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Blackflies (Diptera: Simuliidae) of Southern Guyana with Keys for the Identification of Adults and Pupae - A Review Vol. 99(5): 443-470, August 2004 AJ Shelley/+, LM Hernández, JB Davies* The Natural History Museum, Department of Entomology, Cromwell Road, London SW7 5BD, UK *Liverpool School of Tropical Medicine, Liverpool, UK A revision is made of the previously poorly studied blackfly fauna from the south-western border of Guyana with Brazil. Notes on the biosystematics of the species found are provided, together with keys and illustrations based on their morphology. Of the 14 species recorded, eight are anthropophilic and two of these (Simulium oyapockense s.l. and S. guianense s.l.) are proven vectors of human onchocerciasis in the nearby Amazonia focus of the disease in neighbouring Brazil. Key words: blackflies - Simuliidae - Neotropical region - taxonomy - Guyana
There have been few studies on the Simuliidae in Guyana and all those that have been made involve the border area with Brazil in the Rupununi District. This has largely been due to the lack of simuliids in the swampy coastal regions, the difficulty of access to the interior of the country and the lack of any pathogenic parasites transmitted by these insects. It was in Guyana (then British Guiana) at the end of the last century that relatively non pathogenic, blood inhabiting microfilariae were sent by Dr Ozzard to Manson, who described them as the new species Mansonella ozzardi. It was soon discovered that this filarial species was common in the Caribbean Islands where the vectors were species of Culicoides midges. Eighty years later the discovery of simuliids as vectors of M. ozzardi in Brazil and Colombia (reviewed in Shelley & Coscarón 2001) prompted the work of Nathan et al. (1982), who discovered that Simulium oyapockense s.l. is a vector of M. ozzardi in the Rupununi District of Guyana. At the beginning of the twentieth century studies on anthropophilic Diptera were numerous because of their biting nuisance and, in the case of mosquitoes, their proven role as vectors of pathogenic species of protozoal parasites. The first attempt at study of the Simuliidae in Guyana was made by the government Surgeon General at Georgetown, KS Wise. He had been sent man-biting simuliids by Melville from the upper branches of the Essequibo river (R) (the Rupununi and Siparuni R) and also examined specimens of two species from the same area in the Museum of the Royal Agricultural and Commercial Society of British Guiana in Georgetown. Wise (1911) provided a redescription for one of the species known as the "pium" in Brazil [by the Macuxi indians] and the "cabouri" fly by the Arawak indians in Guyana, and which had already been described in Brazil [by Lutz] as S. amazonicum. This species is not S. amazonicum but S. oyapockense s. l., a species later described in the 1940s from French Guiana (Shelley et al. 1997) and also known in Brazil as the "pium". Wise described the other species as new, S. guianense, which the local indians referred to as the itanimi fly to distinguish it from the smaller pium or cabouri fly. In 1915 Knab described the anthropophilic female, sent to him by Dr Wise from the same area, as the new species S. limbatum. At a time when it was considered that any development of the interior of the country would need to take account of blackfly control, Drs OW Richards and J Smart visited Guyana in 1937. They recorded seven simuliid species from this country and published taxonomic notes and a key to these, as well as other species collected from the Lesser Antilles (Smart 1940). The seven species from Guyana were: S. amazonicum (= S. oyapockense s.l.), S. guianense (= S. perplexum), S. haematopotum (= S. oyapockense s.l.), S. limbatum, S. lutzianum (= S. kabanayense), S. rubrithorax (= S. maroniense s.l.), S. sanguineum (= S. oyapockense s.l.). It is now known that these names represent only five distinct species as indicated in brackets. In most cases the misidentifications are completely understandable because at this time many species were poorly defined morphologically. However, an obvious lapse occurred with pupae identified as S. rubrithorax (with eight gill filaments), which are S. maroniense s.l. (with 18-22 gill filaments). Similarly, the naming of three pupal exuviae (in BMNH collection) as S. lutzianum s.l. (with eight gill filaments) was incorrect as the specimens have 10-13 filaments and are of a species later described as S. kabanayense (Ramírez Pérez & Vulcano 1973). These three specimens were not referred to in the taxonomic discussion of S. lutzianum s.l. in Shelley et al. (1997) because they were known not to be of this species but were not identified at the time. In 1989b Shelley et al. described the new species S. perplexum based on specimens identified by Smart (1940) as S. guianense Wise. The collections by the third author, which have been the most comprehensive for the country, were made in the 1970s when the development of the Rupununi savanna for tourism was being contemplated. One of the constraints to this development was the presence of large numbers of anthropophilic simuliids. This work was necessary for the development of studies on the biology of and a pilot control project for S. limbatum (as S. in-crustatum) and S. oyapockense s.l. (as S. amazonicum/S. sanguineum, S. amazonicum or S. sanguineum complexes) (Humphrys et al. 1977, Rambajan 1981a, b). At this time the taxonomy of the Simuliidae of this region of Latin America was relatively unknown, and it was not until the finding of onchocerciasis in the Brazil-Venezuela Amazonia focus some 400km to the west of the Rupununi District that comprehensive taxonomic studies began. This paper, based on holdings at the Natural History Museum, London (BMNH) mainly including the specimens of Wise, Knab, Smart, and the third author, provides the first modern review of the Simuliidae of Guyana, albeit limited to the south-western frontier area of the country with Brazil. Illustrated keys to the adults and pupae of the 14 species of Guyana are presented, together with biosystematic notes for each species and a list of material examined. CHECKLIST OF THE SIMULIIDAE OF GUYANA KEYS TO THE SIMULIIDAE OF GUYANA NOTES ON THE BIOSYSTEMATICS OF SPECIES ACKNOWLEDGEMENTS JBD wishes to express his gratitude for the help and companionship provided by those he encountered during his main trips to the Rupununi District in 1970 and 1971. In particular, Mr JA Sankey, British High Commission, and his staff; MH Ali, L Frenker, and Dr Egbert, Ministry of Health; C McA Ashley, Chief Development Officer, R Barnwell, K Chung, and S Sagar, District Commissioners; L Lowenfield, FM Wills, and R Dookah, Field Officers, Malaria Eradication Programme. In Kato, the hospitality provided by the store owner Sr Brazão was especially welcome. During a last visit in 1975, assistance was provided by Dr P Munroe, I Rambajan, as well as S Hingwan of CAREC, Trinidad. We are grateful to Dr Peter Adler of CUAC, US, Dr Neusa Hamada of Inpa, Brazil, and Dr P Reiter of IP, France, for the loan of specimens. Map
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+Corresponding author. Fax: +44-207-942.5661. E-mail: ajs@nhm.ac.uk Received 12 January 2004 Accepted 19 May 2004
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