Search

“Hot spring frog” is an informal name used for the Japanese stream tree frog (Buergeria japonica), which is widely distributed in Taiwan and the Ryukyu Archipelago in Japan. Some populations of the species are known to inhabit hot springs. However, water temperature can be extremely high around the sources of hot springs. Thus, it is questionable whether B. japonica selectively inhabits such dangerous environments. To address this question, we conducted a series of observations of water temperature preferences of a hot spring population of B. japonica in Kuchinoshima Island in Japan: (a) a field observation of tadpole density in water pools of different temperatures, (b) a field observation of water temperatures where adult males appear for breeding, and (c) an indoor observation of water temperatures selected by adult females for oviposition. As a result, tadpoles showed a higher density in cooler water. Adult males avoided water pools hotter than 37°C, and adult females selected cooler pools for oviposition. Camera records also showed that adult individuals tend to appear around cooler pools. Thus, we did not find any support for the hypothesis that hot spring frogs prefer hot water. Conversely, they apparently tended to prefer cooler water if it was available. Water temperatures around the sources of the hot spring exceed thermal tolerances of the species and could be a strong selective pressure on the population. Thus, the ability to sense and avoid lethal temperatures may be a key ecological and physiological characteristic for the species that inhabit hot springs.

Water striders (Hemiptera: Gerridae) are predators found on the water surface that prey mainly on arthropods. The feeding on other organisms (dead vertebrates, fishes and tadpoles) is a rare event. To our knowledge, predation of frog eggs by water striders has not yet been reported. We observed that adult water striders, Gerris latiabdominis Miyamoto, 1958 (Hemiptera: Gerridae), preyed on the eggs of three frog species, Pelophylax nigromaculata Hallowell, 1861 (Anura: Ranidae), Rana japonica Boulenger, 1879 (Anura: Ranidae), and Rhacophorus schlegelii Gunther, 1858 (Anura: Rhacophoridae). We found predation by the water striders affects the survival rate of frog eggs floating on the water surface. We suggest that this hunting event would occur in water bodies in which water striders and frogs coexist, especially the region where their phenology overlaps.

The ability to glide has evolved in multiple taxa and is usually associated with highly specialized morphological adaptations. Traits that evolve for one reason, can, however, influence other traits and abilities. In this study, we examined the influence of adaptations for gliding on the jumping and clinging abilities of frogs by comparing specialized flying frogs (Rhacophorus) and unspecialized non-flying frogs (Polypedates) from the family Rhacophoridae. Flying frogs had more webbing, longer legs, and greater clinging abilities than non-flying frogs. Clinging abilities, jumping distance, and gliding distance all correlated positively with body size for both flying and non-flying frogs. We did not, however, find any significant differences between the two groups in horizontal jumping distance or glide distance from a low starting point of 1.56 m. The morphological adaptations that evolved for gliding have not significantly influenced the flying frogs' short-distance jumping abilities, but may have influenced their clinging abilities. Alternatively, there may have been direct selection for clinging ability because of flying frogs' increased need, compared with other frogs, to land on vertical surfaces without slipping off.

Skeletal morphology is directly associated with habitat characteristics. To investigate the arboreal adaptation, we studied the osteological morphology of the forelimbs and the third metacarpals of arboreal frogs (Rhacophoridae and Hylidae) and non-arboreal frogs (Bombinatoridae, Bufonidae, Megophryidae, Ranidae, and Microhylidae) using transparent specimens or X-rays of skeletons. Our results revealed that the bony knob on the third metacarpal, which formed by a dilated and elongated lateral articular cartilage (AL) through endochondral ossification, occurred only in species of Rhacophorinae. The results of the phylogenetic comparative methods and correlation analysis strongly supported the conclusion that the bony knob is a phylogenetic independent evolution trait and had a significant correlation with the arboreal habitat. Furthermore, anatomical observation showed that a muscle adhered to the bony knob. Therefore, we speculated that the bony knob might act as an enlarged attachment point for larger or more musculatures to help with grasping. In addition, the relative length of the hand showed a significant difference between arboreal and non-arboreal species (p = .007), suggesting that longer hands might be an arboreal adaptive trait. Overall, this study leads to a deeper understanding of the arboreal adaptation.

