Treefrog Species Research Articles

Cool temperatures reduce antifungal activity of symbiotic bacteria of threatened amphibians--implications for disease management and patterns of decline.

Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a widespread disease of amphibians responsible for population declines and extinctions. Some bacteria from amphibians’ skins produce antimicrobial substances active against Bd. Supplementing populations of these cutaneous antifungal bacteria might help manage chytridiomycosis in wild amphibians. However, the activity of protective bacteria may depend upon environmental conditions. Biocontrol of Bd in nature thus requires knowledge of how environmental conditions affect their anti-Bd activity. For example, Bd-driven amphibian declines have often occurred at temperatures below Bd’s optimum range. It is possible these declines occurred due to reduced anti-Bd activity of bacterial symbionts at cool temperatures. Better understanding of the effects of temperature on chytridiomycosis development could also improve risk evaluation for amphibian populations yet to encounter Bd. We characterized, at a range of temperatures approximating natural seasonal variation, the anti-Bd activity of bacterial symbionts from the skins of three species of rainforest tree frogs (Litoria nannotis, Litoria rheocola, and Litoria serrata). All three species declined during chytridiomycosis outbreaks in the late 1980s and early 1990s and have subsequently recovered to differing extents. We collected anti-Bd bacterial symbionts from frogs and cultured the bacteria at constant temperatures from 8°C to 33°C. Using a spectrophotometric assay, we monitored Bd growth in cell-free supernatants (CFSs) from each temperature treatment. CFSs from 11 of 24 bacteria showed reduced anti-Bd activity in vitro when they were produced at cool temperatures similar to those encountered by the host species during population declines. Reduced anti-Bd activity of metabolites produced at low temperatures may, therefore, partially explain the association between Bd-driven declines and cool temperatures. We show that to avoid inconsistent antifungal activity, bacteria evaluated for use in chytridiomycosis biocontrol should be tested over a range of environmental temperatures spanning those likely to be encountered in the field.

Geographic variation in the advertisement call of Hypsiboas cordobae (Anura, Hylidae)

Geographic variation in the advertisement call of anuran is commonly observed among conspecific populations. We analyzed the geographic variation of advertisement calls in six populations of the Argentinean treefrog species Hypsiboas cordobae throughout its geographic distribution. The advertisement calls of this species consisted of three, four or five tonal notes. Spectral call variables showed significant differences among populations, as in the first and second inter-note intervals. Discriminant function analysis demonstrated significant multivariate differences among populations. All spectral variables exhibited clinal variation, with frequencies increasing significantly from north to south. These same variables were negatively correlated with the altitudes of the six populations. Mantel tests showed no significant correlation between geographic distances and bioacoustic distances or between altitudinal distances and bioacoustic distances, attributable to that call variations are due to different levels of latitudinal and altitudinal populations studied, and not to the distances between pairs of localities. Altitudinal variation in spectral properties may be attributable to an inverse relation with body size, which varies clinally along the same geographical axis.

Temporal and spatial coherence as cues for across-frequency grouping in treefrogs

Humans exploit environmental regularities in sounds to perceptually bind acoustic energy occurring simultaneously at different frequencies. Such abilities influence vowel perception in speech and timbre perception in music. Other animals solve similar binding problems in the recognition of species-specific acoustic signals. Moreover, they commonly do so using auditory systems that differ in notable ways from that of mammals. This study of two treefrog species investigated temporal and spatial coherence as cues that promote grouping of two spectral bands emphasized in their acoustic signals. In two-alternative choice tests, females preferred temporally and spatially coherent calls over alternatives in which the onsets/offsets of the two bands were time-shifted by more than 25 ms or in which the two bands were spatially separated by 7.5° or more. These results, which suggest temporal coherence and spatial coherence promote across-frequency auditory grouping, are notable given differences in how the two spectral bands are processed by the anuran auditory system. Sound energy in the high- and low-frequency bands primarily enters the auditory system via different pathways (tympanum and body wall, respectively) and is encoded primarily by different papillae in the inner ear (basilar papilla and amphibian papilla, respectively).

