The morphology of the larval oral disc, nostril, skin, and vent tube of tadpoles of Andean stream dwelling Hyloscirtus (Hylidae: Hylinae: Cophomantini) was studied. A wide variation of larval tooth row number is compiled from literature and from observations of Colombian specimens in museums. The marginal papillae are precursors of the tooth rows. The submarginal papillae are organized parallel to the anterior tooth rows and are precursors of the flaps or accessory tooth rows. There is no particular tooth row formula, and no particular marginal papillae arrangement for a species or a recognized species group in the genus. The number of tooth rows and of accessory tooth rows increase with development and size of the tadpole. Two species groups are identified inside Hyloscirtus based on the tooth row formulae, upper jaw sheath morphology, and shape of the nostril of tadpoles. The two groups identified here are different from the three species groups currently recognized for the genus and show well-delimited geographic distributions through the northern Andes. Nostril shape of one species group of Hyloscirtus recognized here is putatively present in all Cophomantini. Spots on the venter associated with neuromasts are present in all the tadpoles of Hyloscirtus studied, and presumably the same as the ones found in some Hypsiboas and Aplastodiscus (Hylidae: Hylinae: Cophomantini). A saccular structure associated with the vent tube covers developing hindlimbs of all tadpoles of Hyloscirtus, and is proposed as a morphological synapomorphy of the genus.

A common legskate from southern Africa, misidentified for the last half century as Cruriraja parcomaculata, is redescribed as C. hulleyi. A number of morphometric and meristic characters are identified that distinguish C. hulleyi from C. parcomaculata ( = triangularis). Cruriraja hulleyi exhibits midback thorns in a continuous row above the anterior half of the abdominal region, the interdorsal space is usually greater than half the dorsal-fin base length, the clasper eperon is not bifurcate, and the clasper ventral surface lacks dermal denticles. Relative to C. parcomaculata, C. hulleyi is larger, has a shorter snout, smaller eyes, a more obtuse snout angle, fewer lower jaw tooth rows, more turns in the spiral valve, more nuchal thorns, exhibits scapular thorn patches and more predorsal midline thorns, and has a spatulate rather than pointed distal tip of the anterior lobe of the pelvic fin. The two species occur in allopatry, with C. hulleyi ranging from Namibia to the Eastern Cape Coast of South Africa and C. parcomaculata distributed from kwaZulu-Natal, South Africa to Mozambique.

A new species of Scincella, previously confused with S. lateralis, is described from the Cuatro Ciénegas Basin, Coahuila, Mexico. The new species differs from all congeners in North and Middle America by possessing two dark, narrow ventrolateral stripes on each side (vs. dark, narrow ventrolateral stripes on each side absent in the other species); from all congeners in North and Middle America, except S. lateralis, by having three or more pairs of nuchal scales (vs. fewer than three pairs of nuchals in the other species) and the first nuchal in contact with the tertiary temporal row (vs. first nuchal usually in contact with the upper secondary temporal in the other species); and from S. lateralis by having longer limbs (limbs overlapping by 1–15 scales when adpressed against body, hindlimb length/SVL ratio 0.30–0.42,  =  0.36; vs. limbs separated by 2–23 scales when adpressed against body, hindlimb length/SVL ratio 0.24–0.37,  =  0.30, in S. lateralis) and usually more scales around midbody (28–30,  =  29.0, n  =  15; vs. 24–29,  =  26.4, n  =  28, in S. lateralis). The new species is geographically closest, and morphologically most similar, to S. lateralis.

Cyphocharax pinnilepis, a species of curimatid characiform apparently endemic to the Rio de Contas system in Bahia, Brazil, is described as new. It is only the sixth member of the Curimatidae known from the coastal rivers of Brazil across the expanse from south of the mouth of the Amazon River to the state of São Paulo, but the third curimatid species from the Rio de Contas. The basis for the assignment of the species to Cyphocharax is discussed, and it is diagnosed from congeners on details of pigmentation, the pattern of scales on the lobes of the caudal fin, meristics, and morphometrics.