AIM: Species with wide distributions spanning the African Guinean and Congolian rain forests are often composed of genetically distinct populations or cryptic species with geographic distributions that mirror the locations of the remaining forest habitats. We used phylogeographic inference and demographic model testing to evaluate diversification models in a widespread rain forest species, the African foam‐nest treefrog Chiromantis rufescens. LOCATION: Guinean and Congolian rain forests, West and Central Africa. TAXON: Chiromantis rufescens. METHODS: We collected mitochondrial DNA (mtDNA) and single‐nucleotide polymorphism (SNP) data for 130 samples of C. rufescens. After estimating population structure and inferring species trees using coalescent methods, we tested demographic models to evaluate alternative population divergence histories that varied with respect to gene flow, population size change and periods of isolation and secondary contact. Species distribution models were used to identify the regions of climatic stability that could have served as forest refugia since the last interglacial. RESULTS: Population structure within C. rufescens resembles the major biogeographic regions of the Guinean and Congolian forests. Coalescent‐based phylogenetic analyses provide strong support for an early divergence between the western Upper Guinean forest and the remaining populations. Demographic inferences support diversification models with gene flow and population size changes even in cases where contemporary populations are currently allopatric, which provides support for forest refugia and barrier models. Species distribution models suggest that forest refugia were available for each of the populations throughout the Pleistocene. MAIN CONCLUSIONS: Considering historical demography is essential for understanding population diversification, especially in complex landscapes such as those found in the Guineo–Congolian forest. Population demographic inferences help connect the patterns of genetic variation to diversification model predictions. The diversification history of C. rufescens was shaped by a variety of processes, including vicariance from river barriers, forest fragmentation and adaptive evolution along environmental gradients.

The Old World tree frogs (Anura: Rhacophoridae), with 387 species, display a remarkable diversity of reproductive modes – aquatic breeding, terrestrial gel nesting, terrestrial foam nesting and terrestrial direct development. The evolution of these modes has until now remained poorly studied in the context of recent phylogenies for the clade. Here, we use newly obtained DNA sequences from three nuclear and two mitochondrial gene fragments, together with previously published sequence data, to generate a well-resolved phylogeny from which we determine major patterns of reproductive-mode evolution. We show that basal rhacophorids have fully aquatic eggs and larvae. Bayesian ancestral-state reconstructions suggest that terrestrial gel-encapsulated eggs, with early stages of larval development completed within the egg outside of water, are an intermediate stage in the evolution of terrestrial direct development and foam nesting. The ancestral forms of almost all currently recognized genera (except the fully aquatic basal forms) have a high likelihood of being terrestrial gel nesters. Direct development and foam nesting each appear to have evolved at least twice within Rhacophoridae, suggesting that reproductive modes are labile and may arise multiple times independently. Evolution from a fully aquatic reproductive mode to more terrestrial modes (direct development and foam nesting) occurs through intermediate gel nesting ancestral forms. This suggests that gel nesting is not only a possible transitional state for the evolution of terrestriality, but also that it is a versatile reproductive mode that may give rise to other terrestrial reproductive modes. Evolution of foam nesting may have enabled rhacophorids to lay a larger number of eggs in more open and drier habitats, where protection from desiccation is important. Terrestrial direct development allows frogs to lay eggs independent of bodies of water, in a diversity of humid habitats, and may represent a key innovation that facilitated the evolution of nearly half of all known rhacophorid species.

The arboreal frog, Chiromantis hansenae (Family: Rhacophoridae), is one of only a handful of South-East Asian amphibian species reported with parental care. We present the first systematic observational and experimental study confirming offspring benefits as a result of this care, which has a number of unusual life-history characteristics. Eggs are unusually small, breeding takes place in large pools, and females attend the eggs. Field observations and an adult removal experiment demonstrated a critical contribution of egg attendance to offspring survivorship. Harsh environmental conditions for offspring appeared to be the prime mover of parental care in this species, with desiccation as the main source of mortality when attending adults are absent. Results confirm females to be the caregivers, making C. hansenae a rare case of maternal egg attendance in a non-directly developing anuran.

