Eonandeva latistyla 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 : 581

Eonandeva latistyla Giłka et Zakrzewska , sp. nov.

Figures 3 , 4

Type material. Holotype. Adult male (tarsi of left mid and hind legs missing) preserved in 8.5 x 7.5 x 3.5 mm piece of amber (Eocene, ~45–40 Ma, Gulf of Gdańsk; CCHH 1754–10; Fig. 3 A).

Derivatio nominis. The Latin adjective derived from ‘ latus ’ and ‘ stylus ’, in reference to the broad gonostylus.

Diagnosis. RM slightly oblique relative to M and R4+5. R4+5 ending distally of M3+4. Gonostylus broadest near apex, with large subapical flattened lobe on median margin. Anal tergite with numerous setae surrounding base of anal point, median setae present. Superior volsella with distinct anteromedian ridge, swollen in apical part, apex medially directed. Inferior volsella with enlarged head-like apical part.

Description. Adult male (n = 1).

Total length 1.70 mm; wing length c. 810 Μm.

Head ( Fig. 3 B). Eyes bare, reniform, without dorsomedian extensions, broadly separated by frons. Frontal tubercles absent. Antenna with 13 well discernible flagellomeres, AR 0.70, plume fully developed. Length of palpomeres 2–5 (Μm): 32, 113, 113, 133. At least 4 setae placed in row in proximal part of clypeus.

Thorax chaetotaxy. Ac at least 7; Dc at least 14 (several setae arranged in small field anteriorly); Scts at least 10; Pa 6 arranged in roundish field.

Wing ( Fig. 3 C). Slender, broadest at 2/3 length, width: 245 Μm, length/width ratio 3.31. Anal lobe not developed. RM slightly oblique relative to R and M. Sc, R2+3 not observed, An vestigial, observed only in proximal part. FCu placed distinctly distally of RM; VR Cu 1.30. 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 tiny separate combs (teeth up to 5 Μm long), at least one comb bearing minute spur (c. 10 Μm long). Sensilla chaetica on ta1 of p2 not observed. Pulvilli absent. For length of leg segments and leg ratios, see Table 1 .

Hypopygium ( Fig. 4 ). Gonostylus c. 90 Μm long, longer than gonocoxite, slightly arcuate, broadest near apex, with large subapical flattened lobe on median margin ( Fig. 4 C). Anal tergite subtriangular, with numerous setae surrounding base of anal point, median setae present (strong setal tubercles observed). Anal point long and slender, tapering slightly to apex. Superior volsella strongly elongated, parallel-sided, bearing distinct anteromedian ridge,

Figures

FIGURE 3. Eonandeva latistyla sp. nov., adult male, holotype CCHH 1754 – 10 (Eocene, ~ 45 – 40 Ma; Baltic amber, Gulf of Gdańsk). A — inclusion in amber; B — habitus; C — wing.

FIGURE 4. Eonandeva latistyla sp. nov., adult male, holotype CCHH 1754 – 10 (Eocene, ~ 45 – 40 Ma; Baltic amber, Gulf of Gdańsk). Hypopygium and its structures in dorsal aspect, photographed in reflected light (A) and drawn (B – D); C — distal part of gonostylus; D — superior volsella (C and D magnified c. 2 times relative to B).

Tables

TABLE 1. Leg segment lengths (Μm) and leg ratios of male Eonandeva latistyla sp. nov.

	fe	ti	ta1	ta2	ta3	ta4	ta5	LR
p1	435	395	345	225	160	90	55	0.87
p2	430	410	270	150	125	80	50	0.66
p3	460	465	300	185	165	95	50	0.65