Fitness attributes acquired in aquatic habitats by amphibians exhibiting complex life histories have been shown to cascade through terrestrial juveniles into adulthood, a phenomenon termed carry-over effects. We explored density-dependent fitness attributes and carry-over effects in Crawfish Frogs (Rana areolata) using a set of field enclosure experiments and a series of field data. Using field enclosures, we hypothesized that 1) at high densities, intraspecific competition would produce smaller Crawfish Frog juveniles that took longer to metamorphose; 2) at high densities, interspecific competition would also produce smaller Crawfish Frog juveniles that took longer to metamorphose; and 3) vertebrate (ambystomatid salamander) predation on Crawfish Frog larvae would reduce survivorship, but by releasing competition pressure would produce relatively larger tadpoles that metamorphosed earlier. Further, we hypothesized 4) that these enclosure results would apply to field data, and that fitness attributes in newly metamorphosed Crawfish Frogs would carry over to first-time breeding adults. Our results confirmed all four hypotheses. Specifically, in Crawfish Frogs, at high densities, both intra- and interspecific competition reduced size (length and mass) at metamorphosis (hypotheses 1 and 2), and predation reduced survivorship and increased size at metamorphosis (hypothesis 3). Finally, we observed density-dependent fitness effects on newly metamorphosed Crawfish Frog juvenile size (length and mass), and carry-over effects from the larval stage on juvenile survival, adult size, and breeding adult numbers (hypothesis 4). In the absence of predators, high densities of intra- and interspecific competitors had no effect on Crawfish Frog larval survivorship. We also present suggestive evidence for compensatory effects. We discuss the potential mechanisms underlying the patterns of these interactions, as well as the role of these relationships in informing management guidelines intended to ensure the future of this species of conservation concern.

All organisms are constrained by limited energy and thus must allocate resources in such a way to maximize fitness. Due to their importance to survival, immunity and performance are each often favored in selective environments and thus may be tradeoffs of each other. To test this tradeoff hypothesis, we compared performance to three constitutive measures of immunity in a wild hybrid population of water snakes (Nerodia clarkii X Nerodia fasciata): agglutination response to sheep red blood cells (SRBC), heterophil: lymphocyte ratio (HLR), and bactericidal ability (BA). Performance was quantified by exercising snakes up to the point of loss of righting response (LRR) and measuring plasma lactate concentration at this point of fatigue. Support for the tradeoff hypothesis was mixed among the immune assays. Bactericidal ability had a significant positive correlation with LRR (P = 0.003, R² = 0.263); this was counter to our tradeoff hypothesis and suggests that individuals invest in both traits simultaneously. We failed to detect a significant relationship between SRBC and performance. A significant negative relationship was found between HLR and LRR (P = 0.005, R² = 0.237). Heterophil: lymphocyte ratio is a balance between innate and acquired immunity that is also indicative of baseline stress. This result showed that snakes with higher HLR are constrained and perform poorly compared to snakes with lower HLR, thus indicating a potential role of stress in affecting performance. Alternatively, this result may denote that internal tradeoffs in the immune system between innate and acquired immunity drive tradeoffs between immunity and performance. Snout–vent length (SVL) was significantly positively correlated with our performance measure (P = 0.012, R² = 0.192). This result may be explained by selection driving increases in performance and/or ontogenetic development of the locomotor apparatus. Similarly, SVL was an important driver of immunity in snakes. Together, these results clearly show an important link exists between multiple physiological traits that are each vital to survival.

Trichomycterus lauzannii, new species, is described from the upper Río Beni basin in La Paz, Bolivia. The new species is distinguished from congeners by the posterior cranial fontanel reduced to a small round opening on the posterior portion of supraoccipital bone and the possession of a rounded anterior cranial fontanel between frontal bones. In addition, the new species can be further distinguished from congeners by the possession of seven or fewer odontodes in the opercular patch, a pelvic fin which does not reach the anus when depressed, round blotches along the side of body, a first pectoral-fin ray prolonged as a short distal filament, and several meristic and morphometric features. Comparisons are given with similar congeners (T. cachiraensis, T. megantoni, T. sketi, and T. steindachneri).

