Helen M. Barber-James

Global diversity of mayflies (Ephemeroptera, Insecta) in freshwater

The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation.

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

BackgroundBaetis 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.ResultsFour 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).ConclusionsThe 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.

The macroinvertebrates of the Cunene River from the Ruacana Falls to the river mouth and assessment of the conservation status of the river.

The proposed construction of a second hydroelectric power-generating dam on the Cunene (Kunene) River on the Namibia-Angola border, more than 100km downstream of the Ruacana hydroelectric power plant, will have a major influence on the aquatic biota of this river. In order to assess the potential impact of this impoundment a more detailed inventory of the biota in the river prior to this development was needed. Unfortunately the river presently does not represent an entirely undisturbed system as the operation of the Ruacana hydroelectric power station since 1970 has had a long-term effect on its biota. In the low-flow mid-summer season in particular, large areas of the river become irregularly inundated and exposed, sometimes on a daily basis, making them unsuitable for macroinvertebrate colonisation. There are six impoundments along the Cunene River upstream of the Ruacana Falls in Angola. These, however, do not have any major disruptive effects on daily flow variation in the Cunene River in Namibia although whole system biological consequences could be considerable but are unstudied. The Cunene River has a diverse freshwater fish fauna but, prior to the surveys reported here, the aquatic macroinvertebrates had been poorly studied. Surveys conducted by staff of the Department of Water Affairs (DWA) of Namibia and the Albany Museum, Grahamstown, in 1997 and 1998 have resulted in 216 aquatic macroinvertebrate species being recorded from Ruacana to the river mouth. The lower Cunene River, flowing through a very arid region, is biogeographically isolated and therefore highly vulnerable to change. The biota recorded reflects a fauna of widespread species and several elements of tropical origin. Several undescribed species may reflect some endemics but because of limited knowledge of the tropical rivers, this cannot be ascertained with certainty. From the aspect of conservation, the river contains a diversity of species with an abundance of filter-feeding species. Further surveys conducted during different seasons will undoubtedly record more taxa.

A preliminary phylogeny of Prosopistomatidae (Ephemeroptera) based on morphological characters of the larvae, and an assessment of their distribution

Until recently, only four species of the monogeneric family Prosopistomatidae were described from the Afrotropical realm; one from Madagascar, and three from sub-Saharan Africa. Recent studies have revealed the family to be more diverse, with a further five species from Madagascar, one from the Comores archipelago and seven from sub-Saharan Africa, which are currently in the process of being formally described. This brings the total number of known species globally to 34. Phylogenetic analysis of morphological features of the larvae reveals that the type species, Prosopistoma variegatum Latreille, 1883, a Madagascan species, along with two other Madagascan species, belongs to a clade which is different to the majority of other Afrotropical species. It is more closely related to the European species, the species from the Middle East and several of the species from the Oriental and Australasian regions. One possible explanation is diversification of this ‘P. variegatum’ clade after Madagascar and India separated from Africa. The precursors of this clade may have been carried northwards on the Indian Plate, and subsequently dispersed to Europe, and to Australia via the Indo-Pacific islands. A concurrent dispersal of the now predominantly mainland African clade may have occurred and, in Madagascar and the Oriental realm, members of this group occur sympatrically with, or in close geographic proximity to, members of the ‘P. variegatum’ clade.

How well are Afrotropical mayflies known? Status of current knowledge, practical applications and future directions

Abstract Mayflies (Ephemeroptera) are a merolimnic insect order (part of the life cycle is aquatic) and play an important role as biological indicators of river ecosystem health. In the Afrotropical realm (including sub-Saharan Africa and Madagascar), this order presently encompasses 122 genera and more than 400 species; all species and 85% of the genera are endemic to the Afrotropics. A great part of the diversity still remains unknown. The specific and generic diversity of mayfly families from Madagascar and from 4 sub-Saharan African subregions (West Africa, western Central Africa, eastern Central Africa, and southern Africa) is presented. A concurrent comparison of this diversity with the level of taxonomic knowledge for each subregion highlights inadequacy of knowledge. It is important for freshwater conservation biologists and ecologists, and for biomonitoring programs, to have a level of certainty when identifying taxa. This preliminary synthesis is intended to stimulate future taxonomic research and collecting efforts in understudied regions that will lead to species descriptions and recognition of the biodiversity of these regions. This information will feed into regional identification keys and enable more accurate species identification. Greater understanding of the diversity of organisms, the foundation for all ecological studies, can be used to refine biomonitoring protocols for freshwater organisms.

