a minimum in late dry season, a cyclic pattern most likely responsible for the observed lines of arrested growth (LAGs) registered in the femoral bone cortex of these lizards. Sequences of LAG dimension and modal distributions of snout–vent lengths (SVL range: 13–32 mm) revealed a slow growth rate (0.66 mm/month) during the first year of life with both genders attaining sexual maturity at 25–26 mm SVL and 18–20 months of age. Longevity did not exceed 48 months. Reproduction appeared seasonal, with the geckos laying eggs at an undetermined frequency during a period lasting approximately seven months. Egg size and incubation time were similar to other Sphaerodactylus of comparable body size. These results indicate special constraints associated with body size in species of Sphaerodactylus living in xerophytic habitats. However, for S. vincenti, a species that extends its range to other mesic/humid habitats in Martinique and three other nearby island banks, it is not known if larger subspecies (up to 40 mm SVL) suffers the same constraints in food intake, growth, and reproduction as observed in this study for S. v. ronaldi.