Pseudoplatychirus was described as a new genus by Doesburg (1955), but Thompson and Rotheray (1998), in the Manual of Palaearctic Diptera, considered it as a subgenus of Platycheirus.
Adapted from Barkalov (2007).
MALE.
Head: Face wide, with distinct tubercle in basal half and deep depressions at sides, entirely (except for shining vitta running from lateral depression to mouth margin) covered with dense gray pollinosity and long, erect white pile combined with vitta of similar black pii running from antennal base to facial depression; gena high, distinctly higher than eye, covered with white pile with admixture of several black pili; pollinosity silvery and with bluish background and brown maculae visible under it; frons very wide, covered with dense gray pollinosity and long black (with admixture of white) pili curled at ends; lunule black; antenna black; basoflagellomere long, about 4 times as long as scape and pedicel combined, slightly narrowed at apex; arista yellow, thickened in basal 3/4 and sharply narrowed in apical 1/4; vertex shining, separated from frons by distinct transverse groove; vertical triangle equilateral (wider than long), covered with black pile anteriorly, and with white hairs on rest of surface; occiput shining, with long white pile and with weak admixture of black pili in upper part near eyes. Eyes small, widely spaced, covered with rather long white pile in middle.
Thorax: Postpronotum blue, bare. Scutum and scutellum bright blue, shining, with weak gray pollinosity, rather sparsely covered with long, erect, delicate, white and black pili. Pleura blue, shining, with long white pili curled at ends; tuft of similar black pili present in posteroventral corner of mesopleuron. Legs, except for 1st and 2nd tarsomeres of protarsus, black, with weak gray pollinosity. Femora slightly widened. Profemur with long curly pili; middle part with white hairs, base with tuft of black pili, and apical 1/3 with black pili. Mesofemur with dense silvery pile in basal half and black curled pili in apical half. Metafemur with curled white pile anteriorly and with several black pili ventrally. Protibia slightly widened at apex, black, paler at apex, covered with short recumbent white pile anteriorly and with long erect black pili posteriorly. Mesotibia with short pale recumbent pili in anterobasal 2/3, erect long black pili in apical 1/3, and long black pili posteriorly. Metatibia with relatively short, subrecumbent, pale pile longer in anterodorsal part; apex of tibia covered anteriorly with tuft of white and black pili about half as long as metatarsus. First and second tarsomeres of protarsus (similarly to those in P. peteri) very strongly widened, white; 1st tarsomere with 3 black vitta (one along anterior margin and two in middle) and with 2 transverse black fascia near apex; upper surface covered with short subrecumbent white pile and bearing row of short dense black pili along posterior margin; 2nd tarsomere considerably narrower and shorter than 1st tarsomere; 3rd–5th tarsomeres dark, not widened. Mesotarsus not modified, with short subrecumbent yellow pile. Metatarsus strongly thickened in basal part, distinctly thicker than metatibia, about as long as other segments combined. Wing relatively narrow, hyaline, with pale brown stigma; cell R entirely covered with microtrichiae above spurious vein (vs); cell BM with narrow bare area in basal part; vein R4+5 weakly and smoothly curved. Haltere brownish, with black capitulum; calypter yellow with dark outer margin.
Abdomen elongate, distinctly longer than head and thorax combined, black, shining, with obsolete gray maculae on terga 3-4 and with gray smear on tergum 2, covered with rather short and sparse white pile longer on terga 1 and 2; sterna black, shining, with weak gray pollinosity and white pile.
FEMALE.
Face, in addition to lateral shining vittae, also with 2 similar vittae running from antennal base toward apex of median tubercle. Gena with dense gray pollinosity nearly concealing black background. Frons very wide, black, shining, with small gray maculae only in middle and at sides. Arista narrowed from middle. Scutum and pleura black. Pile on tibiae short, subrecumbent, pale; only mesotibia with more or less long erect pili on posterior surface; protibia and protarsus not widened, entirely black; metatibia without tuft of long pili at apex. Wing entirely covered with microtrichiae. Abdomen black, terga 2-4 with large shining macuale separated by narrow brown matt vittae. All other characters as in male.
Platycheirus (Pseudoplatychirus) glupovi (Barkalov, 2007).
Barkalov, A.V. (2007) A new for the Russian fauna genus and species of hover-flies (Diptera, Syrphidae). Entomological Review 87(7), 930–933. [Original in Russian, published in Zoologicheskii Zhurnal 86: 1275-1278].
unless otherwise stated