I describe structures around the corner of the mouth of some snakes. Anilius has a large serous superior rictal gland lateral to the quadrato-maxillary ligament and a large serous inferior rictal gland. Other rictal structures of henophidian grade snakes are mesial to the ligament. Cylindrophis has a medium superior rictal gland and a large inferior gland. Two uropeltines have a large superior rictal gland opening into a rictal bulb with thick folded walls. Xenopeltis has a large superior rictal gland opening by three ducts into a thick walled rictal pocket. Aspidites, Calabaria, Exiliboa, Loxocemus, Tropidophis, and Ungaliophis have a rictal pocket into which open glands that may be mucous or serous. Candoia has glands opening around, but not into, a rictal pocket. Bolyerines show no evidence of differentiated rictal structures. Pareas has a superior rictal gland with serous tubules leading to mucous tubules; supralabial gland lobules also have serous leading to mucous tubules and, from about midway forwards, these lobules form a double row; there is no evidence of a dental gland. Two xenodermatines have supralabial serous tubules leading to mucous tubules, but no evidence of alternating mucous and serous cords. I discuss some alternative evolutionary interpretations.

We reevaluated geographic variation and taxonomy in the colubrid genus Chilomeniscus. We used color pattern, head scale morphology, and scale and band counts in an attempt to differentiate the four currently recognized species: the unbanded C. stramineus, banded C. cinctus, and the banded insular forms C. punctatissimus and C. savagei. Because only head scale morphology could be used to discretely diagnose (i.e., no character state overlap) two of the four species, we propose that the current evidence supports the recognition of C. savagei from Isla Cerralvo and two disjunct populations of C. stramineus, one ranging throughout the Baja California peninsula and the other occurring in Arizona, U.S.A., and Sonora and Sinaloa, Mexico. We consider C. cinctus and C. punctatissimus to be junior synonyms of C. stramineus.

We describe a new species of Xenobatrachus from the Bewani and Hunstein Mountains of northwestern Papua New Guinea. It is closely similar to X. mehelyi and X. subcroceus, but it keys out to the X. rostratus species group as defined by Blum and Menzies. It differs from the former species in body size, relative leg length, and advertisement call. It differs from its other 15 congeners in morphological and color pattern attributes and advertisement call, and it represents another frog species apparently endemic to the northern coastal ranges of New Guinea, further supporting identification of this area as a center of regional biotic endemism. This reflects the offshore origin of these ranges in the Solomons Arc system, followed by accretion to the New Guinea mainland during the past ten million years.

The period during which neonatal aquatic turtles migrate from their nests to the water is a critical stage, as mortality is high. Thus, the patterns and targets of natural selection involving the turtles are important to investigate. To evaluate these questions, we incubated eggs of red-eared slider turtles (Trachemys scripta elegans) and overwintered the resulting hatchlings under ecologically-relevant, common-garden conditions in the laboratory. We then performed an experimental release of 358 neonates in the field to investigate the possible effects of (1) water potential of the substrate on which the eggs were incubated (−60 and −100 kPa), (2) body size at the time of release, and (3) clutch of origin on short-term posthatching survivorship. Only clutch significantly affected survivorship in this field study. The lack of an effect of body size on survival may be due to substantially drier weather during the migration period than in previous and subsequent experiments, which may have led to atypical burying behavior by the turtles.

Many lizards autotomize their tails during an encounter with a predator. Tails thrash following autotomy, thus distracting the predator and increasing the probability of escape. Regeneration of the tail occurs rapidly in many species of lizards. We investigated several aspects of the physiology of original and regenerated tails of the gecko Hemidactylus mabouia. Thrashing durations of original and regenerated tails after autotomy were similar, but original tails accumulated significantly more lactate per gram tissue than did regenerated tails. The reduction in lactate concentration paralleled a reduction in protein concentration in regenerated tails suggesting that lower protein concentrations in regenerated tails contributed to lower lactate concentrations. Lactate dehydrogenase (LDH) activity was not significantly different in original and regenerated tails, suggesting that LDH was not responsible for the observed difference in lactate concentrations. Histochemical and immunochemical analyses revealed that the number, size, and type of muscle fibers were not different in original and regenerated tails. Caudal fibers were mainly of the fast, glycolytic type, which presumably support high anaerobic activity of the tail following autotomy.

One component of the courtship display of males in the lizard genus Anolis is the extension and retraction of a large and often colorful throat fan (the dewlap). However, the relative importance of displaying the dewlap during courtship in terms of male mating success is controversial. For this reason, I tested the hypothesis that the display of the male's dewlap during courtship affects male mating success in the lizard Anolis sagrei. The hypothesis was tested in the laboratory by comparing the mating success of experimental males that were surgically prevented from extending their dewlaps to control males that were not prevented from extending their dewlaps. Males in the two treatment groups were housed in individual cages for one week before being used in mating tests. One day prior to the mating tests, I visually exposed a male from each treatment group to the female that it would be paired with during the mating test. On the day of the mating test, each male was removed from its cage and placed into the cage housing the female that it had been able to view. The behavior of the paired males and females was videotaped for two hours. The results did not support the hypothesis. Experimental males did not differ significantly from control males in number of copulations. Moreover, experimental and control males did not differ significantly in the latency period to copulation, copulation duration, or in the sexual receptivity of their female partners. These results provide no evidence that dewlap extension during courtship affects male mating success in Anolis sagrei, at least when males and females are in relatively close physical proximity to each other.

