Platycheirus altotibeticus Nielsen, 2001

R. Nielsen, Tore & Romig, Thomas, 2010, Two new species of the genus Platycheirus Le Peletier & Serville, 1828 and a description of female P. altotibeticus Nielsen, 2001 (Diptera, Syrphidae) from China., Norwegian Journal of Entomology 57, pp. 1-8 : 6-8

Platycheirus altotibeticus Nielsen, 2001

Material examined: 3♂♂, 1♀ CHINA, NW Sichuan vicinity of Tuanjie (Serxu Co.) UTM 47S 0399984 3667047 4100-4600 m 10.- 21.07.2002 leg. T. Romig. 2♂♂, 1♀ in coll. Romig, 1♂ in coll. T. R. Nielsen .

Platycheirus altotibeticus belongs to the albimanus group ( Vockeroth 1990) and was described on basis of a single male from Tibet ( Nielsen 2001: 11-13).

Short diagnosis of the male: head broad, frons angle 130º. Fore legs yellow, tibia broadening evenly towards apex. Basitarsus oblique rectangular in shape. Fore femur behind on basal half with a dense row of some sickle-shaped dark hairs. Abdomen with 4 pairs of yellow spots. Thorax and abdomen white haired.

DESCRIPTION OF FEMALE ( Figures 5A–C )

Head: Figures 5A, B . Face broad, occupying about two thirds of width of head. Vertical triangle, frons and lunulae shining black, except for two small white dust spots and for a slightly pollinose transverse depression in the middle of frons; black haired. Face slightly produced, with light silvery white pollinosity; central prominence and mouth edge black. Genae and postocular orbits with a dense, similar pollinosity as face. The hairs along the eye margins black; central parts of face, genae and postocular orbits white haired. Antennae black.

Thorax: scutum and scutellum shining black with a light bluish grey or brassy metallic lustre, almost all without pollinosity and with short yellow white and scattered long black hairs. Pleurae with moderate sulvery white pollinosity, white haired. – Legs: fore and mid femur and tibia orange yellow, the tarsi grey brown. Hind femur broadly yellow at base, narrowly so at apex. Tibia broadly yellow at apex and in the middle, otherwise black. Hind tarsi black on dorsal side, brownish yellow ventrally. – Wings: the whole wing microtrichose. Veins brownish black, stigma yellow brown. Calypter white yellow, the rim greyish brown. Halter yellow.

Abdomen: Figure 5C . Tergite 1 metallic bluish black, lightly white pollinose. Tergites 2–5 black with blue reflections, each tergite with a couple of rectangular yellow orange, white pollinose spots. Tergites 6–7 yellow, darkened mediodorsally. The long hairs along the side margins yellow, the short hairs on dorsal parts of the tergites mainly follow the ground colour. Sternite 1 grey brown, sternites 2–3 yellow with a dark spot in the middle, the following sternites yellow, lightly white pollinose. The hairs yellow.

Body length (from frons till tip of abdomen) 9.2 mm. Wing length 7.6 mm.

Ecology: The species was caught within tall herbaceous vegetation along rivers, figure 1. These small patches, which are interspersed within large stretches of short grassland, provide the only microenvironment which is reasonably sheltered from the incessant strong wind. It is highly probable also to provide the habitat for the larvae.

Acknowledgements. We want to thank Dr. F. Christian Thompson, Washington for his opinion on P. rubrolateralis sp. n., and Karsten Sund, Natural History Museum Oslo for photographing the new species.

Figures

Figure 5. Platycheirus altotibeticus Nielsen, 2001, female. A: head, latero-dorsal view, B: head, lateral view, C: abdomen.