Hexacola lemnaphilae Gaddi & Diaz, sp. nov.

Hexacola lemnaphilae Gaddi & Díaz sp. nov.

(Figs. 1−9)

Description. Female (Figs. 1−6). Total length 1.17 mm. Body scarcely setose; shinny yellowish brown; club flagellomeres, borders of mesosomal areas and posterolateral part of metasoma darker; mandibles, antennal flagellomeres 1−4, veins and legs yellowish.

Head (Figs. 1−3) in anterior view higher than wide. Antennae with 13 articles, flagellomere 1 straight, longer than 2 (2.5: 1.5); club consisting of seven flagellomeres, with rhinaria. Relative length and width of antennal articles 2.0(1.2): 1.2(1.2): 2.5(0.8): 1.5(0.8): 1.5(0.8): 1.5(0.8): 2.0(1.0): 2.0(1.0): 2.0(1.0): 2.0(1.2): 2.3(1.5): 2.3(1.5): 3.0(1.5). Toruli elevated anteriorly at their external side. Vertex and central area of face smooth, with few short setae. Malar sulcus present. Compoud eyes small, convex, with few short setae. Genae flat. Occiput striate.

Mesosoma (Figs. 3−5) in lateral view scarcely longer than high. Pronotal plate smooth, anterior part faintly transversely striate, median bridge broad, lateral cavities open, posterior margin almost straight. Sides of pronotum smooth, highly setose behind genae, with a row of long setae on upper half of anterior margin. Mesoscutum smooth, convex in profile, in dorsal view as long as wide; anterior parallel lines faint; notauli absent, replaced by a row of long setae which turns anteriorly and continues laterally; suprategular furrows tenuous. Lateral bars reaching in length half of scutellum, broad at their base, dorsally smooth, external sides longitudinally striate. Scutellum and scutellar plate convex in lateral view. Proximal and mid surface of scutellum disk longitudinally striate, distal surface reticulate rugose, posterior margin rounded. Scutellar foveae as long as wide, smooth. Scutellar plate long and narrow, scarcely elevated above the disk, dorsal surface smooth with two setiferous punctures anterior of glandular release pit. Anterodorsal part of mesopleuron depressed; ventral part under mesopleural carina with faint striae; subalar pit absent. Metapleuron subrectangular, poorly sculptured; anteroventral cavity conspicuous and setose; hind margin distinct. Propodeum setose except on the carinae and area between them; propodeal carinae subparallel. Forewings apically rounded, completely hyaline, densely setose; marginal cilliation long; marginal cell open. Mid coxae with a small dorsolateral setose patch; hind coxae with a larger patch of setae posterodorsally.

Metasoma (Fig. 6) sessile. Setiferous ring on base of large tergite dense, broadly interrupted dorsally, with a weak row of long setae on each side posteriorly. Distally smooth.

Male (Figs. 7−9). Total length 1.26 mm. Similar to female except: antennae with 15 articles (Fig. 7), filiform, flagellomere 1 strongly curved, laterally flattened, distally swollen, longer than the following flagellomeres; flagellomere 2 straight and cylindrical, similar to the following flagellomeres. Flagellomeres 1−12 with rhinaria.

Etymology. In allusion to host species Lemnaphila neotropica.

Distribution. Argentina.

Type locality. Buenos Aires: Berisso.

Material examined. HOLOTYPE. 1 Ψ, MLP 5282/1, ARGENTINA: Buenos Aires, Berisso, 4-vii-1970, obtained from puparium of Lemnaphila neotropica Lizarralde det. 1977, collected from a carpet of Lemna minuta (= L. minima) and Azolla filiculoides; Schnack col.; Hexacola Díaz det. (MLP). PARATYPES, 3 ΨΨ, MLP 5282/3−5, and 1 ɗ, MLP 5282/6, same data as Holotype.

Biological comments. Hexacola lemnaphilae Gaddi & Díaz sp. nov. was reared from pupae of L. neotropica (Fig. 9). Little it is known about the biology of this fly, the adults hold a close relationship with the pleustonic carpet, and the larvae are leaf miners and pupate inside least duckweed L. minuta (Lizarralde de Grosso 1977, 1978).