Pialea Erichson, 1840

Schlinger, Evert I., Gillung, Jessica P. & Borkent, Christopher J., 2013, New spider flies from the Neotropical Region (Diptera, Acroceridae) with a key to New World genera, ZooKeys 270, pp. 59-93 : 74-76

Pialea Erichson, 1840

Diagnosis.

Body shape not arched; coloration non-metallic. Head width much narrower than thorax width; hemispherical; ocellar tubercle shape raised, rounded, two ocelli present, anterior ocellus absent; postocular ridge and occiput rounded; posterior margin of eye rounded; eyes densely pilose; not contiguous above antennal base, rarely contiguous below; palpus absent; proboscis length greatly reduced, with sparse pile; antennae located on middle of frons, either nearer to ocellar tubercle or to mouthparts; flagellum elongate, slightly tapered or paddle-shaped; apex with terminal setae present or absent; scapes fused; postpronotal lobes not enlarged or contiguous medially; antepronotum narrow; subscutellum barely visible beneath scutellum; legs not elongated; tibial spines present apically; pulvilli present; wing markings and microtrichia absent; costal vein ending near wing apex; costal margin straight; humeral crossvein absent; radial veins straight; R1 not inflated distally; R4+5 originating at apex of basal cell r4+5 and then forking into veins R4 and R5 (Fig. 36); crossvein 2r-m present between M1 and R4+5, bisecting cell r4+5; cell formed by 2r-m narrow, elongate; R4 without spur vein; M1, M2 and M3 present (M3 fused with CuA1), rarely one M vein or two M veins present, all typically reaching wing margin; discal cell closed; cell m3 present, CuA1 joining M3 and running towards margin; CuA2 fused to A1 before wing margin and running towards margin; anal lobe well developed; alula weakly developed; abdomen greatly rounded, inflated; tergites smooth, rounded.

Comments.

Pialea is a relatively rare South American genus that comprises four species described from Brazil and another one described from Ecuador. The genus was described by Erichson (1840) for his new species Pialea lomata from Brazil. Later, Westwood (1876) named a second species, Pialea lutescens , also from Brazil. Two more species from the Oriental Region were later described in this genus, Pialea jardinei and Pialea auripila ( Brunetti 1912), but they were subsequently transferred to Astomella Latreille, 1809and Astomelloides Schlinger, 1959, respectively ( Schlinger 1956, 1959). Schlinger (1956) revised the genus and described three more species, Pialea antiqua , Pialea capitella and Pialea ecuadoriensis . Pialea is presumably closely related to Stenopialea Speiser, 1920 (a South African endemic genus) and Archipialea Schlinger, 1973 (Chile) based on antennal and wing characters (Schlinger 1973; Barraclough 1985). Pialea are characterized by the fusion of the scapes and the dichoptic eyes (except in Pialea capitella ). Species in this genus also show strong sexual dimorphism in the length, insertion and shape of the antennae, the length of the abdomen and the color and maculation of the body.

Key to species of Pialea