Raffael Ernst

High levels of diversity uncovered in a widespread nominal taxon: continental phylogeography of the Neotropical tree frog Dendropsophus minutus

Species distributed across vast continental areas and across major biomes provide unique model systems for studies of biotic diversification, yet also constitute daunting financial, logistic and political challenges for data collection across such regions. The tree frog Dendropsophus minutus (Anura: Hylidae) is a nominal species, continentally distributed in South America, that may represent a complex of multiple species, each with a more limited distribution. To understand the spatial pattern of molecular diversity throughout the range of this species complex, we obtained DNA sequence data from two mitochondrial genes, cytochrome oxidase I (COI) and the 16S rhibosomal gene (16S) for 407 samples of D. minutus and closely related species distributed across eleven countries, effectively comprising the entire range of the group. We performed phylogenetic and spatially explicit phylogeographic analyses to assess the genetic structure of lineages and infer ancestral areas. We found 43 statistically supported, deep mitochondrial lineages, several of which may represent currently unrecognized distinct species. One major clade, containing 25 divergent lineages, includes samples from the type locality of D. minutus. We defined that clade as the D. minutus complex. The remaining lineages together with the D. minutus complex constitute the D. minutus species group. Historical analyses support an Amazonian origin for the D. minutus species group with a subsequent dispersal to eastern Brazil where the D. minutus complex originated. According to our dataset, a total of eight mtDNA lineages have ranges >100,000 km2. One of them occupies an area of almost one million km2 encompassing multiple biomes. Our results, at a spatial scale and resolution unprecedented for a Neotropical vertebrate, confirm that widespread amphibian species occur in lowland South America, yet at the same time a large proportion of cryptic diversity still remains to be discovered.

ANTHROPOGENICALLY INDUCED CHANGES OF PREDICTABILITY IN TROPICAL ANURAN ASSEMBLAGES

Anthropogenic habitat alteration has long been neglected as a factor in the analysis of predictability patterns in biological communities. We tested this factor by investigating anuran leaf litter assemblages in primary and secondary forests of Tai National Park, Ivory Coast, during two years. We measured predictability of assemblage composition by analyzing correlations between the off-diagonal elements of distance matrices based on (1) species distribution, (2) environmental characteristics, and (3) geographic distance. Pairwise correlations between matrices were significant in all cases when considering data pooled across time and habitats. A different pattern emerged when data were split according to season and disturbance level (i.e., primary vs. secondary habitats). Assemblage composition in primary habitats was correlated with geographic proximity of sites exclusively, indicating otherwise stochastic recruitment from a regional species pool at the local community level. In contrast, assemblage comp...

Patterns of community composition in two tropical tree frog assemblages: separating spatial structure and environmental effects in disturbed and undisturbed forests

An on-going controversy in community ecology involves the debate about the many factors that affect the assembly and composition of a given species assemblage. Theory suggests that community composition is influenced by environmental gradients or biotic processes. This study examines patterns of community composition in two tropical tree frog assemblages of primary and exploited lowland rain-forest sites in the Guiana Shield area of central Guyana, South America and the Upper Guinean rain-forest block of south-western Cote dTvoire, West Africa. We tested community composition and species abundance data of two adult tree frog communities collected on 21 standardized transects during a period of 5 y for evidence of spatial correlation in community composition. We applied simple and partial Mantel tests to separate the effects of environmental variables, spatial distance and spatial autocorrelation on community composition. Whenever environmental effects were accounted for, we found significant positive spatial correlation of community composition. All assemblages appeared to be spatially structured, i.e. sites in close proximity had similar species assemblages. However, spatially structured environmental variation (autocorrelation) did not account for the spatial structure of species incidence. Environmental factors did not prove to be significant predictors of species incidence in any of the assemblages analysed, even if we controlled for spatial effects. Observed correlation patterns of species composition were consistent within respective realms and disturbance regimes. Moreover, general correlation patterns were consistent between geographic regions. These results are in contrast to previously published results from a study on leaf-litter anurans and indicate that group-specific differences must not be neglected when analysing patterns of species composition in anurans as they may drastically alter the outcome of the analysis.

Systematics of spiny-backed treefrogs (Hylidae: Osteocephalus): An Amazonian puzzle

Spiny‐backed tree frogs of the genus Osteocephalus are conspicuous components of the tropical wet forests of the Amazon and the Guiana Shield. Here, we revise the phylogenetic relationships of Osteocephalus and its sister group Tepuihyla, using up to 6134 bp of DNA sequences of nine mitochondrial and one nuclear gene for 338 specimens from eight countries and 218 localities, representing 89% of the 28 currently recognized nominal species. Our phylogenetic analyses reveal (i) the paraphyly of Osteocephalus with respect to Tepuihyla, (ii) the placement of ‘Hyla’ warreni as sister to Tepuihyla, (iii) the non‐monophyly of several currently recognized species within Osteocephalus and (iv) the presence of low (<1%) and overlapping genetic distances among phenotypically well‐characterized nominal species (e.g. O. taurinus and O. oophagus) for the 16S gene fragment used in amphibian DNA barcoding. We propose a new taxonomy, securing the monophyly of Osteocephalus and Tepuihyla by rearranging and redefining the content of both genera and also erect a new genus for the sister group of Osteocephalus. The colouration of newly metamorphosed individuals is proposed as a morphological synapomorphy for Osteocephalus. We recognize and define five monophyletic species groups within Osteocephalus, synonymize three species of Osteocephalus (O. germani, O. phasmatus and O. vilmae) and three species of Tepuihyla (T. celsae, T. galani and T. talbergae) and reallocate three species (Hyla helenae to Osteocephalus, O. exophthalmus to Tepuihyla and O. pearsoni to Dryaderces gen. n.). Furthermore, we flag nine putative new species (an increase to 138% of the current diversity). We conclude that species numbers are largely underestimated, with most hidden diversity centred on widespread and polymorphic nominal species. The evolutionary origin of breeding strategies within Osteocephalus is discussed in the light of this new phylogenetic hypothesis, and a novel type of amplexus (gular amplexus) is described.

