Spilogona maderensis Michelsen

Michelsen, Verner, 2023, Macaronesian Muscidae (Diptera). IV. The genus Helina Robineau-Desvoidy, and description of the male of Spilogona maderensis Michelsen, Zootaxa 5293 (2), pp. 251-276 : 274-275

Spilogona maderensis Michelsen

( Figs 14A–C )

Spilogona maderensis Michelsen ; Michelsen 2021b: 129 ff., figs 3A, B (female, Madeira). Material examined. MADEIRA: [ MZH]. Pico Ruivo [32.76N 16.94W], holotype ♀, 27‒29.vi.1957 (H. Lindberg); Ribeira Frio [32.73N 16.88W], 1♁ 14.v.1959 (S. Panelius).

Description. Male: Medium sized, wing length 5.2mm (n=1). Head and prementum grey pruinose; entire frons suffused with brown, frontal vitta barely darker than frontal triangle; parafacial plates silvery white with a golden brown tinge. Thorax covered in dense grey pruinosity except extensively dark brown on dorsum of mesonotum including scutellar disc and on upper part of anepisternum. Wing membrane rather intensely smoky brown, yet both cross-veins distinctly darker shadowed; calypteres dirty whitish with brown margins, broadly so on lower calypter; halter yellow. Legs black, femora grey pruinose. Abdomen grey pruinose except for shiny brownish black pattern as follows: entire tergite II except narrowly grey along hind margin, tergites III and IV with very large trapezoid marks narrowly separated by grey median stripe; similar but smaller marks present on tergite V. Postpedicel about 2 times as long as wide, anterior apical corner forming a very obtuse angle; arista short-pubescent, longest branches barely as long as its greatest basal diameter. Haustellum conical, short and tick. Head feminized with eyes widely separated by frons. Frons as well as broad frontal vitta parallel-sided; frontal triangle relatively small, extended to middle of frontal vitta. Frons and lower facial margin slightly and equally projecting. Fronto-orbital plate narrow, with 1 reclinate orbital seta and 3 inclinate frontal setae with a few interstitial setulae and bordered laterally by an irregular row of setulae. Dorsocentral setae 2 + 3; presutural acrostichal field with setulae only in irregular rows. Notopleuron without setulae.Anepisternum without interstitial setula(-e). Katepisternal setae 1 + 2, but lower posterior seta much weaker than both upper ones. Scutellum bare on lateral declivity. Vein C distal to subcostal break with extensive row of dorsal setulae; spines at subcostal break inconspicuous. Fore tibia with 1 p seta below middle. Mid femur without subapical ad seta but with a complete row of pv setae; mid tibia before apex with 2 pd setae only. Hind femur with 4 av setae in distal half and 3-4 pv setae in subbasal third; hind tibia with 1 av and 2–3 ad setae. Abdomen with discal setae confined to tergite V and lateral parts of tergite IV. Sternite I bare. Hypopygium not dissected, but exposed cerci forming a strikingly large shield-like plate with long, attenuate, narrowly separated apical prongs.

Taxonomic notes. The male described above is overall very similar to and obviously conspecific with the female holotype of Spilogona maderensis , a species endemic to Madeira. It is easily separated from other species of Spilogona , including the closely related Azorean S. azorensis Michelsen ( Michelsen 2021b) , by the shadowed cross-veins r-m and dm-cu and the dorsal setulae on vein C. A fully feminized male head with a pair of orbital setae is an exceptional condition among Palearctic and Nearctic species of Spilogona , cf. Sorokina & Pont (2013). However, my expectation will be that the unknown male of S. azorensis likewise possesses a feminized head.

Figures

FIGURE 14. Spilogona maderensis Michelsen, male. Habitus (A); head, dorso-lateral (B); abdomen; dorsal (C).