African ZoologyThe trematode Paraconcinnum leirsi n.sp. (Dicrocoeliidae) is described from two rodent species, the African gerbil, Gerbilliscus vicinus, and the spiny mouse, Acomys spinosissimus, from Tanzania. It differs from the description of P. hylomisci found in the Stella wood mouse, Hylomyscus stella, in the Democratic Republic of Congo. Molecular studies were performed by sequencing the near complete 18S rDNA gene of the fluke to assess its phylogenetic position within the Dicrocoeliidae. The resulting estimate of evolutionary divergence between the fluke and other dicrocoeliids was 1.60 ± 0.22% base differences per site. The phylogenetic analysis shows that the fluke is a new species within Dicrocoeliidae falling in a cluster with the genera Corrigia, Lyperosomum, Concinnum and Eurytrema although phylogenetic relationships among these genera are not well resolved. This is the first dicrocoeliid reported from rodents in eastern Africa.