Megophryidae Research Articles

Revision of the little brown frogs in the Gephyromantis decaryi complex with description of a new species

We revise the systematics of a group of little brown leaf litter frogs from Madagascar that are notoriously difficult to di-agnose, the Gephyromantis decaryi complex. Using an integrative combination of molecular data, bioacoustics, and mor-phology, we reveal four divergent evolutionary lineages which all are monophyletic in the mitochondrial gene genealogiesand have unique haplotypes in the nuclear RAG1 gene. We recognize three of these as distinct species and a fourth one ascandidate species which requires additional study for final confirmation and description. The three species are (1) G. de-caryi Angel, 1930, from Midongy and Ranomafana, characterized by relatively long limbs and continuous dorsal folds;(2) Gephyromantis verrucosus Angel, 1930 from Vondrozo and Manombo, herein removed from the synonymy of G. bou-lengeri, including the designation of a lectotype, characterized by irregular tubercles on the dorsum, and G. hintelmannaesp. nov. from Tsitolaka forest near Ambohitsara village and a second nearby site, characterized by a relatively smoothdorsum, short note duration in advertisement calls, and lack of light-dark pattern along the upper lip. A fourth lineage mor-phologically similar and phylogenetically placed sister to G. hintelmannae is characterized by the shortest note durationin calls of the complex but we consider the available data as insufficient to fully assess its status and propose to keep considering this lineage as candidate species Gephyromantis sp. 7 until more specimens and data become available.

Co-Occurrence Patterns of Common and Rare Leaf-Litter Frogs, Epiphytic Ferns and Dung Beetles across a Gradient of Human Disturbance

Indicator taxa are commonly used to identify priority areas for conservation or to measure biological responses to environmental change. Despite their widespread use, there is no general consensus about the ability of indicator taxa to predict wider trends in biodiversity. Many studies have focused on large-scale patterns of species co-occurrence to identify areas of high biodiversity, threat or endemism, but there is much less information about patterns of species co-occurrence at local scales. In this study, we assess fine-scale co-occurrence patterns of three indicator taxa (epiphytic ferns, leaf litter frogs and dung beetles) across a remotely sensed gradient of human disturbance in the Ecuadorian Amazon. We measure the relative contribution of rare and common species to patterns of total richness in each taxon and determine the ability of common and rare species to act as surrogate measures of human disturbance and each other. We find that the species richness of indicator taxa changed across the human disturbance gradient but that the response differed among taxa, and between rare and common species. Although we find several patterns of co-occurrence, these patterns differed between common and rare species. Despite showing complex patterns of species co-occurrence, our results suggest that species or taxa can act as reliable indicators of each other but that this relationship must be established and not assumed.

Differences in the Effects of Selective Logging on Amphibian Assemblages in Three West African Forest Types

AbstractMaking generalizations about the impact of commercial selective logging on biodiversity has so far remained elusive. Species responses to logging depend on a number of factors, many of which have not been studied in detail. These factors may include the natural forest conditions (forest types) under which logging impacts are investigated; but this question has so far remained unexamined. In a large‐scale replicate study we aimed at clarifying the relationship between logging and forest types on leaf litter frogs. We contrast three distinct and naturally occurring forest types, including wet evergreen, moist evergreen and semi‐deciduous forests. Selectively logged sites were compared with primary forest sites for each forest type. We found that the response of frog communities to logging varies in different forest types. In the wet evergreen forest, richness was higher in logged forest than primary forest, while diversity measures were not different between logged and primary forest habitats. In the moist evergreen, richness and diversity were higher in selectively logged areas compared with primary forest habitats. In the semi‐deciduous, logged forests were characterized by drastic loss of forest specialists, reduced richness, and diversity. These results indicate that the net effect of logging varies with respect to forest type. Forest types that are characterized by adverse climatic conditions (i.e., low rainfall and protracted dry seasons) are more likely to produce negative effects on leaf litter anuran communities. For comparisons of the impact of logging on species to be effective, future research must endeavor to include details of forest type.

