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Comparison of advertisement calls of Eleutherodactylus guentheri from different localities in southern and southeastern Brazil revealed considerable acoustic variation among populations. Because of significant differences in call parameters, we conclude that the southern form is a distinct species, for which the name Hylodes henseliiPeters, 1870, is available. Examination of the holotypes of H. henselii and Hylodes guentheriSteindachner, 1864, along with recently collected material, showed that both species are morphologically similar, possibly sibling species. Eleutherodactylus henselii is the southernmost member of the genus Eleutherodactylus occurring in subtropical Atlantic rain forest and Araucaria forest of the Brazilian states of Rio Grande do Sul and Santa Catarina, and Misiones, Argentina. Bioacoustic data suggest that at least one additional cryptic species is involved in the Eleutherodactylus guentheri group.
Phymaturus spurcus was described by Barbour in 1921. In 1931, Burt and Burt placed this species in the synonymy of Phymaturus patagonicus based on their comparison of one paratype of P. spurcus with one specimen of P. patagonicus. Additionally, Burt and Burt considered P. patagonicus a subspecies of Phymaturus palluma. Although some subsequent authors accepted the synonymy of P. patagonicus with P. palluma, the synonymy of P. spurcus with P. patagonicus has gone unquestioned. We examined the type series of P. patagonicus and P. spurcus, as well as new material collected from the type localities of both species. Based on 47 morphological characters of squamation, gular and nuchal folds, precloacal pores, and morphometric data, we conclude that P. spurcus is a valid species, distinct from P. patagonicus and all other Phymaturus. We agree with Cei and Castro's study in 1973 that the population located west of Dolavon, Chubut Province, Argentina, is P. patagonicus of Koslowsky' study in 1898 Because in the original description Koslowsky failed to designate an holotype, we designate Museo La Plata S-778 as the lectotype of P. patagonicus and restrict its type locality to 40 km west of Dolavon, Chubut Province, Argentina. We provide a redescription of P. patagonicus Koslowsky and a redescription of P. spurcus based on the type series of Barbour's study in 1921, with additional data on intraspecific variation in both species.
A new species of Leposoma is described from Ilha do Lago do Prato and Ilha do Açaí, Arquipélago das Anavilhanas, in the lower Rio Negro, state of Amazonas, Brazil. Like all members of the parietale group, it differs from all species of the scincoides group by having wider and shorter dorsal scales and ventrals arranged in regular longitudinal rows. It is further characterized by having conic granules on the sides of neck, three enlarged pairs of chin shields, absence of granules between superciliaries and supraoculars, a longer than wide interparietal with lateral margins almost parallel, 42–44 transverse dorsal rows (the highest number in Leposoma), gular scales small in 13–15 rows (less than 11 in other Leposoma), 30–33 scales around body, 26–27 ventrals, two preanal and four femoral pores on each side in males, one preanal and no femoral pores in females, 13–14 and 19–21 lamellae under finger IV and toe IV, respectively. The new species is sympatric with Leposoma guianense and Leposoma percarinatum and is more similar to the latter.
We examined 142 papers, which contained 603 separate predator-prey trials, to investigate whether unpalatability is an important defense against predation for amphibian eggs and larvae. Although unpalatability is often cited as an antipredator defense, it was rarely demonstrated that 89% of the trials that we reviewed found prey to be palatable. The most extensively studied taxa, the genera Bufo and Rana, were diagnosed unpalatable at rates comparable to all other taxa. Diagnoses of unpalatability were not always consistent for a prey species across different predators and were influenced by experimental method. Despite these limitations and our conservative definition of unpalatability, several patterns emerged. First, across all taxonomic groups, eggs and hatchlings were unpalatable more often than mobile larval stages. Second, species that breed in temporary ponds were more likely to be palatable to fish predators than those that breed in permanent habitats. Third, fish and caudates were more likely to find amphibian prey unpalatable than insect predators. We conclude that unpalatability is rare, but when it occurs, it is a property of an ensemble (predator, prey, and alternative prey) and a life-history stage in a particular circumstance but is not a species-specific attribute. We suggest methods of experimentation that could strengthen future research on the palatability of amphibian eggs and larvae.
