Variation in the wings of adult flies has been used extensively to define various levels of taxonomic identity (families, genera, subgenera, species) throughout the Diptera. Among the crane flies, important characters lie in both wing morphology (shape and composition) and wing venation (arrangement of the wing veins).
Wing morphology
The shape and attributes of the crane fly wing offer characters that help to separate by species and genera. The general condition of the wing is a fully developted with with a compliment of veins. Exceptions to this rule include the apterous genus Chionea and in many species where the wing is occasionally reduced to a brachypterous state, as in Dactylolabis wodzickii Nowicki, Prionolabis rudimentus Alexander, and the two apterous subgenera of Dicranomyia, Peripheroptera and Zalusa. Such a brachypterous condition may occur in one or both sexes, or in populations of individual species (illustrated in Dienske, 1987).
Apart form the anal lobe of the wing the shape of the crane fly wing has not been extensively used for identification or classification. The wing base is characteristiclly narrow and petiolate in form, widening at the point of wing cell a2, also referred to as the anal lobe of the wing. A reduction of the anal lobe is common in subgenera of Dicranomyia and in the genus Thrypticomyia giving the wing a cunciform appearance.
The membranous area between wing veins additionally offers an additional valuable characteristic in the presence of macrotrichia in wing cells. Macrotrichia are strong setiformes arrising from distinct sockets place in the cells of the wing. The presence of macrotricia is largely species specific and variable through genera, but help to define at least Pilaria, Ula, and Ulamorpha.
The use of wing venation has been strongly used to define generic groupings, higher level intrafamiliar relationships, and define the evolutionary history of the group. This use of venation is largely due to the influence of Alexander (1927; 1929) and the importance he placed on wing venation. The interpretation of the wing field used here (Figs. 2 & 3), with some exceptions, is based on the Comstock and Needham system (1889-1899) but differs in the interpretation of the Subcostal, Radial, and Medial wing sectors.
Figure 1. Dorsal view of right wing of Limonia indigena Osten Sacken showing venation (veins: A1, A2: branches of anal veins; C: Costa; CuA: Anterior branch of Cubitus; CuA1, CuA2: Anterior branches of Cubitus; M: Media; R: Radius; R1+2: Anterior branch of Radius plus R2 posterior branch of Radius; R2: R2 posterior branch of Radius connecting Radial sector to Radius; R3, R4, R5: Posterior branches of Radius; RM: Radial-Medial crossvein; Rs: Radial sector; Sc: Subcosta. cells: a1, a1: Anal; bm: Basal Medial; br: Basal Radial; c: Costal; cua1:Anterior Cubital; cup: Posterior Cubital; dm: Discal Medial; m2, m3: Medial; r1, r2, r3, r4, r5: Radial; sc: Subcostal).
Figure 1. Dorsal view of right wing of Lipsothrix sylvia Alexander showing venation (veins: A1, A2: branches of anal veins; C: Costa; CuA: Anterior branch of Cubitus; CuA1, CuA2: Anterior branches of Cubitus; M: Media; R: Radius; R1+2: Anterior branch of Radius plus R2 posterior branch of Radius; R2: R2 posterior branch of Radius connecting Radial sector to Radius; R3, R4, R5: Posterior branches of Radius; RM: Radial-Medial crossvein; Rs: Radial sector; Sc: Subcosta. cells: a1, a1: Anal; bm: Basal Medial; br: Basal Radial; c: Costal; cua1:Anterior Cubital; cup: Posterior Cubital; dm: Discal Medial; m2, m3: Medial; r1, r2, r3, r4, r5: Radial; sc: Subcostal).