We examined the genetic population structure for the Great Plains Toad (Bufo cognatus) in the Chihuahuan Desert of southern New Mexico in order to discern at what spatial scale genetic differentiation is apparent. In addition, we tested whether habitats in the Chihuahuan Desert of southern New Mexico differed in their resistance to gene flow in B. cognatus. We used microsatellites to estimate genetic differentiation in populations that varied in distance from 1 to 60 km. Of 120 pairwise tests of genetic differentiation, 44 were significant. However, differentiation was low between all sites (F_ST  =  0.0–0.087), almost all of the genetic variation being within populations (96.3%). Compared to published studies of other anuran species, populations of B. cognatus in southern New Mexico are among the most genetically homogenous anuran species. Significant isolation by distance did occur over all populations despite the genetic similarity, suggesting that differentiation does occur at a broader scale. In addition, several landscape-based models of gene flow were produced and tested against the allelic data. A community model assigned each plant community a different level of resistance to gene flow. This model was not found to describe the estimated genetic variation between populations better than simple Euclidean distance. However, the river model, which assigned low resistance to the aquatic habitats including the Rio Grande, described the estimated genetic variation better than Euclidean distance, suggesting that the Rio Grande, and potentially other rivers throughout the toad's range, may act as a route of dispersal for B. cognatus, reducing genetic differentiation among distant populations.

A new species of Atractus, previously reported as a disjunct population of A. zidoki south of the Amazon River, differs from all congeners in having an undivided sulcus spermaticus. Herein, we restrict the concept of A. zidoki to populations north of the Amazon River, provide a detailed description of its everted hemipenis, and describe a new species to accommodate the population occurring to the south of the Amazon River. Additionally, we briefly discuss intraspecific variation and the systematic value of the hemipenis structure in snakes, mainly with respect to the genus Atractus.

We describe a new species of anuran from the Cordillera Central, El Copé, Coclé Province, Panama. The species is assigned to the Craugastor rugulosus species series of Neotropical stream-dwelling frogs, which contains 33 species and which ranges from Mexico to central Panama. The new species differs from all other members of the C. rugulosus species series by the combination of the absence of vocal slits and nuptial pads, and the presence of strong toe webbing and a large flap-like tarsal fold. This species experienced population declines in central Panama in 2004 and no remaining populations are known.

We describe a new toadlet species of the genus Brachycephalus from the Atlantic rain forest in the State of São Paulo, in southeastern Brazil. Specimens were collected from the leaf litter at approximately 750 m above sea level. The new species differs from its congers by the following combination of characteristics: SVL in adult males 11.3–12.1 mm and SVL in adult females 13.4–14.2 mm, skin on head and dorsum with co-ossification, general color in life orange with dorsal greenish irregular markings covered with small dark spots and dots, skull hyperossified, spinal processes of sacral and pre-sacral vertebrae hyperossified, and hyperossification of the distal end of the process of the fourth vertebra. The new species shares with most other Brachycephalus species remarkable traits, such as miniaturization and hyperossification of the skeleton. The new species probably occurs in isolation in highlands of the Atlantic Forest.

The broadly distributed Indo-Pacific moray eel Anarchias cantonensis (Schultz, 1943), heretofore treated as a single species, consists of three species: A. cantonensis, A. exulatus, a new species, and A. schultzi, a new species, based on geographic distribution, coloration, external morphometrics, and vertebral counts. We examined 112 specimens and determined that the true A. cantonensis is distributed throughout the eastern Indian Ocean, western Pacific, and tropical central Pacific, and has a mean vertebral formula of 91/93/104. Anarchias exulatus is distributed anti-tropically in the central and southeastern Pacific and is characterized by a unique mottling pattern and a mean vertebral formula of 100/103/114. A third species, named here as A. schultzi, is characterized by a mean vertebral formula of 96/99/109, a plain brown coloration in adult form, and is restricted geographically to Tonga, New Caledonia, the Solomon Islands, and the Caroline Islands. At the Tonga Islands, which reside on the edge of Australian and Pacific tectonic plates, all three species are present, but maintain their morphological distinctiveness and segregate ecologically.