We studied a population of Florida Box Turtles, Terrapene carolina bauri, from September 2002 to December 2003, in the Florida Keys at the southernmost limit of its range. Population structure was estimated to be 7.5% juvenile, 58.75% female, and 33.75% male, resulting in a female biased sex ratio (1 male:1.74 females). Population size was estimated at 39.9–114.4 turtles/6 ha in a pine rockland forest, with an estimated density of 4.8–10.2 turtles/ha. Males had significantly longer carapace and plastron lengths than did females. Comparison of data with other populations of T. c. bauri revealed similar morphological characteristics among populations although this southern population had higher mean body mass than did populations in the central parts of its range.
Effective monitoring of population size is critically important for endemic species with specialized habitat requirements so that timely remedial steps can be taken when declines are detected. We initiated a monitoring study of the endemic plethodontid salamander, Plethodon punctatus, which is generally found in talus habitats over 1000 m in elevation in a narrow range on Shenandoah Mountain on the border of Virginia and West Virginia. We tested congruence of nighttime visual encounter surveys (VES) and mark-recapture estimates of population size. VES was a valid index of the abundances of P. punctatus in the two habitats we surveyed. Sites on the eastern and western sides of Shenandoah Mountain were surveyed, and both methods estimated that population size on the west was approximately twice as high as that on the east. Individuals of this species exhibited a high degree of site fidelity. Cover object searches for species in talus habitats are expected to be of limited value, and we conclude that nighttime visual encounter surveys are most effective for population size monitoring of P. punctatus and other species that live in talus.
A new species of Cyrtodactylus is described from lowland forest of southern Peninsular Malaysia. It differs from all other Cyrtodactylus by having a unique suite of characteristics involving coloration and scalation. This is the third species of amphiban or reptile restricted to the southern portion of the Malay Peninsula.
I describe a new species of blindsnake of the genus Typhlops from Rossel Island, off the southeastern tip of New Guinea. The new species is a member of the Typhlops ater species group and is characterized by having 18 scale rows, 343 middorsal scales, T-V supralabial-imbrication pattern, a distinct pupil, single subocular scale, and by lacking a presubocular scale. Its closest living relative is probably Typhlops inornatus, known from forested habitats on the nearby mainland of New Guinea. The new species is known from only two specimens from northeastern Rossel Island, and it remains uncertain whether it occurs on adjacent islands of the Louisiade Archipelago.
We examined aspects of pre- and postprandial metabolism in the diurnally active Western Fence Lizard, Sceloporus occidentalis, by measuring rates of oxygen consumption (Vo2) and carbon dioxide production (Vco2) at 30°C. Sceloporus occidentalis exhibited strong circadian variation in metabolism that continued throughout digestion, with diurnal peaks in metabolism up to four times as high as nocturnal minimum values (standard metabolic rate, SMR). Metabolism increased with increasing body size (mass range = 3.65–19.02 g), with mass exponents ranging from 0.61–0.82. Metabolism of lizards fed meals equivalent to 1.4, 2.9, and 3.9% of their body mass was elevated above fasting metabolism, although significant differences in metabolism were not detected among the three meal sizes. Maximum metabolism during digestion was from 1.2–1.3 times that of maximum fasting metabolism, a value similar to that of other small, frequently feeding lizards. Specific dynamic action (SDA) ranged from 2.38–22.02 mL O2 and 1.54–14.54 mL CO2, or 0.05 −0.44 kJ, which is equivalent to 9.4–17.0% of the ingested energy. Mean respiratory quotients (RQ) ranged from 0.65–0.68, indicating lipids were the primary energy substrate used during both fasting and digestion.
A diminutive new species of Uperoleia (male snout–vent length, SVL, 17.3–21.3 mm female, SVL 21.8 mm) is described from 30 km south of Darwin, Northern Territory, Australia. The combination of small size, possession of maxillary and premaxillary teeth, and a completely exposed frontoparietal fontanelle distinguish the species from all other Uperoleia. The variation in number of pulses and duration of the advertisement call distinguish the species from the other sympatric Uperoleia species, Uperoleia inundata and Uperoleia lithomoda, as well as from the other Northern Territory species. The proximity of the type locality to Darwin highlights the current inadequate state of knowledge of the northern Australian frog fauna.
