The American Species of the Genus Dictya Meigen (Diptera, Sciomyzidae)

Abstract

Until Curran (1932) published his review of the American species of Dictya, with seven species, the genus had been universally considered to include but one species, umbrarum (Linnaeus), widely distributed in both the palaearctic and nearctic regions. Only Loew in describing Tetanocera pictipes in 1859 had even a suspicion that more than one species existed. Even he stated (as translated in Monogr. No. Amer. Dipt. 1:112, 1862): “A series of specimens enables me to compare this species with the closely allied European Tet. umbrarum Linn. The resemblance of both is so great that I cannot but suspect that they are identical. No difference of structure existing between them, the larger size and browner color of Tet. pictipes alone afford a constant distinguishing character. Future observations will perhaps enable us to decide whether Tet. pictipes is merely a climatic variety of Tet. umbrarum or a different species.” And Osten-Sacken in a footnote to Loew‗s remarks was still puzzled when he examined North American material which agreed in size and color with European specimens. Cresson (1920) stated: “On comparing our material with some specimens from Europe, I cannot detect any differential characters of specific or even varietal importance.”