Platycheirus transbaikalicus, Barkalov & Nielsen & V. & R., 2009

Barkalov, Anatolii V., Nielsen, Tore R., V., A. & R., T., 2009, New material of Central Palaearctic Platycheirus (Diptera, Syrphidae) with description of three new species, Norwegian Journal of Entomology 56, pp. 1-8 : 5-6

Platycheirus transbaikalicus sp. n.

Figures 5A–D

Holotype: Russia, ♂ “Transbaikalia Sokhondo res. Agutsa 14.06.1991 B.P. Zacharov ”. The area is some 250 km south-east of lake Baikal. The holotype is kept in ZMN.

Diagnosis and comparison with related species: the new species belongs to the ambiguus -group ( Vockeroth 1990) and has great resemblance to P. transfugus (Zetterstedt, 1838) . Both species have a shiny metallic mesonotum, tergites 2–4 with oblique orange spots and fore tibia shorthaired, without long setae postero-laterally. The Platycheirus transbaikalicus male differs from male P. transfugus ( Figures 5E–G ) in a longer 3 rd antennal joint, a less swollen frons, eye angle about 90º (105–110º in transfugus ), face narrower and lower part of face more nosy. Fore femur behind with pin like setae (soft hairs in transfugus ), and tergites 2–3 of the abdomen narrower. The yellow spots on tergite 3 are close to front margin of tergite (less so in transfugus ).

Description

Male

Head. Figure 5A–B . Eye angle about 90°. Ocellar triangle bluish black with white and a few black hairs. Frons, face, genae and occiput silvery white dusted. Frons black haired, face, genae and occiput white haired. Antennae: 1 st and 2 nd segments brownish black, 3 rd segment about 1.6 times longer than wide; dark brown, reddish below at extreme base. Arista brown.

Thorax. Figure 5C . Scutum, scutellum and pleurae shining metallic black, only with light greyish dusting, white haired. – Wing: veins greyish brown, on basal half light brown. Stigma yellow. Calypter light greyish yellow, the rim orange yellow. Haltere light orange yellow. – Legs: fore femur orange yellow, posterioly with a row of thin black, blunt ending setae on apical 2/3, white hairs towards femur base. Fore tibia orange yellow, darkened on apical 1/3. Tibia mainly short haired, laterally only with two short white bristly hairs after the middle of left tibia. Tarsus of fore legs greyish brown. Mid and hind femur brownish black, yellow at base and apex. Mid tibia dark yellow with a black ring near the base, hind tibia dark greyish on apical 2/3. Tarsi of mid and hind legs dark grey.

Abdomen. Tergites 1 and 5, and terminalia shining black. Tergites 2–4 dull black, each with a couple of oblique orange spots, all tergites white haired. Sternites light greyish yellow, white haired.

Body length (from frons till tip of abdomen) 7.4 mm, wing length 5.6 mm.

Female: unknown.

Etymology. The species name reflects the mountainous region to the east of Lake Baikal from where the species has been described.

Ecology: unknown.

Figures

Figure 5. Platycheirus transbaikalicus sp. n., male holotype: A–D. A: head, lateral view; B: antenna; C: fore femur; D: abdomen, tergites 1–2. Platycheirus transfugus (Zetterstedt): E–G: E: antenna; F: abdomen, tergites 1–2; G: fore femur.