Colin R. Tilbury

A phylogenetic review of the African leaf chameleons: genus Rhampholeon (Chamaeleonidae): the role of vicariance and climate change in speciation.

The phylogenetic associations among 13 currently recognized African leaf chameleon species were investigated by making use of mitochondrial and nuclear DNA sequence data (44 taxa and 4145 characters). The gene tree indicates two divergent clades within Rhampholeon; this finding is congruent with previous morphological suggestions. The first clade (I) comprises three taxa (R. kerstenii, R. brevicaudatus and R. brachyurus) and is widely distributed in lowland forest and or non–forest biomes. The second clade (II) comprises the remaining Rhampholeon species and can be subdivided into three subclades. By contrast, most taxa belonging to clade II are confined to relict montane forest biotopes. Based on geographical, morphological and molecular evidence, it is suggested that the taxonomy of Rhampholeon be revised to include two genera (Rieppeleon and Rhampholeon) and three subgenera (Rhampholeon, Bicuspis and Rhinodigitum). There is a close correlation between geographical distribution and phylogenetic relatedness among Rhampholeon taxa, indicating that vicariance and climate change were possibly the most influential factors driving speciation in the group. A relaxed Bayesian clock suggests that speciation times coincided both with the northern movement of Africa, which caused the constriction of the pan African forest, and to rifting in east Africa ca. 20 Myr ago. Subsequent speciation among taxa was probably the result of gradual desiccation of forests between 20 and 5 Myr ago.

Phylogenetics of the southern African dwarf chameleons, Bradypodion (Squamata: Chamaeleonidae)

The taxonomic relationships within the dwarf chameleons (Bradypodion) of southern Africa have long been controversial. Although informal phenotypic groups have been suggested, the evolutionary relationships among the 15 recognised species in southern Africa have not been previously investigated. To investigate the relationships among species within this genus, fragments of two mitochondrial genes (16S ribosomal RNA and ND2) were sequenced and analysed using maximum parsimony, maximum likelihood and Bayesian inference. All analyses showed congruent topologies, revealing at least 5 well-supported clades distributed across distinct geographic regions. The mtDNA gene tree indicated that in many instances, geographic location has played a role in shaping the evolution of this group, and that the previously suggested phenotypic groupings do not adequately reflect evolutionary relationships. Furthermore, it appears that some of the currently recognised species (described on morphology) are polyphyletic for mitochondrial sequences, most notably those occurring in the isolated forest patches of north-eastern South Africa, near the Drakensberg Escarpment.

A new species of chameleon (Sanria: Chamaeleonidae: Kinyongia) from the Magombera forest and the Udzungwa Mountains National Park, Tanzania

Abstract A new species of chameleon Kinyongia magomberae sp. nov. (the Magombera chameleon), is described from Magombera forest and the Vdzungwa Mountains National Park, south-central Tanzania. The species status is supported by phylogenetic analyses using mitochondrial and nuclear markers. The new chameleon is similar to K. tenuis and the more widespread Eastern Arc endemic K. oxyrhina in having a single rostral appendage. However, it can be distinguished from these two species by a shorter rostral appendage, which is different in shape and lacks a movable tip. K. magomberae sp. nov. is known from only two forest localities, the lowland and unprotected Magombera forest and the sub-montane Mwanihana forest within the Vdzungwa Mountains National Park. Phylogenetically, this taxon is sister to K. tenuis, and is part of a clade that also contains K. oxyrhina.

A New Dwarf Forest Chameleon from the Udzungwa Mountains of Tanzania, East Africa, (Squamata: Rhampholeon Günther, 1874)

Abstract A new species of Rhampholeon from the montane and submontane escarpment forests of the Udzungwa Mountains is described. This pigmy chameleon has a maximum total length of 64 mm and bears a close morphological resemblance to Rhampholeon uluguruensis, differing mainly by possessing finer cranial scalation and more thornlike hemipenal papillae arranged in two proximal rows of four (occasionally five) and two followed by a single terminal row of four (occasionally five) papillae. The only known populations of this species are found in Udzungwa escarpement forests between 1200 and 2000 m a.s.l. The zoogeography and systematics of related species of the genus Rhampholeon in the Eastern Arc Mountains of Tanzania and Malawi are reviewed and an updated key to the Genus Rhampholeon is presented.