Li, J.T., Li, Y., Murphy, R.W., Rao, D.-Q. & Zhang, Y.-P. (2012). Phylogenetic resolution and systematics of the Asian tree frogs, Rhacophorus (Rhacophoridae, Amphibia). Zoologica Scripta, 41, 557570. The treefrog genus Rhacophorus, a large genus with 80 species, has a wide range, occurring eastward from India to China, Japan, South-east Asia, the Greater Sunda Islands and the Philippines. The phylogenetic relationships and taxonomic recognition of many species are very controversial. To stabilize the taxonomy, the phylogenetic relationships among about 52 species are investigated from 96 samples using mtDNA sequence data. Matrilineal relationships based on maximum likelihood and Bayesian inference methods resolve three well-supported lineages (A, B and C), although the phylogenetic relationships among three lineages remain ambiguous. Analyses support recognition of two previously assigned subgenera, Leptomantis and Rhacophorus, and these correspond to lineages A and B, respectively. Given that we have three strongly supported lineages, that these lineages are morphologically distinct, and the constrained geographic distributions of these groups, we recognize each lineage as a taxon. Subgenus Leptomantis includes species mainly from Malaysia, Indonesia and the Philippines. Subgenus Rhacophorus contains a mix of species occurring in India, Indochina and southern China. Lineage C accommodates species distributed mostly in East Asia, including Japan and China. Based on genetic and morphological data from type localities, the taxonomic recognition of some species needs to be reconsidered. Rhacophorus pingbianensis and Polypedates spinus are considered as junior synonyms of Rhacophorus duboisi. Specimens of Rhacophorus rhodopus from Vietnam and Hainan, China likely represent an undescribed, cryptic species.

Hertwig, S.T., Das, I., Schweizer, M., Brown, R., & Haas, A. (2012). Phylogenetic relationships of the Rhacophorus everetti-group and implications for the evolution of reproductive modes in Philautus (Amphibia: Anura: Rhacophoridae). —Zoologica Scripta, 41, 29–46. This study presents the first phylogenetic analysis of the enigmatic Rhacophorus everetti species group and the first description of its unique tadpole. A total sample of 95 12S and 16S mitochondrial rDNA sequences were compiled including new sequence data from 28 rhacophorid species. Based on 1332 and 1407 bp, respectively, and on the gap coding method applied, a new hypothesis about the phylogeny of rhacophorid tree frogs from Sundaland was obtained. While Rhacophorus was uncovered as a polyphyletic assemblage, the monophyly of the Bush Frogs of the genus Philautus, including the Rhacophorus everettigroup, is robustly supported. We, therefore, transfer the everetti-group to the genus Philautus. As a second step, we recognise Philautus macroscelis (comb. nov.) from Borneo and P. everetti (comb. nov.) from Palawan as distinct allopatric species. Molecular and morphological evidence clearly indicates that each is a distinct lineage with a unique ancestry and discrete evolutionary fate. Moreover, close phylogenetic relationships of several Philautus species from Borneo to taxa from outside Borneo were recovered; P. everetti and P. macroscelis being the only one example. These findings indicate a complex biogeographical history of Sundaland Bush Frogs, which can only be explained by repeated dispersal and vicariance events between the Asian mainland and the Sunda islands. Finally, a single tadpole discovered on Gunung Kinabalu was matched genetically to P. macroscelis. Features of its peculiar external morphology suggest that this larva is endotrophic and possibly nidicolous. A comparable reproductive biology was formerly unknown in rhacophorid tree frogs. The presence of a free-swimming tadpole in Philautus challenges the notion that terrestrial direct development represents an apomorphic character unambiguously shared by all members of this genus. The implications for the evolution of reproductive modes in Bush Frogs are discussed in a phylogenetic context.

The food habits of the endangered giant water bug, Lethocerus deyrolli, were studied in the rice fields of Nose, in the north of Osaka Prefecture, Japan. Field observations revealed that frogs were the most important prey item. Frogs represented 86.4% and 78.6% in the diet of L. deyrolli in spring and summer, respectively. Among seven species of three families (Hylidae, Rhacophoridae, and Ranidae) exploited by L. deyrolli, the most important food item was adult Hyla japonica in spring and juvenile Rana nigromaculta in summer. Fish and aquatic arthropods were not considered important foods for L. deyrolli. The frog-dependent food habits indicate that the recovery and conservation of frogs should be prioritized to protect L. deyrolli from extinction.

