A worldwide review of the genus Arganthomyza Roháček, with revision of the Nearctic species (Diptera: Anthomyzidae).

World representatives of the genus Arganthomyza Roháček, 2009 (Diptera, Anthomyzidae) are reviewed, keyed and their relationships are discussed on the basis of a phylogenetic analysis of morphological characters. The Nearctic species of Arganthomyza are revised, described and illustrated, and first data about their biology and distribution are given. Five new species, A. carbo sp. n. (Canada, USA), A. acuticuspis sp. n. (USA), A. bivittata sp. n. (Canada, USA), A. duplex sp. n. (Canada, USA) and A. disjuncta sp. n. (Canada, USA) are described and A. socculata (Zetterstedt, 1847) is newly recorded from the Nearctic Region (USA: Alaska). Based on the phylogenetic analysis, four main clades/species groups are recognized within Arganthomyza, represented by the following species: A. barbarista Roháček, 2009 (A. barbarista group); A. setiplanta (Roháček, 1987), A. versitheca Roháček, 2009 and A. carbo sp. n. (A. setiplanta group); A. acuticuspis sp. n., A. bivittata sp. n. and A. duplex sp. n. (A. duplex group); A. disjuncta sp. n. and A. socculata (Zetterstedt) (A. socculata group). Considering the contemporary distribution and relationships of Arganthomyza species, it is hypothesized that the A. barbarista group and A. setiplanta group originated in East Asia while the A. duplex group and the A. socculata group each has its origin in the Nearctic Region.