Helina atlantica (Tiensuu)

Michelsen, Verner, 2023, Macaronesian Muscidae (Diptera). IV. The genus Helina Robineau-Desvoidy, and description of the male of Spilogona maderensis Michelsen, Zootaxa 5293 (2), pp. 251-276 : 270-273

13. Helina atlantica (Tiensuu)

( Figs 13A–E )

Enoplopteryx atlantica Tiensuu ; Tiensuu 1938: 5 ff. (Madeira); Frey 1949: 43 (Madeira).

Helina atlantica (Tiensuu) ; Hennig 1957: 161 (Madeira); Hennig 1978: 4 (Madeira).

Material examined. MADEIRA: [ MZH]. Caramujo, 1250m, syntypes 1♁, 1♀ 6–14.viii.1935 (O. Lundblad); Calheta, 1♁ 7.v.1938 ( R. Frey); Ribeira Frio, 2♁ 3.v.1938 ( R. Frey, J. V. Storå); Rabaçal, 1♁ 6–7.v.1938 ( R. Frey); Poiso ‒ Arieira, 1♀ 19.vi.1957 (H. Lindberg) .

Description. Small to medium sized, wing length 4.3–5.7 mm (n = 7). Male: Ground colour dark except legs with ochre yellow femoral apices and tibiae, most parts densely greyish pruinose. Head fully feminized ( Fig. 13A ); broad frontal vitta extensively brownish black, as grey frontal triangle reduced, only extended a little beyond ocellar tubercle; mesonotum with usual pattern of four dark stripes on mesonotum visible in posterior view; wing with both cross-veins narrowly shadowed; abdomen ( Fig. 13B ) with dark brown pattern on tergites III–V consisting of an oblong median mark flanked by subtriangular marks. Eyes bare. Aristal branches very long, up to 1.5 times as long as width of postpedicel. Frons ( Fig. 13A ) formed by a broad, flat frontal vitta separating relatively narrow fronto-orbital plates; these bearing 2 strong, reclinate orbital setae on posterior part followed by 3–4 frontal setae of which the anterior one is strikingly enlarged. Dorsocentral setae 2 + 3; presutural acrostical field with setulae only arranged in 2 narrow, irregular rows; prealar seta very short, but slightly stronger than surrounding setulae; katepisternal setae 2 + 2. Vein C without dorsal setulae. Fore tibia with 1 ad (short) and 1 p seta; mid tibia with 0 ad and 2–3 pd setae; hind femur with 1–3 pv setae on middle third; hind tibia with 1 av, 3–4 ad setae and 1 pd seta on basal third. Slender ovoid abdomen ( Fig. 13B ) with marginal and discal setae on tergites IV and V abundant and strong; sternite V and hypopygium as in Figs 13C–E . Female: apart from usual sexual differences of the abdomen differing from the male by the presence of a greyish frontal triangle extended almost to anterior margin of frontal vitta and hind femur without pv setae.

Distribution. Endemic to Madeira.

Taxonomic notes. The enlarged setae on sternite V and elongated cerci and surstyli are obvious male synapomorphies that Helina atlantica shares with H. vilissima , also endemic to Madeira, and H. parcepilosa , a widespread Palearctic species.

Figures

FIGURE 13. Helina atlantica (Tiensuu), male. Head, dorso-lateral (A); abdomen (B); sternite V (C); hypopygium, caudal (D) and lateral (E). Same scale for C–E.