This study examined diet composition, selection, and trophic morphology among three zooplanktivore silverside fishes (Chirostoma spp.) in an attempt to describe niche partitioning among closely related species in the tropical, shallow Lake Chapala, Mexico. To emphasize species interactions, sampling was carried out at the peak of the dry season (May) when a concentration effect was expected to take place as a consequence of lake volume reduction. Prey selection differed among species: Chirostoma consocium selected cyclopoid and calanoid copepods; C. jordani selected Bosmina and Diaphanosoma; C. labarcae selected Daphnia and Ceriodaphnia. Larger fishes occasionally consumed Hemipteran larvae. Although two Chirostoma species preyed upon the same zooplankton species, prey selection was consistent across size classes. From a total of 32 morphometric and meristic characteristics related to trophic ecology, 13 characteristics differentiated species, according to the discriminant analysis. Ordination including 11 morphometric characteristics and six zooplankton food items graphically separated the three species. The first axis separated species according to prey classes (copepods vs. cladocerans) and gross morphology (head and anal fin lengths). The second axis emphasized size-selective predation on cladocerans (Bosmina vs. Daphnia consumers) and fine trophic morphology (oral gape and the gill rakers' structure). Our findings suggest that the permanence of all three species in a fluctuating environment is the result of the circumvention of competition by niche partitioning, promoted by prey availability, selective predation, and few but critical differences in trophic morphology.

The Fourspine Stickleback (Apeltes quadracus) is a diminutive member of the Gasterosteidae inhabiting a rather narrow zone comprising coastal and near-coastal brackish and freshwater habitats from the Gulf of St. Lawrence to North Carolina. Behavior, morphology, and several other aspects of the biology of A. quadracus have been well studied, yet there are surprisingly few investigations of its life history. Here, we provide data on four reproductive traits for female A. quadracus from seven sites in Nova Scotia, Canada. The sites occur within three distinct regions of Nova Scotia, and encompass a variety of brackish-water and freshwater habitats. Female size, clutch mass adjusted to a common body size, and clutch size adjusted to a common body size differed significantly among the three regions. These traits also showed significant variation across sites within regions. Egg dry mass did not differ across regions, but there was significant variation across sites within regions. Our study, and earlier ones from more southern populations, indicate that there may be variation of evolutionary interest in several traits on multiple spatial scales in this species.

Determining the demographic structure of turtles is important to understanding their population status and conservation needs. Concern has been raised for the long-term persistence of the Western Pond Turtle (Actinemys marmorata) based on demographic analyses using size while ignoring age. Here, we compare the size versus age structures, and examine growth curves, for turtle populations from four sites in the Klamath–Siskiyou ecoregion of northern California and southern Oregon. We show that age structure does not correspond to size structure for two populations. Also, the most abundant of these populations had relatively few small turtles, which suggests inability of previous researchers to locate small turtles. Growth rates and adult size differed among populations, with turtles from two sites in the Coast Range significantly smaller and slower growing than turtles from either a reservoir on the eastern lower slopes of the Coast Range or the Klamath Basin east of the Cascade Mountains. Neither air temperature nor elevation explained the differences in size and growth rates. We hypothesize that larger body size and faster growth rates for some populations of A. marmorata may be due to high local productivity. We show that use of size alone gave an erroneous interpretation of population structure. Finding a few small-sized turtles in populations may not represent a lack of recruitment but, instead, a need to determine the proportion of young turtles based on their actual ages.

