Diversification and historical demography of Rhampholeon spectrum in West-Central Africa.

Pygmy Chameleons of the genus Rhampholeon represent a moderately diverse, geographically circumscribed radiation, with most species (18 out of 19 extant taxa) limited to East Africa. The one exception is Rhampholeon spectrum, a species restricted to West-Central African rainforests. We set out to characterize the geographic basis of genetic variation in this disjunctly distributed Rhampholeon species using a combination of multilocus Sanger data and genomic sequences to explore population structure and range-wide phylogeographic patterns. We also employed demographic analyses and niche modeling to distinguish between alternate explanations to contextualize the impact of past geological and climatic events on the present-day distribution of intraspecific genetic variation. Phylogenetic analyses suggest that R. spectrum is a complex of five geographically delimited populations grouped into two major clades (montane vs. lowland). We found pronounced population structure suggesting that divergence and, potentially, speciation began between the late Miocene and the Pleistocene. Sea level changes during the Pleistocene climatic oscillations resulted in allopatric divergence associated with dispersal over an ocean channel barrier and colonization of Bioko Island. Demographic inferences and range stability mapping each support diversification models with secondary contact due to population contraction in lowland and montane refugia during the interglacial period. Allopatric divergence, congruent with isolation caused by geologic uplift of the East African rift system, the "descent into the Icehouse," and aridification of sub-Saharan Africa during the Eocene-Oligocene are identified as the key events explaining the population divergence between R. spectrum and its closely related sister clade from the Eastern Arc Mountains. Our results unveil cryptic genetic diversity in R. spectrum, suggesting the possibility of a species complex distributed across the Lower Guinean Forest and the Island of Bioko. We highlight the major element of species diversification that modelled today's diversity and distributions in most West-Central African vertebrates.

Systematics of the Central African Spiny Reed Frog Afrixalus laevis (Anura: Hyperoliidae), with the description of two new species from the Albertine Rift.

The geographically widespread species Afrixalus laevis (Anura: Hyperoliidae) currently has a disjunct distribution in western Central Africa (Cameroon, Equatorial Guinea, Gabon, and possibly adjacent countries) and the area in and near the Albertine Rift in eastern Democratic Republic of the Congo and neighboring countries. At least two herpetologists have previously suggested that these disjunct populations represent distinct species, and herein, we utilize an integrative taxonomic approach with molecular and morphological data to reconcile the taxonomy of these spiny reed frogs. We sequenced 1554 base pairs of the 16S and RAG1 genes from 34 samples of A. laevis and one sample of A. orophilus (sympatric with eastern populations of A. laevis), and combined these data with previously sequenced GenBank Afrixalus samples via the bioinformatics toolkit SuperCRUNCH. Phylogenetic trees, dated phylogenetic analyses, and species-delimitation analyses were generated with RAxML, BEAST, and BPP, respectively. Eleven mensural characters were taken from multiple specimens of A. laevis and A. orophilus, and compared with paired t-tests and analyses of covariance. These combined results suggested populations of A. laevis in western Central Africa (Cameroon and Bioko Island, Equatorial Guinea) represent one species, whereas populations from the Albertine Rift and nearby forests represent two undescribed taxa that are sister to A. dorsimaculatus. The two new species (A. lacustris sp. nov. and A. phantasma sp. nov.) are distinguished by our phylogenetic and species-delimitation analyses, significant differences in several mensural characters, qualitative morphological differences, and by their non-overlapping elevational distribution.

Rivers, not refugia, drove diversification in arboreal, sub-Saharan African snakes.

The relative roles of rivers versus refugia in shaping the high levels of species diversity in tropical rainforests have been widely debated for decades. Only recently has it become possible to take an integrative approach to test predictions derived from these hypotheses using genomic sequencing and paleo-species distribution modeling. Herein, we tested the predictions of the classic river, refuge, and river-refuge hypotheses on diversification in the arboreal sub-Saharan African snake genus Toxicodryas. We used dated phylogeographic inferences, population clustering analyses, demographic model selection, and paleo-distribution modeling to conduct a phylogenomic and historical demographic analysis of this genus. Our results revealed significant population genetic structure within both Toxicodryas species, corresponding geographically to river barriers and divergence times from the mid-Miocene to Pliocene. Our demographic analyses supported the interpretation that rivers are indications of strong barriers to gene flow among populations since their divergence. Additionally, we found no support for a major contraction of suitable habitat during the last glacial maximum, allowing us to reject both the refuge and river-refuge hypotheses in favor of the river-barrier hypothesis. Based on conservative interpretations of our species delimitation analyses with the Sanger and ddRAD data sets, two new cryptic species are identified from east-central Africa. This study highlights the complexity of diversification dynamics in the African tropics and the advantages of integrative approaches to studying speciation in tropical regions.

Night stalkers from above: A monograph of Toxicodryas/ tree snakes (Squamata: Colubridae) with descriptions of two new cryptic species from Central Africa.

The genus Toxicodryas, historically included with the renowned Australasian cat-eyed snakes of the colubrid genus Boiga, currently includes two widespread species (T. blandingii and T. pulverulenta) in western, central, and eastern Africa. We leverage findings from a recent phylogenomic and historical demographic analysis of this genus (based on 2848-4471 Rad-seq loci from across the genome), with robust sampling from throughout the ranges of both species, to define two additional taxonomic units, with species boundaries corresponding to river barriers. Additional morphometric data from scores of examined museum specimens and literature records bolster the recognition of these two new cryptic species. We hypothesize that T. blandingii occurs west of the confluence of the Congo and Ubangi rivers, whereas a cryptic new species that is found east of this biogeographic barrier has significantly higher numbers of ventral scale counts in both sexes, additional significant differences in several scale counts, and lower venom toxicity. Toxicodryas pulverulenta occurs west of the Niger Delta in West Africa, whereas a cryptic new species that is found east of this biogeographic barrier has significantly higher numbers of subcaudal scale counts in both sexes. A review of published information regarding morphological variation, ecology, natural history, habitat, and venom is summarized for these four Toxicodryas species.

A new species of Trachylepis (Squamata: Scincidae) from Central Africa and a key to the Trachylepis of West and Central Africa.

A new species of skink, Trachylepis gonwouoi sp. nov. is described from Cameroon and the Republic of the Congo. It differs from all other species of Trachylepis in Central-West Africa by a combination of number of keels on dorsal scales (3-5); moderate SVL (maximum size of 80 mm); number of scale rows at midbody (28-34); number of supracilliaries (6-10); a well defined lateral white stripe, bordered by black, extending from under the eye to the insertion of the hind limb; and a ventral color in life of bright blue-green. Trachylepis gonwouoi sp. nov. was found in association with disturbed forest at elevations from 50 to 1050m. This species is syntopic with T. affinis and T. maculilabris. In order to aid in the identification of Trachylepis in West and Central Africa with the addition of T. gonwouoi sp. nov., we provide an updated key to the Trachylepis found from Mauritania through the Democratic Republic of the Congo. This key combines previous literature that treated Western and Central African taxa separately and represents the most comprehensive key for Trachylepis in West-Central Africa to date.