Gymnotus is the most species-rich and geographically widespread genus of gymnotiform electric fishes and has been widely explored to understand mechanisms of diversification in Neotropical freshwater fishes at a continental scale. Within Gymnotus, the subgenus Lamontianus is a phenotypically distinctive clade with an elongate, cylindrical body shape currently known from four valid species (G. anguillaris, G. cataniapo, G. pedanopterus, and G. tiquie) restricted to rivers draining the Guiana Shield. Here we use aspects of body-surface coloration, meristic, morphological, and osteological data, including cranial, laterosensory pore, and postcranial characters, to diagnose two new species of Lamontianus that inhabit the Aripuanã and Arapiuns rivers that drain the Brazilian Shield. We also use geometric morphometric analyses of head shape to separate the new species from one another and other species of Lamontianus. We report biogeographic distributions for all species of Lamontianus and estimate ancestral geographic ranges and range evolution using the parametric biogeographic program BioGeoBEARS. We use the phylogeny of Lamontianus to test alternative hypotheses regarding lineage divergence times, before or after the formation of the modern East-draining Amazon at c. 10 Ma. Our analysis suggests that diversification in Lamontianus occurred primarily by geographic range fragmentation (vicariance) from an ancestral species distributed across the Western Guiana Shield. These results are similar to those of other Gymnotus and gymnotiform clades, where allopatric speciation and secondary contact due to geographic range expansion are commonly observed. This study brings to 46 the number of valid species of the genus Gymnotus, and to six the number of valid species of the subgenus Lamontianus.

The Southeast Asian cyprinid genus Henicorhynchus has a complicated taxonomic history due to morphological similarities with other genera and among species within the genus itself. Henicorhynchus and its constituent species are herein revised based on morphological examinations of over 1,000 specimens with a particular emphasis on oromandibular structures. Five species are now recognized in the genus. Henicorhynchus entmema and H. caudimaculatus are senior synonyms of H. lobatus and H. lineatus, respectively. Henicorhynchus caudiguttatus is removed from synonymy with H. caudimaculatus. A revised diagnosis of the South Asian cyprinid genus Gymnostomus, previously considered a senior synonym of Henicorhynchus, is also provided.

The acoustic signals in Atelopus (Anura: Bufonidae), a Neotropical genus currently composed of 97 species, are poorly known. In this study, we describe for the first time, the advertisement, release, and agonistic calls of Atelopus laetissimus, an endangered species endemic to the Sierra Nevada de Santa Marta, in northern Colombia. The calling behavior of males was associated with reproduction (advertisement calls) and male–male aggression (agonistic and release calls). We also describe, for the first time, calls from female A. laetissimus, constituting the first case of a female's vocalization in the genus, recorded while one male was trying to clasp her. The diverse acoustic signals described here for Atelopus laetissimus suggest the vocal repertoire in the genus Atelopus may be more complex than is currently realized.

Previous studies have reported egg attendance as the most common protective behavior among the Neotropical frog family Centrolenidae. However, research on the effect of parental care and other factors thought to affect offspring survival is still missing for a great number of species. Here, we performed field observations during day and night to associate male-only care, habitat characteristics, and environmental variables with egg clutch survival in the understudied glass frog, Hyalinobatrachium talamancae. We conducted 34 nest survival models for 39 egg clutches considering constant daily survival rates, temporal variation in the survival probability, and other biotic and abiotic variables thought to affect the survival of embryos. We found that egg attendance was strongly associated with egg clutch survival in H. talamancae. Our results showed similar degrees of parental investment during day and night, accounting for extensive caring periods over one or multiple clutches as paternal care did not hinder re-mating in this species. Egg clutches exhibited daily survival rates of 0.93±0.02, often reaching pre-hatching stages when attended by males. Our results may thus suggest that egg attendance is a major, if not predominant, determining factor of embryo survival in H. talamancae. This study contributes to the understanding of the natural history associated with paternal care in H. talamancae and provides insight into the evolution of prolonged male-only care in the family Centrolenidae.

A new viviparous halfbeak, Nomorhamphus aenigma, new species, from the upper stream of the Cerekang River in central Sulawesi, Indonesia is described. The new species is distinguished from all other zenarchopterids by the complete absence of elongate lower jaws. Although secondary loss of elongate jaws is also known from several hemiramphids, N. aenigma, new species, is clearly different from them by having no elongate jaws throughout ontogeny.

