We report on the remarkable variation and frequency of color morphs within and among eight populations of the Common Gartersnake (Thamnophis sirtalis) in central Manitoba, Canada and one on Isle Royale, Michigan, USA. Five color morph categories are identified, one melanistic and four scored on a qualitative scale based on expression of red pigment. In the most northern population (Jenpeg, 54.464°N, 98.115°W) and two island populations (George Island, Lake Winnipeg, 52.819°N, 97.620°W; Isle Royale, 48.102°N, 88.601°W), all five color morphs were expressed. The northernmost population also exhibited sexual color dimorphism, with female snakes expressing significantly more red than males. In contrast, two central and western populations showed very little variation, with only two of the most similar color morphs present. We provide the first report of erythristic snakes in Manitoba, found in three separate locations around Lake Winnipeg. Melanistic snakes are also reported from three new localities in the province, all widely disjunct from previously identified sites around Lake Winnipegosis. Manitoban and Isle Royale populations are compared with color frequency data from sites in mainland Michigan and in Kansas. Color patterns among populations do not follow traditionally recognized zones of intergradation between T. s. parietalis and T. s. sirtalis. The extreme intrapopulational variation suggests that subspecies of T. sirtalis based on color are of questionable validity.

Three new species of the mesopelagic fish genus Photonectes (Stomiidae, Melanostomiinae, subgenus Photonectes) are described from the Pacific Ocean with species descriptions augmented by new characters: origin of the IP-photophore series, gill-filament length, and jaw-tooth length. Photonectes coffea, new species (central equatorial, north, and western Pacific) has an elongate barbel with two bean-shaped light organs; IV photophores 37–39; dorsal-fin rays 12–13; no blue luminous tissue; one white luminous shoulder spot; all jaw teeth small canines; and gill filaments on first arch extending beyond opercular opening. Photonectes barnetti, new species (North Pacific Gyre) has an elongate barbel with a single ovoid bulb and a white area along the stem; IV photophores 37–39; dorsal-fin rays 13–15; no blue luminous tissue; one or two white luminous shoulder spots; jaw teeth of variable length; and reduced gill filaments on first arch. Photonectes corynodes, new species (central equatorial Pacific) is known from a single specimen and has a barbel with a single hourglass-shaped bulb and a bifid terminal filament, both branches ending in small light organs; IV photophores 34; dorsal-fin rays 15; no blue luminous tissue or white luminous shoulder spots; jaw teeth of variable length; and gill filaments neither reduced nor elongated. A key to the subgenus Photonectes is provided.

Hemigrammus diagonicus, new species, is described from the lower Amazon River floodplain, near Juruti, State of Pará, Brazil. The new species shares with H. silimoni the presence of a dark blotch on the dorsal lobe of the caudal fin, absent in all other species of the genus. It is distinguished from H. silimoni by the autapomorphic presence of the caudal-fin blotch shaped like a bar that extends diagonally from the base of the median rays to the end of the upper lobe rays. Hemigrammus diagonicus, new species, is further distinguished from H. silimoni by a combination of meristic and morphometric characters, such as length of anal-fin base and horizontal eye diameter. Comments on the color patterns displayed by the species of Hemigrammus are presented.

Hemigrammus diagonicus, nova espécie, é descrita da várzea do baixo Rio Amazonas, próximo a Juruti, Pará, Brasil. A nova espécie compartilha com H. silimoni a presença de uma mancha escura no lobo dorsal da nadadeira caudal, ausente em todas as demais espécies do gênero. Distingue-se de H. silimoni pelo formato autapomórfico da mancha na nadadeira caudal, que consiste em uma barra estendendo-se da base dos raios medianos e prolongando-se em sentido diagonal à extremidade dos raios do lobo superior. Hemigrammus diagonicus, nova espécie, pode ser adicionalmente distinguida de H. silimoni por uma combinação de caracteres merísticos e morfométricos como comprimento da nadadeira anal e diâmetro horizontal do olho. Comentários sobre os padrões de coloração das espécie de Hemigrammus são apresentados.

Two new ancistrin genera and species are described from main channels and tributaries of the upper Orinoco River in Amazonas, Venezuela. Micracanthicus vandragti is black with white spots and distinguished by its small body-size, large gas-bladder capsules, and highly protrusible mandibles with short tooth cups and five to eight long teeth per tooth cup. The known range of Micracanthicus vandragti is restricted to the lower Ventuari River and portions of the Orinoco River near its rocky, anastomose confluence with the Ventuari River. Soromonichthys stearleyi is green with small yellow-gold spots on the head and thin vertical bars on the body and has long dentary and premaxillary tooth cups with 39–69 teeth per tooth cup. It is distinguished by its coloration and by its unique pattern of plate loss on the snout: plates absent from mesethmoid surface and anteriormost margin of snout. Soromonichthys stearleyi is known only from Soromoni Creek, a northern tributary of the upper Orinoco draining southern slopes of Mount Duida.

