Redescription and lectotype designation of the endemic South African mayfly Lestagella penicillata (Barnard, 1932) (Ephemeroptera: Teloganodidae).

The imago and nymph of Lestagella penicillata are redescribed based on historic specimens and new material from Table Mountain slopes (Skeleton Gorge and Window Stream), Western Cape, South Africa. A male from Barnard's syntype series is designated as the lectotype. Wear-and-tear of mouthparts, particularly the mandibles, has led to errors in identification of diagnostic characters for the nymphs in earlier publications. Previous descriptions of the mandibles being atrophied, in terms of dentition, are erroneous. The generic diagnosis of Lestagella is modified to account for these errors and intraspecific variability. Adults are distinguished from other Teloganodidae by the combination of a short, detached iMP vein on the forewing, three caudal filaments and gill socket vestiges on segments II - IV. Nymphs are distinguished from other Teloganodidae by a conspicuous head fringe, lamellate gills on abdominal segments II-IV and a dorso-ventrally flattened body. 

Cryptic variation in an ecological indicator organism: mitochondrial and nuclear DNA sequence data confirm distinct lineages of Baetis harrisoni Barnard (Ephemeroptera: Baetidae) in southern Africa.

BACKGROUND: Baetis harrisoni Barnard is a mayfly frequently encountered in river studies across Africa, but the external morphological features used for identifying nymphs have been observed to vary subtly between different geographic locations. It has been associated with a wide range of ecological conditions, including pH extremes of pH 2.9-10.0 in polluted waters. We present a molecular study of the genetic variation within B. harrisoni across 21 rivers in its distribution range in southern Africa. RESULTS: Four gene regions were examined, two mitochondrial (cytochrome c oxidase subunit I [COI] and small subunit ribosomal 16S rDNA [16S]) and two nuclear (elongation factor 1 alpha [EF1α] and phosphoenolpyruvate carboxykinase [PEPCK]). Bayesian and parsimony approaches to phylogeny reconstruction resulted in five well-supported major lineages, which were confirmed using a general mixed Yule-coalescent (GMYC) model. Results from the EF1α gene were significantly incongruent with both mitochondrial and nuclear (PEPCK) results, possibly due to incomplete lineage sorting of the EF1α gene. Mean between-clade distance estimated using the COI and PEPCK data was found to be an order of magnitude greater than the within-clade distance and comparable to that previously reported for other recognised Baetis species. Analysis of the Isolation by Distance (IBD) between all samples showed a small but significant effect of IBD. Within each lineage the contribution of IBD was minimal. Tentative dating analyses using an uncorrelated log-normal relaxed clock and two published estimates of COI mutation rates suggest that diversification within the group occurred throughout the Pliocene and mid-Miocene (~2.4-11.5 mya). CONCLUSIONS: The distinct lineages of B. harrisoni correspond to categorical environmental variation, with two lineages comprising samples from streams that flow through acidic Table Mountain Sandstone and three lineages with samples from neutral-to-alkaline streams found within eastern South Africa, Malawi and Zambia. The results of this study suggest that B. harrisoni as it is currently recognised is not a single species with a wide geographic range and pH-tolerance, but may comprise up to five species under the phylogenetic species concept, each with limited pH-tolerances, and that the B. harrisoni species group is thus in need of taxonomic review.

South African Lagerstätte reveals middle Permian Gondwanan lakeshore ecosystem in exquisite detail.

Continental ecosystems of the middle Permian Period (273-259 million years ago) are poorly understood. In South Africa, the vertebrate fossil record is well documented for this time interval, but the plants and insects are virtually unknown, and are rare globally. This scarcity of data has hampered studies of the evolution and diversification of life, and has precluded detailed reconstructions and analyses of ecosystems of this critical period in Earth's history. Here we introduce a new locality in the southern Karoo Basin that is producing exceptionally well-preserved and abundant fossils of novel freshwater and terrestrial insects, arachnids, and plants. Within a robust regional geochronological, geological and biostratigraphic context, this Konservat- and Konzentrat-Lagerstätte offers a unique opportunity for the study and reconstruction of a southern Gondwanan deltaic ecosystem that thrived 266-268 million years ago, and will serve as a high-resolution ecological baseline towards a better understanding of Permian extinction events.

A reassessment of the genus Oligoneuriopsis Crass, 1947 (Ephemeroptera, Oligoneuriidae, Oligoneuriellini).

The distinction between the two closely related genera Oligoneuriella Ulmer, 1924 and Oligoneuriopsis Crass, 1947 has been much debated. First described from South Africa, Oligoneuriopsis seemed to be a clearly defined genus. However, as the known distribution of the genus widened and knowledge on it expanded, species delimitation based on morphology became less clear due to overlap in several apparently defining morphological characters, especially in the nymphs. This work attempts to reassess Oligoneuriopsis morphology in the context of all currently known species. The type species, Oligoneuriopsis lawrencei Crass, 1947 is redescribed at the imaginal and nymphal stages and a neotype is designated. The putative nymph of Oligoneuriopsis dobbsi (Eaton, 1912) is described based on material collected around Mt Elgon (Kenya). The adults of Oligoneuriella orontensis Koch, 1980 are described for the first time and the species is transferred to the genus Oligoneuriopsis (Oligoneuriopsis orontensis comb. nov.). Egg structure is also described for the first time for the species Oligoneuriopsis skhounate and O. orontensis. Some biogeographical considerations are also given. It is likely that more species will still be discovered, especially in Africa.

Habitat requirements affect genetic variation in three species of mayfly (Ephemeroptera, Baetidae) from South Africa.

This study investigates genetic diversity in three species of Ephemeroptera, one eurytopic and therefore widespread (Afroptilum sudafricanum) and two stenotopic and thus endemic (Demoreptus natalensis and Demoreptus capensis) species, all of which co-occur in the southern Great Escarpment, South Africa. Mitochondrial DNA was analysed to compare the genetic diversity between the habitat generalist and the two habitat specialists. Afroptilum sudafricanum showed no indication of population genetic structure due to geographic location, while both Demoreptus species revealed clear genetic differentiation between geographic localities and catchments, evident from phylogenetic analyses and high FST values from AMOVA. In addition, the phylogenetic analyses indicate some deeper haplotype divergences within A. sudafricanum and Demoreptus that merit taxonomic attention. These results give important insight into evolutionary processes occurring through habitat specialisation and population isolation. Further research and sampling across a wider geographic setting that includes both major mountain blocks of the Escarpment and lowland non-Escarpment sites will allow for refined understanding of biodiversity and associated habitat preferences, and illuminate comparative inferences into gene flow and cryptic speciation.