Parascatella balioptera

Parascatella balioptera

DIAGNOSIS.—Specimens of this species are similar to those of P. penai but are distinguished by the following combination of characters: color of shiny mesofrons dark blue, contrasting distinctly with brown, pollinose parafrons; mesonotal vittae and scutellar disc nearly concolorous with mesofrons although more pollinose; abdomen more slender; apical abdominal segments distinctly shinier than basal ones; fourth abdominal segment of male specimens two-thirds length of more pollinose third segment; white spot in base of cell M2 conspicuous.

DESCRIPTION.—Medium-sized shore flies, length 3.32 to 3.86 mm; mostly brown especially head, becoming olivaceous gray to bluish gray posteriorly, especially on abdomen and with some faintly subshiny to shiny darker blue areas.

Head (Figure 38): Shiny mesofrons with dark, metallic blue luster; pollinose parafrons mostly dull charcoal brown; fronto-orbits mostly concolorous with parafrons but with faint tinges of dark blue luster; dorsalmost postocular setae well developed, subequal with ocellar bristles; some specimens with a third pair of larger fronto-orbital bristles anterior of other pairs. Antenna brown, first and second segments darker with charcoal tinges; face more or less unicolorous, pollinose, grayish brown, sometimes becoming slightly grayer ventrally and dimly subshiny along slope of interfoveal carina; interfoveal carina with distinct crease dorsally; facial setae along oral margin many times longer than remaining facial setae, as long as combined length of antennal segments. Gena grayer than face and with faint subshiny bluish tinges.

Thorax: Generally pollinose, gray to brown. Mesonotal vittae and disc of scutellum subshiny to shiny, color and luster similar to mesofrons but to lesser degree; between vittae mostly brown; acrostichal setae well developed, subequal to dorsalmost postocular setae; mesopleuron and pteropleuron concolorous, faintly olivaceous gray, mesopleuron with some weak bluish tinges around larger mesopleural bristle; sternopleuron, front coxa and extreme anterior portion of mesonotum gray. Femora (Figures 40, 41) mostly concolorous with pleural areas of thorax; tibiae and tarsi darker with faint tinges of charcoal coloration. Wing (Figure 35) infumated, brown; male and female wing similar; whitish spot in cell R3 narrowly rectangular, usually constricted medially and often appearing as 2 spots; basal white spot in cell R5 largest; apical spot in same cell equidistant from alignment of posterior crossvein as basal spot; apical spot usually divided; white spot in discal cell abutting vein M3+4 and irregular in shape; usually with conspicuous although small white spot in cell M2 near mergence of posterior crossvein and vein M1+2.

Abdomen (Figure 39): Basal 2 abdominal segments densely pollinose, grayish blue; apical segments becoming shiner, more bluish and with some brownish coloration; second and third abdominal segments of male specimens very long, subequal, and approximately twice the length of the smaller fourth segment, male abdomen appearing quite long; female abdominal segments more or less subequal.

TYPE-MATERIAL.—Male holotype: “ARG(ENTINA), Juj(uy), 4200 m., Aguas Cal(ientes), 10 km., Ros(ario) d(e) Coyaguayma, 5. XI. 68. Pena.” Allotype and 40 paratypes (29 , 11 ): with same label data as holotype. Other paratypes as follows: ARGENTINA. SALTA: 1 , San Antonio de Los Cobres, 3750 m, 6 Nov 68, L. E. Peña; 2 , 1 , Chorillos, 23 km W San Antonio de Los Cobres, 3800 m, 6-7 Nov 68, L. E. Peña. The holotype, allotype, and most of the paratypes are in the Canadian National collection, Ottawa, type number 15237. Two pairs of male and female paratypes are in the National Museum of Natural History, Smithsonian Institution.

ETYMOLOGY.—Balioptera is a combination of the Greek adjective balios, meaning “spotted,” plus the noun pteron, meaning “wing,” in allusion to the spotted wing in specimens of this species.

GEOGRAPHIC DISTRIBUTION. (Figure 30).—The known distribution of this species is based on data from three localities only. The type-locality is in the province of Jujuy, the other two are in the province of Salta, Argentina. These localities range in elevation from 3700 to 4200 m.

PHYLOGENETIC RELATIONSHIPS.—Specimens of P. balioptera are very distinctive and could only be confused with those of P. penai; they are distinguished from the latter as outlined in the diagnosis. Whether P. penai is the sister species of P. balioptera is as yet unconfirmed, although their joint, overall similarity is probably a good indication. No apotypic character state has been found, however, to corroborate this relationship.