Interstitial Telomeric Sequences (ITS) and major rDNA mapping reveal insights into the karyotypical evolution of Neotropical leaf frogs species (Phyllomedusa, Hylidae, Anura).

BackgroundThe combination of classical cytogenetics with molecular techniques represents a powerful approach for the comparative analysis of the genome, providing data for the systematic identification of chromosomal homologies among species and insights into patterns of chromosomal evolution within phylogenetically related groups. Here, we present cytogenetic data on four species of Neotropical treefrogs of the genus Phyllomedusa (P. vaillantii, P. tarsius, P. distincta, and P. bahiana), collected in Brazil and Ecuador, with the aim of contributing to the understanding of the chromosomal diversification of this genus.ResultsWith the exception of P. tarsius, which presented three telocentric pairs, all the species analyzed had conservative karyotypic features. Heterochromatic patterns in the genomes of these species revealed by C-banding and fluorochrome staining indicated the presence of a large number of non-centromeric blocks. Using the Ag-NOR method and FISH with an rDNA 28S probe, we detected NOR in the pericentromeric region of the short arm of pair 7 in P. vaillantii, pair 1 in P. tarsius, chromosomes 1 and 9 in P. distincta, and in chromosome 9 in P. bahiana, in addition to the presence of NOR in one homologue of chromosome pair 10 in some individuals of this species. As expected, the telomeric probe detected the terminal regions of the chromosomes of these four species, although it also detected Interstitial Telomeric Sequences (ITS) in some chromosomes of the P. vaillantii, P. distincta and P. bahiana karyotypes.ConclusionA number of conservative chromosomal structures permitted the recognition of karyotypic homologies. The data indicate that the presence of a NOR-bearing chromosome in pair 9 is the plesiomorphic condition in the P. burmeisteri group. The interspecific and intraspecific variation in the number and location of rDNA sites reflects the rapid rate of evolution of this character in Phyllomedusa. The ITS detected in this study does not appear to be a remnant of structural chromosome rearrangements. Telomeric repeats were frequently found in association with heterochromatin regions, primarily in the centromeres, which suggests that (TTAGGG)n repeats might be an important component of this heterochromatin. We propose that the ITSs originated independently during the chromosomal evolution of these species and may provide important insights into the role of these repeats in vertebrate karyotype diversification.

Comparing the Status of Two Sympatric Amphibians in the Sierra Nevada, California: Insights on Ecological Risk and Monitoring Common Species

Abstract Basic information on species distribution and abundance is often lacking, even for common species. The historically abundant Mountain Yellow-legged (Rana sp.) and Pacific Treefrog (Pseudacris sp.) species complexes occur sympatrically and are exposed to similar threats. We evaluated the status of these species complexes on national forest lands in the Sierra Nevada, California as part of a long-term bioregional amphibian monitoring program. To determine occupancy and abundance indices, we surveyed all lentic and a sample of lotic habitats in 208 small watersheds (2–4 km2) selected using an unequal probability design where watersheds occupied previously had a higher likelihood of being selected. For Rana sp., results corroborated other assessments that the taxon has declined substantially. We found breeding activity in an estimated 0.04 (SE = 0.01) of watersheds rangewide, 0.47 (SE = 0.04) of watersheds with locality data from 1990–2001, and 0.02 (SE = 0.03) of watersheds with locality data prior ...

Evolutionary origins and genetic variation of the Seychelles treefrog, Tachycnemis seychellensis (Duméril and Bibron, 1841) (Amphibia: Anura: Hyperoliidae)

