Marius Burger

A New Species of Cardioglossa (Anura: Arthroleptidae) from the Upper Guinean Forests of West Africa

Abstract We describe a new frog species of the genus Cardioglossa from the Upper Guinean forests of West Africa. Cardioglossa occidentalis, new species, is found in primary rainforests in Ghana, Ivory Coast, Guinea, Liberia, and Sierra Leone. We demonstrate that this species is morphologically and genetically distinct from C. leucomystax, the species to which these populations were previously assigned. Cardioglossa occidentalis differs from similar congeners by the following combination of markings: fusion or near fusion of all three dorsal lobes (cephalic, scapular, and lumbar); prominent white line extending anteriorly from arm terminates ventral to eye; dark mask extending posteriorly from eye continues unbroken beyond posterior border of scapular lobe; lateral body covered in very few, large dark spots rimmed with thin white. Cardioglossa occidentalis appears related to C. leucomystax, C. melanogaster, and C. schioetzi. This description brings the number of Cardioglossa species to 16.

Cryptic species of sharp-nosed reed frogs in the Hyperolius nasutus complex: advertisement call differences

The sharp-nosed reed frog is widespread in Africa. Although currently recognized as one species, suggestions have been made that more than one species might exist. We analysed 237 calls of 69 males from 19 localities in the western to southern parts of Africa. Calls fall into three groups, which we recognize as cryptic species. Of eight published sound spectrograms, all can be assigned to one of the three species. We recognize Hyperolius nasutus, distributed from western Africa to the Okavango Delta in Botswana; Hyperolius viridis, from the central highlands of northwestern Zambia to southern Tanzania; and Hyperolius acuticeps> which occurs from the Ivory Coast to the southeastern coast of South Africa. We assign published names to the synonymies of these three species. No call data are available for populations in the Congo basin.

Evaluating mechanisms of diversification in a Guineo-Congolian tropical forest frog using demographic model selection

The accumulation of biodiversity in tropical forests can occur through multiple allopatric and parapatric models of diversification, including forest refugia, riverine barriers and ecological gradients. Considerable debate surrounds the major diversification process, particularly in the West African Lower Guinea forests, which contain a complex geographic arrangement of topographic features and historical refugia. We used genomic data to investigate alternative mechanisms of diversification in the Gaboon forest frog, Scotobleps gabonicus, by first identifying population structure and then performing demographic model selection and spatially explicit analyses. We found that a majority of population divergences are best explained by allopatric models consistent with the forest refugia hypothesis and involve divergence in isolation with subsequent expansion and gene flow. These population divergences occurred simultaneously and conform to predictions based on climatically stable regions inferred through ecological niche modelling. Although forest refugia played a prominent role in the intraspecific diversification of S. gabonicus, we also find evidence for potential interactions between landscape features and historical refugia, including major rivers and elevational barriers such as the Cameroonian Volcanic Line. We outline the advantages of using genomewide variation in a model‐testing framework to distinguish between alternative allopatric hypotheses, and the pitfalls of limited geographic and molecular sampling. Although phylogeographic patterns are often species‐specific and related to life‐history traits, additional comparative studies incorporating genomic data are necessary for separating shared historical processes from idiosyncratic responses to environmental, climatic and geological influences on diversification.

Idiosyncratic responses to climate‐driven forest fragmentation and marine incursions in reed frogs from Central Africa and the Gulf of Guinea Islands

Organismal traits interact with environmental variation to mediate how species respond to shared landscapes. Thus, differences in traits related to dispersal ability or physiological tolerance may result in phylogeographic discordance among co‐distributed taxa, even when they are responding to common barriers. We quantified climatic suitability and stability, and phylogeographic divergence within three reed frog species complexes across the Guineo‐Congolian forests and Gulf of Guinea archipelago of Central Africa to investigate how they responded to a shared climatic and geological history. Our species‐specific estimates of climatic suitability through time are consistent with temporal and spatial heterogeneity in diversification among the species complexes, indicating that differences in ecological breadth may partly explain these idiosyncratic patterns. Likewise, we demonstrated that fluctuating sea levels periodically exposed a land bridge connecting Bioko Island with the mainland Guineo‐Congolian forest and that habitats across the exposed land bridge likely enabled dispersal in some species, but not in others. We did not find evidence that rivers are biogeographic barriers across any of the species complexes. Despite marked differences in the geographic extent of stable climates and temporal estimates of divergence among the species complexes, we recovered a shared pattern of intermittent climatic suitability with recent population connectivity and demographic expansion across the Congo Basin. This pattern supports the hypothesis that genetic exchange across the Congo Basin during humid periods, followed by vicariance during arid periods, has shaped regional diversity. Finally, we identified many distinct lineages among our focal taxa, some of which may reflect incipient or unrecognized species.

