A new genus and two new species of gall midges (Diptera: Cecidomyiidae) feeding on Guinea grass <scp><i>Megathyrsus maximus</i></scp> (Poaceae) in Africa

Abstract Two new species of gall midges are described whose larvae feed on the small morphotype of Guinea grass Megathyrsus maximus in Africa. Arabukodiplosis basalis Kolesik, gen. et sp. nov. causes galls at the base of plant's crown in Kenya and Arabukodiplosis vesicaria Kolesik, gen. et sp. nov. causes blister galls on the stems in South Africa and Kenya. Description of the morphology and the sequence of a fragment of the COI mitochondrial gene of the insects are provided. A new genus is erected to contain the two new species. Arabukodiplosis Kolesik, gen. nov. belongs to the supertribe Cecidomyiidi and its closest relative is Mitodiplosis Kieffer, 1914, an African genus containing a single species that induces stem thickening galls on pyp grass Ehrharta villosa (Poaceae) in South Africa. Like Mitodiplosis , Arabukodiplosis Kolesik, gen. nov. cannot be satisfactorily accommodated in any of the currently recognised tribes. The crown of the plant, where A. basalis Kolesik, gen. et sp. nov. forms galls, is where new tillers and shoots originate, so the galls develop where stems would usually form. Stems infested by A. vesicaria Kolesik, gen. et sp. nov. continue to develop above the galls, but the gall is expected to act as a resource sink, reducing the fitness of the host plant. Both species are possible candidates for biological control of M. maximus , which is a serious invasive alien pest outside of its native distribution.