The ability to regenerate lost or amputated limbs varies greatly among amphibians. To gain a better understanding of phylogenetic and ontogenetic factors influencing regenerative ability, regeneration in tadpoles of Hymenochirus boettgeri is described for the first time, then compared to data from closely related Xenopus laevis. Hind limbs of tadpoles of H. boettgeri were amputated at two different levels along the proximo-distal axis of the limb (at the knee and ankle joints), at stages ranging from 52 to 59. Tadpoles were allowed to recover for 15 or 20 days, at which times the amount of regeneration was examined. Observations were made through external morphology and whole-mount histological staining. Hymenochirus, like X. laevis and indeed like most anurans, gradually loses the ability to regenerate hind-limb structures as it progresses through metamorphosis, and this loss occurs in a proximo-distal direction; the ability to regenerate is retained longer, distally. Hymenochirus and Xenopus show similar patterns of limb and digit regeneration. In both pipid species, loss of regenerative ability appears to be correlated with the onset of ossification in the hind limb, although timing of this event differs between the two species.

Scincid lizards have probably lost the external ear opening at least 17 times. Based on features of the middle ear, especially the orientation and attachment of the extracolumella and columella, five basic types of ear loss are recognized. These five types are strongly associated with major lineages. Ear loss seems to be associated with both small size and fossorial habits.

Rheodytes leukops is a bimodally respiring turtle that extracts oxygen from the water chiefly via two enlarged cloacal bursae that are lined with multi-branching papillae. The diving performance of R. leukops was compared to that of Emydura macquarii, a turtle with a limited ability to acquire aquatic oxygen. The diving performance of the turtles was compared under aquatic anoxia (0 mmHg), hypoxia (80 mmHg) and normoxia (155 mmHg) at 15, 23, and 30°C. When averaged across all temperatures the dive duration of R. leukops more than doubled from 22.4 ± 7.65 min under anoxia to 49.8 ± 19.29 min under normoxic conditions. In contrast, aquatic oxygen level had no effect on the dive duration of E. macquarii. Dive times for both species were significantly longer at the cooler temperature, and the longest dive recorded for each species was 538 min and 166 min for R. leukops and E. macquarii, respectively. Both species displayed a pattern of many short dives punctuated by occasional long dives irrespective of temperature or oxygen regime. Rheodytes leukops, on average, spent significantly less time (42 ± 2 sec) at the surface per surfacing event than did E. macquarii (106 ± 20 sec); however, surface times for both species were not related to either water temperature or oxygen level.

We describe a new species of Phrynobatrachus from the Western part of the Upper Guinean rain forest, West Africa. Phrynobatrachus phyllophilus sp. nov. differs from all other known West African Phrynobatrachus by a combination of morphological and acoustical characters. It is most similar to Phrynobatrachus guineensis from which P. phyllophilus is distinguished by its almost white belly, presence of only one dark bar on femur and tibia, shape of the thumb in reproductive males, advertisement call, reproductive mode, and selection of different forest types. Phrynobatrachus phyllophilus is the first known species of the genus that deposits small clutches of eggs rich in yolk on leaves, in close vicinity to extremely small puddles on the forest floor. Its preferred habitats are swampy areas of primary rain forest. We also describe the tadpole of P. phyllophilus and the advertisement call of P. guineensis.

A new species of Phyllomedusa, related to Phyllomedusa megacephala, is described from the high plateaus of the state of Goiás and Distrito Federal, Brazil. The new species is characterized by medium size, small finger pads, short and narrow head, thin body, vertical snout in profile, very granulate belly, chest without reticular pattern, transversal bars in the mandible, and flanks with reticular black, sepia, or purple pattern over yellow or orange background.

Phrynosoma orbiculare bears one pair of horns on the midline parietal bone (P₂), two pairs on each squamosal bone (S₁ and S₂), and one horn on each frontal bone (F₀). Reduced major axis (RMA) regression statistics for the relationship of each horn to head length, and of head length to body length, were estimated and compared for significant differences in slopes, size at smallest head length, and size at greatest head length. F₀ and P₂ increase at different but low rates, but S₁ and S₂ grow at a significantly faster rate and approach P₂ length toward the upper end of the head length range. This suggests an adaptive role for the cranial horn array in adult lizards. No sexual differences were found in these relationships, but there were significant subspecific differences in the relationships of head length to body length and of S₁ and S₂ to head length. This allometry of the cranial horn array is hypothesized to represent a plesiomorphic condition among the horned phrynosomatids.

