Aleiodes arcticus (Thomson, 1892)

van Achterberg, Cornelis & Shaw, Mark R., 2016, Revision of the western Palaearctic species of Aleiodes Wesmael (Hymenoptera, Braconidae, Rogadinae). Part 1: Introduction, key to species groups, outlying distinctive species, and revisionary notes on some further species, ZooKeys 639, pp. 1-164 : 43-47

Aleiodes arcticus (Thomson, 1892) Figs 63-64, 65-75

Rogas arcticus Thomson, 1892: 1679; Tobias 1986: 83 (transl.: 138) (examined).

Rhogas arcticus ; Fahringer 1932: 285.

Aleiodes arcticus ; Shenefelt 1975: 1165-1166; Papp 1985a: 155 (lectotype designation), 1991: 96; Belokobylskij et al. 2003: 398.

Type material.

Lectotype, ♀ (ZIL), “Lpl” [= Lapland, North Sweden]).

Additional material.

3 ♀, 2 ♂ (G. Várkonyi personal coll., NMS) Finland, Ks. Salla 752.61, Värriö H, ex Pygmaena fusca , collection dates (of host larva) between 15.vi and 28.vi.1995, G. Várkonyi; 1 ♂ (G. Várkonyi personal coll.) Finland: Ks. Salla 752.61 Värriö H 21.vi.1995, G. Várkonyi; 1 ♀ (BMNH) Finland, Kuusano, Mäntytunturi, on snow, 29.vi.1935, G.J. Kerrich; 1 ♂ (NMS) S. Norway, Jotunheimen, Giendersheim, 1000-1500 m, 7.vii.[1966], J.E. & R.B. Benson; 2 ♂ (BMNH) S. Norway, Buskerud Fylke Geilo, 1000-1100 m, 16-24.vi.1965, J.E. & R.B. Benson; 1 ♂ (RMNH) Norway, Oppdal, Kongsvoll, Vestbekken, 28.vi.1978, J.O. Solem; 1 ♀ (BMNH) Sweden, Torne Lappmark, Tornehamn, 4.vii.1954, J.E. & R. B. Benson; 1 ♀, 1 ♂ (BMNH, NMS) Switzerland, Grisons, Müstairtal, Funt da S. Charl, 2400 m, 9.vi 1960 and 3.vii.1960, J.E. & R.B. Benson; 1 ♂ (BMNH) Switzerland, Grisons, Engadine National Park, 2380 m, 1.vii.1960, J.E. & R.B. Benson; 1 ♂ (BMNH) Switzerland, Valais, Arolla, 8000 ft, 9.vii.1935, J.E. & R.B. Benson; 1 ♂ (BMNH) Switzerland, Valais, near Verbier, 8000-8500 ft, 27.vi.1959, J.E. & R.B. Benson.

Biology.

This boreoalpine species is univoltine, passing the winter as a mummy. The only known host is the ennomine ( Macariini ) geometrid Pygmaena fusca (Thunberg) (5:1; G. Várkonyi /Finland), which feeds on Empetrum and Vaccinium (G. Várkonyi personal communication) and probably occurs throughout the range of the parasitoid. The small mummy (Fig. 64) is short, broad and dorsally elevated.

Diagnosis.

Maximum width of hypoclypeal depression 0.3-0.4 × minimum width of face (Fig. 70); OOL 1.9 × diameter of posterior ocellus; mesoscutum, orbita and malar space black; precoxal sulcus largely granulate; trochanters, trochantelli and pterostigma largely black(ish); mesoscutum without a longitudinal carina on mesoscutum medio-posteriorly; apical half of marginal cell of hind wing parallel-sided or slightly widened; vein M+CU1 of fore wing apically at about same level as vein 2-CU1 (Fig. 65); vein r of fore wing 0.6-0.9 × vein 3-SR (Figs 63, 65); vein 1-SR of fore wing linear with vein 1-M (Fig. 65); all femora and tibiae reddish or yellowish brown; fore and hind femora moderately stout (Figs 68-69); fourth metasomal tergite curved posteriorly in dorsal view (Fig. 67), lateral crease distinct and following tergites more or less retracted; length of fore wing 3.4-3.9 mm.

Description.

Redescribed ♀ (BMNH) from Müstairtal (Switzerland), length of fore wing 3.7 mm, of body 4.6 mm.