The family Bufonidae is nearly cosmopolitan in distribution and contains 33 genera. The monotypic bufonid genus Atelophryniscus was described relatively recently from Honduras. This taxon was distinguished from Bufo on the basis of its unusual gastromyzophorus tadpole. Stream-dwelling gastromyzophorus tadpoles are atypical within Bufonidae and when Atelophryniscus was described, this type of tadpole was unknown among members of the genus Bufo. To investigate the phylogenetic placement of this taxon, we analyzed 83 previously published morphological characters for a sampling of Old and New World bufonids and included newly coded data. The data indicate that (1) there are no autapomorphies supporting the recognition of Atelophryniscus; (2) this taxon is embedded within the genus Bufo; and (3) it is sister to Bufo veraguensis of South America.
Clearcutting and other forest management practices that remove canopy and disturb ground cover may exacerbate the risk of desiccation, particularly for newly metamorphosed amphibians. We examined dehydration rates of juvenile Mole Salamanders (Ambystoma talpoideum) in relation to burrow availability in four experimental forest management treatments. Juvenile salamanders (N = 41) were confined to small enclosures in four treatments representing a range of habitat disturbance: clearcut with coarse woody debris (CWD) removed; clearcut with CWD retained; thinning; and an unharvested control of second-growth, mature loblolly pine. Half of the salamanders in each habitat treatment were provided with artificial burrows. Water loss over 72 h was significantly higher in the clearcut with CWD retained than in the other three treatments. Most water loss occurred during the first two nights, when salamanders may have been most active. Only 40% of salamanders without burrows survived in the clearcuts, versus 90% in the thinned stand and 100% in the control. Ninety percent of the salamanders with access to a burrow survived in the clearcuts versus 100% in the thinning and control. We found no correlation between soil moisture and water loss and attribute higher desiccation rates in the clearcuts to high temperatures (> 44°C). Although habitat changes resulting from thinning did not lead to increased desiccation, complete canopy removal greatly increased risk of mortality caused by desiccation. Our results also demonstrate that this risk is strongly mediated by the availability of burrows.
One of the most fundamental problems in monitoring animal populations is that of imperfect detection. Although imperfect detection can be modeled, studies examining patterns in occurrence often ignore detection and thus fail to properly partition variation in detection from that of occurrence. In this study, we used anuran calling survey data collected on North American Amphibian Monitoring Program routes in eastern Maryland to investigate factors that influence detection probability and site occupancy for 10 anuran species. In 2002, 17 calling survey routes in eastern Maryland were surveyed to collect environmental and species data nine or more times. To analyze these data, we developed models incorporating detection probability and site occupancy. The results suggest that, for more than half of the 10 species, detection probabilities vary most with season (i.e., day-of-year), air temperature, time, and moon illumination, whereas site occupancy may vary by the amount of palustrine forested wetland habitat. Our results suggest anuran calling surveys should document air temperature, time of night, moon illumination, observer skill, and habitat change over time, as these factors can be important to model-adjusted estimates of site occupancy. Our study represents the first formal modeling effort aimed at developing an analytic assessment framework for NAAMP calling survey data.
Capture/recapture studies significantly increase our knowledge of the natural history of anuran amphibians. Many different methods have been employed in these studies, but a number of new techniques still require experimental validation. During two reproductive seasons in a Cerrado remnant in southeastern Brazil, we investigated the movement patterns and habitat use of the pepper frog, Leptodactylus labyrinthicus, using a spool-and-line device. This low-cost device did not appear to interfere with the activities of the frogs and allowed for constant monitoring, showing precise routes of movement and great predictability of relocations. Both sexes were active at night. During the day, males and females made use of retreat sites under vegetation or in burrows constructed by small- and medium-sized mammals. Males and females did not use standardized routes; there were no significant differences between their movements, and movements were not correlated with body size or environmental conditions. Individuals are able to move further than 100 m per day, a characteristic that may enable this species to colonize or recolonize open areas.
Costs and benefits of territorial defense may vary with the number of intruders that a resident simultaneously encounters. Our study examined whether or not aggressive or escape behavior of female Plethodon cinereus would increase as the number of intruders simultaneously entering her territory increased from zero to one to two. We allowed 30 focal female P. cinereus to establish territories in laboratory chambers and tested each female in five randomly sequenced treatments: (1) one female intruder; (2) two female intruders; (3) one male intruder (4) two male intruders; and (5) a surrogate control (no live intruders). We recorded the behavior of the focal salamanders in response to the intruders. Across the five treatments, females differed significantly in amount of time in threat and escape behaviors and in total number of bites. Post hoc comparisons found that relative to the control females displayed significantly more time in threat behavior toward one male intruder and significantly more time in escape behavior in the presence of two male intruders, but they exhibited no significant differences toward one or two female intrudes. The post hoc comparisons for bites found no significant differences. We infer that for female P. cinereus the benefit of guarding prey in a territory outweighed the cost of defense (possible injury) when a single male was introduced into her territory, but the cost of defense exceeded the benefit when two male intruders were simultaneously introduced into her territory.
