Bibio siebkei Mik, 1887

Skartveit, John, 2010, The larvae of European Bibioninae (Diptera, Bibionidae), Journal of Natural History 36 (4), pp. 449-485 : 473

Bibio siebkei Mik, 1887 (®gures 68±74)

Larva not previously described. Greyish white, with a slight silky lustre, especially on pleura.

Head. Reddish brown. Head capsule width. First instar 0.24±0.26 mm (n = 7). Second instar 0.29±0.33 mm (n = 45). Third instar 0.36 mm (n = 1). Fourth instar 0.49 mm (n = 1). Fifth instar 0.56±0.67 mm (n = 12). Sixth instar 0.73±0.85 mm (n = 7). Seventh instar 0.88±1.05 mm (n = 19). Labrum (®gure 68) with a pair of short, peg-like setae on transverse carina. Mandible (®gure 69) with four teeth. Maxilla (®gure 70): comb with approximately six teeth, six to nine round`holes’ and pointed spines on inner surface, maxillary palp with series of three to ®ve spines on membraneous area. Prementum (®gure 70) with prominent anterior corners and 8±12 sensillae. Stemmata absent in the specimens examined. Antenna diameter ca 50 m m with ®ve or six small and short sensillae.

Body. Processes rather short and pointed. Dorsal processes arranged in three pairs, the outermost processes slightly longer than the four central processes. Postspiracular processes as long as twice spiracle diameter, located two spiracle diameters behind spiracle. Processes on ninth abdominal segment located some distance from hind edge of segment, approximately 3/5 as long as segment. Cuticle: outline of scales rather diVuse, spines appear to be situated directly on the cuticle. Prothorax (®gure 71) scales just behind head small with one slender spine. Area in front of ®rst process row: scales 30±40 m m wide, oval with two to ®ve pointed spines approximately as long as scales. The most anterior smaller scales located between process rows. Transverse bands with spineless scales rather narrow. Mesothorax, metathorax (®gure 72) and ®rst abdominal segments: larger scales mostly with three or four spines, second to seventh abdominal segments (®gure 73) scales with one to three spines, average spine number decreasing caudad, eighth abdominal segment: scales with one very stout and blunt spine. Ninth abdominal segment (®gure 74) scales without spines but some with blunt pegs, outline of scales very weakly de®ned, area posterior to processes with scales carrying short pegs. Ventral surface of ninth abdominal segment covered with scales with slender, single spines. Spiracles projecting approximately one-half spiracle diameter from cuticle surface.

Distribution. Holarctic. The Alps, Scandinavian mountains, Northern Russia including Novaya Zemlya, North America from Alaska and BaYn Island to Colorado ( Fitzgerald and Skartveit, 1997). Con®ned to high altitudes and subarctic areas.

Ecology. In Scandinavia, found mainly on lichen heaths and barren mountain slopes in the lower and mid-alpine zones. Larvae probably feed mostly on lichens. Life cycle takes 2 years (Skartveit and Solhùy, 1997).

Material. Norway, HOI: Eidfjord , 1.4 km SE Stigstuv tourist hut, lichen heath 1225 m a.s.l. T. Solhùy leg., 333 larvae ( ZMUB) .