Dicerura formosa Mamaev, 1998

Jaschhof, Mathias & Spungis, Voldemars, 2018, Towards reliable identification of male Dicerura: descriptions of three new and seven poorly known species in the Palearctic region (Diptera: Cecidomyiidae, Porricondylinae), Zootaxa 4422 (1), pp. 85-103 : 94-95

Dicerura formosa Mamaev, 1998

Figs 16–18

We identified our specimens from sketches made by one of us (MJ) while examining the holotype of D. formosa in 2012. Mamaev’s (1998) description of this species, whose only illustration was a schematic drawing of the gonostylus, is insufficient for specific identification. Dicerura formosa , described originally from southern Siberia, is newly reported here from two additional northern European countries.

Diagnosis. Characters to differentiate D. formosa from the other species of the formosa group are as follows.

The slightly bent gonostylus, whose apex is clearly tapered, bears large setae posteriorly and clearly smaller setae medially, the latter intermingled with short, dense microtrichia ( Fig. 16 , ↓1). The ventral gonocoxal emargination is

slightly convex basally, reinforced by sclerotization, and bordered by two pairs of gonocoxal processes, of which the ventromedial processes are ovate ( Fig. 16 , ↓2), while the dorsolateral processes are elongate and slightly bent ( Fig. 16 , ↓3). The semicircular collar of the tegmen has 5 inconspicuous, sclerotized knobs ( Fig. 18 ). The ninth

tergite is unusual in two different aspects. First, the posterior edge has a small, broadly V-shaped incision ( Fig. 17 , ↓4) that is bordered on the inside by subtriangular, densely microtrichose protuberances, and second, the anterior edge is broadly rounded (convex) and reinforced by sclerotization, not straight and faint as in other Dicerura . Two non-genitalic characters uncommon in Dicerura , which were not mentioned in Mamaev’s (1998) description of D. formosa , are the presence of setae on the anepisternum and the long, sometimes even complete M1+2.

Material examined. Sweden: 11 males, Lule Lappmark, Jokkmokk, Kaltisbäcken NR, herb-rich old-growth taiga near stream, 31 July–28 August 2016, MT, M. & C. Jaschhof (specimens nos CEC1386–CEC 1389 in NHRS, nos CEC1390–CEC 1393 in SDEI, nos CEC1394–CEC 1396 in IBUL). Estonia: male, Läänemaa, Kunila near Lihula, 10–25 July 2010, MT, R. Nikkel & EMTP (in IZBE).

Figures

FIGURES 16–18. Dicerura formoSa, male, from Sweden. 16: Genitalia, ventral. 17: Ninth tergite, dorsal. 18: Tegmen and ejaculatory apodeme, ventral. Scales 0.05 mm. Arrows refer to characters described in the diagnosis.