Paradelia arctica Ringdahl 1933

14. Paradelia arctica (Ringdahl, 1933)

Figs. 78–81.

Hylemyia (Nupedia) intersecta var. arctica Ringdahl, 1933b: 16, 17.

Pseudonupedia arctica (Ringdahl); Ringdahl 1959: 293.

Pseudonupedia intersecta arctica (Ringdahl); Hennig 1972: 439, plate figs. 703, 712. Paradelia arctica (Ringdahl); Griffiths 1987: 800, figs. 956, 959, 964.

For further references and synonymy see Hennig (1972: 439) and Griffiths (1987: 800).

Taxonomic remarks. The present taxon was earlier synonymized with the widespread, variable P. intersecta, but Griffiths (1987) concluded, based on a morphometric study of the outer lamellae of male sternite V, that two distinct species are involved.

Description. In most respects agreeing closely with P. intersecta, but differs as follows:

Smaller, wing length 2.8–4.2mm vs. 3.6–5.1mm. Calyptrae invariably whitish, much paler than darkly infuscated wing base. Knob of haltere brownish infuscated. Arista short, thickened on more than basal third, very short-pubescent.

Male. Parafrontals at narrowest part of frons separated by linear frontal vitta. Outer lamellae of sternite V (Figs. 78, 79) with a lower length/width ratio. Hypopygium (Figs. 80, 81) rather inseparable from that of P. intersecta.

Female. Head and body darker, olive grey to olive brown dusted. Dark brown mesonotal stripes broader and three in number. Knob of haltere infuscated with brown.

Material examined. NORWAY [ZMUC]: from high altitude sites (> 1000m) in the provinces of Hedmark (north), Oppland (north) and Sør-Trøndelag (inner). SWEDEN [MZLU]: only from the northern provinces Lule Lappmark and Torne Lappmark.

Numerous specimens further seen from all faunal districts of Greenland (Michelsen 2006b).

Distribution. Apparently, P. arctica replaces P. intersecta above the tree line in all arctic and elevated northern landmasses of Eurasia and North America, but data are currently lacking for many parts of the Palaearctic Region including Russia.