The hyperoliid frog Tachycnemis seychellensis, the only species of its genus, is endemic to the four largest granitic islands of the Seychelles archipelago and is reliant on freshwater bodies for reproduction. Its presence in the Seychelles is thought to be the product of a transoceanic dispersal, diverging from the genus Heterixalus, its closest living relative (currently endemic to Madagascar), between approximately 10–35Ma. A previous study documented substantial intraspecific morphological variation among island populations and also among populations within the largest island (Mahé). To assess intraspecific genetic variation and to infer the closest living relative(s) of T. seychellensis, DNA sequence data were generated for three mitochondrial and four nuclear markers. These data support a sister-group relationship between T. seychellensis and Heterixalus, with the divergence between the two occurring between approximately 11–19Ma based on cytb p-distances. Low levels of genetic variation were found among major mitochondrial haplotype clades of T. seychellensis (maximum 0.7% p-distance concatenated mtDNA), and samples from each of the islands (except La Digue) comprised multiple mitochondrial haplotype clades. Two nuclear genes (rag1 and tyr) showed no variation, and the other two (rho and pomc) lacked any notable geographic structuring, counter to patterns observed within presumably more vagile Seychelles taxa such as lizards. The low levels of genetic variation and phylogeographic structure support an interpretation that there is a single but morphologically highly variable species of Seychelles treefrog. The contrasting genetic and morphological intraspecific variation may be attributable to relatively recent admixture during low sea-level stands, ecophenotypic plasticity, local adaptation to different environmental conditions, and/or current and previously small population sizes. Low genetic phylogeographic structure but substantial morphological variation is unusual within anurans.

Stronger transferability but lower variability in transcriptomic‐ than in anonymous microsatellites: evidence from Hylid frogs

A simple way to quickly optimize microsatellites in nonmodel organisms is to reuse loci available in closely related taxa; however, this approach can be limited by the stochastic and low cross-amplification success experienced in some groups (e.g. amphibians). An efficient alternative is to develop loci from transcriptome sequences. Transcriptomic microsatellites have been found to vary in their levels of cross-species amplification and variability, but this has to date never been tested in amphibians. Here, we compare the patterns of cross-amplification and levels of polymorphism of 18 published anonymous microsatellites isolated from genomic DNA vs. 17 loci derived from a transcriptome, across nine species of tree frogs (Hyla arborea and Hyla cinerea group). We established a clear negative relationship between divergence time and amplification success, which was much steeper for anonymous than transcriptomic markers, with half-lives (time at which 50% of the markers still amplify) of 1.1 and 37 My, respectively. Transcriptomic markers are significantly less polymorphic than anonymous loci, but remain variable across diverged taxa. We conclude that the exploitation of amphibian transcriptomes for developing microsatellites seems an optimal approach for multispecies surveys (e.g. analyses of hybrid zones, comparative linkage mapping), whereas anonymous microsatellites may be more informative for fine-scale analyses of intraspecific variation. Moreover, our results confirm the pattern that microsatellite cross-amplification is greatly variable among amphibians and should be assessed independently within target lineages. Finally, we provide a bank of microsatellites for Palaearctic tree frogs (so far only available for H. arborea), which will be useful for conservation and evolutionary studies in this radiation.

Behavioral strategies and signaling in interspecific aggressive interactions in gray tree frogs

Interspecific aggression has important consequences for ecological processes and the evolution of behavioral strategies. We examined interspecific aggressive interactions in the 2 gray tree frog species, Hyla chrysoscelis and Hyla versicolor. These species call side by side in the same ponds, and acoustic interference occurs because of the similar spectral characteristics of their vocalizations. The aggressive calls of these 2 species, although very similar, were statistically distinguishable: calls of H. chrysoscelis were more strongly amplitude modulated than those of H. versicolor. We used playbacks and staged interactions to characterize the behaviors of males exposed to heterospecific competitors or their signals. Males readily responded with aggression to heterospecific individuals and playbacks of their calls. These behaviors were qualitatively similar in both intraspecific and interspecific interactions, but there were some significant differences. First, males of H. chrysoscelis were more aggressive toward playbacks of conspecific advertisement calls than toward those of H. versicolor. There were no significant differences in this respect in H. versicolor. Second, interspecific interactions were usually more escalated than intraspecific interactions and more likely to end with the loser moving away from its opponent. Although neither species had an advantage in staged interactions, behavioral responses were asymmetrical because H. versicolor was more likely than H. chrysoscelis to initiate physical contact. Previous studies showed that H. versicolor suffers from a greater reduction in attractiveness than H. chrysoscelis in the presence of heterospecific call overlap. Thus, the asymmetries in aggressive behavior between the 2 species may be related to differential costs of heterospecific competition.

