Helius formosus Krzemiński, 1993

Kania, Iwona, 2014, Subfamily Limoniinae Speiser, 1909 (Diptera, Limoniidae) from Baltic amber (Eocene): the genus Helius Lepeletier & Serville, 1828, Zootaxa 3814 (3), pp. 333-352 : 336-337

Helius formosus Krzemiński, 1993

( Figs 2 A–C)

v*.1993 Helius formosus Krzemiński , p. 600, figs. 8–9.

Material examined. Holotype: No. 225 (female) ( ZMHB); additional material: No. 212/116 (female) ( MEPAS); No. MP/3340 (female); No. MP/3341 (female) ( ISZP).

Diagnostic characters. Rostrum less than twice as long as the head, longer than palpus, only slightly shorter than antenna; antenna only 1.2x the length of the rostrum, palpus 0.75–0.8x the length of the rostrum; the last palpal segment almost 1.25x the length of all the preceding segments together; vein r-m rather short, cross-vein mcu in approximately proximal 1/3 of d-cell base length.

Redescription. Body: the length of specimens 5.34–7.54 mm, (5.7 mm holotype).

Head ( Fig. 2 A): rostrum 0.89–1.16 mm long, 0.1–0.11 mm wide, 1.09 mm long, 0.09 wide (holotype), less than twice as long as the head; antenna 16-segmented, 1.09–1.24 mm long (holotype), short, approximately 1.2x the length of the rostrum ( Fig. 2 B); scape cylindrical, large; pedicel large, its distal part conspicuously widened; first flagellomere barrel-shaped, flagellomeres 2–5 oval, short, flagellomeres 6–10 cylindrical, elongated; flagellomeres 2–8 with two elongated setae; flagellomeres 9–13 with three additional setae, much longer than the length of flagellomeres which they occur, 2–3 times longer than the segments bearing them ( Fig. 11 D); last one at least twice the length of penultimate.

Palpus ( Fig. 2 A): 0.61–0.81 mm long (holotype); the length of last palpal segment 0.35–0.40 mm, 0.38 mm (holotype), penultimate 0.11–0.15 mm (holotype), first and the second segments 0.09–0.10 mm (holotype); the last palpal segment almost 1.25x the length of the all the preceding segments together.

Wing ( Figs 2 C, 11E): wing 5.34–7.52 mm length and 1.05–1.97 mm wide; pterostigma present, large and oval; vein Sc elongated, ending opposite 3/4 the length of Rs; cross-vein sc-r before the end of Sc; R1 ending at the level of R2+3+4 midlength; r-r (R2) atrophied; R2+3+4 elongated and sinuous; cell r2 very wide; d-cell very broad and large, closed; M3 longer than d-cell and longer than half the length of R5; cross-vein m-cu in proximal 1/3 of d-cell base; A1 and A2 elongated, slightly subsinuous.

Male hypopygium unknown, female ovipositor long and narrow.

Remarks. The species distinctly differ from H. minutus ( Krzemiński, 1993) in ration of the lengths of rostrum and the head. In H. formosus rostrum is slightly less than twice as long as the head, in H. minutus rostrum is longer than head only approximately 0.2x. In H. minutus antenna is more than twice longer than rostrum, in H. formosus antenna is only 1.2x the length of the rostrum. In H. minutus the last palpal segment is about equal two preceding segments together, in H. formosus it is longer.

These two species from Baltic amber also differ by wing venation: in H. formosus vein Sc is elongated, ending opposite 3/4 the length of Rs, in H. minutus this vein is shorter, ending opposite 1/3 of Rs. Cross-vein sc-r ending before the end of Sc in H. formosus , in H. minutus at the end. In H. formosus R1 ending opposite 1/2 not opposite 1/ 4 of R2+3+4.

Figures

FIGURE 2. Helius formosus Krzemiński 1993, No. 225 (female), holotype; A, head; B, relation between the length of palpi (p), antenna (a), rostrum (r) and head (h); C, wing venation.

FIGURE 11. Morphology of Helius from Baltic amber. A – B H. fossilis sp. nov., No. 587 (RS 64) (male), holotype, A. the body, lateral view; B. head, lateral view C. H. hoffeinsorum sp. nov., No. 1462 (male), hypopygium; D – E H. formosus Krzemiński, 1993, No. 225 (female), holotype, D. antennae, E. wing. Abbreviation of male hypopygium: gx—gonocoxite, ing—inner gonostylus, oug—outer gonostylus, aed—aedeagus, p—paramere.