Surfperches (Embiotocidae) are a unique family of viviparous fishes that have internal fertilization, gestation to the sub-adult stage, and live-birth; therefore, maternal investment is extremely high. This invokes the expectation that brood size is limited and females should be choosy and select few mates. Yet multiple paternity occurs in all eight species examined to date, with high prevalence ranging from 92–100%. Most surfperches are found along the Eastern Pacific coast, but Ditrema temminckii is distributed in the Western Pacific and we found differences in their mating strategy compared to other surfperches. In D. temminckii, prevalence of multiple paternity was only 60%. Further, the average number of sires was only 1.86 per brood even though brood sizes ranged from 12–45, and paternity was skewed, with the majority of paternity allocated to a single male. We propose that these differences may be associated with strong female selection on males in this species. Finally, we evaluated whether the number of fathers is an accurate estimate for the number of mates by comparing the number of alleles detected from fathers within the brood to the number of alleles from mates via genotyping alleles from spermatozoa within the uterine sac and found no significant difference, suggesting that the number of sires is a reasonable estimate for the number of mates in D. temminckii.

Reproductive physiology is influenced by environmental pressures, particularly in ectothermic species living in harsh climatic conditions. Studying the period of time in which males exhibit semen availability and their sperm traits constitutes a powerful tool to evaluate the fertility potential of males because sperm size and sperm velocity have been proposed as determinants in fertilization success. Pristidactylus achalensis is a lizard endemic to the highest mountain areas in Central Argentina and shows a pattern of seasonal activity. Here, we study the period of time when males possess sperm during the active season and characterize the spermatozoa based on sperm morphometric and dynamic traits among males and within ejaculate. Males possess sperm in their ejaculates only during the spring months of the active season, suggesting that reproductive activity is restricted to this time. Spermatozoa of Pristidactylus achalensis show intra-specific variation in sperm traits among males and within ejaculate, suggesting different reproductive potential among males. Since this species only occupies the highest areas of the mountains and is categorized as vulnerable, basic information about reproduction and sperm physiology could be useful for potential population conservation strategies.

A new species of glyptosternine catfish of the genus Exostoma is described from the Chakpi River, a tributary of the Chindwin-Irrawaddy drainage in northeastern India. The new species can be distinguished from congeners of the Chindwin-Irrawaddy drainage except E. chaudhurii and E. vinciguerrae in having an adipose fin confluent (vs. separate) with the upper procurrent caudal-fin rays. It differs from E. chaudhurii in having anastomosing, rounded (vs. parallel) striae on the anterolateral surfaces of the lips and from E. vinciguerrae in having shorter adipose-fin base (29.1–32.3% SL vs. 35.4–39.4). This is the sixth species of Exostoma known from the Chindwin-Irrawaddy drainage.

The anti-equatorial labrid Pseudojuloides elongatus has a wide but disjunct distribution across the Western Pacific and Eastern Indian Oceans, with populations occurring in Western Australia, southern Japan, and the southwest Pacific Ocean. Principal component analysis of morphological characters and coalescent-based species-tree estimates of mitochondrial and nuclear DNA markers suggest that these populations are under incipient stages of divergence. The three allopatric populations differ strongly in coloration patterns of both sexes, particularly in terminal males, suggestive of reproductive isolation. We redescribe Pseudojuloides elongatus on the basis of nine paratypes and two additional specimens from eastern Australia and Norfolk Island, and describe two new species, Pseudojuloides crux, new species, from Western Australia, and P. paradiseus, new species, from southern Japan. The complex is distinguished from other members of the genus in sharing the following combination of characters: body elongate; dorsal-fin rays IX,12; pectoral-fin rays 12; no median predorsal scales; and usually 27 lateral-line scales. We briefly comment on anti-equatorial biogeographical patterns and Pseudojuloides argyreogaster from the Western Indian Ocean.

Competition for resources between sympatric species can result in reduced fitness. Resource partitioning allows the minimization of competitive pressures, consequently promoting the coexistence of a diversity of species. We tested the hypothesis that the Striped Plateau Lizard (Sceloporus virgatus) and the Ornate Tree Lizard (Urosaurus ornatus) that occur in sympatry in the Chiricahua mountains of Arizona, USA have distinct ecological niches to minimize interspecific competition. We compared the activity times, perch microhabitat characteristics, and diet of these insectivorous lizards to test the prediction that they partition resources. Although we found no difference between the two species in the time at which lizards become active in the morning nor in the composition of their diets, the two species used different structural perch microhabitats. The Ornate Tree Lizard selected higher and narrower perches with more closed canopy than the Striped Plateau Lizard, and males generally occupied higher perches than females. These differences in perch microhabitat use may reduce interspecific competition and allow these two sympatric species to cohabitate.