Restricted natural hybridization between two species of litter frogs on a threatened landscape in southwestern Brazilian Amazonia

Natural hybridization between allopatric species following secondary contact has been poorly documented for Neotropical anurans inhabiting the Amazonian lowlands. We conducted a genetic survey across a contact zone between two species of litter frogs, Allobates hodli and Allobates femoralis (family Dendrobatidae), located on the left riverbank of the upper Madeira River, State of Rondonia, Brazil. We obtained tissue samples from 11 sampling sites on both riverbanks, covering approximately a 400 km long transect. We evaluated the genetic relationships between samples using haplotype networks and a distance-based phylogenetic tree obtained from a dataset of 16S rRNA mtDNA sequences. Estimates of genetic diversity, population structure, and the identification of sites where genetic admixture occurred were carried out by means of frequency-based methods and Bayesian inference on mtDNA and a set of four microsatellite loci, including samples collected throughout the study area. A reduced dataset including only microsatellite loci genotyped from samples on the left riverbank was applied in assignment tests for detecting levels of admixture at the contact zone and adjacent sampling sites, and for detecting and quantifying hybrid individuals. Our results suggest that genetic introgression between A. hodli and A. femoralis is restricted to the core area of the contact zone, where potential hybrids are less frequent than parental genotypes. Effects on the genetic variability of adjacent populations are only detected at sites located 1.5 km downstream and upstream of the core area, suggesting the existence of selection against hybrids, possibly mediated by postzygotic isolation mechanisms. The contact zone between A. femoralis and A. hodli is the first well delimited suture line between anuran species ever documented in the Brazilian Amazon. The settlement of two dams along the upper Madeira River poses an immediate threat to the gene flow and hybridization balance observed between the populations studied. Our results provided guidelines for a current monitoring program, aiming at the impacts of dams on this evolutionary system’s dynamics.

Sorting out Lalos: description of new species and additional taxonomic data on megophryid frogs from northern Indochina (genus Leptolalax, Megophryidae, Anura)

Frogs in the subgenus Lalos of the genus Leptolalax (Megophryidae) are highly diversified in continental Asia and consist of about 17 nominal species. These frogs are small, inconspicuous, and of high superficial morphological similarity. We here formulate a hypothesis of phylogenetic relationships and assess the amount of genetic variation among genealogical lineages on the basis of 536bp of mitochondrial 16S rDNA sequences. Combining molecular data with a study of morpho-logy, morphometric divergence and geographical proximity, we tested hypotheses of species identity. We (1) used character-based and morphometric analyses to assign the onymophoronts (type specimens) of species in Lalos available to us to respectively one of the main clades, in order to propose the best potential correct taxonomic and nomenclatural allocation for the individuals included in the molecular study, and (2) tried to also assign the historical museum specimens to these molecular taxonomic units and to reclassify them whenever necessary. We also used the molecular data to match tadpoles with adults and provide tadpole descriptions for species the larvae of which were previously unknown. Specimens, that could neither be allocated to a molecularly characterised species (on the basis of their DNA “barcode”) nor to a morphologically defined species named on the basis of a type specimen, are described here as new species. Based on this integrative set of data and analyses we describe two new species, Leptolalax eos n. sp. and Leptolalax nyx n. sp., we resurrect Leptolalax minimus, and reassess the distribution of the species studied. We propose changes in the Red List status of L. pelodytoides and L. ventripunctatus and suggest a conservation status for the new species described herein.

Differences in Escape Behavior between a Cryptic and an Aposematic Litter Frog

Abstract Clay models have been used to investigate the relative antipredator effectiveness of cryptic and of aposematic coloration in litter frogs, but such studies do not account for possible differences in prey escape behavior. We examined the escape behaviors of two litter frogs, the cryptic Craugastor bransfordii and the brightly colored and toxic Oophaga pumilio, in response to a human predator. For all individuals, we measured the distance between the frog and the observer at the instant of flight and the distance between frog's initial and final positions in the field. The cryptic C. bransfordii had a shorter flight initiation distance than did nonvocalizing individuals of the brightly colored O. pumilio. In addition, we noted that vocalizing O. pumilio males had a shorter flight initiation distance than did either nonvocalizing male or female O. pumilio. These findings demonstrate that a cryptic and an aposematic litter frog differ in their escape response to a predator. These results also suggest...