We examined how male and female túngara frogs, Physalaemus pustulosus, respond to variation in the frequency spectrum of the chuck component of the advertisement call. We varied chuck frequency in two different ways. In the fixed frequency series, the sequence of calls within each series had chucks of the same dominant frequency. Different fixed-frequency series had chucks of different dominant frequencies designated as high, high–medium, medium, medium–low, or low frequency relative to variation in the test population. In the second varying frequency series, the sequence of calls varied in the chuck's dominant frequency such that the individual series had the same average frequencies as the high, high–medium, medium, medium–low, and low fixed-frequency experiments. Both males and females tended to respond more to lower-frequency chucks. The responses of both sexes to the same mean chuck frequency was similar to the fixed- and varying-frequency series of chucks.

Fundamental issues in the study of predator-prey interactions include addressing how prey coexist with their predators and, moreover, whether predators promote coexistence among competing prey. We conducted a series of laboratory experiments with a freshwater assemblage consisting of two predators that differed in their foraging modes (a crayfish, Procambarus sp., and the western mosquitofish, Gambusia affinis) and their prospective anuran prey (tadpoles of the narrow-mouthed toad, Gastrophryne carolinensis, and the squirrel treefrog, Hyla squirella). We examined whether competition occurs within and between these two prey species and, if so, whether the non-lethal presence of predators alters the outcome of competitive interactions. We also asked whether the two species of prey differ in their susceptibility to the two types of predators and whether interspecific differences in predator avoidance behavior might account for this variation. Our results indicated that Gastrophryne was a stronger competitor than Hyla; at high densities, Gastrophryne reduced the body size of both congeners and conspecifics, as well as the proportion of surviving conspecifics that metamorphosed. However, the presence of mosquitofish did not alter the outcome of this competition, nor did either type of predator affect the density-dependent responses of Gastrophryne. In laboratory foraging trials, the number of tadpoles of each prey species that was killed, but not completely consumed by mosquitofish, was similar for Gastrophryne and Hyla. Yet, significantly more individuals of Gastrophryne than of Hyla were the first prey eaten by mosquitofish; there was no difference in the number of individuals of each species eaten by crayfish. Overall, more individuals of Gastrophryne than of Hyla were killed and completely eaten by mosquitofish at the end of the experiment. The two species of prey did not differ in their spatial avoidance of either type of predator, suggesting that this behavior did not play a significant role in the differential vulnerability of the prey to predation. By reducing the abundance of G. carolinensis, the potential exists for predators, such as mosquitofish, to ameliorate this species' competitive impact on other species. In this way, predators may promote coexistence of species within some assemblages of amphibians.

We investigated the genetic structure of wood frog (Rana sylvatica) populations in a woodland habitat around Lake Itasca, Minnesota, USA. Based on published studies of wood frog movement patterns, we expected to find genetic differentiation at inter-population distances exceeding a few kilometers. We sampled 10 populations separated by 95 m to 9.6 km. Of five microsatellite loci developed for a study of R. sylvatica in North Dakota, only three were polymorphic in the Itasca sample. We found some evidence for statistically significant differences among populations, with the greatest magnitude estimates of F_ST derived from comparisons involving the most isolated populations. The smallest geographic distance associated with a statistically significant genetic difference was 1070 m, but most populations were very similar in allele frequencies, even at distances greater than several kilometers. Small sample sizes and the small number of loci limited the strength of any conclusions regarding fine-scale population structure. Itasca populations were significantly different than populations from Nelson County, North Dakota, a distance of over 200 km, with F_ST estimated at about twice the largest pairwise estimates among Itasca samples. Even at this distance, however, there were substantial similarities in the overall pattern of allele frequencies at four of the five loci.

We investigated the impacts of PIT-tagging and tattooing on survival, condition, and egg laying in Alpine newts (Triturus alpestris) by both field and laboratory experiments. A laboratory experiment made it possible to compare impacts of each marking technique with control groups of unmarked newts. This experiment consisted of a 3 × 3 factorial plan (population, replication, and marking) using 90 individuals of each sex. Neither survival nor body condition were affected by marking. No variation was detected between marking treatments. However, marked females laid significantly more eggs than control females. We assume that such higher reproductive outputs are responses to the stress induced by skin injury by both marking techniques, but this hypothesis remains to be tested. The field experiment consisted of monitoring a newt population in a pond where individuals (n = 121) were marked by either marking technique. No difference in survival or in body condition was detected between marking treatments. Either technique reliably met the requirements of data processing. The present study shows that data obtained with both techniques can be regarded as similarly suitable for estimating population parameters. However, because of better long-term reading reliability, PIT-tagging appears to be the preferred one, provided that body size is sufficiently large to accomodate a transponder.