Macrostomus occidentalis, 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 : 55-58

Macrostomus occidentalis , n. sp.

( Figs. 20–22 , 40 )

Diagnosis. Postcranium black dorsally, rather yellow ventrally; thorax, abdomen and legs predominantly yellow; male fore tarsomeres 1–3 light brown, not white distally; hind tarsomere 1 with 7 slender dorsal setae; cell dm rather truncate; M1, M2 and A1 rather evanescent distally; male tergite 8 acute distally with apex rather blunt.

Description. Male. Frons approximately one­third of anterior ocellus width. Face slightly wider than frons only at apex. 1 pair of ocellar setae. Postcranium black dorsally, yellow ventrally. Postgena with slender setae. Antennae black with scape and pedicel yellow; flagellum trisegmented. Palpus yellow. Thorax yellow with yellow to gray­brown pruinescence. 4 dorsocentral setae; 1 presutural supra­alar seta; no postsutural supra­alar seta; 3 notopleural setae; 2 pairs of scutellar setae; 3–5 antepronotal setae; 1–3 tiny proepisternal setae; 3–5 katatergital setae. Legs entirely yellow with apex of hind femur and all tarsi slightly light brown. Slightly stronger setae: hind femur with 5–6 anteroventral subapical stronger. Slender setae: hind trochanter with 1 posterior long and slender; hind tibia with 7 dorsal; hind tarsomere 1 with 7 dorsal. Wing with costal margin and pterostigma inconspicuously light brown­infuscated; cell dm rather truncate; M1, M2 and A1 rather evanescent distally. Halter yellow with knob slightly brown. Abdomen yellow with dorsal half of terminalia black. Terminalia. Tergite 8 ( Fig. 20 ) with rather blunt projection distally. Epandrium ( Fig. 21 ) with anterodorsal and posterodorsal lobes of subequal length. Anterior cercus ( Fig. 21 ) rather elongate; posterior cercus with bifid apex, slender anterodorsal setae and a small inconspicuous simple protuberance at margin. Hypandrium ( Fig. 22 ) membranous at posterior basal half, without strong setae and with a rather membranous paired protuberance distally.

Female. unknown.

Size. Body not measured; wing 3.4 mm.

Geographical distribution. Colombia (Cauca) ( Fig. 40 ).

Material. Holotype ɗ: COLOMBIA [Cauca], Buenaventura, xi.6.1950, Michelbacher and Ross (CAS).

Holotype condition. Left antenna and left mid leg lost. Abdomen in glycerine.

Etymology. From Latin occidens = west, in reference to the distribution, west of the Andes.

Discussion. M. occidentalis appears related to M. ferrugineus (Fabricius) and M. fulvithorax (Curran) which all possess a rather long and truncate tergite 8 projection (although shorter and more acuminate in M. ferrugineus , shorter and truncate in M. fulvithorax ). M. occidentalis differs from both in the structure of the male genitalia and in the postcranium, which lacks a dorsal shinning spot (present in the other two species), as well as in hind tarsomere 1, which bears 7 slender dorsal setae (maximum of 5 in the other two species).

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 20 – 22. Macrostomus occidentalis, n. sp., holotype ɗ. 20, tergite 8, dorsal view, right setae not represented; 21, epandrium and cerci, lateral view; 22, hypandrium and phallus, lateral view.