It is commonly thought that predators use olfactory cues to find turtle nests and that these cues are diminished by rainfall. We studied the relationship between rainfall on the date of oviposition and depredation of nests of the Painted Turtle, Chrysemys picta, on a major nesting beach between 1996 and 2003. We analyzed two scenarios: rainfall versus no rainfall on the date of oviposition; and no rainfall versus intense or weak rainfall on the date of oviposition. For the first scenario, we found no consistent association between rainfall and nest depredation before hatching. In 1996, rainfall on the date of oviposition appeared to increase the chance of nest depredation; in 2000, it appeared to decrease the chance of nest depredation; and there was no statistically significant relationship in the remaining years or overall. In the second analysis, the relative amount of rain was associated with nest depredation before hatching. Nests constructed on days with a larger amount of rain were less likely to be depredated than nests constructed on days with no rain or smaller amounts of rain. Nests constructed on days with smaller amounts of rain were more likely to be depredated than nests constructed on days with no rain.
Previous studies have shown that territorial Red-Backed Salamanders (Plethodon cinereus) react aggressively toward intruding Eurycea cirrigera. Our study tested the hypotheses that male and female Red-Backed Salamanders have short-term memory of such territorial intrusions. We allowed focal males and females of P. cinereus to establish territories in laboratory chambers and then presented them with a caged E. cirrigera (treatment 1) or a caged surrogate control (treatment 2). When the cages were removed, the focal salamanders were alone for 5 min and then exposed to an intruding conspecific of the opposite sex. Males (but not females) exhibited significantly more time in threat displays toward the conspecifics in treatment 1 (displacement of territorial aggression) than in treatment 2. We infer, then, that at least males have short-term memory of a past “event” of territorial intrusion.
A unique rudimentary ovarian structure known as the Bidder's organ (BO) occurs at the anterior end of the gonads of male bufonids. I examined BO volume in reproductively active (RA) versus nonreproductively active (NRA) males of Bufo woodhousii to examine changes in BO volume in relation to reproductive status. BO volume was larger in NRA males, suggesting that cues associated with sexual maturity influence BO volume.
Reptilian eggshells are a potential source of nutrients for developing embryos. Embryonic Snapping Turtles (Chelydra serpentina) used calcium and magnesium from the eggshell during development. This supplemental source of calcium provided more than twice the amount of calcium present in freshly laid egg yolk to developing embryos. Calcium was preferentially mobilized from the sides and bottom of the eggshell. Scanning electron micrographs of eggshells indicated that this preferential use affected the structural integrity of the eggshell, which presumably facilitates pipping. The mass and concentration of calcium in the chorioallantoic membrane increased significantly during later development, suggesting that this membrane plays a critical role in mobilization of calcium during development. This is the first study to demonstrate mobilization of eggshell magnesium by embryonic turtles.
Bothrops pubescens is a member of the neuwiedi complex that occurs in southern Brazil and Uruguay. We studied the ecology of B. pubescens from a field site (at Santa Maria, Rio Grande do Sul, Brasil) and based on preserved specimens from the state of Rio Grande do Sul, Brasil. In Santa Maria, individuals were collected during visual encounter surveys (VES), in pitfall traps with drift fences and during incidental encounters. Most snakes found in the field were on the ground, mainly on leaf litter, in mosaics of light and shadow or in completely shaded areas. In disturbed areas, snakes were usually associated with country houses and agricultural fields. Snakes were found much more frequently in forests and forest edges than in open habitats. The diet of B. pubescens comprised small mammals (56.2% of individual prey found), anurans (21.2%), lizards (7.5%), snakes (7.5%), birds (5.0%), and centipedes (2.5%). Prey predator mass ratios ranged from 0.002–0.627, and larger snakes tended to consume larger prey. Bothrops pubescens seems to be able to survive in disturbed areas, mainly those close to forests, and this ability may be facilitated by its generalized feeding habits.