We describe the diet of Crotalus lepidus klauberi (Banded Rock Rattlesnake) using samples collected in the field and from museum specimens, as well as several records from unpublished reports. Most records (approximately 91%) were from the northern Sierra Madrean Archipelago. Diet consisted of 55.4% lizards, 28.3% scolopendromorph centipedes, 13.8% mammals, 1.9% birds, and 0.6% snakes. Sceloporus spp. comprised 92.4% of lizards. Extrapolation suggests that Sceloporus jarrovii represents 82.3% of lizard records. Diet was independent of geographic distribution (mountain range), sex, source of sample (stomach vs. intestine/feces), and age class. However, predator snout–vent length differed significantly among prey types; snakes that ate birds were longest, followed in turn by those that ate mammals, lizards, and centipedes. Collection date also differed significantly among prey classes; the mean date for centipede records was later than the mean date for squamate, bird, or mammal records. We found no difference in the elevation of collection sites among prey classes.

The twin-spotted rattlesnake (Crotalus pricei) is a small-bodied pitviper that has received little attention in the literature to date. The species reaches the northern limit of its range in southeastern Arizona, where it inhabits higher elevations than any of the state's 10 other rattlesnake species. During 1997–2000, we captured, measured, and marked 127 C. pricei in Arizona's Chiricahua Mountains between 2530 and 2900 m elevation. We also used radiotelemetry to track the movements of 16 C. pricei in the study area during 1997–1998. Mean (± SE) snout–vent length of C. pricei was 387.8 ± 8.3 mm (range = 168–572), and mean mass was 53.5 ± 3.3 g (range = 3.6–188.5). Based on fecal analyses, lizards constituted the bulk of prey (74%), but the diet of C. pricei also included mammals, birds, and a conspecific. Mating was concentrated in August and early September and parturition took place during late July and August. Mean number of embryos was 3.94 ± 0.34 (range = 1–6) and female reproduction appeared biennial or less frequent. Based on shed and growth rates, female C. pricei develop embryos at 4–5 years of age. Gravid females maintained warmer body temperatures relative to substrate temperature than nongravid females or males, presumably by spending more time basking than other snakes. Radiotelemetry revealed that movement patterns varied from year to year, as males moved over six times farther per week during the 1998 monsoon season (July to September) than during the 1997 monsoon season. Additionally, use of talus slopes by males decreased during 1998. During dry years, such as 1998, males may be forced off talus into cooler microclimates where resources are less concentrated than on talus.

During four consecutive years, I used a mark-recapture method to study the relationship between breeding cycle and changes in male body condition in an Andean population of Hyla labialis. The annual weather pattern consisted of a long unimodal rainy season from February to November and a short dry season in December and January. A pronounced unimodal annual pattern in body condition was positively correlated with the amount of local rainfall. The annual reproductive cycle began during the rainy season in August or September, when males had high body energy reserves. Breeding activity ended in April or May of the following year, when males were in poor body condition. Reproductive activity was divided into two breeding periods by a short reproductive recess during the dry season. The annual cycle ended with a recovery period during the wettest months, when males regained their body condition while breeding activity ceased. Abundance of males and mated pairs was bimodal, with a high peak in October during the first breeding period and a lower peak in February during the second breeding period. Abundance was low during the driest and wettest months of the year. Individually marked males participated in up to seven consecutive breeding periods. Males found repeatedly in the same breeding period had the lowest body condition. A male's body condition declined as his time at the breeding aggregation increased and improved during recovery periods. Although rainfall pattern seemed to influence the amount of breeding activity, body condition seemed to determine the onset and end of the annual breeding cycle.