Creteuchiloglanis, new genus, is established for three species previously placed in Pareuchiloglanis (P. gongshanensis, P. kamengensis, and P. macropterus) and two new species described herein. Creteuchiloglanis is distributed in the upper Mekong River (Lancang-Jiang) basin west to the Brahmaputra River basin and is distinguished from Pareuchiloglanis by a unique combination of characteristics involving the form of the connection of the lower lip to the maxillary barbel, premaxillary tooth patches, and the morphology of the dilator, operculi, sternohyoideus, and adductor pelvicalis superficialis muscles. Creteuchiloglanis brachypterus, new species, from the upper Irrawaddy River basin in China, is diagnosed by a unique combination of characteristics involving pectoral- and pelvic-fin length, caudal-peduncle length and depth, pelvic-fin position, caudal-fin length, eye size, body and head depth, and coloration. Creteuchiloglanis longipectoralis, new species, from the upper Mekong River (Lancang-Jiang) basin, is diagnosed by a unique combination of characteristics involving pectoral- and pelvic-fin length, caudal-peduncle length and depth, pelvic-fin position, body and head depth, post-adipose fin distance, number of dorsal-fin rays, and coloration. New diagnoses are provided for previously described congeners C. gongshanensis from the upper Salween River (Nu-Jiang) basin, C. kamengensis from the Brahmaputra basin, and C. macropterus from the upper Irrawaddy River and upper Salween (Nu-Jiang) basins.

Fundulus capensis Garman, 1895 was described from the unique holotype said to be from False Bay, Cape of Good Hope, South Africa. Largely ignored by killifish taxonomists, its classification has remained ambiguous for over a century. Radiography and computed tomography of the holotype reveal skeletal details that have been used in modern phylogenetic hypotheses of cyprinodontiform lineages. Osteological synapomorphies confirm it is a cyprinodontiform killifish and allow us to identify it to species. The first pleural rib on the second vertebra and a symmetrical caudal fin with hypural elements fused into a fan-shaped hypural plate corroborate its classification in the cyprinodontiform suborder Cyprinodontoidei. The twisted maxilla with an anterior hook and the premaxilla with an elongate ascending process both place it in the family Fundulidae. The pointed neurapophyses of the first vertebra that do not meet in the midline and do not form a spine exclude it from the family Poeciliidae. Presence of discrete exoccipital condyles excludes it from the subfamily Poeciliinae. Overall shape, position of fins, and meristic data agree well with those of the well-known North American killifish, F. heteroclitus. Fundulus capensis Garman, 1895, redescribed herein, is considered a subjective synonym of Fundulus heteroclitus (Linnaeus, 1766). Provenance of the specimen remains a mystery.

The hylid frog genus Scinax is the most species-rich within Hylinae, with more than 100 recognized species grouped in the S. catharinae and S. ruber clades. The karyotypes of 14 species of the S. catharinae clade and 14 of the S. ruber clade were analyzed, several of them for the first time. All studied species presented 2n  =  2x  =  24 biarmed chromosomes (FN  =  48) and no identifiable sex chromosomes. There are two alternate states associated with the size and morphology of pair 1, corresponding to the S. catharinae clade and to the S. ruber clade. The morphology of pairs 2 and 6 also differentiate the species of both major clades. Species of the S. ruber clade in general have Ag-NORs in pair 11, as is commonly observed among hylines with 2n  =  24. The Ag-NORs' position in the long arms of pair 11 is interstitial in S. fuscomarginatus, S. fuscovarius, S. nasicus, S. similis, S. squalirostris, and S. uruguayus, and terminal in S. acuminatus, S. curicica, S. duartei, S. granulatus, S. hayii, and S. perereca. The single exception among species of the S. ruber clade is S. alter, which has terminal Ag-NORs at the long arms of pair 3. Most species of the S. catharinae clade have Ag-NORs in pair 6, representing a putative synapomorphy of this clade, while the Ag-NORs in pair 11 that occur in S. canastrensis are most parsimoniously interpreted as a reversion. C-banding is predominantly centromeric, but in the S. catharinae clade there is a greater amount of heterochromatin than in the S. ruber clade. This study corroborates the occurrence of informative variation, some already considered in a previous cladistic analysis, and reports new characters, outlining the significance of cytogenetic data for the systematics of Scinax.

