A synopsis of the Afrotropical Tricorythidae

The Tricorythidae of the Afrotropical Region is currently composed of five described genera, three of which are thought to be restricted to Madagascar (Madecassorythus Elouard and Oliarioniny, Ranorythus Oliarinony and Elouard, and Spinirythus Oliarinony and Elouard), one which is restricted to Africa (Dicercomyzon Demoulin), and one which is thought to be distributed on both landmasses (Tricorythus Eaton). Based on sexual dimorphism, manifest in the relative eye size of mature male and female nymphs and adults and on the structure of the genitalia of adult males, it is proposed that there are two additional genera in Africa, as yet undescribed. One of these genera is represented by a species currently placed in Tricorythus (T. discolor [Burmeister]). Several other undescribed species within South Africa have been identified as belonging to the group. A second lineage is represented by Tricorythus tinctus Kimmins, from Uganda, the only currently described species. There are also several more undescribed species of this group widespread in Africa

The biogeography of the Prosopistomatidae, with a particular emphasis on Southern African species

The mayfly family Prosopistomatidae consists of the single genus Prosopistoma Latreille. Its known distribution includes species from Africa, Madagascar, the Comores, Europe, the Levant, India, Sri Lanka, China, Vietnam, the Philippines, Malaysia, Sumatra, Java, the Solomon Islands, Papua New Guinea and northern Australia. A tropical Gondwanaland origin of the family has been suggested. No species are currently known from the Neotropical or Nearctic regions, though the family may yet be discovered in northeastern South America, since this region separated from West Africa only c.120 mya. Focussing on southern Africa, several undescribed species have recently been discovered, with interesting implications to the biogeography on a more localised scale. In the western Cape, a prosopistomatid species has been collected in the Olifants River, extending the distribution of this family further south into a more temperate region. Geological evidence indicates that the Olifants River was connected to the Orange River during the Tertiary period. Prosopistomatidae are known from the Orange River today, and the presence of the family in the Olifants River in the western Cape supports the geological evidence of the historical link between these two rivers. Another unexpected discovery was from the Buffalo River in the eastern Cape, at 33ºS. A subtropical zone extends along the east coast of South Africa as a result of the warm Agulhas current offshore, allowing the southerly extension of the distribution of more tropical species.Research Update on Ephemeroptera & Plecoptera: Proceedings of the Tenth International Conference on Ephemeroptera, 8-11 August 2001, Perugia, Italy. University of Perugia, Perugia, Italy, pp. 263-270

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

Systematics, morphology, phylogeny and historical biogeography of the Mayfly family Prosopistomatidae (Ephemeroptera: Insecta) of the world

The diversity, classification and historical biogeography of the mayfly family Prosopistomatidae are explored. First, the higher classification of the Ephemeroptera is reviewed, focussing on the phylogenetic placement of the Prosopistomatidae relative to other mayfly families. All relevant literature from 1762 to 2010 is synthesized. Baetiscidae are established as the probable sister lineage of Prosopistomatidae, the two constituting the superfamily Baetiscoidea. Next, qualitative morphological variation within the Prosopistomatidae is reviewed and revised, emphasizing nymphs because imaginal specimens are few. The labium and associated structures and the hypopharynx of nymphs, and the highly-derived wing venation of the imaginal stages, are re-interpreted. The structure of the male tarsal claws changes considerably between subimago and imago, which, together with deeply scalloped ridges on male imaginal forelegs and unusual pits on the female thorax, are interpreted as providing an unusual mating mechanism. These structures provide morphological characters for species definition and phylogenetic analyses. Two approaches to species delimitation are explored. First, morphometric variation is analysed using Principal Component Analysis, revealing groupings that can be interpreted as species, although there is some overlap between them. Discriminant Function Analysis shows that head width and carapace shape have the most value in identifying nymphs of different species. The carapace of Prosopistoma nymphs is shown to grow allometrically and gradually, in contrast with that of Baetisca, indicating a difference in early ontogeny. Second, an Artificial Neural Network algorithm applied to nymphal morphological characters accurately identified species. This computer-driven artificial intelligence method has power to provide future easy-to-use electronic identification aids. Phylogenetic analysis of nymphal morphology using the parsimony method shows two clades of Prosopistomatidae, one sharing characters with the type species, Prosopistoma variegatum and the other predominating in Africa, although also occurring in Asia; these clades are named the “P. variegatum” and “African” clades, respectively. Parsimony analysis of adult morphology supports these two clades, but supertree analysis obscures the relationships, nesting the “P. variegatum” lineage within the other clade. Preliminary molecular phylogenetic analysis of the 16S rRNA, (mitochondrial) 18S rRNA and Histone-3 genes using Bayesian Inference methods does not support the two clades shown by morphology. Instead, there is a strong relationship between the European species and one African species, with the single Asian representative being most distantly related. These results are limited by lack of fresh material, patchy taxon sampling, and problems with finding suitable primers. A molecular clock program, BEAST, calibrated using fossils, suggests divergence times for the oldest crown-group Prosopistoma clade, represented by the Asian P. wouterae, of about 131 Ma, with the youngest species, the African P. crassi, of 1.21 Ma. Stem-group relationships are analysed using parsimony analysis, focussing on wing characters of the Baetiscoidea, other extant mayfly lineages, and extinct stem-group lineages. This suggests that the Baetiscoidea diverged from main-line Ephemeroptera earlier than any other extant mayfly lineage. This approach expands upon ideas hinted at by earlier scientists. Finally, historical biogeographical analysis of the distribution of known Baetiscoidea s.s. stem-group fossils implies a once Pangean distribution of the lineage. Changing palaeo-climate, catastrophic extinction events and plate tectonic movements in relation to the distribution of crown-group species are reviewed. Other approaches to historical biogeography that build on both morphological and molecular phylogenies are used to interpret disperalist and vacarianist arguments. Distribution patterns of eight unrelated freshwater organisms which share a similar distribution pattern are compared, assuming that shared patterns indicate similar historic biogeographic processes. The distribution of recent Prosopistoma species is seen to be the product of evolution resulting from both vicariance and dispersal. In conclusion, this thesis encompasses a variety of disciplines. It successfully recognises new characters and distinguishes previously unknown species. It uses new approaches to delimiting species and known methods to determine phylogeny from several angles. The analysis of stem-group relationships offers an insight into possible early lineage splitting within Ephemeroptera. Interpretation of historical biogeography allows for both a Gondwanan origin of Prosopistomatidae, with rafting of species on the Deccan plate to Asia, and for subsequent dispersal from Asia down to Australia and across to Europe, and possibly back to Africa