Feeding Site Selection by Frog-Biting Midges (Diptera: Corethrellidae) on Anuran Hosts

A critical challenge of obtaining a blood meal resides in selecting a feeding site at the host. We investigate the feeding sites of species of frog-biting midges (Corethrella spp) on tungara frogs, Engystomops pustulosus (Cope), and two species of treefrogs, Dendropsophus ebraccatus (Cope) and Dendropsophus microcephalus (Cope). To investigate the differences in midge feeding sites, we performed field observations, histological sections of the frogs and examined the mouthparts of the midges. Feeding sites are predicted by the vascular properties of the skin in different body areas of the frogs. According to optimal foraging theory, the midges should feed on host body areas that maximize blood intake. Contrary to optimal foraging theory predictions, however, their feeding sites correspond to body areas with high intensity host defensive behavior.

Morphometrics of two sympatric species of tree frogs in Korea: a morphological key for the critically endangered Hyla suweonensis in relation to H. japonica

Although DNA taxonomy is readily available, morphological keys are still valuable for quick and easy identification of species on site. In Korea, Hyla japonica is widespread throughout the country, whereas Hyla suweonensis occurs in the lowlands of western central Korea. H. suweonensis is rapidly disappearing and was consequently designated as critically endangered by the Korean government. We measured 19 characters for male individuals of the two tree frog species to develop a morphological key for identification. Our morphometric analyses indicated that the two tree frog species differed significantly in means of all morphological characters. In general, H. suweonensis was smaller and more slender than H. japonica. Moreover, the distributions of five characters related to head width and the angle between eyes and ipsilateral nostrils did not overlap in the two species and may be used for species identification. Because the character differences between the two species are small, all five characters should be used together to reliably distinguish the two tree frog species. Besides being used as a morphological key, our result in size difference leads to several research questions about microhabitat niche selection and competition between the two Korean tree frog species.

A new and possibly critically endangered species of casque-headed tree frog Aparasphenodon Miranda-Ribeiro, 1920 (Anura, Hylidae) from southeastern Brazil.

A new species of casque-headed tree frog of the genus Aparasphenodon is described from the municipality of Cataguases (21°20'S, 42°45'W; 288 m a.s.l.) in the Atlantic Rain Forest of Minas Gerais State, southeastern Brazil. Aparasphenodon pomba sp. nov. is characterized by medium size (males, snout-vent length, SVL 51.6-60.5 mm; females, SVL 58.7-62.1 mm); snout almost round in dorsal view; dorsum and limbs with cream-colored reticulation on dark-brown background; spots on ventral surface cream-colored; lips white; cream-colored dorsolateral stripe originating on the snout, crossing the upper eyelid and extending posteriorly to the axilla level; and red iris.

Comparative Cryo-SEM and AFM studies of hylid and rhacophorid tree frog toe pads

Cryo-scanning electron microscopy (cryo-SEM) and atomic force microscopy (AFM) offer new avenues for the study of the morphology of tree frog adhesive toe pads. Using these techniques, we compare toe pad microstructure in two distantly related species of tree frog, Litoria caerulea, White (Hylidae) and Rhacophorus prominanus, Smith (Rhacophoridae), in which the toe pads are considered to be convergent. AFM demonstrates the extraordinary similarity of both surface microstructures (largely hexagonal epithelial cells surrounded by deep channels) and nanostructures (an array of nanopillars, ca. 350 nm in diameter, all with a small dimple at the apex). The cryo-SEM studies examined the distribution of the fibrillar cytoskeleton within the different layers of the stratified toe pad epithelium, demonstrating that the cytoskeletal elements (keratin tonofilaments) that lie at an angle to the surface are relatively poorly developed in L. caerulea, clearly so in comparison to R. prominanus. Cryo-SEM also enabled the visualization of the fluid layer that is critical to a toe pad's adhesive function. This was achieved by examination of the frozen fluid residues left behind after removal of a toe within the cryo-SEM's experimental chamber. Such 'toeprints' demonstrated the presence of a wedge of fluid surrounding each toe pad, as well as fluid filling the channels that surround each epithelial cell. Cryo-SEM was used to examine epithelial cell shape. In a sample of 582 cells, 59.5% were hexagonal, the remainder being mainly pentagonal (23.1%) or heptagonal (16.1%). The distribution of differently-shaped cells was not random, but was not associated with either pad curvature or the distribution of mucous pores that provide fluid for the frogs' wet adhesion mechanism. Our main finding, the great similarity of toe pad structure in these two species, has important implications for biomimetics, for such convergent evolution suggests a good starting point for attempts to develop adhesives that will function in wet conditions.