Ecology of the Brazilian Flea Frog Brachycephalus didactylus (Terrarana: Brachycephalidae)

Abstract Brachycephalus didactylus, a leaf litter frog endemic to the Brazilian Atlantic rain forest, is considered the world's smallest tetrapod. Currently, there is little information about the ecology of this species. In this study, we estimated the population density and analyzed the diet, sexual dimorphism, and some reproductive aspects of two populations of B. didactylus in Rio de Janeiro State, Brazil. The estimated density was 4.0 and 1.2 ind/100m2, suggesting that this is not a locally rare species. However, collecting these frogs may be difficult because of their very small body size (< 11.0 mm SVL) and cryptic color pattern. Individuals from the two populations did not differ in body size, but females from one population were significantly larger than were males. In both populations, the most important food items consumed were Acari and Collembola, most of them measuring less than 1.0 mm in length. Females of the two populations had 3.6 ± 1.3 and 2.5 ± 0.8 mature oocytes averaging 1.6 ± 0.5 mm ...

A new species of Leptolalax (Anura: Megophryidae) from southern Vietnam

We describe a new species of small megophryid frog from the Langbian Plateau in southern Vietnam, the southernmost record of Leptolalax from Vietnam. Leptolalax bidoupensis sp. nov. is distinguished from its congeners by a combination of a dark brownish red ventral surface with white speckling on entire ventral surface including throat, arms and legs, small size (23.6–24.6 mm in four adult males and 29.2–29.4 mm in two adult females), bicoloured iris (coppery red upper half, fading to pale silver ventrally), a mostly smooth skin texture with no skin ridges, and relatively short tibia (male TIB:SVL 0.44–0.46). The male advertisement call of the new species, consisting of 6–9 single-pulsed notes with a dominant frequency of 1.9–3.8 kHz, is also unique among Leptolalax species for which calls are known. From the morphologically similar L. applebyi and L. melicus, L. bidoupensis sp. nov. differs by 9.3% and 9.6% sequence divergence at the 16S mtDNA gene. At present, the new species is known from montane evergreen forest between 1620–1730 m elevation, within an area of 1 km 2 . We suggest the species should be considered Data Deficient following IUCN’s Red List categories.

Morphological and ecological uniformity in the funnel-mouthed tadpoles of Malagasy litter frogs, subgenus Chonomantis

We report results of a morphological and ecological study on the funnel-mouthed tadpoles of litter frogs in the subgenus Chonomantis, genus Mantidactylus, from Madagascar. The larvae of these riparian frogs are characterized by umbelliform oral discs and absence of well developed keratodonts. Based on specimens identified by DNA barcoding we provide general morphological descriptions for the larvae of all eight nominal species plus two candidate species of Chonomantis, and describe the buccal anatomy of seven species. We detected only minor morphometric differences amongst species in mainly the relative size of the oral disc. In addition we found one candidate species (here named Mantidactylus sp. 59) to be characterized by rudimentary keratodont rows, Mantidactylus brevipalmatus by enlarged lungs, and Mantidactylus aerumnalis by a distinct colour pattern. Ecological data gathered in 30 streams in the Ranomafana area indicated important abundance differences amongst species. Mantidactylus melanopleura and Mantidactylus opiparis, which are the two most widespread species over Madagascar, were also locally most abundant in Ranomafana but interestingly showed no diagnostic morphological differences and fully overlapped in morphometric variables. Microhabitat choice of Chonomantis in Ranomafana was characterized by a clear preference for slow-moving stretches of streams with a substrate of submerged dead leaves. In general Chonomantis tadpoles were thus remarkably similar in their morphology and ecology. Considering the high degree of sympatric occurrence, with up to five species of the subgenus co-occurring along the same stream, this indicates a rather low influence of larval competition in creating selective pressures for specialization in these frogs. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162, 149–183.

