Crumomyia pedestris (Meigen, 1830)

Roháček, Jindřich, 2012, Wing polymorphism in European species of Sphaeroceridae (Diptera), Acta Entomologica Musei Nationalis Pragae 52 (2), pp. 535-558 : 539

1. Crumomyia pedestris (Meigen, 1830)

( Figs. 1 , 5–11 )

Material examined. More than 890 specimens (483 JJ 410 ♀♀, with only 7 JJ 3 ♀♀ macropterous, 2 JJ 2 ♀♀ submacropterous and the rest brachypterous to almost micropterous) from Czech Republic, Slovakia – localities listed by ROHÁČEK (1975b, 1980, 1986, 1991, 1999, 2011) and ROHÁČEK & BARTÁK (2001). Additional localities: CZECH REPUBLIC: MORAVIA: Hrubý Jeseník Mts. – Rejvíz res. ( V. Kavalcová leg.). SLOVAKIA: Velká Fatra Mts. – Rakša res. (J. Roháček leg.).

The species is usually strongly brachypterous to almost micropterous ( Figs. 1 , 7–10 ).Already GUIBÉ (1939) obtained macropterous specimens during his breeding experiments but suggested that they are less viable. On the basis of his results RICHARDS (1951) stated that only the dominant micropterous homozygotes and heterozygotes occur in the wild. However, since 1975 the macropterous specimens were also found in the field several times ( ROHÁČEK 1975b, 1991; PAPP 1976). Originally ( ROHÁČEK 1975b) I considered the macropterous and submacropterous forms ( Figs. 5, 6 ) to be atavistic specimens very rarely occurring among the usual micropterous specimens in natural populations. This opinion proved to be incorrect in the light of recent findings. The macropterous forms ( Fig. 5 ) seem to occur in only some populations, particularly in those living in drier habitats, e.g. in runs of small mammals. However, the preferred habitats of Crumomyia pedestris are very damp meadows and boggy alder forests where its larvae develop in dead snails. In my opinion the wing polymorphism and, subsequently, the now prevailing strong brachyptery evolved in consequence of the adaptation of this species to the extreme humidity of its preferred habitat niche where long wings are strongly disadvantageous.

Figures

Figs. 1–4. Wing polymorphic Sphaeroceridae. 1 – Crumomyia pedestris (Meigen, 1830), brachypterous male, body length 3.4 mm (Czech Republic: Úvalenské louky res. nr. Krnov); 2 – Pteremis fenestralis (Fallén, 1820), brachypterous male, body length 1.5 mm (Czech Republic: Jizerské hory Mts.– Jizerka); 3–4 – Pullimosina (Pullimosina) meijerei (Duda, 1918): 3 – macropterous female, body length 1.6 mm (Slovakia: Muránska planina Mts. – Šarkanica res.); 4 – male with ambiguous wings, body length 1.45 mm (Slovakia: Muránska planina Mts. – Bobačka cave env.). Photos by J. Roháček.

Figs. 5–11. Crumomyia pedestris (Meigen, 1830), wings. 5 – macropterous female; 6 – submacropterous female (both Slovakia: Tatranská Kotlina – Šarpanec); 7 – large brachypterous female; 8 – medium brachypterous female; 9 – strongly brachypterous female; 10 – almost micropterous male (all Czech Republic: Úvalenské louky res. nr. Krnov); 11 – macropterous male with additional dm-cu cross-vein (Slovakia: Tatranská Kotlina – Šarpanec). Scale: 0.5 mm. Photo by J. Roháček.