Cimbebasia 18: 191-206, 2003 191 A review of the taxonomy of African Odonata - finding ways to better identification and biogeographic insight Klaas-Douwe B. Dijkstra Gortestraat 11, NL-2311 MS Leiden, The Netherlands: e-mail: [email protected] The taxonomy of the approximately 850 species of sub-Saharan African Odonata is relatively well-known, probably due to the impoverished nature of the fauna as compared to that of other tropical regions. The need for revisions, study of higher classification, comprehension of (often clinal, environmentally induced) variability and knowledge of larvae, phylogeny and biogeogra- phy are stressed. Taxonomic priorities are discussed for each family. Supportive activities include the production of identification manuals for a broader public, the accumulation of supplemen- tary material and the conservation of existing collections. A list of genera with estimated num- bers of species, taxonomic status and references is provided, as well as a list of important regional works. INTRODUCTION biogeography. The first priority for the taxonomy of African Odonata is, therefore, revisions. Although not as well studied as the Holarctic and Australasian Region’s faunas, knowledge of the REVISIONS & REVIEWS taxonomy of African Odonata is well ahead of those of the Oriental and Neotropic Regions. The It is hardly an exaggeration to say that all genera main reason is that the African fauna is relatively require at least some study. Elliot Pinhey tackled impoverished, harbouring only about 60% of the many problems, as can be seen from the nume- number of species found in each of the two other rous referrals to his work in the Appendix. Due to tropical regions. The writer here defines the Afri- their size, large genera generally have the greatest can fauna as that occurring south of the Sahara, problems. Pseudagrion is by far the largest genus with the inclusion of the Indian Ocean islands with almost a hundred species. Phyllomacromia and (Comoros, Madagascar, Mascarenes and Sey- Trithemis both number around forty species, Chloro- chelles). It numbers around 850 species, placed in cypha, Paragomphus and Orthetrum nearly thirty, and 125 genera. The former figure is about 15% of the Ceriagrion, Platycnemis, Gynacantha, Notogomphus and World total. Around 95% of species are not found Phyllogomphus about twenty. Other larger genera beyond the region. Despite the fact that the Afri- are Lestes, Nesolestes, Agriocnemis, Elattoneura and can Odonata are relatively well-known, numerous Zygonyx. Subtraction of the well-studied genera taxonomic issues remain uncertain, or at least from the largest genera creates an idea of revision unsettlingly hazy. Elucidating the relationships be- priority (vide Appendix). Besides full-scale revisions, tween species, and finding ways to distinguish many smaller issues of suspected synonyms, no- them, is perhaps the primary challenge of African menclature, mix-ups, identification problems and odonatology. This knowledge is required as a fun- species limits require attention. Some of the larger dament for future research, particularly for the al- genera that appear fairly well sorted could be re- most untouched field of African odonate viewed to straighten out the identification of the Proceedings of the 1st PHAON Meeting presented at the 2nd WDA International Symposium of Odonatology, Gällivare, Sweden, 26th July 2001. 192 Cimbebasia 18, 2003 species. The problems are reviewed for each family backgrounds of them might be. Examples are the below. forms of Palpopleura lucia (Drury, 1773) (e.g. O’Neill & Paulson 2001) and Eleuthemis buettikoferi Ris, HIGHER CLASSIFICATION 1910 (Lempert 1988) and the subspecies of Atoco- neura biordinata (Karsch, 1899) (Longfield 1953). Next to taxonomic work with a species-group (most often genus) approach, there are numerous LARVAE problems in higher classification that require to be addressed. These are often relative to the fauna of Most of what has been published on African Odo- the Oriental Region, with which the African fauna nata (and most of what is written in this review) is has most in common. It is a lucky coincidence that about adults, but perhaps the greatest taxonomic when Elliot Pinhey’s ‘trailblazer’ Frederic Fraser frontier lies in the field of the larval stages. Al- began studying the African fauna intensively in though their study has (logically) lapsed behind, the 1940s, he had about twenty years of experi- the larvae or exuviae of many genera have been ence of the oriental fauna. Many of the higher described. Numerous genera and species are still level problems are worldwide issues, and the awaiting such descriptions. The study of larvae knowledge of the African fauna shall profit from shall offer a whole new set of characters for phylo- research in this field. The phylogeny of the genetic study. Many species are much easier to col- Odonata is still much debated (e.g. Bechly 1995; lect as larva than as adult (e.g. corduliids and gom- Lohmann 1996; Trueman 1996). Especially the use phids) and, therefore, larvae also hold promise of molecular techniques, which are