A new species of Leptolalax (Anura: Megophryidae) from Laos

We describe a new species of megophryid frog in the genus Leptolalax from southern Laos. Leptolalax aereus sp. nov. is distinguished from its congeners by a combination of size (25.1–28.9 mm in 28 adult males, 27.1–38.6 mm in 12 adult females), absence of distinct black or dark brown dorsolateral markings on head, near immaculate white chest and belly, head length greater than head width, no webbing or lateral fringing on fingers, rudimentary webbing between toes I–IV and no webbing between toes IV–V, toes with weak lateral fringing, and a call consisting of an average of 3–4 notes containing 1–2 pulses, and with a dominant frequency of 6187.5–7875 Hz. The new species is associated with rocky streams in semi-evergreen and evergreen forest between 284–511 m elevation.

A new species of Leptolalax (Anura: Megophryidae) from Vietnam and further information on Leptolalax tuberosus

We describe a new species of megophryid frog from central Vietnam. Leptolalax croceus sp. nov. is most similar to L. tuberosus, but distinguished from this and all other Leptolalax species by its bright orange belly in life and by its unique, complex advertisement call consisting of 4–6 variably pulsed notes with a dominant frequency of 2635–3000 Hz. In contrast, L. tuberosus has an advertisement call consisting of a single, weakly pulsed note lasting 54–78 ms with a dominant frequency of 2584–2756.2 Hz. Leptolalax croceus sp. nov. can be further distinguished from its congeners by a combination of an indistinct tympanum, highly tuberculate dorsum, medium body size (22.2–27.3 mm in 16 adult males), head slightly wider than long, rudimentary webbing between toes I–III, no webbing between toes III–V, no lateral fringing on toes, and no ventrolateral glands. The new species is only known from a single locality in evergreen forest at 1316 m elevation. Males were found calling from leaf litter and low vegetation adjacent to a shallow, rocky stream. We suggest the species should be considered Data Deficient following IUCN’s Red List categories.

A new species of Leptolalax (Anura: Megophryidae) from northeastern Cambodia

We describe a new species of megophryid frog in the genus Leptolalax from the Kon Tum Plateau in northeastern Cambodia. Leptolalax melicus sp. nov. is distinguished from its congeners by a combination of an off-white to pale pink ventral surface with diffuse dark brown blotches and distinct white speckling, finger I &lt; II, an absence of webbing and dermal fringes on fingers, slight basal webbing and no dermal fringes on toes, body size (19.5–22.7 mm for seven adult males), an absence of ventrolateral glandular lines, dorsum mostly smooth with no skin ridges, and a unique advertisement call consisting of a single long introductory note containing 8–50 pulses, followed by 3–11 predominantly single-pulsed notes, and with an average dominant frequency of 3560–3610 Hz. Leptolalax melicus can be further distinguished from the morphologically similar L. applebyi in having more distinct dorsal patterning, and significantly larger pectoral and femoral glands. Leptolalax melicus and L. applebyi also differ by 6.1% sequence divergence at the 16S mtDNA gene. All specimens of L. melicus were found near rocky streams in evergreen forest between 650–850 m elevation. We suggest the new species should be considered Data Deficient following IUCN’s Red List categories.

Molecules meet macroecology—combining Species Distribution Models and phylogeographic studies

Combination of various techniques allows the identification of unique genetic lineages and/or taxa new to science via integrative taxonomy approaches. Next to molecular methods such as DNA ‘barcoding’ and phylogeographic analyses, Species Distribution Models may serve as compliment techniques allowing spatially explicit predictions of a species’ potential distribution even across millennia. They may facilitate the identification of possible recent and historical gene flow pathways. Herein, we highlight advantages of the combination of both molecular and macroecological approaches using the African miniature leaf litter frog Arthroleptis xenodactyloides as example.

Small, specialised and highly mobile? The tree-hole breeding frog, Phrynobatrachus guineensis, lacks fine-scale population structure

