Pteremis fenestralis (Fallén, 1820)

Roháček, Jindřich, 2012, Wing polymorphism in European species of Sphaeroceridae (Diptera), Acta Entomologica Musei Nationalis Pragae 52 (2), pp. 535-558 : 540-546

4. Pteremis fenestralis (Fallén, 1820)

( Figs. 2 , 18–22 )

Material examined. About 1,000 specimens (378 JJ 630 ♀♀, with only 14 JJ 32 ♀♀ brachypterous, rest macropterous) from Czech Republic and Slovakia – localities listed by ROHÁČEK (1980, 1984, 1986, 1995, 2009 a, 2011), ROHÁČEK & BARTÁK (1999, 2001) and ROHÁČEK et al. (1998, 2005). Additional localities. FINLAND: Helsinki (L. Tiensuu, R. Frey leg.), Kyrkslätt ( R. Frey leg.), Muonio (Sahlberg, Palmén leg.), Kajana (Hellén leg.), all in Zoological Museum, Helsinki. GREAT BRITAIN: ENGLAND: Oxford, University park (J. Roháček leg.). AUSTRIA: Tyrol, Obergurgl Mt. (H. Troger leg.), Hohe Tauern, Badgastein (H. Stockner leg), in Zoologisches Institut, Universität Innsbruck. CZECH REPUBLIC (only examples of localities): BOHEMIA: Čistá u Sokolova (Dlabola leg.), Jelení u Karlových Var (Škaloudová leg.), Horská Kvilda, Ondřejov (M. Chvála, M. Barták leg.), Lipno nad Vltavou, Klášterec nr. Vimperk, Pěkná 2 km W, Doupovské hory – Lochotín (J. Roháček leg.), Žíšov – Doubí (J. Máca leg.), Praha – Holešovice, Praha – Šárka, Jíloviště, Úvaly, Kunice,Velké Popovice,Veltrusy, Struhařov, Sokoleč, Třebotov, Předhrádí, Vlkov nad Lužnicí (all M. Barták leg.), Hluboká nad Vltavou, Lešany (I. Kovář leg.), Jizerské hory Mts. – Jizerka, Bohdaneč (B. Mocek leg.), Malý Pěčín, Palupín u Strmilova (J. Roháček leg.). MORAVIA: Řásná u Telče, Třešť, Brno, Moravský kras – Mariánské údolí, Nedvědice, Vranovská přehrada – Cornštejn, Lednice, Moravičany, Kouty nad Desnou, Bělá pod Pradědem, Nýznerov, Vidnava, Úvalenské louky nr. Krnov, Opava, Chvalíkovice nr. Opava, Klokočov, Bílé Karpaty – Radějov, Moravskoslezské Beskydy Mts. – Tanečnica Mt. (J. Roháček leg), Moravskoslezské Beskydy Mts. – Muřinkový vrch Mt. (M. Barták leg.), deposited in coll. Národní muzeum, Praha; Slezské zemské muzeum, Opava; Muzeum Soběslav; Muzeum východních Čech; coll. M. Barták, Praha. SLOVA- KIA: Štúrovo, Hegyfarok, Bieľ, Pribylina (M. Barták leg.), Stankovany nr. Kraľovany, Vysoké Tatry Mts.– Štrbské pleso, Vysoké Tatry Mts.– Velická dolina, Regetovka nr. Bardejov (J. Roháček leg.), coll. Slezské zemské muzeum, Opava and coll. M. Barták, Praha. POLAND: E. Poland: Bondary, Bialowieża – Budy 2 km NE, Bialowieża 4 km S – Czerlon (J. Roháček leg.). ROMANIA: BANAT: Sfânta Elena 2.5 km NE (J. Roháček leg.). GREECE: PIERIA: Olympos Mts. – Karyá env. (J. Roháček leg.).

A typical wing polymorphic species ( HACKMAN 1964) but this phenomenon seems to be restricted only to North European and some, usually montane, Central European populations. The brachypterous form of P. fenestralis had long been considered a different species, Pteremis nivalis (Haliday, 1833) , and COLLIN (1956) was the first to recognize its conspecificity with P. fenestralis . Also Pteremis subabterus Frey, 1946 was found to be another short-winged form of this species ( HACKMAN 1964). The percentage of the brachypterous specimens clearly increases in more northern latitudes or higher altitudes ( ROHÁČEK 1975b). The venation of brachypterous forms strongly vary in some populations ( Figs. 19–22 ), which enabled speculation on the general trends in the modification of venation during the evolution of brachypterous species (see below). P. fenestralis chiefly lives in mosses, Sphagnum and grass tufts in wet open habitats as well as damp forests. It is common in mountains but rare in lowlands, particularly in southern Europe where the populations seem to be purely macropterous.

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.18–22. Pteremis fenestralis (Fallén, 1820), female wings. 18 – macropterous; 19 – atypical brachypterous with dm-cu present; 20 – typical brachypterous (= Borborus nivalis Haliday, 1833); 21 – brachypterous with terminal part of R2+3 lost; 22 – strongly brachypterous (all Czech Republic: Hrubý Jeseník Mts.– Rejvíz res.). Scale: 0.5 mm. Photo by J. Roháček.