Macrurohelea ventanensis n. sp.

(Figs. 33–36, 49–50)

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Diagnosis. Males: the only species with a pale brown halter; tergite 9 abruptly tapered on basal 1/5, with rounded apex; tergite 10 with straight margins, apex straight with small, rounded apicolateral process with single divergent seta; parameres stout, nearly straight, widely separated, subparallel, with slender, slightly hooked, curved, fingerlike apical process; aedeagus basal arch deeply concave, heavily sclerotized, distal portion more lightly sclerotized, apex with a short hyaline quadrate process. Females unknown.

Male. Head (Fig. 33) brown. Eyes separated medially by width of 2.5 ommatidia with numerous short interommatidial spicules. Antennal flagellomeres distinctly separated; flagellomeres 1–8 broadly moniliform, 9–10 narrow, slightly elongate, 11–13 more elongate, 13 longest. Palpus brown; segment 3 with small sensory pit slightly distad of mid-length; segment 4 0.66 length of segment 3, segment 5 slightly longer than segment 3, with bulbous apex; palpal ratio 2.00–2.50 (2.25, n =2). Thorax (Fig. 34) uniformly dark brown; scutum with 3 stout prealar setae, one postalar seta; scutellum with 4 stout, long setae. Legs medium brown; femora, tibiae very slender, greatly elongate; ventral palisade setae on tarsomere 1 of fore, hind legs; tarsomeres 4 cordiform; tarsal claws small, mostly straight, slightly curved on extreme bifid tips. Wing (Fig. 35) membrane pale, slightly infuscated with minute microtrichia; anterior veins yellowish brown, posterior veins paler; 2 nd radial cell twice as long as 1st; cell r 3 with poorly developed intercalary vein; r-m crossvein slightly shorter than petiole of M; medium-size macrotrichiae on costa; wing length 1.31–1.35 (1.33, n =2) mm, width 0.45–0.47 (0.46, n = 2) mm; costal ratio 0.59–0.63 (0.61, n =2); halter pale brown. Abdomen brown. Genitalia (Figs. 36, 49–50). Tergite 9 abruptly tapered on basal 1/5, distal portion broad, elongate with rounded apex, extending 0.75 length of gonocoxites. Tergite 10 with straight margins, apex straight with small rounded divergent apicolateral process with single medium-size seta; cercus slender, fingerlike. Sternite 9 2.4x broader than long, posteromedian margin with shallow excavation. Gonocoxite stout, twice as long as wide, with rounded sub-basal mesal extension; gonostylus 0.77 length of gonocoxite, proximal ¼ broadest, distal ¾ greatly curved with pointed apex. Parameres (Fig. 49) broadly separated, heavily sclerotized; basal apodeme stout, laterally directed, apex blunt; distal halves stout, nearly straight, sub-parallel, with slender, slightly hooked, apical, curved finger-like process.Aedeagus (Fig. 50) broadly triangular, 0.80 length of basal width; basal arm stout, laterally directed with curved truncate tip; basal arch deeply concave, heavily sclerotized, extending nearly 2/3 of total length; distal portion lightly sclerotized, tapered distally, with a short, apical hyaline quadrate process.

Female. Unknown.

Type material. Holotype male, paratype male, labeled “ Macrurohelea ventanensis Spinelli, Ronderos and Grogan ”, “ Argentina, Buenos Aires, Reserva Parque Prov. Ernesto Torquinst, arroyo Ventana, 38º03’31.7’’S, 62º01’11.8’’W, 574 m, XI/2012, A. Siri – M. Donato, Malaise trap.

Distribution. Argentina, known only from the type-locality in southern Buenos Aires province.

Derivation of specific epithet. The specific epithet is in reference to Sierra de la Ventana, where the type-series was collected.

Discussion. Males of this new species are similar to those of M. kuscheli . However, in M. kuscheli flagellomeres 4–9 are fused, and the aedeagus is slightly triangular with the distal portion slender, bifid, with short, separated tips.