Evolutionary relationships, species delimitation and biogeography of Eastern Afromontane horned chameleons (Chamaeleonidae: Trioceros)

The Eastern Afromontane Region (EAR) contains numerous endemic species, yet its reptile diversity remains relatively poorly understood. We used molecular data to examine species diversity of the Sub-Saharan chameleon genus Trioceros. In particular, we focus on establishing species boundaries for taxa with disjunct distributions across the fragmented mountains of the EAR, including T. affinis, T. balebicornutus, T. deremensis, T. harennae, T. tempeli and T. werneri. We applied three species-delimiting approaches, General Mixed Yule-Coalescent (GMYC), a Bayesian implementation of the GMYC, and Bayes Factor Delimitation to estimate species diversity. Using a dated phylogeny, we also examined spatial and temporal diversification patterns in Trioceros. We found strong congruence between different species delimitation approaches, with all methods suggesting that species diversity is currently underestimated. In particular, T. werneri consists of at least four candidate species (i.e. species awaiting description) with some mountain ranges (Uluguru and Udzungwa) having potentially more than one species. Most interspecific divergences between extant Trioceros lineages are estimated to be >5Mya, consistent with a Pliocene origin of the endemic montane fauna, as exhibited in other taxonomic groups. Multiple, overlapping geographic events (climate and/or geomorphological changes) might account for speciation patterns in Trioceros given the dating results.

A new Dwarf Chameleon (Sauria: Bradypodion Fitzinger, 1843) from the Cape Fold Mountains, South Africa

Abstract A new dwarf chameleon, Bradypodion atromontanum Branch, Tolley & Tilbury sp. nov., is described from mountain fynbos habitat in the Great Swartberg Mountains, Western Cape Province, South Africa. It is closest geographically to Bradypodion gutturale but distinguished by its smaller size, less tuberculate scalation, genetic divergence, and restriction to Mountain Fynbos habitat. Although its known distribution falls in the conserved Swartberg Nature Reserve, it should be classified as Vulnerable due to its very restricted range.

Cryptic diversity in Rhampholeon boulengeri (Sauria: Chamaeleonidae), a pygmy chameleon from the Albertine Rift biodiversity hotspot

Several biogeographic barriers in the Central African highlands have reduced gene flow among populations of many terrestrial species in predictable ways. Yet, a comprehensive understanding of mechanisms underlying species divergence in the Afrotropics can be obscured by unrecognized levels of cryptic diversity, particularly in widespread species. We implemented a multilocus phylogeographic approach to examine diversity within the widely distributed Central African pygmy chameleon, Rhampholeon boulengeri. Gene-tree analyses coupled with a comparative coalescent-based species delimitation framework revealed R. boulengeri as a complex of at least six genetically distinct species. The spatiotemporal speciation patterns for these cryptic species conform to general biogeographic hypotheses supporting vicariance as the main factor behind patterns of divergence in the Albertine Rift, a biodiversity hotspot in Central Africa. However, we found that parapatric species and sister species inhabited adjacent habitats, but were found in largely non-overlapping elevational ranges in the Albertine Rift, suggesting that differentiation in elevation was also an important mode of divergence. The phylogeographic patterns recovered for the genus-level phylogeny provide additional evidence for speciation by isolation in forest refugia, and dating estimates indicated that the Miocene was a significant period for this diversification. Our results highlight the importance of investigating cryptic diversity in widespread species to improve understanding of diversification patterns in environmentally diverse regions such as the montane Afrotropics.

A fatal bite from the burrowing asp Atractaspis corpulenta (Hallowell 1854)

Bites from the various species of Atractaspis are a common occurrence in Africa but deaths are very unusual. Of the 19 described species, the clinical effects of the bite of only seven have been described, and in only three (Atractaspis irregularis, Atractaspis microlepidota and Atractaspis engaddensis) have fatalities been documented. A case of envenomation is described following a bite to a finger by Atractaspis corpulenta, which resulted in sudden death approximately two and a half hours later. The victim received antivenom and although anaphylaxis to this cannot be ruled out, we consider it to be unlikely to be the cause of death. A late autopsy was performed and the findings and their interpretation are discussed. The previous case fatalities, toxic fractions and clinical effects of Atractaspis venom are briefly reviewed.