Macrostomus furcatus, Rafael & Cumming, 2009

Rafael, José Albertino & Cumming, Jeffrey M., 2009, Revision of the genus Macrostomus Wiedemann (Diptera: Empididae: Empidinae). I. The ferrugineus species-group, Zootaxa 2064 (1), pp. 39-56 : 48-50

Macrostomus furcatus , n. sp.

( Figs. 5a–j , 9 )

Diagnosis. Thorax, abdomen and legs predominantly yellow; postcranium black with gray pruinescence; male tergite 8 with blunt distal forked projection. Female hind tibia with pinnate scales along most of dorsal surface and ventral basal third.

Description. Holotype male. Frons approximately half anterior ocellus width. Face slightly wider than frons only at ventral margin. Postcranium black. Antenna black with pedicel yellowish. Palpus yellow. Thorax shining yellow with yellow to gray-brown pruinescence. Setae: 4 dorsocentrals; 1 supra-alar presutural; 2 pairs of scutellars; 3-5 antepronotals; 1–3 tiny proepisternals; 3–5 katatergitals. Legs shining yellow with apex of mid and hind femora, apex of hind tibia and all tarsi black, except fore and mid tarsomere 1 mostly yellow and fore tarsomeres 1–3 white distally. Mid tibia with two slightly stout dorsal setae at median third; hind tibia with 4–5 slender dorsal setae; first hind tarsomere with three longer dorsal setae. Wing with costal and apical margin brown infuscated ( Fig. 5a ). Halter dark yellow to brown. Abdomen shining yellow with black terminalia. Tergite 8 ( Fig. 5b ) with blunt bifid distal projection. Epandrium with anterodorsal and posterodorsal protuberances of subequal length ( Fig. 5c ). Anterior cercus somewhat elongate; posterior cercus rounded distally, with a few anterodorsal setae and two internal protuberances, one longer and apparently bifid anteriorly and other small and simple posteriorly ( Figs. 5d–e ). Hypandrium ( Fig. 5f ) with a few setae medially and paired serrated protuberances distally.

Size. Body length 3.1 mm; wing length 3.2 mm.

Female. Frons slightly wider than anterior ocellus width; face narrower than frons, approximately one third anterior ocellus width. First hind tarsomere with one longer dorsal seta; hind tibia with pinnate scales on most of dorsal surface and ventrally on basal third. Wing wider than in male, more brown infuscated ( Fig. 5g ). Terminalia black sparsely gray pruinose. Tergite 8 and sternite 8 as in Figs. 5h–i . Genital fork as in Fig. 5j . Internal egg oval.

Size. Body length 3.2 mm; wing length 3.3 mm.

Geographical records. Brazil (Amazonas, Acre states), Fig. 9 .

Material. Holotype ♂: BRASIL, Amazonas , Pq [Parque] Nac [ional] [do] Jau, Seringal, 27.iv–03.v.1995 / / arm[adilha] Malaise, J.A. Rafael & J.[F.] Vidal ( INPA).

Paratypes: same data as holotype (1♀ INPA); Pq. Nac. Jau, Rio Jau, Seringalzinho, 015028S–613523W, 01.viii.1995, varredura, J.A. Rafael & J. Vidal (1♂ INPA, in glycerin); Igarapé Miratucu, Ig. do Gerlei, 015700S–614900W, 23–28.vii.1985, arm. Malaise, J.A. Rafael & J.Vidal (1♀ INPA, in glycerin); S. Izabel do R . Negro, Maturacá, 11–13.x.1990, arm. Malaise, J.A. Rafael (1♂ CNC); Acre, Cruzeiro do Sul, Rio Moa , 073702S–724615W, 15–28.xi.1996, varredura, mata, J.A. Rafael, J. Vidal & R . L. Menezes (1♂ CNC) .

Holotype condition. Good, not dissected.

Etymology. From Latin furca = fork, in reference to the furcated projection of male tergite 8.

Discussion. Macrostomus furcatus differs from all other species of the M. ferrugineus species-group by tergite 8 ending in a blunt bifid distal projection, by the shape of the posterior lobe of the cercus, and by the serrated apex of the hypandrium.

Figures

FIGURE 5. Macrostomus furcatus, n. sp., paratypes from Amazonas. A–F, male; A, wing; B, tergite 8, dorsal view with right setae omitted; C, terminalia, lateral view; D, detail of posterior cercus; E, detail of posterior cercus in alternate view; F, hypandrium and phallus, lateral view. G–I, female; G, wing; H, tergite and sternite 8, lateral view; I, sternite 8, ventral view; J, genital fork, ventral view. Scales: B–C,H–I = 0.2 mm; D,E,J = 0.1 mm.

FIGURE 9. Distribution map of species belonging to the Macrostomus ferrugineus species-group with tergite 8 truncated or forked distally. Symbols represent the known collection localities as follows: diamond = M. longipennis, n. sp.; open circle = M. furcatus, n. sp.; open triangle = M. flavus, n. sp.; square = M. fulvithorax; star = M. occidentalis.