Systematics of the shoot fly subgenusatherigona s. str. (diptera: muscidae) of South Africa

[摘要] English: Atherigona Rondani, 1856, is considered one of the most speciose genera of Muscidae, with 131 species presently known from the Afrotropical Region. The genus has been studied by numerous taxonomists since the 1800s, with some species having been described as part of Anthomyia Meigen, 1803 and Coenosia Meigen 1826. Historically it was placed as part of the Coenosiinae due to the presence of some similar diagnostic characters. It was later provisionally placed in the Phaoniinae, as a separate tribe Atherigonini, on the basis of its many autapomorphies. The unique morphology of its puparial form and affinities of the larvae to the Reinwardtiinae (= Azeliinae: Reinwardtiini) have further warranted it being placed in its own separate subfamily, Atherigoninae. Its two subgenera can easily be distinguished, with males of Atherigona s. str. having a trifoliate process and in most cases also a hypopygial prominence, and females a pair of anterior plates on tergite 8. These structures are absent from the other subgenus Acritochaeta Grimshaw, 1901.Over the past 188 years 39 papers have been published dealing with shoot fly species occurring in the Afrotropical Region in which 125 new species of Atherigona s. str. have been described, 43 of which are included in the present study (Chapter 2). Not much is known of South African species in terms of taxonomy and distribution, as most species described from the country were included in past revisions by happenstance. This phenomenon is the main justification for the present study.Species of Atherigona s. str. are known to occur on graminaceous plants, such as certain crops, i.e. sorghum, wheat, millet and barley, as well as wild grasses. Due to the wide distribution of their host plants, the flies obviously also have a wide distribution and have been recorded throughout most of Africa (Chapter 3), and in many parts of the world where graminaceous crops are grown.Whilst the majority of species are not considered pests, several species are damaging. The most serious pest species is the sorghum shoot fly, A. soccata Rondani, 1871. The larvae damage the growth points of crop seedlings, leading to typical dead heart symptoms. This severely stunts the growth phenology of the plants, leading to considerable yield loss.Sixty-eight South African species of the subgenus Atherigona s. str. are treated within this study (Chapter 2) including 25 new species based on male specimens. These are A. albicornis sp. n., A. capitulata sp. n., A. chrysohypene sp. n., A. convexa sp. n., A. danielssoni sp. n., A. erectisetula sp. n., A. flavifinis sp. n., A. flaviheteropalpata sp. n., A. heteropalpata sp. n., A. kirkspriggsi sp. n., A. latibasilaris sp. n., A. libertensis sp. n.,A. londti sp. n., A. ndumoensis sp. n., A. nesshurstensis sp. n., A. oblonga sp. n.,A. parviclivis sp. n., A. parvihumilata sp. n., A. piscatoris sp. n., A. rimapicis sp. n., A. stuckenbergi sp. n., A. tigris sp. n., A. umbonata sp. n., A. vernoni sp. n. and A. zulu sp. n. Atherigona hancocki van Emden, 1940 is designated as junior synonym of A. divergens Stein, 1913. The known diversity for the South African region is increased from approximately 35 to 43 species. An illustrated key to identify the males of the subgenus is also included in the chapter.The distribution of Atherigona s. str. within South Africa is determined through the use of recorded and georeferenced specimen record localities (Chapter 3). A regression analysis is performed to determine the degree of sampling bias, using calculated species richness and species occurrence grid data. It is determined that there is 74.47 % correlation between the two variables, indicating a reasonably high sampling bias. The maps generated also showed that Tier 1 protected areas within the savanna and grassland biomes have the highest species richness, which highlights the importance of these areas for the preservation of the country's natural heritage, but also theeffect that these areas have with regard to sampling bias.

[发布机构] University of the Free State