Eonandeva helva Giłka et Zakrzewska, 2015

Zakrzewska, Marta & Giłka, Wojciech, 2015, Eonandeva gen. nov., a new distinctive genus from Eocene Baltic amber (Diptera: Chironomidae), Zootaxa 4044 (4), pp. 577-584 : 578-581

Eonandeva helva Giłka et Zakrzewska , sp. nov.

Figures 1 , 2

Type material. Holotype. Adult male (tarsi of all legs missing) preserved in 12 x 5 x 4 mm piece of amber (Eocene, ~45–40 Ma, Gulf of Gdańsk; CCHH 1754–1; Fig. 1 A).

Derivatio nominis. The Latin adjective—amber, amber-coloured.

Diagnosis. RM relatively long, continuous with M, slightly oblique relative to R. R4+5 ending slightly distally of M3+4. Gonostylus slender, parallel-sided, with small subapical flattened lobe on median margin. Anal tergite with strong setae on posterior margin, median setae absent. Superior volsella cylindrical, apex posteromedially directed. Inferior volsella with slightly enlarged apical part.

Description. Adult male (n = 1).

Total length 1.55 mm; wing length c. 900 Μm.

Head ( Fig. 1 B). Eyes bare, reniform, without dorsomedian extensions, broadly separated by frons. Frontal tubercles absent. Antenna with 13 well discernible flagellomeres, AR 0.73, plume fully developed. Length of palpomeres 2–5 (Μm): 32, 101, 117, 133. At least 6 setae placed in row in proximal part of clypeus.

Thorax chaetotaxy. Ac at least 12; Dc at least 16 (several setae arranged in small field anteriorly); Scts at least 5, minute; Pa 6 arranged in roundish field.

Wing ( Fig. 1 C, D). Slender, broadest at 2/3 length, width: 275 Μm, length/width ratio 3.27. Anal lobe not developed. RM relatively long, continuous with M, slightly oblique relative to R ( Fig. 1 D). Sc, R2+3 and An not observed. FCu placed distinctly distally of RM; VR Cu 1.43. Veins ending as follows (in order from base to tip): Cu1, R1, M3+4, R4+5, M1+2. Squama bare.

Legs. Spur of fore leg tibia not observed. Mid and hind leg tibia with 2 minute well separated combs (teeth up to 10 Μm long), each comb bearing more or less curved spur (c. 15–20 Μm long), spurs of mid leg slightly unequal in length.

Hypopygium ( Fig. 2 ). Gonostylus c. 100 Μm long, distinctly longer than gonocoxite, slender, arcuate, parallelsided, with small subapical flattened lobe on median margin ( Fig. 2 C). Anal tergite subtriangular, with 5–6 strong setae on posterior margin on each side of anal point, median setae absent. Anal point long and slender, slightly tapering to apex. Superior volsella strongly elongated, parallel-sided, cylindrical, slightly curved, apex posteromedially directed ( Fig. 2 D). Digitus or digitiform extension not observed. Inferior volsella with slightly enlarged apical part armed with sparse setae.

Figures

FIGURE 1. Eonandeva helva sp. nov., adult male, holotype CCHH 1754 – 1 (Eocene, ~ 45 – 40 Ma; Baltic amber, Gulf of Gdańsk). A — inclusion in amber; B — habitus; C — wing; D — RM vein area of wing.

FIGURE 2. Eonandeva helva sp. nov., adult male, holotype CCHH 1754 – 1 (Eocene, ~ 45 – 40 Ma; Baltic amber, Gulf of Gdańsk). Hypopygium and its structures in dorsal (A – D) and ventral aspect (E), photographed in reflected light (A), in transmitted light (E) and drawn (B – D); C — distal part of gonostylus; D — superior volsella (C and D magnified c. 2 times relative to B).