This study presents nuclear DNA datasets of nine microsatellites for a new sample of Pacific Bluefin Tuna (Thunnus orientalis) from its common spawning grounds and ten loci for an additional collection of Yellowfin Tuna (T. albacares) from a locale of possible admixture in the western Pacific. Population genetic analyses of these nuclear DNA datasets support within-sample diversities that are similar to each other and to other tuna, multiple cases of heterozygote deficit or excess, and no instances of linkage disequilibrium. Bayesian estimates of effective population size are exceeded by those of census population size (as obtained from fisheries catch data) by a factor of >500. Further Bayesian inferences indicate that the individuals of the sample of T. orientalis belong to a single population, whereas those of the collection of T. albacares may derive from two or more. We now call for more critical testing of these preliminary results with additional geographic samples and automated microsatellite genotyping.

Hybridization of the box turtles Terrapene carolina and T. ornata has been reported throughout their sympatric range. Herein, eight polymorphic microsatellite loci and one mitochondrial polymorphism were used to assess patterns of introgression between these two species, both of which are of conservation concern. We estimated standard population statistics, population assignments, and ancestry for 28 T. carolina, 17 T. ornata, and ten putative T. carolina–T. ornata hybrids from southwest Texas. Both parental populations had high observed heterozygosity and allelic diversity, and there was high gene flow between the two parental species. Ancestry values were sporadic and typical of species that have been hybridizing. Approximately 86% and 76% of T. carolina and T. ornata, respectively, were correctly assigned to their species. Seven of the hybrids had a high level of ancestry for T. carolina and three resembled T. ornata. Interestingly, all T. carolina, putative hybrids, and one T. ornata had haplotypes of T. carolina, whereas all but one T. ornata had haplotypes of T. ornata. These results suggest that hybridization has occurred for several generations within this population, and we discuss how such hybridization may influence population structure for such species of concern.

Although many tortoise species inhabit drought-prone regions with potentially limiting resources, these species have long, iteroparous lives. To assess reproductive responses to variation in rainfall, and to understand interactions among egg size, body size, body condition, and rainfall, we studied egg production in the Namaqualand Speckled Padloper, Homopus signatus signatus, in Springbok, South Africa, in five consecutive spring seasons. Annual rainfall was low and varied substantially (131–226 mm). The percentage of females that were gravid (36–75%) differed among years and correlated with the amount of rain in the months prior to nesting. Gravid females had a higher body condition than that of non-gravid females, presumably because individual variation in resource acquisition caused some females to forfeit reproduction. The body condition of gravid and non-gravid females differed among years and was lowest in the year of lowest rainfall. In most years, egg size correlated to female size, but neither female size nor egg size differed among years. Egg size did not significantly correlate to maternal body size in dry years, when other determinants, such as body condition, seemed to outweigh the effect of body size. Egg volume represented up to 11.9% of female shell volume. The adult shell is somewhat flexible dorso-ventrally, which may help females accommodate the large egg, as indicated by the larger shell height and volume of gravid compared to non-gravid females. Large eggs may be advantageous for H. s. signatus, as larger hatchlings may survive better in arid environments. Since the range of H. s. signatus is threatened with aridification, the effects of drought on egg production may seriously challenge the long-term survival of populations.

The subgenus Nenirana of North American ranid frogs encompasses Pickerel Frogs (Lithobates palustris), Crawfish Frogs (L. areolatus), Gopher Frogs (L. capito), and Dusky Gopher Frogs (L. sevosus). All four species inhabit caves, crevices, stump holes, and/or burrows when not in breeding wetlands. Crawfish Frogs obligately inhabit crayfish burrows as their primary retreat sites, and in this study we examine whether the deep, small-bore crayfish burrows used by Crawfish Frogs have influenced Crawfish Frog morphology. Specimens of all four species of Nenirana were radiographed and snout–urostyle length, maximum headwidth, head length, femur length, and tibiofibula length were measured from films. Our results suggest that if Crawfish Frog morphology is a response to life in burrows, it is due in part to having the size characteristic of being the largest member of the clade and in part through the shape characteristic of generally exhibiting an intermediate morphology between Pickerel Frogs and the two Gopher Frog species. Not all shape metrics, however, are intermediate; among Nenirana, Crawfish Frogs have the longest hindlimbs and the relatively bluntest snouts. Further, Crawfish Frogs exhibit positive allometry in headwidth, a reversal of the ancestral pattern exhibited by Pickerel Frogs. None of the morphological features of Crawfish Frogs fit neatly into known or predicted functional/morphological cause-and-effect relationships associated with burrow occupancy. It may be that the ranid body plan is generalized enough to permit Crawfish Frogs to inhabit, despite being unable to dig, deep small-bore burrows without undergoing major morphological changes.