Gladwyn Kingsley Noble was the first investigator to collectively examine courtship glands and correlate their function to the tail-straddling walk in plethodontid salamanders. While mental glands and caudal courtship glands have received the majority of attention since Noble's seminal work, Noble described other glands from Eurycea bislineata that were putatively involved in courtship that have received little or no attention (e.g., glands at the temporal regions of the heads of males). Previous studies demonstrated that heads of males enlarge during the mating season and some studies indicated that the enlargement was because of Noble's previously described temporal glands; however, current consensus of male head enlargement is that skeletal muscle hypertrophy is the cause of the head growth. In this study, we examined male and female E. bislineata throughout the year to test Noble's hypothesis that males possess courtship glands in the integument of the temporal regions of their heads and to assess what underlying tissues are involved with male head enlargement during mating. We found that the temporal regions of male heads change dramatically from non-mating to mating months, exemplified by two-dimensional geometric morphometrics. This variation is a result of M. levator mandibulae externus hypertrophy rather than glandular activity underlying the integument. Although no glandular masses isolated at the temporal regions of the heads result in this dynamic shape change, simple alveolar glands that resemble stereotypical courtship glands are found in the integument of only males from the mating season. These putative courtship glands are scattered amongst mucous and serous glands within the integument around the eyelids to at least the posterior termination of the cranium. The function of these glands is unknown but is probably involved with pheromone production, similar to more thoroughly examined courtship glands.

Assembled here is a reasonably complete list of annotated codes for historical and modern natural history collections associated with lost and extant specimens of fossil and Recent fishes, amphibians, and reptiles. A total of 3,845 codes are anchored to about 2,064 distinct collections and/or institutions in 155 countries. At least 633 of those collections are exclusively paleontological or include fossil specimens. The list is primarily derived from the scientific literature and may serve as a resource for plainly citing specimens in publications and for linking such citations to records in online databases.

Many invasive species may be constrained in their ability to invade high latitude or elevation habitats due to limits of cold tolerance. However, isolated populations at the edge of these species' geographic ranges may face a combination of strong selection and lack of maladaptive gene flow that allows them to adapt to the cold and invade further. Here we show that an isolated population of Gambusia affinis (on Cape Cod, MA, USA), one of the most invasive fish in the world, can survive temperatures lower than any reported tolerances for other populations, with large, long-lived females showing more tolerance than males. Indeed, male acute cold tolerance appears insufficient, suggesting the population may persist through winters mainly via the ability of mated females to delay offspring production until spring. This combination of female cold tolerance and life history may open the door for further expansion of this invasive species into high latitude freshwater habitats.

Pseudojuloides pluto, new species, is described on the basis of the holotype and 11 paratypes from Wake Island, northeastern Micronesia, and nine paratypes from the Maug Islands, Northern Mariana Islands. The new species has previously been confused with Pseudojuloides atavai, but molecular analysis of mitochondrial COI reveals a difference of 6.8% in sequence data between both species, in addition to differences in meristic, morphometric, and coloration details. A second new species, Pseudojuloides proserpina, is described from Fatu Hiva, Marquesan Islands on the basis of the male holotype. The two new species are closely allied to Pseudojuloides atavai, and together form a species complex that differs from other members of the genus in having males that share the following combination of characters: interspinous membrane between the anterior two to three spines of the dorsal fin with a black spot; head extensively reticulate (reduced in P. pluto, new species); dorsal-fin base with a pink stripe; abdominal region behind pectoral and pelvic fins pale lilac to orangey pink (width of this region dependent on species) with a crosshatch or honeycomb pattern; and extensive black coloration over at least posterior half of body. Additionally, females of both P. atavai and P. pluto, new species, are distinctly bicolored (versus unicolored and suffused in all other congeneric species). Although the female form of P. proserpina, new species, is not known, it is likely that it shares this general coloration pattern, which may serve as an additional character uniting members of the Pseudojuloides atavai complex. We briefly discuss the phylogenetic relationships of Pseudojuloides inferred on the basis of mitochondrial DNA.