Homotropus dimidiatus

Homotropus dimidiatus (Schrank 1802, Ichneumon) (comb. nov.)

Bassus planus Desvignes 1862

Homotropus crassicrus Thomson 1890 (syn. nov.)

Homotropus nudus Dasch 1964a (syn. nov.)

Diagnosis. Fore wing length 4.3–6.3 mm. Antenna of both sexes with 20 to 21 flagellomeres; in females, apical flagellomeres with ventral surface covered by short, thick bristles and devoid of multiporous plate sensilla, in males with narrow, long tyloids 7 to 14/15. Face very strongly coriaceous but distinctly punctate centrally. Clypeus weakly excised, with lobes rounded. Mesopleuron strongly coriaceous and matt over entire surface, with some weak punctures along anterior margin. Mesoscutum strongly coriaceous and densely punctate. Hind coxa with hind surface strongly coriaceous and matt. Fore wing areolet closed, vein 3rs-m usually unpigmented. Propodeum with at most pleural carina and lateral longitudinal carinae indicated, coriaceous, smoother on petiolar area. Female metasoma gradually tapered posterior to fourth segment. First tergite without median dorsal carinae, without longitudinal wrinkles, 1.0–1.1 times as long as wide in females, 1.0– 1.4 in males; second tergite basally evenly coriaceous, 0.6–0.7 times as long as wide in females, 0.75–0.85 in males, second tergite 0.86–1.1 times as long as first tergite; spiracle of third tergite on dorsal part, above lateral fold.

Colouration of females. Antenna brown. Head and mesosoma black, sometimes with yellow on central face patch, separated from yellow on clypeus, yellow on mouthparts, hind corner of pronotum, tegula, subtegular ridge, shoulder mark, entire mesepimeron, scutellum laterally and apically. Legs orange, coxae usually orange, fore coxa dark, at least basally, sometimes all coxae dark basally, femora orange, hind tibia white with a dark apex and sometimes subbasal marking, often also dark on outer side, hind tarsus dark. Metasoma black.

Colouration of males. As in females but additionally with lower mesopleuron and mesosternum mostly yellow or at least with a broad yellow stripe, hind tibia with outer side almost always brown. Tergite 3 usually with two large yellow basal spots.

Material examined. Lectotype of Bassus planus Desvignes: United Kingdom. 1♂, at BMNH (very incomplete specimen, metasoma and hind legs missing; interpretation thus somewhat uncertain). Lectotype of Homotropus crassicrus Thomson: Sweden, Öland. 1♀, at ZIL. Holotype of Homotropus nudus Dasch, examined by Erich Diller (personal communication).

New for Austria: Tirol, Zillertaler Alpen, Stillupp-Kees, 2700m, leg. E.Jäckh, 16.VIII.1926. 1♀, at ZSM. New for Switzerland: Valais, Champéry, Col de Bretolet, 1920m, N46.143, E6.7968, VIII.1964. 1♀, at MZL.

Austria (1), Finland (2), Germany (4), Hungary (3), Iceland (1), Netherlands (1), Norway (2), Russia (1), Sweden (70), Switzerland (6), United Kingdom (50).

Distribution. Holarctic and Oriental.

Figures. Antenna ♀ (Fig. 5), habitus (Fig. 31 A), male terminal sclerites (Fig. 37 F).

Notes. The identity of Ichneumon dimidiatus Schrank is somewhat uncertain, as the type has been lost (Townes et al. 1961). The original description, though not very detailed, points to a male Homotropus with a dark outer side of the hind tibia, and later authors described the taxon accordingly (e.g. Morley 1906; Morley 1914; Schmiedeknecht 1926; Beirne 1941). In most collections examined, there are only male specimens under that species, the majority of which correspond to male Homotropus crassicrus Thomson. I here follow this interpretation of the name dimidiatus, which takes priority over H. crassicrus.