Wing polymorphism in European species of Sphaeroceridae (Diptera)

Abstract: The wing polymorphism is described in 8 European species of Sphaeroceridae (Diptera), viz. Crumomyia pedestris (Meigen, 1830), Phthitia spinosa (Collin, 1930), Pteremis fenestralis (Fallén, 1820), Pullimosina meijerei (Duda, 1918), Puncticorpus cribratum (Villeneuve, 1918), Spelobia manicata (Richards, 1927), Spelobia pseudonivalis (Dahl, 1909) and Terrilimosina corrivalis (Villeneuve, 1918). These cases seem to belong to three types of alary polymorphism: i) species with separate macropterous and brachypterous forms – Crumomyia pedestris, Pteremis fenestralis, Pullimosina meijerei; ii) species with a continual series of wing forms ranging from brachypterous to macropterous – Puncticorpus cribratum, Spelobia pseudonivalis, Terrilimosina corrivalis; iii) similar to the foregoing type but with only slightly reduced wing in the brachypterous form – Phthitia spinosa, Spelobia manicata. The variability of venation of wing polymorphic and brachypterous species of the West-Palaearctic species of Sphaeroceridae was examined and general trends in the reduction of veins during evolution are defined. These trends are found to be different in Copromyzinae (C. pedestris) and Limosininae (all other species) where 6 successive stages of reduction are recognized. The first case of a specimen (of Pullimosina meijerei) with unevenly developed wings (one normal, other reduced) is described in Sphaeroceridae. Causes of the origin of wing polymorphism, variability of wing polymorphic populations depending on geographical and climatic factors, importance of wing polymorphism in the evolution of brachypterous and apterous species and the probable genetic background of wing polymorphism in European species are discussed. Pullimosina (Pullimosina) meijerei is recorded for the first time from the Svalbard Islands (Norway) and Terrilimosina corrivalis is newly recorded from Romania.

Key words: Diptera, Sphaeroceridae, wing polymorphism, evolution, wing venation, variability, Europe, Palaearctic Region