Ringdahlia, Michelsen, Verner, 2014

Michelsen, Verner, 2014, Taxonomic assessment of Chirosiomima Hennig (Diptera: Anthomyiidae), with proposal of a new genus for Hylemyia curtigena Ringdahl, Zootaxa 3790 (1), pp. 86-102 : 97

Genus Ringdahlia gen. n.

Type species: Hylemyia curtigena Ringdahl, 1935 .

Etymology. The new genus is named after the Swedish dipterist Oscar Ringdahl (1885–1966), author of the type species. He was a dedicated collector of Diptera Brachycera from all parts of Sweden. His early acquaintance with the German dipterist Paul Stein (1852–1921) may have given him the impetus to take special interest in the muscoid families ( Muscidae , Fanniidae and Anthomyiidae ). He soon became the foremost authority on this important but notoriously difficult group of flies in Scandinavia.

Diagnosis. The following combination of characters may help to separate male and female Ringdahlia from other anthomyiid genera: medium sized, sexually dimorphic, body and appendages extensively dark-coloured; arista short-pubescent; male head ( Fig. 28 ) in lateral view with antenna inserted beneath the middle and gena narrow, only half as wide as postpedicel; female frons relatively narrow, on lower part only one-third of total width of head ( Fig. 30 ); setulae on upper occiput and anterior declivity of thorax rather coarse and blunt ( Figs. 28, 30 ); presutural rows of acrostichals wider apart from each other than their distance to dorsocentral rows and with setulae present between rows ( Fig. 30 ); vein C with v setulae; mid tibia with 0 av, 1 ad, 4–6 pd and 0 pv setae; hind tibia with 3–4 pd setae, without p or pv setae, apically without pd and pv setae; male terminalia of unique structure in respect to epandrium, cercal plate and surstyli ( Figs. 33–39 ); female oviscapt ( Fig. 43 ) short, basally thick with large tergites VI and VII partly exposed and covered in grey dusting; field of enlarged spiniform scales developed in ventral “intersegmental” membrane of segment VIII.

Relationships. Hennig (1972, 1976a) admitted that his attempts to classify Hylemyia curtigena Ringdahl in a “modern” genus were either preliminary or poorly substantiated. As shown in the following, morphology presents ample justification for classifying the present species in a new genus, Ringdahlia gen. nov. At first sight, the male of R. curtigena ( Fig. 27 ) looks unremarkable with the typical appearance of an aerial anthomyiid fly, perhaps suggestive of a Botanophila or Lasiomma species. On closer inspection, the male terminalia exhibit a wealth of autapomorphic details presenting no obvious hints on relationships to existing anthomyiid genera. The small, extensively membranized distiphallus is superficially suggestive of Botanophila , but such relationship is not supported by the slender, articulated pregonites. The female, that has now become available for study, has an oviscapt ( Fig. 43 ) without any of the defining characteristics of Chirosiomima ( Fig. 12 ). Besides that, the morphology of the female presents no evidence in support of a closest relationship to any known genus or group of genera.

Figures

FIGURE 43. Ringdahlia curtigena, female from Finland, oviscapt, flat mount. Scale bar: 0.25 mm.

FIGURES 27 – 30. Ringdahlia curtigena. 27, 28. Male from Finland, habitus and head, lateral views. 29. Female from Finland, labella. 30. Female from Finland, head and anterior thorax, anterodorsal view. Scale bars: 1 mm (27); 0.5 mm (28, 30); 0.1 mm (29).

FIGURES 31 – 42. Ringdahlia curtigena, males from Finland. 31. Tergosternites VI – VIII and sternites IV and V, laterodorsal view. 32. Sternite V, lateral view. 33. Hypopygium, posterior view. 34. Same, after removal of cerci. 35. Hypopygium, lateral view. 36 – 39. Cerci, dorsal, anterior, anteroventral and lateral views (x = ventral sclerite complex; y = bowed sclerite rod. 40. Pregonite (left) and postgonite, lateral view, 41. Phallapodeme, phallus and ejaculatory pump, lateral view. 42. Phallapodeme and phallus, anterolateral view. Scale bars: 0.25 mm.

FIGURES 10 – 12. Chirosiomima spp. 10. C. obscurinervis, male from Iran, sternites IV and V. 11. C. obscurinervis, lectotype male from Ghana, hypopygium, posterolateral view. 12. C. gestroi, female from Tunisia, oviscapt, flat mount (s = sternite; sp = spiracle; t = tergite). Scale bars: 0.25 mm.