Hyperolius castaneus

Abstract: The species richness of seven montane anuran communities of the Albertine Rift was assessed with visual and acoustic transects. A total of 28 anuran species were detected. The highland anuran communities at (2000–2800 m) were dominated by up to nine Albertine Rift endemic species considered threatened by IUCN Red List criteria, whereas the community at lower elevation included mainly wide-ranging, least-concern species. Cluster analyses of the presence/absence data on the overall array of species indicated that Ahl's reed frog (Hyperolius castaneus) is a suitable umbrella species for the highland Albertine Rift endemics. Hyperolius castaneus was always among the first species collected at each site, either by visual detection or by acoustic detection based on the characteristic advertisement and aggression calls which were emitted during the day and at night. The ease of its detection in the field makes this species an ideal candidate for rapid assessments of priority sites for conservation measures.

Abstract: The endangered warbler Bradypterus graueri is endemic to the Albertine Rift, where it is restricted to montane swamps above 1900 m across the region. We studied genetic structure among six populations sampled across the species’ distribution in northern Burundi, Rwanda, Uganda and the eastern Democratic Republic of Congo. A total of 2117 base pairs of mitochondrial data were sequenced. Phylogenetic analyses and network reconstruction of B. graueri haplotypes recovered three clades with a defined geographical pattern: clade 1, Virunga Volcanoes and Kigezi Highlands; clade 2, Rugege Highlands; and clade 3, Kahuzi-Biega Highlands; clades 2 and 3 are sisters to each other. Both landscape dynamics and historical climate are likely to have played a role in the diversification of this species. The divergence between clade 1 and clades 2 and 3 (168.5 Ka, 95% HPD 108.5, 244.4) coincides with a prolonged period of aridity in tropical Africa between 130-270 Ka. Similarly, the divergence between clades 2 and 3 (99.4 Ka, 95% HPD 55.4, 153.8) corresponds with a period of aridity just prior to 94 Ka. Populations sampled from the eastern arm of the central Albertine Rift (Kigezi and Rugege Highlands) show a coincident increase in effective population size after the Last Glacial Maximum at c. 15 Ka, whereas those sampled from Kahuzi-Biega on the western arm of the rift do not. Despite the perceived higher vagility of bird species relative to other vertebrates, the degree of phylogeographic structure among populations of B. graueri is similar to that reported for small mammals (Hylomyscus vulcanorum, Lophuromys woosnami, Sylvisorex vulcanorum) and a frog Hyperolius castaneus sampled across the central Albertine Rift. Collectively our results suggest that climate dynamics associated with late-Pleistocene cycles had a significant influence on driving the population genetic structure and associated levels of genetic diversity in B. graueri and other small terrestrial vertebrates. Our results have implications for the conservation of B. graueri and other endemics to the Albertine Rift, particularly in the context of other phylogegeographic studies centered on this biodiversity hotspot. This article is protected by copyright. All rights reserved.

Abstract: Tadpoles of Hyperolius castaneus and Hyperolius jackie were found in the Nyungwe National Park in Rwanda and adjacent areas. Tadpoles of both species were identified by DNA-barcoding. At the shore of a bog pool three clutches of Hyperolius castaneus of apparently different age, all laid on moss pads (Polytrichum commune, Isotachis aubertii) or grass tussocks (Andropogon shirensis) 2-5 cm above the water level, were found. One clutch of Hyperolius castaneus was infested by larval dipterid flies. The most recently laid clutch contained about 20 eggs within a broad egg-jelly envelope. The eggs were attached to single blades of a tussock and distributed over a vertical distance of 8 cm. A pair of Hyperolius castaneus found in axillary amplexus was transported in a plastic container to the lab for observation. The pair deposited a total of 57 eggs (15 eggs attached to the upper wall of the transport container, 42 eggs floated in the water). Embryogenesis of the clutch was monitored in the plastic container at 20 ± 2 °C (air temperature) and documented by photos until Gosner Stage 25. The description of the tadpole of Hyperolius castaneus is based on a Gosner Stage 29 individual from a series of 57 tadpoles (Gosner stages 25-41). The description of the tadpole of Hyperolius jackie is based on a Gosner Stage 32 individual from a series of 43 tadpoles (Gosner stages 25-41). Egg laying behavior and embryogenesis are unknown for Hyperolius jackie. The labial tooth row formula for both species is 1/3(1) with a narrow median gap of the tooth row. Variation in external morphology was observed in size and labial tooth row formula within the species. With the tadpole descriptions of Hyperolius castaneus and Hyperolius jackie, 36 tadpoles of the 135 known Hyperolius species have been described, including five of the eleven Hyperolius species known from Rwanda.