Plecia gracilenta ( Heyden & Heyden, 1865 ) Stat. Reinst.

Skartveit, John & Wedmann, Sonja, 2021, A Revision of fossil Bibionidae (Insecta: Diptera) from the Oligocene of Germany, Zootaxa 4909 (1), pp. 1-77 : 25-26

Plecia gracilenta ( Heyden & Heyden, 1865) Stat. Reinst. (figs. 31, 119)

Protomyia gracilenta Heyden & Heyden, 1865: 28

Penthetria gracilenta (Heyden & Heyden) Handlirsch 1907: 957 .

Plecia gracilenta (Heyden & Heyden) Statz 1943: 33

Plecia ♂ Nr. 9 Statz, 1943: 33.

Localities: Rott. Also in Aix-en-Provence and Chadrat, France.

Material examined: Holotype (male) NHMUK In 58805 (figs. 31, 119)

Additional material (females, provisionally associated) STIPB A-549, Siegburg Rott-544.

Description:

Female (provisionally associated, N=2)

Total length 5.4 mm (N=1). The specimen are relatively poorly preserved, but one detached wing is well preserved. Colour is uniformly brown, probably not original colour.

Head: Length 0.70 mm, width 0.70 mm (N=1). Antenna apparently a little conical, segments not possible to count.

Thorax: Length 1.8 mm. Poorly preserved. Haltere light brown.

Wing: Length 4.8 mm, width 1.7 mm, length/width = 2.8. Light brown fumose, veins brown and distinctive throughout, relatively fine. Humeral vein present, subcosta distinctive only apically. Pterostigma invisible. Costa extends to one third the distance between apices of R 4+5 and M 1. R 2+3 short, nearly straight. R 4+5 apically gently curved. R-M a little oblique. Fork of CuA relatively wide, CuA 2 bent basad in apical third. Vein measurements are given in Table 4.

Legs: Brown, femora slightly thickened. Most parts are missing in the specimen at hand.

Abdomen: Length 3.5 mm, width 1.1 mm. Cylindrical.

Male (N=1):

Total length 6.9 mm. Entirely black, rather slender build.

Head: Length 1.0 mm.Antenna relatively slender, segments not possible to count, flagellum 0.51 mm long, 0.09 mm wide. Ocellar tubercle tall and prominent. Rostrum not protruding.

Thorax: Length 1.9 mm. Pile not apparent. Haltere brown.

Legs: Black, slender. Fore tibia 1.7 mm long, 0.19 mm wide, first fore tarsomere 0.66 mm long, hind tibia 2.2 mm long, 0.22 mm wide, first hind tarsomere 0.57 mm long, 0.14 mm wide.

Wing: Length 4.4 mm, width 1.7 mm, length/width = 2.5. Light brownish fumose, veins brown. Details in venation not possible to see.

Abdomen: Length 4.0 mm, slender and cylindrical.

Terminalia: Gonostylus apparently rather long and straight.

Discussion: The terminalia illustrated by Skartveit & Nel (2017: Fig. 147–148) may possibly be from a different species. The species was synonymised with Plecia lygaeoides ( Heer, 1849) by Skartveit & Nel (2017), but closer studies of the type material of P. lygaeoides suggest the two are not the same ( Skartveit & Krizmanic 2020), accordingly we here reinstate it as a valid species. Statz (1943) only referred to Heyden & Heyden’s description of the species but apparently had not seen any additional material.