Neotype erection, redescription of the larva and first description of the winged stages of Prosopistoma variegatum Latreille, 1833 (Insecta: Ephemeroptera) from Madagascar

The history of the early descriptions of Prosopistoma is reviewed, and the steps taken to trace the original material described as Prosopistoma variegatum Latreille, 1833 are outlined. Eaton (1884) designated P. variegatum as the “type” of the genus Prosopistoma. Because only the larva was described by Latreille (1833) and this material is no longer available, a larva of this species was selected as the neotype. Scanning electron micrographs of some of the key larval characters provide additional detail for morphological characters not previously described in the Prosopistomatidae. The associated adult male and subimaginal male and female collected from the same sites as verified larvae of P. variegatum are described for the first time.

New species and generic delimitation of the Afrotropical genera Bugilliesia Lugo-Ortiz & McCafferty, 1996; Cheleocloeon Wuillot & Gillies, 1993 and Delouardus Lugo-Ortiz & McCafferty, 1999 (Ephemeroptera: Baetidae)

The larval stage of the genera Bugilliesia Lugo-Ortiz & McCafferty 1996; Cheleocloeon Wuillot & Gillies, 1993 and Delouardus Lugo-Ortiz & McCafferty, 1999 are remarkably similar. In order to avoid inaccuracy in generic placement, we propose new generic diagnoses with new discriminating characters. The setation of the labrum, details of the right and left prostheca, the shape of the maxillary palp and the shape of the legs are the most reliable characters for separating the different genera. Based on this, the generic attribution of Cheleocloeon mirandei Lugo-Ortiz & McCafferty, 1997 is incorrect and the species must be transferred to Bugilliesia as B. mirandei n. comb. A new species of Bugilliesia is described from South Africa. This greatly increases the distribution of Bugilliesia to include the whole of the Afrotropical region including Madagascar. A new species of Cheleocloeon is also described, confirming the presence of this genus in Madagascar.

Freshwater invertebrate fauna of the Tristan da Cunha islands (South Atlantic Ocean), with new records for Inaccessible and Nightingale Islands

As part of a multidisciplinary floristic-faunistic study, a three week survey of the invertebrate fauna of Inaccessible Island (South Atlantic Ocean) was carried out in October/November 1989. In addition, one day of collecting was done on Nightingale Island. This paper deals only with the fauna associated with freshwater ecosystems from these islands, some of which are usually associated with marine or brackish conditions. On Inaccessible Island, five distinct types of freshwater body were identified—pH neutral streams, acidic streams (pH 5), an open pool of standing water (pH 6), areas of acidic bog, and seepages down rock faces. The survey, the most comprehensive for Inaccessible Island to date, has resulted in the discovery of 19 aquatic invertebrate species previously unrecorded on Inaccessible Island, two new to Nightingale Island, and 14 of which are new to the Tristan da Cunha archipelago. Many of the species are known from other parts of the world, indicating a low degree of endemicity within the freshwater invertebrate community. Recolonisation from the source populations, preventing an isolated gene pool, may account for the low endemicity. Several of the species have a degree of salinity tolerance, enabling them to withstand transportation across tracts of ocean, and others have marine origins.

Deeper knowledge of shallow waters: reviewing the invertebrate fauna of southern African temporary wetlands

Temporary lentic wetlands are becoming increasingly recognised for their collective role in contributing to biodiversity at the landscape scale. In southern Africa, a region with a high density of such wetlands, information characterising the fauna of these systems is disparate and often obscurely published. Here we provide a collation and synthesis of published research on the aquatic invertebrate fauna inhabiting temporary lentic wetlands of the region. We expose the poor taxonomic knowledge of most groups, which makes it difficult to comment on patterns of richness and endemism. Only a few groups (e.g. large branchiopods, ostracods, copepods and cladocerans) appear to reach higher richness and/or endemicity in temporary wetlands compared to their permanent wetland counterparts. IUCN Red List information is lacking for most taxa, thus making it difficult to comment on the conservation status of much of the invertebrate fauna. However, except for a few specialist groups, many of the taxa inhabiting these environments appear to be habitat generalists that opportunistically exploit these waterbodies and this is hypothesised as one of the reasons why endemism appears to be low for most taxa. Given that taxonomy underpins ecology, the urgent need for more foundational taxonomic work on these systems becomes glaringly apparent.