Two new Phrynobatrachus species (Amphibia: Anura: Phrynobatrachidae) from the Republic of the Congo

We describe two new species of puddle frogs, genus Phrynobatrachus, from the south-western Republic of the Congo. One of them, P. horsti sp. nov., occurs also in neighbouring Gabon and is morphologically most similar to the Cameroonian P. ruthbeateae. It differs from the latter species by smaller males with longer thighs and shanks. The new species comprises various colour morphs but always has less conspicuous black borders between flanks and belly than P. ruthbeateae. The distinct and large black axillary blotch of P. ruthbeateae is either much smaller in P. horsti sp. nov., or broken into numerous irregularly shaped smaller dots. Similarly, a black transversal line at the anterior ventral border of thighs and the black face mask is less distinct and irregularly delimitated in P. horsti sp. nov. when compared to P. ruthbeateae. The mean genetic difference in the sampled region of the 16S rRNA gene between P. horsti sp. nov. and 40 other western African congeners range from 3.66-18.10%. The second new species, P. mayokoensis sp. nov., differs from all other known congeners by the combination of a compact and warty body, the absence of a spiny eyelid tubercle and pedal webbing, a conspicuous black triangle on throat and anterior part of the belly, and a distinct large red blotch on the anterior-proximal surface of the thighs. It exhibited a mean genetic difference in the 16S rRNA to 40 other western African congeners ranging from 1.34-16.98%. The genetically most similar sequence stems from a GenBank entry of a Gabonese frog, determined as P. ogoensis. A comparison of the new species with P. ogoensis syntypes confirmed their specific distinctiveness, most convincingly underlined by the absence of pedal webbing in the new species and the pronounced pedal webbing in P. ogoensis. The GenBank entry thus most likely is based on a misidentification and P. mayokoensis sp. nov. may also occur in neighbouring Gabon. The discovery of the two new frog species is further evidence of the huge gap in our knowledge concerning the species richness in the Guineo-Congolian rainforests.

Diversity and biogeography of frogs in the genus Amnirana (Anura: Ranidae) across sub-Saharan Africa

Frogs in the genus Amnirana (family Ranidae) are widely distributed across sub-Saharan Africa and present a model system for exploring the relationship between diversification and geography across the continent. Using multiple loci from the mitochondrial (16S) and nuclear genomes (DISP2, FICD, KIAA2013, REV3L), we generated a strongly supported species-level phylogeny that provides insights into the continental biogeography of African species of Amnirana, which form a monophyletic group within the genus. Species delimitation analyses suggest that there may be as many as seven additional species of Amnirana in Africa. The biogeographic history of Amnirana is marked by several dispersal and vicariance events, including dispersal from the Lower Guinean Forest into the Congo Basin. In addition, phylogeographic patterns within two widespread species, A. albolabris and A. galamensis, reveal undescribed cryptic diversity. Populations assigned to A. albolabris in western Africa are more closely related to A. fonensis and require recognition as a distinct species. Our analyses reveal that the Lower and Upper Guinean Forest regions served as important centers of interspecific and intraspecific diversifications for Amnirana.

Two new species of long-fingered frogs of the genus Cardioglossa (Anura: Arthroleptidae) from Central African rainforests

Abstract We describe two new frog species of Cardioglossa (Family Arthroleptidae) from Central Africa. The new species are found in the rainforests of western-central Democratic Republic of the Congo and the Republic of the Congo near the Gabonese border, respectively. We demonstrate that these species are morphologically and genetically distinct from each other and all other species of Cardioglossa. Both new species lack the dorsal hour-glass pattern present in many species of the genus, but they can be distinguished from each other and related species by distinctive colour patterns on their lateral surfaces and extremities. Both new species most closely resemble C. gratiosa, which occurs in the Atlantic coastal forests extending from Cameroon through Gabon. The new species can be differentiated from C. gratiosa by the absence of black transverse bars on all limbs or by distinctive lateral colouration. Analysis of mitochondrial ribosomal 16S DNA sequences reveals low to moderate levels (1.9–7.5%) of divergence between these new species and closely related species of Cardioglossa. The floodplains of the Congo and Ubangi Rivers may be important geographic barriers for many of these species. The occurrence of these two new lowland species in the Congo Basin reveals that the distribution and diversity of Cardioglossa in this region was underestimated. In addition, we elevate C. nigromaculata inornata to species-level status, based in part on newly available colour photographs from 1950 of specimens from the only known locality.