No reproductive character displacement in male advertisement signals of Hyla japonica in relation to the sympatric H. suweonensis

Reproductive interaction between closely related taxa may leave a distinctive signature in which populations of interacting taxa are more dissimilar in sympatry than in allopatry. An ideal condition for such a pattern of reproductive character displacement (RCD) may occur when a population has limited gene flow and experiences strong selection pressure, exerted by an interacting taxon in areas of sympatry. In Korea, there are two closely related treefrog species: Hyla japonica, which is distributed widely throughout the country, and Hyla suweonensis, which occurs sympatrically in a narrow strip of western coastal plains. H. suweonensis is only found within the distribution of H. japonica. These two species have a similar single-note call structure. Here, we tested the possibility of RCD in H. japonica by examining geographic variation in advertisement calls. Although means of temporal and spectral characters were significantly different between the two species, sympatric populations of H. japonica and H. suweonensis overlapped in distributions of most characters. Furthermore, allopatric and sympatric H. japonica populations did not differ in all call characters. Weak genetic differentiation between sympatric and allopatric populations of H. japonica implied either substantial gene flow or recent genetic isolation. Possible explanations for no RCD in male advertisement calls of H. japonica include a difference in fine temporal characteristics between the two species, migration between sympatric and allopatric localities in H. japonica, RCD in female preferences in H. japonica, and weak selection pressure by H. suweonensis.

Maintenance of Ancestral Sex Chromosomes in Palearctic Tree Frogs: Direct Evidence from Hyla orientalis

Contrasting with the situation found in birds and mammals, sex chromosomes are generally homomorphic in poikilothermic vertebrates. This homomorphy was recently shown to result from occasional X-Y recombinations (not from turnovers) in several European species of tree frogs (Hyla arborea, H. intermedia and H. molleri). Because of recombination, however, alleles at sex-linked loci were rarely diagnostic at the population level; support for sex linkage had to rely on multilocus associations, combined with occasional sex differences in allelic frequencies. Here, we use direct evidence, obtained from anatomical and histological analyses of offspring with known pedigrees, to show that the Eastern tree frog (H. orientalis) shares the same pair of sex chromosomes, with identical patterns of male heterogamety and complete absence of X-Y recombination in males. Conservation of an ancestral pair of sex chromosomes, regularly rejuvenated via occasional X-Y recombination, seems thus a widespread pattern among Hyla species. Sibship analyses also identified discrepancies between genotypic and phenotypic sex among offspring, associated with abnormal gonadal development, suggesting a role for sexually antagonistic genes on the sex chromosomes.

Two novel genera and one new species of treefrog (Anura: Rhacophoridae) highlight cryptic diversity in the Western Ghats of India.

