Tetragoneura obirata Plassmann 1990

3. Tetragoneura obirata Plassmann, 1990

(Fig. 2: C, D)

Tetragoneura obirata Plassmann, 1990: 62

= Tetragoneura sibirica Maximova, 2001: 140 syn. n.

Holotype: SWEDEN: 3, Norrbyn, 11.9–20.9 1986, (ZSM, K.Müller leg.). Specimen, initially kept in alcohol, was sent to us by P.Chandler as a slide preparation. Parts of the body and genitalia are mounted in DMHF (Dimethyl Hydantoin-Formaldehyde Resin) separately on one slide.

Other material examined. FINLAND: 1 3, Lkw: Muonio, Ounas–Pallastunturi NP, (METLA, J. Jakovlev leg.) 15.8– 15.9.2006; 1 3, Ok: Kuhmo, Riihisuo, 12.9.– 07.10.1997 (FRIP, Kuussaari leg.); 3 3, Kb: Ilomantsi, Kotavaara, 08.9.– 29.9.1998 (METLA,Tietäväinen leg); 1 3, Kb: Ilomantsi, Tapionaho, 18.8.– 22.8.1994, (FRIP, Polevoi leg). RUSSIA, KARELIA: 2 3, Kon: Kivach, 06.9.– 20.10.1990 (FRIP, Polevoi leg); 4 3, Kon: Kivach, 0 2.9.2002 (Polevoi leg); 1 3, Kb: Tolvojärvi, 07.9.– 13.09.1999 (FRIP, Tietäväinen leg.).

Description. Male (n=5).

Head dark-brown to black, grey dusted, covered with pale hairs and setae. Lateral ocellus separated from eye margin by distance of 3.4–4.5 times its own diameter. Palpus yellowish-brown. Clypeus dark-brown to black clothed with short hairs. Antenna brown, pedicel yellow to brown, base of first flagellomere yellow to yellowishbrown. Fifth flagellomere 1.2–1.4 times as long as wide. Pedicel with long seta apically. Eyes densely covered with minute hairs.

Thorax. Scutum and scutellum shining dark-brown to black. Scutum clothed with evenly distributed pale hairs and longer bristles. Pleurae dark-brown, thinly grey dusted. Antepronotum and proepisternum with pale hairs and bristles, the rest of the pleurae bare.

Wing length 2.91–3.19 [mean value 3.09] mm. Wing hyaline, faintly infuscated in distal 1/3. Veins yellow, costa and radius brownish. C extending slightly beyond the middle of distance between R5 and M1. Sc short, ending free. R4 developed, forming elongated small cell (about 5–7 times longer than wide). R1 2.8–4.1 times as long as ta. Stem of M-fork about 1.8–2.6 times as long as ta. Base of CuA-fork lies under or slightly distal to the base of ta. Macrotrichia well developed on radial viens, distal 2/3–1/2 of ta, distal 3/4 of M1, distal 7/8 of M2, branches and stem of CuA-fork (with exception of basal part) and A1. Haltere yellow.

Legs yellow. Trochanters darkened ventrally. Hind femur darkened in apical 1/3–1/2. Front tibia with 0–1 pd and 2–4 small pv. Mid tibia with 3–5 ad 2–5 pd, 4–5 p and 5–9 pv. Hind tibia with 12–15 ad, 12–16 pd and 7– 9 p. Ratio of tibia to first tarsomere for front, mid and hind legs: 1.39–1.51 [1.45]; 1.47–1.59 [1.53]; 1.87–2.06 [1.96]. Front tibia with one spur, mid tibia with two spurs (av spur about 2/3 as long as pv spur), hind tibia with two spurs (av spur is about 3/4 as long as pv spur). Sensory organ on t2 not developed.

Abdomen dark-brown, covered with pale hairs. Terminalia (Fig. 2: C, D) brown. Gonocoxites with median cleft, reaching the middle of their height, and rounded submedian lobes covered with short hairs. Gonostylus divided into two lobes apically, ventral lobe bearing a row of setae. Tergite 9 narrow transverse, cerci triangular with one strong seta at apex.

Female unknown

Remarks. Type specimen of T.obirata (body and terminalia preserved in alcohol) is considerably damaged. Nevertheless, the terminalia, though being slightly contracted, allow unambiguous identification. Identity of T.sibirica to T.obirata was confirmed by Y. Maximova (pers. comm.). Three closely related species with bifid gonostylus (ardeiceps group) are known from Patagonia (Duret 1989).

Distribution. Euro-Siberian; with scattered records only from Finland, Sweden, North-West Russia (Kjaerandsen et al. 2007) and West Siberia (Maximova 2001).

Biology. Collected with Malaise trap and sweep netting mostly in spruce dominated forests.