Macrostomus tarsalis, Rafael, José Albertino & Cumming, Jeffrey M., 2006

Rafael, José Albertino & Cumming, Jeffrey M., 2006, New species of Macrostomus Wiedemann (Diptera, Empididae) from Colombia, Ecuador and Peru, Zootaxa 1136, pp. 49-64 : 60-64

Macrostomus tarsalis , n. sp.

( Figs. 29–39 , 40 )

Diagnosis. Prosternum yellow; anterolateral part of scutum, including postpronotal lobe without pruinosity; female hind leg with ventral pinnate scales at distal quarter of femur and some dorsal near middle of femur, dorsal along dorsal face and ventral at basal half of hind tibia; male hind tarsomere 3 widened in dorsal view; cell dm rather acute; M1, M2 and A1 rather distinct.

Description. Male. Head lost. Thorax black with prosternum yellow; gray­blue pruinose with anterolateral part of scutum, including postpronotal lobe without pruinosity. 3 dorsocentral setae, the mid one weaker; 3 notopleural setae; 4–5 antepronotal setae; 2 proepisternal setae being one strong; 7–8 katatergital setae. Legs, predominantly yellow with apex of mid femur and apex of mid tibia, distal half of hind femur, entire hind tibia and all tarsi, black; tarsomere 2 inconspicuously yellow medially. Slightly stronger setae: mid tibia with 1 anterodorsal near base, 2–3 ventral very short along distal three­quarter; hind femur with 2 anterior at basal three­quarter and at distal three­quarter, no anteroventral setae. Slender setae: hind tibia with 4 dorsal; hind tarsomere 1 with 1 dorsal. Hind tarsomere 3 modified, widened in dorsal view. Wing ( Fig. 29 ) brown­infuscated at costal cell, pterostigma and apex of cell r2+3; cell dm rather acute; M1, M2 and A1 rather distinct. Halter light yellow to white. Terminalia ( Figs. 30–33 ). Tergite 8 ( Fig. 30 ) with large broad projection and wide basal median cleft; sternite 8 ( Fig. 31 ) with posterolateral projection. Epandrium ( Fig. 32 ) with anterodorsal and posterodorsal lobes of subequal height. Anterior cercus elongate; posterior cercus complex, slightly bifid distally with long slender setae at margin; with a wide ventral protuberance with elongate digitiform yellow setae distally, internally with elongate protuberance with short distal yellow setae and a smaller and thinner simple protuberance near base of the latter. Hypandrium ( Fig. 33 ) with large sinus at apex and a unique protuberance inside sinus, many long setae on distal posterior half.

Female. Frons wider than anterior ocellus width; face approximately anterior ocellus width, without pruinosity; 2 pairs of ocellar setae; postgena setae rather long. Prosternum yellow and propleuron partially yellow. 3–4 dorsocentral setae; 3–4 antepronotal setae (dorsocentral and antepronotal setae variable in the same specimen). Slightly stronger setae: mid tibia with 1 anterodorsal near base, 1 posterodorsal near middle, 2 posteroventral at base and apex of median third and 1 anteroventral at apex of median third. Pinnate scales on hindleg ( Fig. 34 ): ventral at distal quarter and some dorsal thinner near middle of femur; dorsal along dorsal face and ventral at basal half of tibia. Wing ( Fig. 35 ) wider than in male, brown­ infuscated at costal and r1 cells and apex of r2+3 cell.

Terminalia ( Figs. 36–39 ). Tergite 8 and sternite 8 as depicted in Figs. 36 . Tergite 8 ( Fig. 38 ) with large distal cleft. sternite 8 ( Fig. 37 ) rather membranous ventrally. Genital fork ( Fig. 39 ) elongate with short lateral arms not projected laterally. Genital chamber membranous.

Size. Body length not measured; wing 4.8 mm.

Geographical distribution. Ecuador ( Fig. 40 ).

Material. Holotype ɗ: ECUADOR, Napo­Pastaza, 2–8 mi [les] N[orth] of Puyo, 953 m, II.9.1955 (sic), E.I. Schlinger & E.S. Ross collectors (CAS). Paratype. Same data and same pin as the holotype (1Ψ CAS).

Holotype condition. Head lost. Right wing mounted in microslide; terminalia in glycerine together with female terminalia of paratype.

Etymology. From Greek tarsos = tarsus, in reference to the shape of the hind tarsomere 3.

Discussion. As mentioned previously, M. tarsalis apparently belongs to the same group as M. alpinus , M. ciliaticosta and M. lineatus , on the basis of these species possessing a rather membranous area medially on the hypandrium. M. tarsalis is distinct from the remaining species in having tergite 8 with a large broad distal projection and a wide basal median cleft, sternite 8 with a posterolateral projection, and the hypandrium with a large sinus at the apex and many long setae on the distal posterior half.

Figures

FIGURE 40. Distributions of new species of Macrostomus. Symbols represent the known collection localities as follows: square = M. alpinus; diamond = M. ciliaticosta; circle = M. lineatus; star = M. occidentalis; triangle = M. penai; cross = M. tarsalis.

FIGURES 29 ­ 33. Macrostomus tarsalis, n. sp., holotype ♂. 29, wing; 30, tergite 8, dorsal view, right setae not represented; 31, sternite 8, ventral view, left setae not represented; 32, terminalia, lateral view; 33, hypandrium and phallus, lateral view.

FIGURES 34 ­ 39. Macrostomus tarsalis, n. sp., paratype Ψ. 34 right anterior leg, posterior view, larger and pinnate setae represented; 35, wing; 36, tergite 8 and sternite 8, lateral view, setae not represented; 37, sternite 8, ventral view, left setae not represented; 38, female tergite 8, dorsal view, setae not represented; 39, female genital fork.