Apsilocephalidae Nagatomi, Saigusa, Nagatomi and Lyneborg, 1991a

Greenwalt, Dale E., Amorim, Dalton De Souza, Hauser, Martin, Kerr, Peter H., Fitzgerald, Scott J., Winterton, Shaun L., Cumming, Jeffrey M., Evenhuis, Neal L. & Sinclair, Bradley J., 2022, Diptera of the Middle Eocene Kishenehn Formation II, Palaeontologia Electronica (a 22) 25 (2), pp. 1-52 : 27

Family Apsilocephalidae Nagatomi, Saigusa, Nagatomi and Lyneborg, 1991a

Type genus and species Apsilocephala longistyla Kröber, 1914

Palaeoapsilocephala Hauser and Greenwalt gen. n.

Figures 16-17

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Type species. Palaeoapsilocephala kishenehnensis Hauser and Greenwalt by present designation.

Included species. Palaeoapsilocephala pusilla ( Hennig, 1967; Psilocephala ) comb. n.; Palaeoapsilocephala vagabunda ( Cockerell, 1927; Rueppellia ) comb. n.

Diagnosis. Antenna with scape less than twice as long as thick and pedicel square. Postpedicel elongate triangular; first stylus segment short and square, second stylus segment elongate, four to five time as long as its greatest width. Hind femur thickened, more than twice the width as the associated tibia. Epandrium without articulated surstyli.

Differential diagnosis. Palaeoapsilocephala differs from the extant Apsilocephala by the shape of the antenna, which has the last stylus segment more than twice as long as the nearly rounded postpedicel, the hind femur being only slightly thicker than the tibia, as well as the presence of articulated surstyli on the epandrium. Kaurimyia Winterton and Irwin, 2008 can be separated from Palaeoapsilocephala by the apically enlarged hind tibia and the swollen hind tarsus. A number of morphological similarities are shared between Palaeoapsilocephala and Clesthentia White, 1914 . While the postpedicel in Clesthentia is more egg-shaped in contrast to the more triangular shaped postpedicel in Palaeoapsilocephala , this is not a necessarily a significant character to separate two genera. Other differences are the elongated, ventrally projected surstyli of Clesthentia , which could be an autapomorphy for this genus. The epandrium of Kaurimyia is much more similar to P. pusilla and P. kishenehnensis , with the triangular edges laterally expanding over the tip of the oval cerci. The lack of an apical bristle on the apex of the antenna in Clesthentia could also be considered a character to distinguish the two genera. The last two characters could not be confirmed with all the fossil taxa, because, for P. vagabunda only one female is known, and the apical bristle on the antenna can only be discerned in the amber fossil P. pusilla . The extinct genera (See Remarks) are distinguished from Palaeoapsilocephala by long spines on the hind femur ( Irwinimyia Zhang, Wang and Yeates, 2018 ), the row of posterior setae on the fore femur and the lack of a pterostigma ( Kumaromyia Grimaldi and Hauser, 2011 ).

Figures

FIGURE 16. Palaeoapsilocephala kishenehnensis Hauser and Greenwalt gen. and sp. n., USNM 717195, Male. A, Habitus; B, Antennae; C, Drawing of antennae; D, Right wing; E, Drawing of right wing. Scale bars equal 2.0 mm (A), 0.15 mm (B), and 1.0 mm (D).

FIGURE 17. Palaeoapsilocephala kishenehnensis Hauser and Greenwalt sp. n., USNM 717195. A, Hind tibia spurs; B, Genitalia. C, Drawing of genitalia. Scale bars equal 0.5 mm (A, B).