Female Physalaemus enesefae prefer long calls, low and average dominant frequency calls, and calls repeated at short intercall intervals over short calls, high dominant frequency calls, and calls repeated at long intercall intervals. I tested the hypothesis that males modify their vocal behavior when faced with potential competitors in ways that make them more attractive to females and that the more attractive the competitor, the greater the modification. In playback experiments, I examined the responses of males to the same stimuli used to test female responses: long and short calls, calls with low or high dominant frequency, long and short intercall intervals, and average calls for all traits. Among the variables analyzed, only the intercall interval was modified in the presence of the experimental stimuli. Males significantly reduced the intercall interval (called at a faster rate) in response to all experimental calls, compared with that when vocalizing alone, except in response to short calls and to long intercall interval calls. Males did not respond differently to calls of average and above average attractiveness. There was no difference in the intercall interval in response to average and above average attractive stimuli. However, the intercall interval in response to unattractive calls was significantly longer than that in response to calls of average attractiveness. The results partially support the hypothesis: males modify their spontaneous calling behavior when faced with a competitor but do not show finely tuned graded responses in relation to the attractiveness of the competitor.

Anuran maxillary, squamosal, and ilial elements from the Late Eocene of Hampshire and the Isle of Wight in southern coastal England represent a new species, Thaumastosaurus wardi, of this previously monotypic genus. Teeth, represented for the first time in the fossil record of this genus, are of the pedicellate type but appear to have specialized swollen tooth crowns. Based on the unique pit and ridge sculpturing of the cranial bones, the pedicellate teeth, and ilial characters of Thaumastosaurus, the genus resembles the leptodactylid genus Caudiverbera (Telmatobiinae) of the modern fauna of Chile and the Miocene of Argentina. It is suggested, however, that Thaumastosaurus should be considered of uncertain familial relationships (familia incertae sedis) until adequate material becomes available.

Organisms are predicted to make trade-offs when foraging and predator avoidance behaviors present conflicting demands. Balancing conflicting demands is important to larval amphibians because adult fitness can be strongly influenced by size at metamorphosis and duration of the larval period. Larvae in temporary ponds must maximize growth within a short time period to achieve metamorphosis before ponds dry, while simultaneously avoiding predators. To determine whether tadpoles trade off between conflicting demands, I examined tadpole (Pseudacris triseriata) activity and microhabitat use in the presence of red-spotted newts (Notopthalmus viridescens) under varying conditions of pond drying and hunger. Tadpoles significantly decreased activity and increased refuge use when predators were present. The proportion of active time tadpoles spent feeding was significantly greater in predator treatments, suggesting tadpoles adaptively balance the conflicting demands of foraging and predator avoidance without making apparent trade-offs. Tadpoles responded to simulated drying conditions by accelerating development. Pond drying did not modify microhabitat use or activity in the presence of predators, suggesting tadpoles perceived predation and hunger as greater immediate threats than desiccation, and did not take more risks.

A new species of Hyla is described from Cerro Jaua, 1600 m, Bolívar State, Venezuela. The external appearance of the new species closely resembles Hyla benitezi and Hyla lemai but differs from these species in having cream-colored digits and webbing (in live specimens), a golden iris, less foot webbing, no quadratojugal, and a characteristic advertisement call that consists of a rhythmically repeated note with a dominant frequency between 3260 and 3450 Hz.

The temporal pattern, basin construction and egg-laying of the Neotropical gladiator frog Hyla boans were studied along a small stream that enters the Manu River in Peru in August 2000. Initially we located 60 basins, which were all destroyed by flood waters; subsequently 89 basins were constructed in the same area. In basins where eggs were deposited, oviposition usually occurred on the night the basin was constructed (60%) or during the following night (30%). Of the breached basins that were initially unused the first night, but were subsequently used, 91% were repaired before oviposition. Significantly more basins were located on the top of sand islands than in the center or along the other edges. Basins with eggs had significantly higher rims than those without eggs, and new basins and those with eggs had deeper water than basins with tadpoles or old basins that were disintegrating. Of the basins constructed following the flood, 55% ultimately had eggs, 89% of the eggs hatched in these basins, and 91% of the tadpoles reached maturity or left the basin when the rims were breached. Of the eggs that hatched, 89% of the clutches hatched on the second day after egg-laying, and 11% hatched on the third day. Of the total 146 basins we located, tadpoles reached maturity in five of the original 60 and in 38 of the 86 basins constructed after the flood, for an overall success rate of 29%. However, considering only those basins with eggs, 43 of 81 clutches were successful (53%).