During the last two decades, major taxonomic rearrangements were instituted in the anuran family Ranidae. Most of these changes were not based on phylogenetic analysis, and many are controversial. Addressing the phylogeny of Ranidae requires broader taxon sampling within the superfamily Ranoidea, the phylogenetic relationships and higher classification of which are also in a state of flux. No comprehensive attempt has yet been made to reconstruct ranid phylogeny using both morphological and molecular data. In the present contribution, data from 178 organismal characters were collated for 74 exemplar species representing the families Arthroleptidae, Hemisotidae, Hyperoliidae, Mantellidae Microhylidae, Petropedetidae, Rhacophoridae, Sooglossidae, and most subfamilies of Ranidae. These were combined with � 1 kb of DNA sequence from the mitochondrial 12S rDNA and 16S rDNA gene regions in a simultaneous parsimony analysis with direct optimization. Results support the classification of Hemisus with the brevicipitine microhylids, confirm that Arthroleptidae (and its two component subfamilies Astylosterninae and Arthroleptinae) are monophyletic, and advocate the recognition of Leptopelidae. Monophyly of Ranidae is compromised by recognition of Petropedetidae, Rhacophoridae and Mantellidae, which should be recognized as subfamilies of Ranidae at present. Furthermore, Petropedetidae was found to be grossly paraphyletic, comprising three clades which are all considered separate subfamilies of Ranidae, i.e., Petropedetinae, Phrynobatrachinae and Cacosterninae. Three well defined subfamilies of Ranidae were consistently retrieved as monophyletic in a sensitivity analysis, i.e., Tomopterninae, Ptychadeninae and Pyxicephalinae. However, Ptychadeninae and Pyxicephalinae were embedded in Raninae and Dicroglossinae, respectively. Ceratobatrachinae is removed from Dicroglossinae. Dicroglossinae is synonymized with Pyxicephalinae. A new subfamily Strongylopinae is proposed. Raninae should be conservatively treated as a ‘‘metataxon’’ (sensu Ford and Cannatella, 1993) until such time as it is fully revised. Tomopterninae is removed from synonymy with Cacosterninae. Morphological synapomorphies are reported for major monophyletic clades retrieved in the simultaneous analysis with equal weights. The present study found that many Old World clades appear to contain both African and Asian taxa, contrary to the findings of some recent biogeographical analyses. This study demonstrates the value of broad taxonomic sampling in ranid phylogeny, and highlights the immense contribution that can be made from detailed morphological data. � The Willi Hennig Society 2005.

Microhylid spermatozoa show the autapomorphic condition of possessing a thin post-mitochondrial cytoplasmic collar. Their spermatozoa are apomorphic in several respects. They have lost the distinct nuclear shoulder, endonuclear canal and axial perforatorium observed in urodeles, caecilians and primitive frogs, possess a conical perforatorium and apomorphically lack any fibres associated with the axoneme. The spermatozoa of Cophixalus , however, differ in several respects from those of the other microhylids examined. Cophixalus spermatozoa are longer in almost all measurements, the acrosome vesicle is cylindrical and does not completely cover the putative perforatorium, the perforatorium is asymmetrical and composed of fine fibres, the nucleus is strongly attenuated and narrower, and the mitochondria are elongate. The absence of fibres associated with the axoneme is an apomorphic condition shared with the Ranidae, Rhacophoridae and Pipidae.

We studied the intraspecific interactions among oophagous Chirixalus eiffingeri tadpoles that occupied the same water-filled bamboo stumps at Chitou, Taiwan. We monitored the growth of newly-hatched tadpoles in unoccupied and occupied bamboo stumps in the field where the latter contained large tadpoles that hatched from earlier clutches. The growth of the small, late-hatching tadpoles in occupied nests was suppressed by the presence of large, early-hatching tadpoles. However, small tadpoles that were physically separated from large tadpoles in a perforated container grew at about the same rate as small tadpoles living in pools without large tadpoles. Thus, the slower growth of the late-hatching tadpoles was probably caused by behavioural interference competition with the early-hatching tadpoles. In the laboratory, we kept large and small tadpoles together in containers and did not feed them for 6 days. The large tadpoles did not cannibalize the small tadpoles. Although large tadpoles may scavenge dead tadpoles, the effects of scavenging on growth were negligible. Interactions among cohabiting C. eiffingeri tadpoles are similar to those among the oophagous tadpoles of several hylid species that use phytotelmata. Results suggest that behavioural interference competition is the principal type of intraspecific interactions among the oophagous, non-predatory tadpoles of hylid and rhacophorid frogs.

