Dilophus borealis Skartveit, 1993

Skartveit, John, 2010, The larvae of European Bibioninae (Diptera, Bibionidae), Journal of Natural History 36 (4), pp. 449-485 : 480-482

Dilophus borealis Skartveit, 1993 (®gures 98 ±104)

Larva not previously described. Whitish, body with quite short (indistinct) processes only on the terminal two segments. Total length not possible to measure in the available specimens but probably 7±8 mm full grown. Alcohol-conserved specimens tend to curve upwards. Mostly in alpine habitats.

Head. Head capsule width full-grown 0.61±0.81 mm (n =10), last-but-on e instar 0.50 mm (n = 1), second last-but-on e instar 0.31±0.35 mm (n = 13). Labrum as in ®gure 98. Mandible (®gure 99) with four teeth. Maxilla (®gure 100) mesally with one strong tooth, comb consisting of four teeth of which the lateral two are distinct, palp with approximately ten sensillae. Prementum (®gure 100) with six sensillae, median projection more prominent than front edges. Stemmata absent. Antenna somewhat elevated, diameter ca 25 m m with one large and several smaller sensillae.

Body. With processes only on the three last segments: four short dorsal processes in the hind end of the ninth abdominal (twelfth) segment, three pairs of short dorsal processes near the hind edge of the eighth abdominal (eleventh) segment and one pair of very short (wart-like) dorsolateral processes on the seventh abdominal (tenth) segment. Cuticular scales: triangular in lateral view, oval, prothorax (®gure 101) scales closely packed, 10±13 m m wide with three to six slender, pointed spines which are somewhat longer than scales, on metathorax (®gure 102) scales spaced by approximately one scale width, ca 10 m m wide, with two to four spines, ®rst abdominal segment scales mostly with two to three spines, fourth abdominal segment scales (®gure 103) 10±15 m m wide, with indistinct outline and one to three spines, ninth abdominal segment (®gure 104) scales approximately circular, diameter 10±15 m m with one to three short spines. Ventral surface of ninth abdominal segment with oval scales 7±10 m m wide with two to three spines. Spiracles protruding approximately one-half spiracle diameter from cuticle, weakly pigmented and sometimes hard to see, those on ninth abdominal segment with rather indistinct ecdysal scars.

Distribution. Scandinavia ( Skartveit, 1993), Finland ( Skartveit, 1999), Switzerland, France, Spain ( Skartveit and Haenni, 1997), northwestern Russia ( Nartshuk, 1995).

Ecology. Mainly a boreoalpine species, found from the subalpine zone and up to the upper part of the lower alpine zone. A few records exist from lowland localities in Scandinavia. Found mostly in meadows.

Material. Norway, HOI: Eidfjord , 1.1 km SSE Stigstuv tourist hut, dry meadow 1275 m a.s.l., 8 August 1972 11 larvae , 31 August 1972 13 larvae. Quick Trap, T. Solhùy leg. ( ZMUB) .