The eggs of Afronurus LESTAGE, 1924 (Ephemeroptera: Heptageniidae): a cue for phylogenetic relationships

Scanning electron microscopy (SEM) investigation carried out on the eggs of Afronurus scotti, A. harrisoni, A. peringueyi, and A. ugandanus, has provided some chorionic details useful for a comparison between these species. In all the species, the egg chorion is decorated with sparse granules and shows two kinds of knob-terminated coiled threads (KCTs). The first kind is represented by small KCTs (5-7 ?m in diameter) densely concentrated at each egg pole; the second kind encompasses large KCTs (60- 80 ?m in length) situated equatorially. The micropyle has an oval to round sperm guide (15-20 ?m long; 12- 18 ?m wide), and a well-defined rim. The polar KCTs expand towards the equatorial KCTs in A. scotti, A. harrisoni, and A. peringueyi, but in A. ugandanus there is a large clear area between polar and equatorial KCTs. A chorionic pattern very close to that of these Afronurus species is shared only by species belonging to the Asiatic genus Cinygmina. In addition, examination of the labrum of the nymphs belonging to both genera, indicates a very similar morphology, in the curved sclerification in the basal region of the labrum, a feature that contrasts with the almost straight shape presented by other heptageniid genera (e.g. Electrogena species). Egg and labrum characteristics are advocated to hypothesise a close phylogenetic relationship between the South-African Afronurus and the Asiatic Cinygmina genera

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

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

A taxonomic and ecological review of Pseudocloeon glaucum (Agnew)(Ephemeroptera: Baetidae)

Pseudocloeon masai (Lugo-Ortiz and McCafferty), P. nadineae (Lugo-Ortiz and McCafferty) and P. quintum (Agnew) are junior subjective synonyms of P. glaucum (Agnew). Larvae of P. glaucum manifest a wide range of variation in mouthpart morphology, particularly with respect to the development of the distomedial process of segment 2 of the labial palps, body size, general body colour and abdominal colour pattern. Such variation is observed in different cohorts and populations, and explains why several names have been applied to the same species. Larvae of P. glaucum also have considerable ecological tolerance, accounting for the abundance and widespread distribution of the species in the Afrotropical Region. New records from Kenya, Lesotho, Namibia and Zimbabwe are provided

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

A non-paraphyletic classification of the afrotropical genus Acanthiops Waltz & McCafferty (Ephemeroptera: Baetidae)

Acanthiops Waltz & McCafferty (Ephemeroptera: Baetidae) is shown to be a monophyletic grouping defined by an anteromedially emarginate and laterally expanded and flattened pronotum in the larva. Attempts to restrict the concept of Acanthiops to Ac. marlieri (Demoulin) and re-erect Afroptiloides Gillies, syn. n., for Ac. elgonensis Lugo-Ortiz & McCafferty, Ac. griffithsi Lugo-Ortiz & McCafferty, Ac. tsitsa Barber-James & McCafferty, Ac. variegatus (Gillies), Ac. varius (Crass) and Ac. zomba Lugo-Ortiz & McCafferty, are shown to be based on inconsistent and inadequate morphological features that result in a paraphyletic taxonomy. The unofficial separate treatment of Ac. cooperi (Gillies & Wuillot) and Ac. erepens (Gillies) under Platycloeon Gillies & Wuillot is also shown to be paraphyletic. Acanthiops faro Barber-James & McCafferty, sp. n., is described from larvae from Guinea, and is distinguished by the combination of a papillate projection on labial palp segment 2, small tubercles on terga 1-8 and abdominal colour pattern. Acanthiops io Lugo-Ortiz & McCafferty, sp. n., is described from larvae from the Democratic Republic of Congo, and is distinguished by the combination of a papillate projection on palp segment 2, elongate tubercles on terga 1-9 and abdominal colour pattern. The larva of Ac. erepens (Gillies) is redescribed to incorporate morphological features and variability previously not accounted for, and larvae originally assigned to Baetis cataractae Crass are shown to be equivalent to Ac. erepens. New locality data or emendations on locality data are provided for Ac. griffithsi, Ac. tsitsa Barber-James & McCafferty and Ac. varius (Crass)