A New Phrynobatrachus from the Upper Guinean Rain Forest, West Africa, Including a Description of a New Reproductive Mode for the Genus

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

A New Reproductive Mode for the Genus Phrynobatrachus: Phrynobatrachus alticola Has Nonfeeding, Nonhatching Tadpoles

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A new giant species of Arthroleptis (Amphibia: Anura: Arthroleptidae) from the Krokosua Hills Forest Reserve, south-western Ghana

We describe a new giant species of Arthroleptis from the eastern part of the Upper Guinean rain forest, West Africa. This species from the Krokosua Hills Forest Reserve, south-western Ghana is the largest member of the genus from West Africa. It differs from all known West African Arthroleptis by its large size, its peculiar coloration and a number of morphological characters, such as e.g. an extremely broad head. Arthroleptis krokosua sp. nov. is most similar to large members of the genus from East and Central Africa, particularly A. variabilis and A. adolfifriederici from which it differs in lateral and ventral colouration patterns, larger size (> 43 mm), as well as head shape (heads width / snout-vent length: 0.45; 0.40 in A. variabilis and A. adolfifriederici). Genetic divergence in 550 bp of 16S rRNA was 4.97–5.14 % between the new species and A. variabilis. The new species seems to have no apparent affiliations to any other West African member of the genus. All other West African Arthroleptis are much smaller in size and differ in body shape.

First Record of the Genus Acanthixalus Laurent, 1944 from the Upper Guinean Rain Forest, West Africa, with the Description of a New Species

Abstract We describe a new species of Acanthixalus from southwestern Ivory Coast. Acanthixalus sonjae sp. nov. differs from the Central African Acanthixalus spinosus genetically by 4.6 % in the investigated 16S rRNA. Morphologically adult frogs are very similar to A. spinosus. Male A. sonjae have wider heads and probably smaller gular glands than A. spinosus. Tadpoles of A. sonjae differ by much longer tails. Acanthixalus sonjae males are apparently mute. The new species is semiaquatic and lives in large water-filled cavities of trees in secondary and primary rain forest. Tadpoles complete metamorphosis in three months. They are at least partly carnivorous.

Assessing the molecular phylogeny of a near extinct group of vertebrates: the Neotropical harlequin frogs (Bufonidae; Atelopus)

Neotropical harlequin frogs, Atelopus, are a species-rich bufonid group. Atelopus monophyly has been suggested but intergeneric, interspecific and intraspecific relationships are poorly understood. One reason is that morphological characters of harlequin frogs are often difficult to interpret, making species delimitations difficult. Molecular analyses (DNA barcoding, phylogeny) may be helpful but sampling is hampered as most of the more than 100 Atelopus species have undergone severe population declines and many are possibly extinct. We processed mitochondrial DNA (12S and 16S rRNA) of 28 available ingroup samples from a large portion of the genus’ geographic range (Bayesian Inference, Maximum Likelihood). Our samples constitute a monophyletic unit, which is sister to other bufonid genera studied including the Andean genus Osornophryne. In contrast to previous morphological studies, our results suggest that Osornophryne is neither sister to Atelopus nor nested within it. Within Atelopus, we note two major clades with well supported subclades, one Amazonian–Guianan Clade (Flavescens-spumarius Clade plus Tricolor Clade) and an Andean–Chocó–Central American Clade (Varius Clade plus all other Atelopus). The first mentioned includes all species that possess a middle ear (i.e. stapes) except for A. seminiferus lacking it (like all remaining Atelopus). Previously proposed species groups based on frog-like versus toad-like overall appearance (i.e. Longirostris and Ignescens Groups) or phalangeal reduction in the thumb (i.e. Flavescens Group) are not monophyletic in our phylogeny, thus characters used to define them are not considered synapomorphies. We show that genetic divergence can be high between species belonging to different clades, in spite of their phenetic similarity (e.g. A. pulcher, Atelopus sp. 2). On the other hand, within the same clade, colour can vary tremendously, while genetic divergence is low (e.g. A. flavescens and allies). These observations demonstrate that Atelopus taxonomy is complicated and that an integrative approach is required before ‘splitting’ or ‘lumping’ nominal species.

A New Squeaker Frog (Arthroleptidae: Arthroleptis) From the Cameroon Volcanic Line With Redescriptions Of Arthroleptis adolfifriederici Nieden, 1911 “1910” and A. variabilis Matschie, 1893

Abstract We describe a new species of squeaker frog (Arthroleptis) from Mt. Manengouba in southwestern Cameroon. The new species is distinguished from other Cameroonian Arthroleptis by moderately larger body size; a darkened throat and posterior thigh, both with many white spots; and, in females, a fourth finger longer than the first and second fingers. This species corresponds to a Cameroonian taxon previously identified as Arthroleptis adolfifriederici but which has been long recognized as distinct. Multivariate morphometric analysis demonstrates that the new taxon is distinct from Arthroleptis variabilis, which occurs in the surrounding lowlands. Because of the general similarity of the new species to A. variabilis and its previous confusion with A. adolfifriederici, redescriptions of the latter two species are provided. This refinement of taxonomic knowledge will facilitate future study of cryptic or undescribed large Arthroleptis from western, central, and eastern Africa.