Cardiasilus gen. nov.

Figs 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 19

Type species.

Cardiasilus aysu sp. nov. by present designation.

Etymology.

From the Greek feminine word kardia = heart + asilus = common epithet of robber flies. The name refers to the distinct inflated epandria, somewhat heart ideogram-shaped in dorsal view. The gender is masculine.

Diagnosis.

Head. Antenna ~ 3 / 4 as long as eye height (Fig. 2 A). Scape and pedicel subequally long (Fig. 2 E). Postpedicel lanceolate, laterally compressed and slightly tapering towards apex, about as long as scape and pedicel combined (Fig. 2 E). Stylus slightly longer than postpedicel, composed of two elements (Fig. 2 E). Face wide, slightly narrowing at antennal level and slightly gibbous at lower 1 / 3, mystax restricted to gibbosity (Fig. 2 D). Frons with parallel slopes, slightly concave at antennal level, twice wider than higher (Fig. 2 D). Palpus one-segmented, short, ~ 1 / 5 length of proboscis. Proboscis ~ 3.5 / 5 as long as eye height (Fig. 2 C). Thorax. Acrostichal setae indistinct (Fig. 2 C). Anterior dorsocentral macrosetae absent, scutum with three to four pairs of posterior dorsocentral macrosetae (Fig. 2 C). Scutellum tumid with pair of marginal macrosetae (Fig. 2 B). Anatergite bare. Postmetacoxal area membranous. Legs. Femora swollen. Wing. Distinctly shorter than abdomen, with bifurcation of veins R 4 and R 5 placed before apex of discal cell by approx. length of r-m cross vein (Fig. 2 G). Distance between apex of veins R 4 and R 5 ~ 1.5–2 × longer than distance between apex of veins R 5 and M 1 (Fig. 2 G). Cells m 3 and cua closed and petiolate before wing margin (Fig. 2 G). Abdomen. Abdominal sternites 2–6 with two to three pairs of pale yellow macrosetae mid-laterally (Figs 2 H, 6 E, 9 E). Sternite 8 with mid-posterior digitiform projection almost as long as sternite 8 length (Figs 3 E, 7 E, 10 E). Terminalia. Epandria inflated laterally and posteriorly, resembling the ideogram of heart in dorsal view. Phallus long and thin, longer than length of hypandrium plus gonocoxite, divided into two prongs along its entire length (i. e., Fig. 3 A – C, F – I).

Remarks.

Cardiasilus gen. nov. is similar to Myaptex Hull by the inflated male epandria (Fig. 14 A – D), but can be easily distinguished by the following set of characters: postpedicel lanceolate, approx. as long as length of scape and pedicel combined (Fig. 2 E, F); face slightly gibbous at lower 1 / 3 (Fig. 2 C); scutum lacking distinct rows of acrostichal setae; anterior dorsocentral setae absent; femora mostly covered with short black setae (Fig. 2 C); male sternite 8 with a long digitiform projection at posterior margin (Figs 2 H, 3 C, E); gonocoxite L-shaped, with rounded apex and covering the gonostylus versus postpedicel oval, shorter than scape and pedicel combined (Fig. 13 C); face distinctly gibbous at lower 2 / 3 (Fig. 13 C); scutum with two distinct rows of acrostichal setae (Fig. 13 A, C); three to four pairs of anterior dorsocentral macrosetae; femora mostly covered with long vestiture of white setae (Fig. 13 A); male sternite 8 without projections at posterior margin; gonocoxite squared at base, with a digitiform apicoventral projection acute apically (Fig. 14 F) in Myaptex . It is also similar to some undescribed Lecania Macquart species, including Nerax eurylabis (Wiedemann, 1828) a species that belongs in Lecania (unpublished data) with inflated male epandria, but can be easily distinguished by the scutellum with one pair of apical macrosetae and the abdominal sternites with macrosetae (scutellum bare in Lecania or at most bearing tiny, short setulae and sternites only with sparse setae).

Distribution.

The new genus is known to occur only in the state of Mato Grosso do Sul (Central-West Brazil) and department of Cordillera (Central-West of the Oriental Region of Paraguay), in biomes of Pantanal and Chaco, respectively (Fig. 19).