Amphibian diversity in the Western Ghats-Sri Lanka biodiversity hotspot is extremely high, especially for such a geographically restricted area. Frogs in particular dominate these assemblages, and the family Rhacophoridae is chief among these, with hundreds of endemic species. These taxa continue to be described at a rapid pace, and several groups have recently been found to represent unique evolutionary clades at the genus level. Here, we report DNA sequences, larval and breeding data for two species of rhacophorid treefrog (Polypedates bijui and a new, hitherto undescribed species). Remarkably, they represent unique, independent clades which form successive sister groups to the Pseudophilautus (Sri Lanka) + Raorchestes (India, China & Indochina) clades. We place these species into two new genera (Beddomixalus gen. nov. and Mercurana gen. nov.). Both of these genera exhibit a distinct reproductive mode among Rhacophoridae of peninsular India and Sri Lanka, with explosive breeding and semiterrestrial, unprotected, non-pigmented eggs oviposited in seasonal swamp pools, which hatch into exotrophic, free-living aquatic tadpoles. Relationships and representation of reproductive modes in sister taxa within the larger clade into which these novel genera are placed, is also discussed. These results suggest that more undescribed taxa may remain to be discovered in South Asia, and the crucial importance of conserving remaining viable habitats.

A new red-eyed treefrog of Agalychnis (Anura: Hylidae: Phyllomedusinae) from middle Magdalena River valley of Colombia with comments on its phylogenetic position.

We describe a new species of the charismatic red-eyed treefrogs (genus Agalychnis) from middle Magdalena River valley of Colombia (05°50'8.04"N, 74°50'16.55"W, 380 m a.s.l.). The new species is readily distinguished from all species members of the group by having orange flanks with small white warts. Phylogenetic analysis of DNA sequences of 16S rRNA gene recovered the new species as a member of the Agalychnis callidryas group. The presence of a red hue in the iris and a golden reticulated palpebral membrane, putative synapomorphies of the clade, support this hypothesis. Our analysis suggests that Agalychnis terranova sp. nov is closely related to A. callidryas from Central America and is proposed as its sister species with an uncorrected genetic distance of 5.69% between these taxa. The phylogenetic position and the geographic distribution of the new taxon add new lights to the presence of a biogeographic disjunction between Middle America lowlands, the Pacific region and Magdalena River valley of Colombia.

A new species of the Scinax catharinae group (Anura, Hylidae) from Serra da Canastra, southwestern state of Minas Gerais, Brazil

We describe Scinax pombali sp. n. a new species of treefrog of the Scinax catharinae group from Serra da Canastra, municipality of Capitólio (20°36'03''S, 46°17'34.9''W, 987 m a.s.l.), located in the Cerrado domains of the State of Minas Gerais, Southeastern Brazil. The new species is characterized by its small size, blotches and color pattern on dorsal surface and hidden regions of flanks and thighs, canthus rostralis lightly concave and well marked, absent nuptial pad, and lack of externally differentiated inguinal gland. Additionally, we describe the tadpole of this new species, which is characterized by the large-sized oral disc and presence of a large number of marginal papillae (two to three rows on its dorsal portion and some rows in unorganized arrangement on its lateroventral portion).

Benefits and costs of using a lungworm parasite to control invasive toads in Australia