Data on population dynamics and distribution are of primary interest to biologists because they reveal information about the species' ecology and evolution and are thus essential for conservation efforts. Patchily distributed species are especially interesting for conservation studies, because of their sometimes very specific environmental requirements. An example of a highly specialised species is the leaf litter frog Phrynobatrachus guineensis. This small species (<20 mm) is short lived, presumably weakly mobile and highly specialised because it uses tree-holes and other small water-filled cavities with very particular abiotic and biotic characteristics for breeding. Previous field studies revealed that P. guineensis exhibited a clumped distribution in Taï National Park (TNP), Ivory Coast, suggesting that the park's population might be subdivided into several (sub)populations. We therefore investigated the population genetic structure of the park using four microsatellite loci, which are the first described microsatellite markers for any African anuran in general and for a species of the family Phrynobatrachidae in particular. In contrast to our expectations, we detected only a slightly significant genetic differentiation based on allele frequencies. We found no correlation between the geographic and genetic distances (isolation by distance) and Bayesian clustering revealed no genetic substructure. We did, however, detect small but significant genetic differentiation between subsequent seasons. The most probable explanation for the lack of population structure is that P. guineensis is more mobile than expected. Adults, most likely females but possibly also juveniles, are able to traverse matrix habitats in which no breeding activities were detected. The temporal genetic differentiation may be the consequence of genetic drift due to high mortality rates and/or non-random mating. Both explanations would be consistent with our field data.

Ecology of Ischnocnema parva (Anura: Brachycephalidae) at the Atlantic Rainforest of Serra da Concórdia, state of Rio de Janeiro, Brazil

Ischnocnema (Brachycephalidae) includes many species that are important members of the leaf litter frog communities in the Atlantic Rainforest of Brazil. Ischnocnema parva (Girard, 1853) is endemic to the Atlantic Rainforest biome and is restricted to the forests of southeastern Brazil. Currently, the available information about the ecology of I. parva is scarce. We studied the diet, the habitat use, reproduction and density of I. parva in an area of Atlantic Rainforest at the Concórdia mountain range, Rio de Janeiro. Individuals of I. parva were captured in April 2005 using different sampling methods: time constrained search (transects), plots of 5 x 5 m (25 m²) on the litter, and pitfall traps with drift fences. We found 240 frogs; 35 females and 205 males. Females (mean SVL = 19.1 mm) were significantly larger (F1,238 = 143.016, R² = 0.375, p < 0.001) than males (13.2 mm). The species preyed mainly on arthropods, with ants and isopods being the most important items, both showing high values of importance index (Ix = 50.0 and 26.7, respectively). Ischnocnema parva is a terrestrial species whose preferential microhabitat at the Serra da Concórdia was the litter of the forest floor (78.7%). The activity was predominantly crepuscular-nocturnal and the estimated density of I. parva was 24.9 ind/100 m². For the eight ovigerous females captured, the mean number of mature oocytes per female was 25 (range: 22-30) and the oocyte mean diameter was 1.11 mm (N = 40 oocytes). Oocyte number increased with female body size (R² = 0.504, F1,6 = 6.107, p < 0.05, N = 8), indicating that as females increase in size they produce larger clutches. Some ecological aspects such as diet and microhabitat use were similar to that observed for an insular population of I. parva, whereas reproductive traits differed. Thus, long term studies are necessary to understand the extent to which these differences are explained by environmental factors.

Calcified Integumentary Structures in Anurans

Although often overlooked, the integument of many vertebrates is reinforced by skeletal elements. In anurans these calcified structures include osteoderms, bone‐rich elements, and the lamina calcarea, a calcified, acellular layer that lacks collagen. We investigated the histology of anuran integument with a special focus on taxa developing skeletal elements. When present, the lamina calcarea forms a thin but discrete horizon at the interface between the superficial and deep dermis. This layer is rich in glycosaminoglycans (GAG) and is structurally unlike bone and cartilage. In contrast, anuran osteoderms are composed of cellular bone with limited GAG. A partial ontogenetic series of the tree frog Phyllomedusa bicolor provides the first details of anuran osteoderms development. In P. bicolor osteoderm development begins as a cluster of small calcified centres localized over the head. With continued body growth, osteoderms become larger in size and become distributed across the dorsal and ventral surfaces of the body, and across the limbs. The leaf litter frog Brachytarsophyrys cariensis is unusual in developing both osteoderms (on the dorsal body surface) and a lamina calcarea (on the ventral body surface). Our data shows that anuran integument has the ability to form skeletal elements and suggests that these elements arose in multiple anuran lineages.Grant Funding Source: NSERC

A new species of Leptolalax (Anura: Megophryidae) from Mizoram, North-eastern India

