Macrostomus fusciventris, 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 : 43

Macrostomus fusciventris , n. sp.

( Figs. 2a–f , 8 )

Diagnosis. Thorax and legs predominantly yellow, abdomen shining black; postcranium black with gray pruinescence; male tergite 8 acute distally; female without pinnate scales on hind tibia. Female wing approximately as wide as male wing, entirely brown infuscated.

Description. Holotype male. Frons approximately one third anterior ocellus width. Face slightly wider than frons only at ventral margin. Postcranium black. Antenna black. Palpus brown. Thorax predominantly shining yellow, brown to black on disc of scutum, scutellum and subscutellum, sometimes with dark spot extending to front of scutum between dorsocentral setae; gray pruinescence more distinct on darker spots. Setae: 4 dorsocentrals; 1 supra-alar presutural; 1 pair of scutellar; 3–5 antepronotals; 1–3 tiny proepisternals; 3–5 katatergitals. Legs shining yellow with apex of mid and hind femora, entire hind tibia and mid and hind tarsi black; fore tarsus brown to black except tarsomere 2 white banded medially and tarsomere 3 white distally. Mid tibia with one dorsal seta at basal fifth; hind tibia with five slender dorsal setae intercalated with 5–6 shorter setae; first hind tarsomere with four longer dorsal setae. Wing with costal margin, pterostigma and distal patch brown infuscated ( Fig. 2a ); M 1 and M 2 slightly evanescent apically, not evanescent. Halter brown. Abdomen shining black with tergite 1 yellow laterally. Tergite 8 ( Fig. 2b ) acute distally. Epandrium with posterodorsal protuberance distinctly longer than anterodorsal protuberance. Anterior cercus thinner distally; posterior cercus with many anterodorsal and slender dorsal setae incurved, simple with few short spine-like setae at apex ( Fig. 2c–d ). Hypandrium ( Fig. 2e ) with a few setae medially, paired outward curved protuberances distally and acute subapical process medially.

Size. Body length 3.4 mm; wing length 3.6 mm.

Female. Frons approximately anterior ocellus width; face narrower than frons, approximately half anterior ocellus width. Fore tarsi black. Mid tibia with no setae on basal fifth; hind tibia with three slender dorsal setae on distal half and three shorter setae on basal half; first hind tarsomere with two longer dorsal setae; hind leg without pinnate scales. Wing slightly wider than in male, entirely brown infuscated ( Fig. 2f ) with anal margin lighter. Halter dark brown to black. Terminalia similar to M. flavus .

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

Geographical records. Brazil (Amazonas, Acre states), Fig. 8 .

Material. Holotype ♂: BRASIL, Amazonas , Pq [Parque] Nac [ional] [do] Jau , Rio Jau, Seringalzinho, 015028S–613523W, 01.viii.1995 // varredura, J.A. Rafael & J.F. Vidal ( INPA).

Paratypes: same data as holotype (1♂ 1♀ INPA, 1♀ CNC); Seringal, 27.iv–03.v.1995, varredura, J.A. Rafael & J.F. Vidal (1♂ INPA, 2♂ CNC); Acre, Cruzeiro do Sul, Rio Moa , 073702S–724615W, 15–28.xi.1996, varredura, mata, J.A. Rafael, J.F. Vidal & R. L. Menezes (2♂ 1♀ INPA, one male and one female in glycerin) .

Holotype condition. Good, not dissected.

Etymology. From Latin fuscus = black, ventris = belly, in reference to the black color of the abdomen.

Discussion. Macrostomus fusciventris , n. sp. appears close to M. ferrugineus (Fabricius) , M. fuscithorax , n. sp. and M. melanothorax , n. sp. on the basis of the shape of male tergite 8, which is acute distally. Macrostomus fusciventris has the thorax predominantly yellow unlike M. fuscithorax and M. melanothorax , which both have a black thorax. It differs from M. ferrugineus , which also has a predominantly yellow thorax, in having an entirely black abdomen rather than a yellow or reddish abdomen, and in having one pair of scutellar setae rather than two pairs (rarely one pair in M. ferrugineus ). It also differs from M. ferrugineus in the shape of the posterior cercus and the epandrium with the posterodorsal protuberance distinctly longer than anterodorsal protuberance.

Figures

FIGURE 2. Macrostomus fusciventris, n. sp., paratypes from Acre. A–E, male; A, wing; B, tergite 8, dorsal view with right setae omitted; C, terminalia, lateral view; D, detail of posterior cercus; E, hypandrium and phallus, lateral view. F, female wing. Abbreviations: AC, anterior cercus; EP, epandrium; PC, posterior cercus; T8, tergite 8; ST8, sternite 8. Scales: A = 0.5 mm; B,C,E–G = 0.2 mm; D,H = 0.1 mm.

FIGURE 8. Distribution map of species belonging to the Macrostomus ferrugineus species-group with tergite 8 acute distally. Symbols represent the known collection localities as follows: solid circle = M. fuscithorax, n. sp.; square = M. fusciventris,, n. sp.; solid triangle = M. melanothorax, n. sp.; open circle = M. ferrugineus.