Predation has long been known as a structuring force of larval amphibian assemblages with aquatic vertebrates and insect larvae being noted as important predators. However, no studies report predation by micro-predators (i.e., organisms less than one half the size of amphibian eggs) on eggs or larvae. Here we report the consumption of Green Frog (Rana clamitans) eggs by at least four species of the crustacean class Ostracoda (Dolerocypris sinensis, Cypridopsis vidua, Eucypris fuscatus, Physocypria sp.). We initially observed Green Frog egg consumption in microcosms containing sediment from stormwater management ponds. We subsequently conducted feeding studies in which we manipulated densities of three of the species and recorded time to complete consumption of a single egg. Ostracods often consumed eggs in three days (before eggs hatched), but did not appear to attack tadpoles in the microcosms. Overall density of ostracods was correlated with egg mortality in the microcosms and Eucypris fuscatus consumed eggs most efficiently during feeding trials. Because one of the ostracods we observed feeding on amphibian eggs (C. vidua) is common among temporary wetlands, and one (D. sinensis) represents the first reported occurrence of the species in North America, there is a need for further investigations of ostracod predation on amphibian eggs under field conditions.

In the Sierra Nevada Mountains of California, Yosemite Toads (Anaxyrus canorus) have declined throughout their range where Brook Trout (Salvelinus fontinalis) have been widely introduced. Amphibians that evolved in fishless habitats often lack the necessary chemical defenses and behavioral responses to avoid predation. True Toads (family Bufonidae), however, possess noxious chemicals that often deter predators. Our goal was to test whether eggs, tadpoles, and postmetamorphic toads of A. canorus are a palatable food source for S. fontinalis, assess the antipredator behavior of tadpoles of A. canorus by exposing them to various predator chemical cues, and determine sublethal effects on three lifestages of A. canorus from sampling by S. fontinalis. We found that eggs, tadpoles, and postmetamorphic toads of A. canorus exhibit absolute unpalatability to S. fontinalis. In addition, tadpoles of A. canorus did not exhibit a significant difference in behavior when exposed to chemical stimuli. Moreover, observational experiments revealed that trout would sample, then reject lifestages of A. canorus unharmed, while trout readily consumed tadpoles of Pacific Chorus Frog (Pseudacris regilla). We therefore infer that early lifestages of A. canorus likely possess existing chemical defenses as a result of interactions with native predators that adequately protect them from nonnative trout predation. Although trout removal often leads to the recovery of other Sierra Nevada amphibian populations, trout removal would likely have no effect on populations of A. canorus given our results. Therefore, we suggest that other factors thought to be contributing toward A. canorus decline should be investigated before efforts are concentrated on removing trout from toad habitats.

The effect of increased turbidity levels on aquatic organisms is an increasing concern for aquatic biologists. Recent studies show reduced foraging efficiency of drift-feeding fish species, which are highly visual predators, with increasing water turbidity. Similar to fish, many aquatic turtle species are highly visual aquatic predators that may be negatively affected by increasing water turbidity. We used Eastern Painted Turtles (Chrysemys picta) to test the hypothesis that increasing water turbidity would decrease prey capture efficiency. We classically conditioned eight C. picta to search for a food item when presented with a novel stimulus, and then measured the time it took each turtle to find a prey item under a range of 26 turbidity levels (≤40 nephelometric turbidity units, NTUs) presented in a random order. All turtles were successfully trained within 29 days to search for the food item when presented with the stimulus. Turbidity had no effect on the probability of successful prey capture. Turtles located the prey item in 97% of trials regardless of turbidity level. Turbidity had a minor effect on time to prey capture, increasing from an average of 30 seconds at a turbidity level of 2 NTUs to 55 seconds at 40 NTUs. Overall, turbidity level explained approximately 2% of the variation in the time it took a turtle to locate a prey item. These results contrast sharply with a nearly identical study, which showed that turbidity explained 70% and 90% of the variation in drift-feeding fish reactive distance and prey capture success respectively, and that a turbidity of only 9–10 NTUs reduced fish foraging performance by 50%. We suggest that resilience to turbidity effects on foraging proficiency among generalist species may be important to understanding their persistence in more degraded aquatic environments compared to more specialized species.