A new species of megophryid frog of the genus Leptolalax is described from the Tamdil wetlands of Mizoram State, north-eastern India. L. tamdil new species, is compared with congeners from India and other parts of south-east Asia. The new species is diagnosable in showing the following combination of characters: SVL 32.3 mm in the only male and 31.8 mm in the only female known; dorsum tuberculate; eyelids with tubercles; tympanum and supratympanic fold distinct; supratympanic fold extending to posterior edge of tympanum; macroglands, including preaxillary, pectoral, femoral and ventrolateral glands present; Finger II &gt; I; toe tips not dilated, bearing dermal fringes; relatively long hind limbs, with heels in contact when limbs are held perpendicular to body; dorsum with dark blotches; flanks with small dark blotches; dark tympanic mask present; venter pale; labial bars present and limbs with dark cross-bars.

The description of a cryptic species related to the pan-Amazonian frog Allobates femoralis (Boulenger 1883) (Anura: Aromobatidae)

We describe a new species of litter frog from western Brazilian Amazon previously referred to as Allobates femoralis (Boulenger 1883). The new species is allopatric to A. femoralis and its known occurrence is restricted to terra-firme forests on the left bank of the upper Madeira River and southeastern State of Acre. This species is distinguished from A. femoralis and from other species in the A. femoralis group by presenting two-note advertisement calls and conspicuous reddish-orange color on ventral surfaces of hind limbs and posterior abdomen. Phylogenetic analyses based on a fragment of the 16S rRNA mitochondrial gene suggest the new species is the sister group to a clade referred to as A. femoralis occurring in southern State of Acre, from which it is distinguished by six unambiguous nucleotide substitutions, in addition to exclusive advertisement calls and color patterns. The new species is more distantly related to A. femoralis sensu stricto occurring near the A. femoralis type locality in the Peruvian Amazon. Summarizing evidence from molecular phylogenetic analysis, genetic distances and available data on advertisement calls, we identify one possible case of genetic introgression between lineages in this group and highlight the potential for the description of more species within the A. femoralis complex.

Phylogenetic relationships of megophryid frogs of the genus Leptobrachium (Amphibia, Anura) as revealed by mtDNA gene sequences

By investigating genealogical relationships, we estimated the phylogenetic history and biogeography in the megophryid genus Leptobrachium (sensu lato, including Vibrissaphora) from southern China, Indochina, Thailand and the Sundaland. The genealogical relationships among the 30 named and unnamed taxa were estimated using 2009 bp of sequences from the mitochondrial DNA genes 12S rRNA, tRNA(val), and 16S rRNA using maximum parsimony, maximum likelihood, and Bayesian inference methods. The genus Leptobrachium was a well-supported monophyletic group that contained two major clades. One clade had three subclades primarily from disjunct regions including Borneo, Peninsular Malaysia and Java, and Thailand. The Bornean subclade included one species each from the Philippines and Sumatra. The other major clade consisted of two subclades, one from Indochina and the other from southern China (Vibrissaphora). Divergence times estimated an old evolutionary history of each subclade, one that could not be explained by the geohistory of Southeast Asian major landmasses.

Neoriojatrema mokokchungensis n. g., n. sp. (Monogenea: Polystomatidae: Polystomatinae) from the urinary bladder of a megophryid frog, Xenophrys glandulosa, in Nagaland, north-eastern India

A new monogenean fluke, collected from the urinary bladder of a megophryid frog, Xenophrys glandulosa Fei, Ye & Huang, 1991 from Mokokchung and Tuensang districts of Nagaland, north-eastern India is described. Of the six genera under the subfamily Polystomatinae (Polystomatidae) known so far, the present form comes closer to Eupolystoma Kaw, 1950; Pseudopolystoma Yamaguti, 1963 and Riojatrema Lamothe-Argumedo, 1964, in all of which the opisthaptor lacks large hooks. However, a combination of characters, namely, shape of the body, rounded or bulbous pharynx, intestinal caeca not joining posteriorly in the opisthaptoral region, ovary located in the anterior third of the body and presence of vaginal apertures, sets the present form apart from all these genera, and also from the known species of Riojatrema. These differences warrant the establishment of a new species and a new genus to accommodate the present form. The validity of this new monogenean, named as Neoriojatrema mokokchungensis after the type locality of the fluke, is discussed.