Head. Antennal segments 40, length of antenna as long as fore wing, its subapical segments about 1.7 × as long as wide; frons mainly superficially granulate and with some rugulae anteriorly, weakly shiny; OOL 1.9 × diameter of posterior ocellus and granulate as vertex, with satin sheen; clypeus moderately convex, narrow and coriaceous; ventral margin of clypeus thick and depressed (Fig. 70); width of hypoclypeal depression 0.3 × minimum width of face (Fig. 70) and face mainly coriaceous with some rugulae dorsally and long setae; length of eye 1.1 × temple in dorsal view and temple subparallel-sided behind eye; occiput behind stemmaticum granulate and occipital carina absent ventrally and narrowly interrupted dorsally; clypeus below lower level of eyes (Fig. 70); length of malar space 0.5 × height of eye in lateral view; eyes somewhat protruding (Figs 70-72).

Mesosoma. Mesoscutal lobes largely granulate-coriaceous, matt and medio-posteriorly rugose, middle lobe without a longitudinal carina; notauli narrow, shallow and very finely crenulate; prepectal carina narrow lamelliform medio-ventrally, not reaching anterior border of mesopleuron; precoxal area of mesopleuron granulate; mesopleuron above precoxal area (except large smooth and shiny speculum) granulate, but dorsally finely rugose; medially metapleuron granulate and with some rugae, rather shiny; mesosternal sulcus narrow and rather deep, with longitudinal carina posteriorly; mesosternum rounded posteriorly; scutellum moderately convex, mainly granulate and largely non-carinate laterally; propodeum rather directly lowered posteriorly and granulate-rugose, median carina complete, without tubercles.

Wings. Fore wing: r 0.7 × 3-SR (Fig. 65); 1-CU1 subhorizontal, 0.1 × as long as 2-CU1; r-m 0.9 × 2-SR, and 0.8 × 3-SR; second submarginal cell rather small (Fig. 65); vein M+CU1 of fore wing apically at about same level as vein 2-CU1 (Fig. 65); vein 1-SR of fore wing linear with vein 1-M; cu-a subvertical, not parallel with CU1b, straight; 1-M nearly straight posteriorly. Hind wing: apical half of marginal cell slightly widened apically (Fig. 65); 2-SC+R short and longitudinal; m-cu present, pigmented.

Legs. Tarsal claws setose; hind coxa granulate-coriaceous, with satin sheen; hind trochantellus twice longer ventrally than wide; length of fore and hind femora 5.5 and 4.0 × their width, respectively (Figs 68-69); inner apex of hind tibia without comb; length of inner hind spur 0.4 × hind basitarsus.

Metasoma. First tergite 0.7 × as long as wide posteriorly, convex and latero-posteriorly non-lamelliform; first–second tergites finely and densely irregularly rugulose and with median carina (Fig. 67); medio-basal area of second tergite absent; second suture narrow, deep and finely crenulate; third tergite with median carina (except posteriorly), third–fourth tergites very finely rugulose-coriaceous; fourth tergite convex medially and apically; fourth tergite with sharp lateral crease; remainder of metasoma largely retracted; ovipositor sheath truncate apically and moderately setose.

Colour. Black (including coxae); palpi basally, tegulae, pterostigma, veins, trochanters and trochantelli dark brown; remainder of palpi and legs yellowish brown; wing membrane slightly infuscate.

Variation. Antennal segments of ♀ 39(1), 40(2), 41(0), 42(1), of ♂ 38(1), 39(2), 40(2); length of fore wing 3.4-3.7 mm; maximum width of hypoclypeal depression 0.3-0.4 × minimum width of face; vein r of fore wing 0.6-0.8 × vein 3-SR; median carina of middle mesoscutal lobe absent or weakly indicated; legs (except basally) vary from largely yellowish brown to largely dark brown with base of hind femur and tibiae paler than remainder of legs; second submarginal cell of fore wing rather variable in shape, but some are as trapezoidal as in Aleiodes reticulatus , with which this species is closely related.

Notes.

Recorded as British by Morley (1916), but in error as the three specimens (CMIM) on which the record was based have been examined and prove to belong to Aleiodes similis (Curtis). A series from Austria (Hohe Tauern, various altitudes ca 2300 m (MSC)) and also specimens from similar elevations in Switzerland (BMNH) have a habitus similar to Aleiodes arcticus but differ considerably from our concept of Aleiodes arcticus in being more coarsely rugose (including mesopleuron), the head being longer and behind the eyes narrower, outer orbits brownish (i. e. lighter in colour than the rest of the temple), antennal segments longer, second cubital cell usually longer. It is considered to be a different species placeable in the bicolor -group, but with apical tergites retracted and hind coxa short.