Sexual Dichromatism Drives Diversification Within a Major Radiation of African Amphibians

Theory predicts that sexually dimorphic traits under strong sexual selection, particularly those involved with intersexual signaling, can accelerate speciation and produce bursts of diversification. Sexual dichromatism (sexual dimorphism in color) is widely used as a proxy for sexual selection and is associated with rapid diversification in several animal groups, yet studies using phylogenetic comparative methods to explicitly test for an association between sexual dichromatism and diversification have produced conflicting results. Sexual dichromatism is rare in frogs, but it is both striking and prevalent in African reed frogs, a major component of the diverse frog radiation termed Afrobatrachia. In contrast to most other vertebrates, reed frogs display female-biased dichromatism in which females undergo color transformation, often resulting in more ornate coloration in females than in males. We produce a robust phylogeny of Afrobrachia to investigate the evolutionary origins of sexual dichromatism in this radiation and examine whether the presence of dichromatism is associated with increased rates of net diversification. We find that sexual dichromatism evolved once within hyperoliids and was followed by numerous independent reversals to monochromatism. We detect significant diversification rate heterogeneity in Afrobatrachia and find that sexually dichromatic lineages have double the average net diversification rate of monochromatic lineages. By conducting trait simulations on our empirical phylogeny, we demonstrate our inference of trait-dependent diversification is robust. Although sexual dichromatism in hyperoliid frogs is linked to their rapid diversification and supports macroevolutionary predictions of speciation by sexual selection, the function of dichromatism in reed frogs remains unclear. We propose that reed frogs are a compelling system for studying the roles of natural and sexual selection on the evolution of sexual dichromatism across both micro- and macroevolutionary timescales.

Phylogeny and biogeography of the African burrowing snake subfamily Aparallactinae (Squamata: Lamprophiidae)

Members of the snake subfamily Aparallactinae occur in various habitats throughout sub-Saharan Africa. The monophyly of aparallactine snakes is well established, but relationships within the subfamily are poorly known. We sampled 158 individuals from six of eight aparallactine genera in sub-Saharan Africa. We employed concatenated gene-tree analyses, divergence dating approaches, and ancestral-area reconstructions to infer phylogenies and biogeographic patterns with a multi-locus data set consisting of three mitochondrial (16S, cyt b, and ND4) and two nuclear genes (c-mos and RAG1). As a result, we uncover several cryptic lineages and elevate a lineage of Polemon to full species status. Diversification occurred predominantly during the Miocene, with a few speciation events occurring subsequently in the Pliocene and Pleistocene. Biogeographic analyses suggested that the Zambezian biogeographic region, comprising grasslands and woodlands, facilitated radiations, vicariance, and dispersal for many aparallactines. Moreover, the geographic distributions of many forest species were fragmented during xeric and cooler conditions, which likely led to diversification events. Biogeographic patterns of aparallactine snakes are consistent with previous studies of other sub-Saharan herpetofauna.

A phylogeny and genus-level revision of the African file snakes Gonionotophis Boulenger (Squamata: Lamprophiidae)

ABSTRACT The sub-Saharan African file snake genus Gonionotophis is currently comprised of 15 species. However, the concept of this genus has been confounded by morphological and genetic differences between the constituent taxa. Due to the dearth of DNA samples, a taxonomic assessment has been impractical to date. We therefore sequenced two mitochondrial and one nuclear marker (16S, cyt b, and c-mos) from 45 samples representing ten species of Gonionotophis to construct a molecular phylogeny using Bayesian and likelihood approaches. Four divergent and well-supported clades were recovered, including: (1) grantii + brussauxi; (2) poensis + stenophthalmus; (3) nyassae; and (4) capensis, chanleri, crossi, guirali and savorgnani. Based on these results and morphological data, the genus Gonionotophis is restricted to the first clade, Mehelya is resurrected for the species in the second clade, and new genera are described for the remaining two clades. ZooBank—urn:lsid:zoobank.org:pub:A82CFAD6-E2E0-439E-90BB-9224E225426B