Invasive Oriental Weatherfish (Misgurnus anguillicaudatus) populations have become established in many countries worldwide. To understand the invasive potential of this non-indigenous species, information about its demography and life history within these novel habitats is needed. Here we present data supporting the use of pectoral fin morphology for determining sex within a population of weatherfish in and around Boise, Idaho, USA. Enlargement of the second pectoral-fin ray and presence of a lamina circularis was seen in males both mature and immature. No such morphology was seen in females. Examination of gonadal tissue confirmed external sex determination in 99% of mature females, 97% of mature males, and 70% of juveniles less than 10 cm total length. This study is the first to verify use of sexually dimorphic fin characteristics as a field diagnostic in an invasive population of Oriental Weatherfish.

Contaminants, including pesticides, can affect an organism's health by weakening its immune system, potentially making it more susceptible to parasites. We used one measure of immune function, leukocyte profiles, and compared these for 82 Northern Leopard Frogs, Lithobates ( = Rana) pipiens, occupying five wetlands with different exposures to the herbicides atrazine and metolachlor, and tested for associations between blood parasites and leukocyte profiles. Hepatozoon spp. (likely H. clamitae) were the only blood parasites detected and were found in only seven (8.5%) frogs. These parasites were associated with fewer eosinophils per leukocyte and higher heterophil∶lymphocyte ratios, although we cannot distinguish cause and effect. Heterophils, lymphocytes, and eosinophils per total number of leukocytes also differed significantly among wetlands, but variation could not be attributed consistently to pesticide contamination.

Embryos of California Grunion, Leuresthes tenuis (Atherinopsidae), must be able to tolerate incubation in an unpredictable environment, and then respond rapidly when the environment becomes favorable for hatching. Since embryos of L. tenuis do not hatch until triggered by an environmental cue, we were able to experimentally generate and examine hatchlings of specific known ages for a series of embryos from the same fertilization date, by hatching them at intervals throughout the extended incubation period. During this time, most morphological features did not develop as they would have if the embryo had hatched into larval life. This study examined the development of embryos of L. tenuis extending incubation from the time of hatching competence, at approximately ten days post fertilization (dpf), to the time of embryonic death at 35 dpf. The embryos during extended incubation arrest most aspects of development, including organogenesis and fin development. Melanophores, sagittal otoliths, and marginal teeth continue to develop in embryos until hatching or embryonic death. Thus individual L. tenuis of the same chronological age may be either embryonic or larval, at very different stages of development, depending on which day hatching takes place. This example of heterokairy may be a useful new model for studies in developmental biology.

The distinctive hump on the forehead of large individuals of the Humphead Wrasse, Cheilinus undulatus, a protogynous hermaphroditic reef fish, is often assumed to be a male-associated secondary sexual characteristic, but this has never been evaluated. A unique opportunity arose to obtain confiscated specimens, 161 females and 17 males, ranging in body sizes from 20.8 to 129.0 cm total length (TL), making this evaluation possible for the first time. The hump was quantified in terms of its maximum angle of elevation, and its development was determined to be size-associated. A notable hump was recorded in 16 females and all 17 males, becoming visible around 37.0 cm TL, and all specimens ≥75.0 cm TL exhibited a distinctive hump, irrespective of sex. There was a linear and positive correlation between body size and maximum angle of hump elevation for both sexes; males tended to have larger humps because they were larger in body size rather than because of sexual dimorphism for hump development. The development of a cephalic hump or a horn on the forehead has been documented in several groups of reef fishes, and its possible adaptive significance in different groups is discussed.

Freshwater fishes exhibit a high diversity of colors and color patterns. In particular, fishes of the genus Etheostoma have colors perceived by humans as red, orange, yellow, green, and blue in a variety of combinations. We used reflectance spectrophotometry to evaluate color diversity quantitatively among four species of Etheostoma: E. baileyi, E. coosae, E. zonale, and E. zonistium. Three spectral types were identified, corresponding to colors perceived by humans as ‘blue’ or ‘green,’ ‘red’ or ‘orange,’ and ‘yellow.’ Species differences in the peak wavelengths of the ‘blue’ and ‘green’ spectra were observed, and these complex spectra also differed in reflectance in the long-wavelength portion of the spectrum. Species also differed in the midpoint reflectance of ‘red’ and ‘orange’ spectra. By presenting preliminary descriptions of spectral properties of breeding males, we provide a framework for further investigations into the evolution of breeding coloration and visual ecology in darters.