Nigranitida gibba Webb

Webb, Donald W. & Metz, Mark A., 2004, The South American genus Nigranitida Metz (Diptera: Therevidae: Therevinae) with the description of three new species, Zootaxa 757, pp. 1-16 : 8-10

Nigranitida gibba Webb spec. nov.

Etymology: gibber (Latin) = humpbacked, protuberant, swollen. This name refers to the shape of the basodorsal lobe on the gonostylus and is used as an adjective.

Diagnosis. Like Nigranitida costata and N. irwini in lacking setae on the katepisternum. Like N. irwini in having the maxillary palpus and halter yellow. It differs from the male of N. irwini in having the setae on the mesonotum black intermixed with white appressed setae; the hypoproct extending beyond the apex of the cercus ( Fig. 11 ); the apical margin of the gonocoxite ventral view short, broadly pointed ( Fig. 12 ); the gonostylus with a basodorsal lobe and a thin lateral flange ( Fig. 15 ); the anterior margin of the ejaculatory apodeme truncate ( Fig 16 ); and the ventral apodeme bearing a pair of ventromedial projections ( Fig. 17 ). The female of gibba is unknown.

Description of holotype male (MEI 073578).

Body length 5.8 mm.

Head. Length 0.70 mm. Ommatidia smaller ventrally and laterally. Frons pruinescence gray with small median dark area dorsally; setae absent. Antenna (pedicel and flagellum missing); scape dark reddish brown, pruinescence gray, length 0.08 mm, length/ width 1.0, setae pale brown, short. Parafacial pruinescence silver gray. Maxillary palpus yellow; length 0.30 mm, length/width 5.0; setae pale yellow. Genal setae white. Occipital setae white ventrally becoming pale yellow dorsolaterally; macrosetae dark reddish brown, scattered.

Thorax. Macrosetae 2 np, 1 sa, 1 pa, 0 dc, 2 sc. Mesonotum dull brown, pruinescence brownish gray; setae black, erect intermixed with white, appressed setae. Pleuron dark reddish brown, pruinescence silver, dense; setae white on propleuron, anepisternum, laterotergite, metanepisternum, and scutellum, absent on katepisternum. Wing. Length 3.5 mm, length/width 2.9. Membrane opaque, diffuse pale brown; veins and pterostigma brown. Halter pale yellow. Legs. Femora brown, pruinescence white; ventral setae white; av 2:1:4, pv 0:0:3. Tibiae dark yellowish brown, apex brown. Tarsi dark reddish brown.

Abdomen. Cuticle dark reddish brown, posterior fourth of each tergite yellow, pruinescence white, dense; dorsal setae white, appressed, lateral setae white, erect. Terminalia . Dark yellow. Epandrium ( Fig. 11 ) quadrate, lateral margins tapered posteriorly, anterior margin emarginate medially, posterolateral margin short, broadly pointed, setae dark yellow. Hypoproct ( Fig. 11 ) quadrate, posterior margin slightly emarginate, ending distal to apex of cercus. Gonocoxite ventral view ( Fig. 12 ) quadrate, rounded laterally, tapering posteriorly to broad, almost truncate point, setae dark yellow; dorsal view ( Fig. 13 ) gonocoxal bridge broad; lateral view ( Fig. 14 ) rectangular, tapering apically to broad rounded point. Gonostylus ( Fig. 15 ), basodorsal lobe short, irregular shaped; ventral margin straight, setae dark yellow; lateral surface with flat pointed flange ( Fig. 13 ). Aedeagus with dorsal apodeme ( Fig. 16 ) oval, sides rounded, anterior fourth narrowed, anterior margin truncate; ventral apodeme ( Fig. 17 ), anterior margin truncate, tapering laterally to fine point, ventral surface with pair of small, ventromedial projections; distiphallus ( Fig. 16 ) tapered posteriorly, lateral view ( Fig. 18 ), sinuate; ejaculatory apodeme ( Fig. 16 ), anterior half moderately expanded laterally, anterior margin truncate, not reaching anterior margin of dorsal apodeme.

Female. Unknown.

Biology. Nigranitida gibba was hand netted in November. Specimens Examined. The holotype male (MEI 073578) was collected in ARGEN­ TINA : Catan Li, near cow ponds, 21.xi. 1989, 900m, by S. A. Marshall and is deposited in DEBU.

Figures

FIGURES 11 – 18. Nigranitida gibba spec. nov. 11. Tergite 8, epandrium, cerci, hypoproct, dorsal view. 12. Sternite 8, hypandrium, gonocoxite, ventral view. 13. Gonocoxite, hypandrium, dorsal view. 14. Gonocoxite, left lateral view. 15. Gonostylus, left lateral view. 16. Aedeagus, dorsal view (inset ejaculatory apodeme cross­section). 17. Aedeagus, ventral view. 18. Aedeagus, left lateral view. Scale = 0.1 mm.