Platycheirus occultus Goeldlin, Maibach and Speight, 1990

Prokhorov, A. V., Popov, G. V. & Zaika, M. I., 2018, New Records Of Hoverflies (Diptera, Syrphidae) From Ukraine. Iii. Pipizinae And Syrphinae, Vestnik Zoologii 52 (3), pp. 241-250 : 244-246

Platycheirus occultus Goeldlin, Maibach and Speight, 1990 (figs 15–18)

Material examined. Ukraine. Kyiv Region: Irpin env., 50.51 N 30.27 E, edge of mixed forest along railway, 11.04.2017, 1 Ơ (A. Prokhorov) .

D i s t r i b u t i o n: Belarus, Britain, Czech Republic, Denmark (incl. the Faroe Islands), Finland, France, Germany, Hungary, Ireland, Italy (Apennines), Liechtenstein, Norway, Poland, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland; Azerbaidjan, Iran, Turkey ( Holinka & Mazánek, 1997; Reemer, 2000; Jensen, 2001; De Groot et al., 2010; Tóth, 2011; Speight, 2017; Mielczarek, 2018); Ukraine (first record).

Diagnosis. This species belongs to P. clypeatus group of species ( Speight & Goeldlin de Tiefenau, 1990; Bartsh et al., 2009). This group can be recognized by the entirely black antenna, orange-brown markings on the abdominal tergites, facial prominence and upper mouth-edge projecting anteriorly no further than the frontal prominence, male fore tibiae widening progressively from base to apex ( Speight & Goeldlin de Tiefenau, 1990). Male differs from similar species ( P. angustatus (Zetterstedt, 1843) , P. europaeus Goeldlin, Maibach & Speight, 1990 and P. ramsarensis Goeldlin, Maibach & Speight, 1990 ) by the underside of the basotarsomere of the fore tarsus with a straight, pale central furrow, sometimes ending in a small round pit containing a black mark (fig. 18) (in P. angustatus , P. europaeus and P. ramsarensis the underside of the basotarsomere of the fore tarsus with a V-shaped pale furrow), the distal half of all segments of the fore tarsus without a brown/black maculae ventrally (fig. 18) (in the aforementioned species, the distal half of the segments 2–3 of the fore tarsus often with a brown/black maculae ventrally). From similar P. magadanensis Mutin, 1999 it differs by the pale furrow on the underside of the basotarsomere of the fore tarsus starting at its base and ending in a pit that is more readily visible than the furrow (in P. magadanensis , the underside of the basotarsomere of the fore tarsus with a relatively broad, shining furrow covering the central third of its length); posterior side of the fore femur (in addition to the bent, white seta) with several bent hairs (in P. magadanensis , posterior side of the fore femur (except for the bent, white seta) with only straight hairs) (Bartsh et al., 2009). Platycheirus occultus differs from the similar P. clypeatus (Meigen, 1822) by the pale furrow on the underside of the basotarsomere of the fore tarsus ending already in the middle of the segment (sometimes we see only a pit at the centre of the segment, as on fig. 18) (in P. clypeatus , the pale furrow on the underside of the basotarsomere of the fore tarsus ending near the apex), and at least the basal quarter of the posterior side of the fore femur is black (fig. 17) (in P. clypeatus , the fore femur more or less entirely yellow, at most slightly black at base) ( Speight & Goeldlin de Tiefenau, 1990; Bartsh et al., 2009). From similar P. angustipes Goeldlin, 1974 it can be separated by the distal half of all segments of the fore tarsus without a brown/black maculae ventrally (fig. 18) (in P. angustipes , the distal half of all segments of the fore tarsus with a large brown/ black maculae ventrally), the fore femur is black/dark brown for less than the half of length (fig. 17) (in P. angustipes , the fore femur is black/dark brown for 3/4 of length), and surstyli entirely pale-haired (in P. angustipes , the base of surstyli often with the long black bristly hairs mixed with the pale yellow bristly hairs) ( Speight & Goeldlin de Tiefenau, 1990; Van Veen, 2010).

Note. The biotope where the specimen was found is corresponding with ones of cluster B ( Reemer, 2000), this is the highest part of Irpin River floodplain near mixed forest consisting mainly of Quercus , Pinus , Padus and Carpinus .