Plethodontid salamanders within the genus Desmognathus range from species that are primarily aquatic to species that are fully terrestrial. Thus, these species are a good model system to use for a comparison of the effect of tail loss on maximal swimming and running performance, and propensity for caudal autotomy in closely related species that primarily inhabit either aquatic or terrestrial environments. I examined the effect of caudal autotomy on maximal swimming and running speeds in D. quadramaculatus (a larger, more aquatic species) and in D. ocoee (a smaller, primarily terrestrial species). Prior to tail loss, aquatic burst speeds were greater than terrestrial burst speeds for individuals of D. quadramaculatus, but the converse was true for individuals of D. ocoee. During aquatic locomotion in each species, burst speed was significantly reduced after autotomy. With the loss of about 65% of tail length, swimming burst speed declined about 50% for D. quadramaculatus and 40% for D. ocoee. Terrestrial burst speed was not reduced in either species after autotomy. These results show that tail loss is costly for primarily aquatic desmognathine salamanders in terms of a reduction in maximal locomotor performance. The time required for caudal autotomy increased significantly with body size in each species, and larger individuals of D. quadramaculatus would bite prior to autotomy. Thus, larger individuals of D. quadramaculatus may utilize caudal autotomy less readily and rely more on alternative antipredator mechanisms such as biting, and this may be related to a higher locomotor cost of autotomy for such individuals.

The African Jewelfish (Cichlidae: Hemichromis letourneuxi) is a predatory, non-native fish that has recently (since 2000) begun to expand its geographic range across south Florida. The salinity tolerance of H. letourneuxi was unknown, and thus it was unclear whether the species could use estuarine or coastal environments. The response of H. letourneuxi to chronic change in salinity was evaluated here by exposing fish to progressively increasing salinities (0–80 ppt). Fish were held at target salinities for a minimum of 30 days. The species showed excellent survival from 0–50 ppt. At 60 ppt, only 25% of the fish survived, and mean estimated survival time was 12 days. Above 60 ppt, mortality was 100%. Fish grew equally well from 0–50 ppt. In another experiment, fish were transferred directly from freshwater to various salinities from 5–35 ppt (seawater) and held for seven days, after which survivors were returned to freshwater. All fish transferred directly from freshwater to salinities up to 20 ppt survived; only 56% survived when transferred from freshwater to 25 ppt, and none survived transfer above 25 ppt. Experimental results indicated that H. letourneuxi can persist easily in salinities prevalent in coastal environments, even during periods of hypersalinity common in south Florida estuaries. Salinity will not restrict its dispersal by coastal pathways.

The keratinized mouthparts of tadpoles are complex structures that play a significant role in feeding. Recent evidence has shown that the keratinized labial teeth function in two ways: to anchor the oral disc to a substrate and to rake material from it. Reports of tadpoles with missing or deformed keratinized oral structures have increased. Yet, the impact missing teeth has on feeding remains unexplored. Here we use high speed videography (500 frames per second) of tadpoles of Southern Leopard Frog (Lithobates sphenocephalus [ = Rana sphenocephala]) to study how missing teeth affect feeding. Specifically, we test the hypothesis that the number of teeth present correlates with two metrics of the effectiveness of a tadpole to rake material from a substrate. Those are the duration of the full gape cycle (opening and closing of the jaws) and of the closing phase (closing of the jaws once attached to a substrate). We found a significant positive relationship between duration of time of the closing phase of the gape cycle and the number of labial teeth present. Thus, tadpoles with fewer teeth were in contact with a planar algal-covered substrate for a shorter duration than tadpoles with more teeth. Given the reports of tadpole mouthpart abnormalities, data relating feeding kinematics of tadpoles with missing labial teeth are relevant in assessing the impact these abnormalities have on larval performance. Our data indicate that tadpoles missing labial teeth forage less effectively than tadpoles with undamaged dentition. This may help explain the pattern of reduced growth and developmental rates commonly observed in tadpoles raised in polluted environments or infected with pathogens that attack keratinized oral structures.