used increas- for biogeographic and ecological research. The rear- ingly to study Odonata, holds the promise of ing of larvae to adults must be especially stimu- new phylogenetic insights. lated, as it is the most reliable means to establish their specific identity. THE PROBLEM OF VARIABILITY PHYLOGENY & BIOGEOGRAPHY One of the greatest practical problems in African Odonata taxonomy is that of variability, particu- Taxonomic research can be taken beyond the level larly in size and melanisation (intensity of black of nomenclature and identification. With the aid of phylogenetic analysis and molecular techniques, pigmentation). Much of this variation is related hypotheses of the evolutionary history of African to environmental conditions. The African Conti- Odonata may be created. Combined with distri- nent forms a vast, rather continuous landmass, bution data, this may serve to understand more and many of the species are wide-ranging. Nu- about the climatology and geography of Africa merous gradients in humidity and temperature lie and the origins and dispersive capacity of its drag- across the continent, with the seasons adding an- onflies. Odonata have a number of biological ad- other dimension of environmental variation. vantages in this regard. Their strong relation with Specimens have been collected only fragmentarily freshwater and different types of vegetation (par- along these clines in space and time, which may ticularly the forest-savanna contrast) make drag- result in the false perception of discreteness in onflies sensitive to the environmental vicissitudes forms. The status of countless subspecies, as well which characterise the continent’s history. The spe- as species, may be re-assessed with these recurrent cies range from extremely good to very poor disper- variation trends in mind. Particularly sensitive to sers, which offer insight in different degrees of vi- this problem are genera in which structural charac- cariance and dispersal. The Odonata are also a rela- ters are of little taxonomic value (Chlorocypha) and tively ancient group, giving it a deep grasp in time. groups that are difficult to collect (Gomphidae). It of course remains to be seen (from the biogeo- In cases where discrete forms exist, one must ask graphic and phylogenetic analyses advocated) if the why these are not worthy of species status, and if present-day representatives are descendants of such they are forms, what the ecological or behavioural ancient faunas. This combination of advantages Dijkstra – A review of African Odonata taxonomy 193 is distinct from that of other well-studied groups, such as vertebrates, butterflies and plants. There- fore, what may be learnt from Odonata about Af- rican biogeography may be not only of affirma- tive, but even of supplementary value. REVIEWS OF THE FAMILIES The Appendix lists genera of African Odonata. Figure 1. Male of Chlorocypha tenuis Longfield. “It For each genus the number of species, and the has been realized for many years that some of the need for revision and biogeographic valuation, are confusion is due to maturation changes in colour and estimated. An attempt is also made to provide the markings” writes Pinhey (1967a) in his revision of most recent, comprehensive or relevant references, the African Chlorocyphidae. This variability still i.e. those treating all species known (at the time of cripples the taxonomy of the group, which is poor writing), a large proportion thereof, or that pro- vide a good overall impression of the genus. In in morphological characters, today. the following paragraphs the taxonomic status of each family is briefly outlined. These reviews are LESTIDAE, PERILESTIDAE & SYNLEST- not exhaustive, but do stipulate the most urgent cases. IDAE AMPHIPTERYGIDAE & CALOPTERYG- These families are small and taxonomically well- IDAE known. Lestes has been split into several (sub-) genera, six of which are recognised in Africa (Pinhey Due to the small numbers of species in these fami- 1980b). The value of these can only be assessed lies and their conspicuous nature, they are well- after a complete phylogenetic treatment of this known. The generic distinction between Sapho and cosmopolitan group. Most of the African Umma requires some attention, especially in rela- synlestids have limited ranges and knowledge of tion to the species puella Sjöstedt, 1917, that is vari- their phylogeny would yield insight into the bio- ably placed in either genus (G.S. Vick pers. comm.). geography of the Cape Region. CHLOROCYPHIDAE MEGAPODAGRIONIDAE This family was treated in its totality by Pinhey Coryphagrion grandis exhibits a strong ecological (1967a). Nevertheless, the taxonomy is still un- and morphological resemblance to the neotropical sound as a result of the lack of structural charac- giant damselflies (Pseudostigmatidae). Thorough ters in this group (Figure 1). As a result, the mor- investigations should reveal whether these are phological basis of the genera is rather slim. Prob- mere analogies, or if the two are actually related lems are greatest in the red-bodied Chlorocypha spe- (Clausnitzer & Lindeboom 2002).