Journal of East African Natural History 96(1): 83–93 (2007) TWO NEW SPECIES OF MUSCIDAE (DIPTERA) FROM KENYA, ASSOCIATED WITH FLOWERS OF ACACIA SPECIES (FABACEAE MIMOSOIDEAE) AND BALANITES SPECIES (BALANITACEAE) Adrian C. Pont Oxford University Museum of Natural History Parks Road, Oxford OX1 3PW, UK pont.muscidae@btinternet.com Katherine C. R. Baldock Institute of Evolutionary Biology, University of Edinburgh Kings Buildings, West Mains Road, Edinburgh EH9 3JT, UK K.Baldock@ed.ac.uk. ABSTRACT Two new species of Muscidae (Diptera) are described from Kenya: Pyrellia acaciae sp.n. and Hydrotaea cilitibia sp.n. P. acaciae appears to be not uncommon and was found almost exclusively on flowers of species of Acacia (Fabaceae) (A. brevispica, A. etbaica, A. gerrardii, A. nilotica and A. tortilis), and its activities may contribute towards the pollination of these species. H. cilitibia was much more rarely encountered and, with one exception, was found only on flowers of Balanites species (Balanitaceae). Keywords: Pyrellia, Hydrotaea, new species, Kenya, Acacia INTRODUCTION It is remarkable that since publication of the Afrotropical Diptera catalogue a quarter of a century ago (Pont, 1980), rather few new taxa of Muscidae have been described from the Afrotropical region, and this reflects the dearth of available taxonomic expertise rather than any lack of collecting activity in the region. The family Muscidae is a large, cosmopolitan family, and around 930 species are known from the Afrotropical region. Of the two genera discussed in this paper, Pyrellia Robineau-Desvoidy is a relatively small Old World genus of 22 species with a mainly Palaeotropical distribution, whilst Hydrotaea Robineau-Desvoidy, with some 135 species, is found in all regions, though it is most diverse in the Holarctic region. DESCRIPTION OF THE STUDY SITE The two new species described here were collected in the course of an investigation of the insect flower visitors to species of Acacia at Mpala Research Centre, Laikipia District, Kenya (37°52’E, 0°17’N; 1850 m).