Chytridiomycosis, a disease caused by the fungus Batrachochytrium dendrobatidis (Bd), potentially disrupts osmoregulation or respiration across the skin of amphibians it infects, releases toxins into the host, or both. We investigated whether infection with Bd alters water balance or metabolic rate of the hylid frog Litoria raniformis. Frogs were held in laboratory conditions simulating those in which Bd epizootics had been observed in the field. We inoculated six frogs with infective Bd zoospores, held the subjects in individual containers, and compared their course of infection and associated physiological measures with those of six controls. Experimental subjects exhibited clinical signs of chytridiomycosis during the early period of infection, one week after they were inoculated, possibly due to invasion of Bd into the skin. These clinical signs were accompanied by significant inhibition of rehydration through the skin. However, we detected no changes in metabolic rate attributable to chytridiomycosis after one week. Five months after inoculation, all but one of the infected subjects had survived. Molecular testing confirmed that surviving frogs, although aclinical, still were infected. Control and infected subjects showed no difference in water balance or metabolism. These results provide evidence of inhibited rehydration in individuals exhibiting clinical signs of chytridiomycosis. However, aclinical chytridiomycosis does not severely affect amphibian skin function. Frogs that survive infection by Bd, even if they remain infected, may suffer no significant impairment in their physiological responses. The disease progression, with initial clinical signs of chytridiomycosis followed by apparent full recovery, is consistent with an adaptive immune response to Bd infection. Further research is needed to determine how Bd causes clinical chytridiomycosis and the immunological mechanisms by which hosts respond to Bd.

Variability in anesthetic effect is frequently observed in individuals within a species, yet few studies have investigated its causes in reptiles. To evaluate potential sources of variability in reptile anesthesia, we conducted experiments to test for effects of body temperature, body condition, gravidity, and time post-feeding on the recovery time of Red-sided Garter Snakes (Thamnophis sirtalis parietalis) anesthetized with methohexital sodium (Brevital Sodium). The mean recovery time of snakes anesthetized at 21°C was 125 min, at 26°C it was 86 min, and at 31°C it was 64 min. There was a significant correlation between body condition and recovery time, with thinner snakes experiencing longer recovery times. Gravid snakes anesthetized within five weeks of parturition had a mean recovery time that was twice as long as nongravid snakes of a similar mass. Time post-feeding did not have a statistically significant effect on the recovery time in snakes that were anesthetized one, three, and ten days after consuming 30% of their body mass in food. Based on our findings, we provide recommendations for producing more predictable results when using methohexital sodium in reptiles.

Declines and extinctions of amphibians in well-protected habitats suggest that global atmospheric factors may be responsible. We tested effects of field exposures of ultraviolet radiation (UV-B) on embryo hatching success and time to hatching in three anurans that inhabit high elevation areas of the Sierra Nevada in California, USA. While few obvious environmental impacts have occurred in the high elevation area of the Sierra Nevada, two of the three most common anurans, the Yosemite Toad (Bufo canorus) and the Southern Mountain Yellow-legged Frog (Rana muscosa), have suffered severe population declines while the sympatric Pacific Treefrog (Pseudacris regilla) has remained relatively abundant. Previous studies have shown that hatching of P. regilla embryos at lower elevations are not affected negatively by UV-B radiation. We hypothesized that differences in UV sensitivity may help explain why P. regilla remain abundant while B. canorus and R. muscosa have declined sharply. We conducted field experiments at two remote sites above 3030 m elevation over two years. No effect of UV-B was found on hatching success or rate of development in embryos of B. canorus, P. regilla, or R. muscosa, except for a small, context-dependent increase in time to hatching in R. muscosa. We recommend that research efforts on these species in the Sierra Nevada concentrate on post-hatching effects of UV-B, or on other decline hypotheses.