We examined genetic variation and structure in mitochondrial DNA sequences of sharp-tailed snakes (Contia tenuis) from California and southern Oregon. Maximum parsimony and maximum likelihood analyses distinguish two mitochondrial lineages: a north coast clade restricted to cool evergreen forest along the Pacific Coast; and an interior/south clade widespread throughout California. The southern limit of the north coast clade is congruent with that of several other vertebrate taxa, a historical pattern consistent with a long-term marine embayment. We interpret additional phylogeographic pattern as resulting from either gene flow or incomplete lineage sorting. Genetic, distributional, ecological, and morphological data suggest that north coast and interior/south mitochondrial lineages of C. tenuis are distinct at the species level.

A new frog, Philautus griet sp. nov., is described from Munnar in the Western Ghats of India. Molecular phylogenetic analyses of a 548 bp fragment of the mitochondrial 16S rRNA-gene confirm its placement in the genus Philautus (Anura, Ranidae, Rhacophorinae). In its small size, general brown coloration, and reduced webbing on toes, the new species is similar to Philautus bombayensis and Philautus tinniens. However, relative to P. griet, P. bombayensis differs by the invariable presence of greyish-black and yellow spots in the groin and on the inside of the thighs, and P. tinniens can be distinguished by the dark side of the head and the yellow inner fingers and toes. Phylogenetic analyses of Indian and Sri Lankan Philautus have identified Philautus charius as the sister taxon of P. griet. However, the latter can be readily distinguished by its smaller adult size (20.7–22.1 mm, N = 5, vs. 27.5–30.9 mm, N = 10, in P. charius) and lack of black coloration with yellow spots on the posterior surface of the thighs. The 30 km wide Palghat Gap, dividing the Western Ghats into northern and southern components, may have played a role in the vicariant isolation of these species.

We examined feeding relationships between Hyla japonica and Rana nigromaculata in rice fields of central Japan, where they forage syntopically. Hyla japonica and recently metamorphosed Rana nigromaculata overlapped greatly in body size and took prey of similar size and type. However, H. japonica foraged in rice fields during its breeding season (May to July), whereas R. nigromaculata began metamorphosis later in July. Therefore, they seldom coexisted and seemed to partition food resources temporally. By the following spring, R. nigromaculata froglets grew larger than adult H. japonica and used different food resources, suggesting food resources were partitioned by body size. These patterns of food partitioning, which were consistent in two study sites where the dominant species differed, may account for coexistence of H. japonica and R. nigromaculta throughout their wide distributions.

Rreproductive features of a population of Mabuya mabouya were studied in a wet tropical habitat with a bimodal precipitation regime. The sex ratio was approximately 1:1, and females were larger than males. Males matured at a SVL of 72 mm and are continuously reproductive throughout their adult life. Two groups of females were found reproducing simultaneously: primiparous females that reached a minimum size at their first reproduction and continued to grow during the gestation period and multiparous females of larger size that exhibited more limited growth. Primiparous females began preovulatory follicular growth and ovulated at juvenile sizes (60–74 mm SVL). Reproductive activity of the females appeared aseasonal. However, births occurred during the dry months, producing a bimodal pattern of neonate recruitment into the population. Gestation of four to seven embryos lasted approximately 10 months. Litter size was related to female SVL. The maximum follicular size corresponded to a microlecithal egg, and the percentage of growth of the embryo during development indicated a substantial matrotrophy. Accumulation of abdominal fat bodies in males or females was unrelated to season, and the relative quantity of fat accumulated was smaller in males. Stored fats decreased in the last phase of gestation, indicating a higher energetic cost during the final growth phase of the embryo. The reproductive traits of M. mabouya are comparable to those of other South American Mabuya, but this population possesses particular features related to the environmental conditions of its tropical habitat that suggest local adaptation.