We examined diet of introduced Bullfrogs (Rana catesbeiana) and three native frog species (Rana limnocharis, Rana nigromaculata, and Bufo bufo gargarizans) co-occurring at a group of ponds on Daishan Island, east of China, to gain insight into the nature of potential interactions between Bullfrogs and native frog species. For postmetamorphic Bullfrogs, aquatic prey items dominated volumetrically. Prey size, diet volume and volumetric percentage of native frogs in diet increased with Bullfrog body size. The number and volumetric percentage of native frogs in the diet were not different for female and male Bullfrogs, and both were higher for adults than for juveniles. Diet overlap between males and juveniles was higher than that between males and females and between females and juveniles. Diet overlap with each native frog species of male Bullfrogs was lower than that of female Bullfrogs and juvenile Bullfrogs. We did not exam effects of Bullfrogs on native frogs but our results suggest that the primary threat posed by juvenile Bullfrogs to native frogs on Daishan Island is competition for food, whereas the primary threat posed by male Bullfrogs is direct predation. Female Bullfrogs may threaten native frogs by both competition and predation. These differences among Bullfrog groups may be attributed to differences in body size and microhabitat use.
The positive relationship between hind-limb length and perch diameter is well established in Anolis lizards, both among populations of some species and among species. Interspecific comparisons indicate that longer legs confer an advantage for increased running speed on broad substrates, whereas shorter limbs provide greater maneuverability on narrow surfaces. In this light, phenotypic plasticity for hind-limb length previously detected in Anolis sagrei may be adaptive because hatchlings exposed to only broad substrates developed relatively longer hind limbs for their body size compared to hatchlings exposed to only narrow substrates. We tested the generality of hind-limb length plasticity in Anolis by conducting a hatchling growth experiment on Anolis carolinensis, a distant relative of A. sagrei and a different type of habitat specialist. Similar to A. sagrei, A. carolinensis grown in cages with different sized perches showed hind-limb length plasticity, but the magnitude of difference between treatments and sexes was less for A. carolinensis than for A. sagrei. This finding suggests either hind-limb plasticity is widespread within the genus Anolis or that it has evolved independently at least twice.
Temporal patterns of embryonic metabolism integrate ontogenetic changes in the energetic costs of growth and maintenance. Unlike most other chelonians, which show a peaked pattern of embryonic metabolic rate (MR) over time, turtles of the family Emydidae have been depicted with unimodally increasing patterns. We incubated eggs of the emydid Chrysemys picta picta under standard conditions at 30°C and serially measured rates of oxygen consumption. Five eggs showed clear decreases in MR before hatching; two others that hatched during MR measurements showed increases in MR associated with muscular activity. MRs of hatchling turtles were lower than those of prehatching embryos for at least 60 days, suggesting persistent costs of biosynthesis in yolk-dependent late-stage embryos and early hatchlings.
Long-term effects of hybridization and introgression are influenced by performance of hybrids in habitats of parental species. The treefrogs Hyla cinerea and Hyla gratiosa, which typically breed in permanent and temporary habitats, respectively, have occasionally hybridized throughout the Southeastern United States. To predict in which of the parental habitats effects of hybridization might be strongest, I performed experiments to evaluate predation on tadpoles of H. cinerea, H. gratiosa, and F1 hybrids with predators typical of the breeding habitats of the parental species. Hybrid tadpoles had lower survival with sunfish than odonate naiad (dragonfly) predators and tended to increase hiding behavior in response to sunfish predation. Tadpoles of H. gratiosa also had higher survival with odonates than sunfish, but H. cinerea had similar survival with both predator types. These results suggest that hybrids are most likely to survive and return to breed in temporary habitats used by H. gratiosa. Thus, hybridization and introgression might be more likely to have adverse effects on populations of H. gratiosa than H. cinerea.
Thin sections through the dentary of two specimens of the Late Cretaceous mosasaur Clidastes propython document the upright (vertical) position of developing replacement teeth. Snakes are the only squamates with replacement teeth that develop in a nearly horizontal, posteriorly inclined position. The thin sections also corroborate the finding in 2003 by M. L. Caldwell, L. A. Bundy, and D. O. Lamourex that interdental ridges fully separate successive teeth at their base in mosasaurs, at least on the dentary. This feature is also seen in alethinophidian snakes among squamates, but it remains unknown for more basal members of the mosasauroid clade, and it is absent in scolecophidian snakes.