Platycheirus (Eocheilosia) ronana (Miller, 1921).
Miller, D.W. (1921) Material for a monograph on the Diptera fauna of New Zealand. Part II, family Syrphidae.Transactions and Proceedings of the Royal Society of New Zealand 53, 289-333. [1921.08.08]
Miller (1921) described this species as Cheilosia ronana from Rona Bay, New Zealand. Hull (1949) described the subgenus Eocheilosia for Cheilosia species with males widely dichoptic and proposed Cheilosia ronana Miller as subgenotype. Thompson and Vockeroth (1989) placed the species ronana and the subgenus Eocheilosia under the genus Platycheirus. Males of Platycheirus ronana are holoptic.
From original description (Miller 1921).
A medium-sized somewhat hairy elongate fly with a brilliant coppery thorax and brownish-black abdomen.
MALE . Eyes bare, dichoptic; ocellar triangle black, clothed with short brownish-yellow hairs; front somewhat swollen, dull blue-black but with a greyish re:flection, densely clothed with blackish hairs; lunular area semicircular and black; 1st antennal joint blue-black; 2nd joint brownish; 3rd ovate, brick-red, darker in some lights, and with pale-grey reflections; arista black. Face more or less vertical; shiny greenish-black; clothed with a dense greenish-grey tomentum except on the protuberances (one below end of antennae and the other above oral margin); cheeks greenish-black, clothed with short silvery hairs, which extend over the blue-black occiput particularly along the orbits.
Thorax and scutellum brilliant cupreous, with blacker re:flections; clothed with short yellowish hairs, longer on the scutellum and pleurae and forming a distinct fringe on the dorsum across the scutellar suture. Wings slightly tinged with brown, stigma pale brown, veins brown; vein M1 angulated and with a stump from this point into cell R; squamae and anti-squamae tinged with pale brown; halteres golden-yellow. Legs brownish-yellow with an indistinct fuscous spot in the centre of femora and tibiae; posterior tibiae and protarsi somewhat swollen; tarsi, except the anterior and middle protarsi, blackish-brown; posterior tarsi with a golden reflection beneath caused by the vestitute.
Abdomen elongate, the sides parallel; clothed with short silvery hairs, longer at the sides; dull blackish-brown (though somewhat reddish), except the shiny greenish-black basal segment; the sides of each segment narrowly cupreous; a pair of indistinct greyish spots, caused by the vestiture, and seen best with the unaided eye, across the anterior margin of 3rd and 4th segments.
New description:
MALE.
Head: Face with small, round facial tubercle, black, entirely silvery pollinose except tubercle and lunule, black pilose; frons black, silvery pollinose, black pilose; gena black, yellow and black pilose; vertical triangle black, black pilose; holoptic, eye bare; antenna dark brown, basoflagellomere orange ventrally; arista bare; occiput black, silver pollinose, yellow pilose.
Thorax: Scutum shiny black except postalar callus brown, silvery pollinose anterolaterally, yellow pilose on anterior half, black and anterior pilose on posterior half; postpronotum bare; notopleuron; scutellum shiny black, black and yellow pilose, subscutellar fringe complete with long yellow pili. Pleuron black, silvery pollinose, yellow pilose on dorsal katepisternum, posterior anepisternum, anepimeron and katepimeron; metasternum bare; calypter yellow; plumula whitish; halter yellow; spiracular fringes yellow. Wing: Wing membrane mostly hyaline; microtrichose, except cells R1, R and BM bare basally. Vein M1 with a short spur into cell R4+5 and vein M2 present. Alula broad, microtrichose. Legs: Entirely brown except coxae and trochanters dark brown and 3rd and 4th pro- and mesotarsi and whole metatarsus dark brown; yellow pilose except tarsi black pilose.
Abdomen: Parallel-sided, as broad as thorax. Dorsum black, epicuticle with ridges, black pilose dorsally and laterally except 1st tergum yellow pilose laterally and 2nd tergum yellow pilose laterally on anterobasal 4/5 and 2nd, 3rd and 4th terga yellow pilose dorsally on bluish maculae; 1st tergum black, bluish-silvery pollinose anteriorly; 2nd tergum black; 3rd, 4th and 5th terga black with 2 anterolateral bluish iridescent maculae, broadened laterally; sterna dark brown, mostly yellow pilose, except 5th and posterior terga black pilose.
unless otherwise stated