Pizzatto & Shine (2012) noted the serious impacts that the introduced cane toad Rhinella marina has caused to its predators in Australia. The toad’s range is expanding at an increasing rate and additional negative consequences are predicted. Control measures have been ineffective or in some cases have not been tried. Female toads have a very high fecundity, and the species has a high potential growth rate. High removal rates of the toad population are needed to eliminate the species, suggesting that physical removal is not practical (Shine & Doody, 2010). One approach to controlling the toad species is biological control, which has been effective in some cases in Australia and elsewhere (Saunders et al., 2010). Biological control usually involves introduction of a species that in its native range controls the population of the pest species. However, introducing an exotic species as a biocontrol agent can have negative effects on nontarget species and potentially on ecosystem function (Simberloff & Stiling, 1996). Use of a native species as a biological control agent eases these concerns, but may involve a protocol to increase the abundance and distribution of a native control agent. In the case of the cane toad, one goal of biocontrol can be slowing the rate of expansion. Individuals at the leading edge of expansion have greater locomotor endurance, and the authors suggest that this may be due to escape from a lungworm parasite that infects toads behind the leading edge. Therefore, the authors test aspects of a general hypothesis that posits that lungworm parasites can be used as a biocontrol agent to slow the toads’ advance. This may not be an entirely satisfactory solution, but slowing the toads’ advance might buy time to develop other ways to control the species’ numbers. As the lungworm is already present in the toads and likely was present in the toads when they were introduced to Australia in 1935, it is not considered an exotic species. The authors suggest that one way to increase the prevalence of lungworm infection is to infect a native tree frog species, Litoria caerulea, which does not seem to be negatively affected by the parasite. They also propose three primary assumptions necessary for biocontrol to work in this case: the parasite does not harm the tree frogs, the tree frogs can maintain an infection over the long term, and infective larvae of the parasite can be transmitted to cane toads and reduce viability of the toads. They test aspects of these assumptions in their paper. Pizzatto and Shine showed that the tree frogs were infected at a 50% rate at the end of the experiment, and this was after placing the lungworm in the mouths of the frogs. All parasite-exposed frogs survived, and their growth rate was not different from that of uninfected controls. It would be important to compare the growth of infected frogs and uninfected frogs as the ‘parasite-exposed’ treatment apparently contained frogs that were not infected or had cleared the infection. Of those frogs that were infected, they had on average a low intensity (1.67 parasites per frog). It is unclear that this intensity would have the desired effect of transmission of larvae to toads. To test for transmission to the toads, lungworm larvae were put in boxes housing five toads. About half of the toads were infected under these laboratory conditions. In terms of fitness effects on the toads, there was no survival difference between infected and uninfected, no difference in body mass and no difference in sprint speeds. The authors did find that toads exposed to lungworms had lower stamina than did controls. Laboratory conditions are likely to maximize transmission of parasites as toads were under high density conditions, and their movements were constrained. However, under these conditions, parasite prevalence in frogs and toads averaged 50%. Importantly, only minor fitness effects were seen in the toads. Based on these results, it seems doubtful that control would be effective in nature. There are other reasons to be skeptical that biocontrol would be effective in this case. Is the lungworm a factor in population control in other parts of the toads’ range where prevalence is high? If not, why would it be expected to work bs_bs_banner

A new species of Gracixalus (Amphibia: Anura: Rhacophoridae) from northern Vietnam

We describe a new species of small tree frog from northern Vietnam based on morphological differences and molecular divergence. Gracixalus waza sp. nov. is distinguishable from its congeners and other small rhacophorid species on the basis of a combination of the following characters: (1) size small (snout-vent length of males 27.1–32.9 mm, of females 37.6 mm); (2) head as wide as or wider than long; (3) vomerine teeth absent; (4) snout rounded and long (16–18 % of the snout-vent length); (5) spines on upper eyelid absent; (6) tibiotarsal projection absent; (7) dorsal skin smooth; (8) dermal fringes on forearm and tarsus absent; (9) dorsal surface of head and body greyish-green to moss-green with dark brown pattern forming an inverse Y marking; and (10) throat and chest with dark marbling. Our molecular data showed that the new species is nested in the same group with Gracixalus jinxiuensis sensu lato.

Effects of the Anuran Tadpole Assemblage and Nutrient Enrichment on Freshwater Snail Abundance (Physella sp.)

Abstract Alterations of aquatic ecosystems, such as nutrient enrichment and changes in community composition, can potentially have effects that pervade the entire community. We investigated the effects of nutrient enrichment and changes in the presence and density of two species of tadpoles, American toad (Anaxyrus americanus) and Gray treefrog (Hyla versicolor), on freshwater snail abundance (Physella sp.). At low tadpole density, there was no difference in the abundance of Physella sp. among treatments. At high tadpole density, treatments with both species of tadpoles present and nutrient enrichment had a higher abundance of Physella than all other treatment combinations. Mesocosms with high tadpole densities had lower periphyton dry mass than those with low overall tadpole density. At the end of the experiment, increased abundance of Physella was related to earlier metamorphosis in A. americanus and H. versicolor and higher proportions of H. versicolor metamorphosing and surviving. Nutrient enrichment ...