Vocalizations of Boophis madagascariensis (Rhacophoridae) males were recorded in a mid-elevation rain forest in eastern Madagascar. Call notes made by males of this species were classified into 28 types. This represents the largest known call repertoire of any amphibian. The calls range widely in spectral characteristics from a narrowband, nearly pure-tone to broadband ‘rip’ notes, to even broader band, pulsatile ‘iambic’ notes consisting of up to 23 pulses. Even considering all ‘iambic’ notes as variants of one type, there remain eight distinct call notes produced by this species. Morphological analysis of the vocal musculature of B. madagascariensis revealed no obvious adaptations for unusual glottal flexibility or function. Playback studies using a subset of the call notes as stimuli were carried out in the animals’ natural habitat to determine the functional significance of several of the call notes. At the lowest playback levels, there was a significant tendency for males to produce rip notes in immediate response to either rip or iambic note stimuli. At the higher playback levels, we identified one sequence of iambic notes that consistently evoked a significant iambic note response from males. A permutation test on call note transitions during spontaneous calling revealed that call note pairs occurred inconsistently and unpredictably. The evolutionary significance of an extended vocal repertoire, matched counter-calling and a random call note production scheme is discussed.

Both triploids and gynogenetic diploids (GDs) were produced to clarify the relationship between the sex-chromosome constitution and the expression of sex in the common bell-ring frog, Buergeria buergeri. The sex differentiation of triploids in B. buergeri is quite remarkable. Triploid frogs consisted of three sex genotypes, ZZZ, ZWW and ZZW. All ZZZ triploids were males, and all ZWW triploids were females. It is very interesting that half of the ZZW triploids became female, and the other half became male. The GD frogs consisted of two sex genotypes, ZW and ZZ, which did not differ from the controls in sex differentiation. Since the ratios of ZZ and ZW eggs were significantly different among female parents, it is assumed that most (approximately 80-90%) of the eggs made pre-reductional division in some females and post-reductional division in others during meiosis. It seems that ZW eggs were produced by the occurrence of recombination between the centromere and the sex-determining genes in B. buergeri. It was also found that the number of Z chromosomes in each cell of these triploids and GDs agreed with that of the nucleoli in each cell.

Skin of the Indian tree frog, Polypedates maculatus (Rhacophoridae), was studied in the context of self-wiping behaviour which functions to expel and distribute cutaneous secretions recently shown to retard evaporative water loss. The secretions contain both mucus and lipids and are derived from a common gland considered to be homologous with characteristic anuran mucous glands. The glands are bipotent and secrete both mucus and lipoid products which are evidently mixed within the glandular lumen. Another type of gland resembling characteristic anuran serous (or granular) glands is found in dorsal but not ventral skin, whereas the lipid-secreting mucous glands are found in skin associated with all body surfaces. There is no distinct, lipid-secreting gland present in the skin of this species other than the mucous glands. These histochemical data complement the earlier finding that resistance to evaporative water loss in this species is relatively small compared with phyllomedusine 'waterproof frogs which also exhibit wiping behaviour associated with secretion of lipids. Thus, wiping behaviour may have evolved in association with mucous secretions before dominant lipoid secretions resulted from strong selection for water conservation.

