Bisubcosta L. PAPP, 2006

Papp, L., Merz, B. & Földvári, M., 2006, DIPTERA OF THAILAND A summary of the families and genera with references to the species representations, Acta Zoologica Academiae Scientiarum Hungaricae 52 (2), No. 2, pp. 97-269 : 129

Bisubcosta L. PAPP , gen. n.

( Figs 126–128 )

Type species: Bisubcosta oligoradiata L. PAPP , sp. n.

Gender: feminine.

Head globular, proboscis and palpi minute. Flagellomeres 14, flattened lateromedially, basal one much longer than broad, flagellomeres 10–13 quadrate, apical flagellomere with a cylindrical apical process ( Fig. 128 ). Two lateral ocelli, no anterior ocellus.

Scutum not much arched. Laterotergite bare. Scutellum short quadrate. No membranous area below scutellum. Metanotum strongly conical. Prosternum quadrate (divided sagittally) and bare.

Coxae thickened and comparatively long. Tibial spurs very long (see below): 0: 1: 1.

Two longitudinal subcostal veins: Sc1 terminates in costa ( Fig. 126 ), Sc2 ends free but close to costa. No R4 vein ( Fig. 127 ). R1 and R5 setose dorsally. R5 very long, much downcurving, like in Macroceridae . M1–2 stalk long. Cu2 short. A1 vein short, slightly longer than half of the distance of its base to wing margin, no A2 vein but only a short shadow (fold) of a vein. Alula minute, long triangular, calypter long but low, with long hairs.

Abdomen very narrow basally (see below). Male tergite 9 much broader than long, subtriangular. Gonocoxite long and not high, consequently ventral genital opening large: much longer than broad. Gonostylus broad and thick, no basal lobe.

Second subcostal vein (Sc2) is only a Sc1-R1 cross-vein in majority of cases in Mycetophilidae . However, in Keroplatidae Sc 2 is clearly a longitudinal vein, ending in R1 radial vein, e.g. in species of Xenoplatyura . Although it may completely missing ( Xenokeroplatus ) or reduced and ends close to H vein ( Keroplatus ). Though Nauarchia MATILE and some spp. of Euceroplatus have similar R5, this form is not common in the Keroplatidae .

Bisubcosta gen. n. does not key out to couplet 9/ 13 in MATILE’ s (1990) key, since there is no R4 vein. If we leave this character out of consideration, and since tibial microchaetae are well ordered in rows in whole their length, we may go to couplet 16: Nauarchia MATILE, 1990 , whose antenna is similar but otherwise that is not related.

Etymology. The generic name refers to the possession of two true subcostal veins, which is exceptional.

Figures

Figs 126–128. Biscubcosta oligoneura sp. n., holotype.126 = base of right wing, 127 = apical half of left wing, 128 = apex of flagellums