Riidiger Wagner and Paul L.Th. Beuk. Diagnosis. Dixidae (meniscus ... Cuppen (1979, 1980), Cuppen & Moller Pillot. (1978), Van Dael (1982), Higler et al.
Riidiger Wagner and Paul L.Th. Beuk
Diagnosis. Dixidae (meniscus midges) are medium-sized (less than 5.0 mm), yellow-brown to grey culicoid Nematocera. Head with dichoptic compound eyes; ocelli absent; antennae elongate, 16-segmented. Thorax with colour patterns of yellow and brown stripes on scutum and pleurae. Wing translucent and without scales; veins with a radial and medial fork. Legs elongate, fore and mid tibiae with short spurs; claws simple, empodium small, no pulvilli. Abdomen elongate greyish brown. Male genitalia rotated by torsion of segments 5-8; shape of gonocoxite and gonostyles specific. Lateral and ventral view of female terminalia specific. The lack of scales on the wings and non-funtional mouthparts are distinctive features. Larvae eucephalic, head non-retractile and heavily sclerotized. Ventral side of the abdominal segments with ambulatory combs, dorsal sides of some species with 'crowns' of setae. Terminal complex covers a pair of open spiracles. Shape and numbers of crowns, combs and the terminal complex allows the distinction of species groups; species distinction is more difficult, but sometimes possible, in pupae almost impossible.
In
Biology. Larvae are restricted to the edge of water. They rest in a very characteristic U-shaped position at the water meniscus or just above the waterline on emergent structures. Dixa larvae prefer running waters; Dixella larvae predominate on stagnant waters. Pupae also rest in a U-shaped position on the banks. Several generations seem to develop in a year. On springs often a spring and an autumn generation are found. Adults are bad flyers. Females deposit greyish, disk-shaped eggmasses at the water's edge. General references. Disney (1999b [keys, ecology]), Peters (1981 [general, keys to genera]), Rozkosny (1990 [catalogue]), Wagner (1997b [general, keys to genera]). References to Dutch fauna. Cuppen (1979, 1980), Cuppen & Moller Pillot (1978), Van Dael (1982), Higler et al. (1981), Krebs (1982), De Meijere (1950a), Mol (1984), Popma (1982), Rozkosny (1990), Van der Wulp & De Meijere (1898). NL: 14
B: 11
D: 16
UK: 15
World: 400
DIXIDAE DIXA
Meigen, 1818
dilatata Strobl, 1900 maculata Meigen, 1818
added by Cuppen (1979: tab. 11) provisionally added by De Meijere (1950a: 1); confirmed by Van Dael (1982: 26) and Popma (1982: 99, bijl. V)
101
Family
Dixidae
nubilipennis Curtis, 1832 added by Higler et al. (1981: 18) puberula Loew, 1849 = maculata Meigen, 1818: misident. sensu Van der Wulp & De Meijere, 1898 Dyar & Shannon, 1924 aestivalis (Meigen, 1818) amphibia (De Geer, 1776) aprilina (Meigen, 1818) attica (Pandazis, 1933) autumnalis (Meigen, 1838) filicornis (Edwards, 1926) martinii (Deus, 1934) nigra (Staeger, 1840) obscura (Loew, 1849) serotina (Meigen, 1818)
DIXELLA
102
added by Cuppen (1979: tab. 11) added by Cuppen (1980: 36) added by Cuppen (1980: 36, 103, 111) added by Cuppen & Moller Pillot (1978: 19) added by Van Dael (1982: 26)