Reproductive behavior of the foam-nesting treefrog,Rhacophorus arboreus, is described. Oviposition was made either by an amplectant pair (a female, and an amplectant male) alone or by an amplectant pair and other males (joiners). The snout-vent length of males and females was negatively correlated with the date of the first appearance in the pond. The period of staying in the pond in males was longer than that in females. Physical body contacts of other males, and encounter calls by ampletant males were frequently observed before oviposition with joiners. Snout-vent length of the female and an amplectant male were positively correlated. Encounter calls by amplectant males were likely to precede movement of females. There was no difference of snout-vent length between amplectant males and joiners. Females moved the hindlimbs more frequently than males during oviposition. Amplectant males made encounter cells more frequently in oviposition with joiners, than oviposition without joiners. The patterns of transitions between acts of females and amplectant males were similar between oviposition with and without joiners. Females more frequently responded to amplectant males than joiners. Both the duration of a bout of the movements of hindlimbs of females and the interval between the bouts were longer in oviposition without joiners than that with joiners. The number of the movements per bout in oviposition without joiners was smaller than that with joiners. Encounter calls by amplectant males during oviposition tended to precede the hindlimb movements of females.

Amphibians are remarkable in having a tongue that is propelled from the mouth, to impact on, adhere to, and pull prey into the buccal cavity. Although sometimes listed as a characteristic defining the class, it is only among certain salamanders and frogs that the tongue appears to be flipped out rather than moved by incremental control. Its action is thus analogous to that of the projectile tongue of chameleons (Gnanamuthu, 1930; Gans, 1967), rather than to the merely extensible tongue of anteaters, some birds, and snakes. The mechanism of the tongue of frogs, which is propelled by the rotation of "soft" tissues about the mandibular symphysis, is fundamentally distinct from that of the tongue of salamanders, which is hurled anteriorly by a forward shift of the hyobranchial skeleton (Regal, 1966; Ozeti and Wake, 1969; Lombard and Wake, 1976; Larson and Guthrie, 1976). The tongue has been used in the 19th Century and through the present as a "taxonomic character" in the classification of frogs (cf. Lynch, 1973). However, the structure, function and evolution of this complex lingual system has received but minimal attention. Perhaps symptomatic of such neglect is that an obscure but beautiful study of the ontogeny and morphology of the tongue and its intrinsic muscles in 42 species of frogs (MagimelPelonnier, 1924) has not been brought to light in any subsequent treatise on the frogs (Noble, 1931; Werner, 1930; Reeder, 1964; Blair, 1972; Vial, 1973) and, indeed, in the major handbook of vertebrate anatomy (Nishi, 1938). The mechanical basis of tongue projection has long been discussed and debated, mainly for the advanced genera Rana and Bufo (Duges, 1827, 1835; Hartog, 1901; Gaupp, 1901; Barclay, 1942; Gnanamuthu, 1933; Boiker, 1937). Recently its mechanism has been explained anew (Tatarinov, 1951; Gans, 1961, 1962), though experimental confirmation is still lacking. It is commonly assumed that the condition of Rana or Bufo can be generalized at least for anurans belonging to "nonarchaic" or "modern" taxonomic groups, such as the Ranidae, Bufonidae, Hylidae, Leptodactylidae, and Rhacophoridae, in which the tongue is attached in front with a "free flap posteriorly." The "archaic" taxonomic groups, the Ascaphidae (here both Liopelma and Ascaphus but see Savage, 1973), Discoglossidae, Pipidae, and Rhinophrynidae, are supposed to differ, having noneversile, posteriorly attached, or even completely margined tongues when present. The function of such tongues remains unstudied. We propose here that statements such as "tongue present" or "tongue absent" and even "tongue with free flap posteriorly," do not necessarily define shared character states, but conceal critical biomechanical complexity and evolutionary parallelisms. It is not our intention here to present a comprehensive monograph on frog tongue structure and function. We document (1)

The construction of foam nests by the Anura seems to be a habit that has evolved separately in all the main zoogeographical regions. Chiromantis is a large tree frog weighing up to 5.5 g which is restricted to the Ethiopian region. This genus comprises three species which are found in the three main African biomes from rain forest (C. rufescens), through woodland (C. xerampelina) to semi-arid savannah (C. petersii). The female of C. rufescens is shown in this study to construct her nest with the assistance of three males, and like the other two species, the nests are always fastened to objects over temporary water sources. Although the rain forest and savannah species are the same size the latter lays twice as many eggs as the former. Additionally it is shown that the eggs of C. petersii are only half the size of C. rufescens. These facts can be correlated with the degree of permanence of the water source over which the nest is constructed. Features of the water economy and ecology are also described.