1	Body almost entirely yellow (Fig. 89). Calypter entirely white. Frons strongly widened. Eye 2 × height of gena	A.tridentata (Loew)
–	Body almost entirely brown (Fig. 88). Calypter margin and hairs dark. Frons not much wider than eye. Eye at least 3 × height of gena	2
2	Vein dm-m present (Fig. 435). Wing length 1.9–2.0 mm♂, 1.9–2.2 mm♀. Ocellar triangle as long as wide. Gena horizontal on posterior 1/2, angled upwards on anterior 1/2. Three ori. Two dorsocentral setae. Acrostichal setulae in six irregular rows	A.nitida (Malloch)
–	Vein dm-m absent (Fig. 436). Wing length 1.8–2.4 mm♂, 2.1–2.6 mm♀. Ocellar triangle wider than long. Genal margin straight, angled upwards. Two ori with anterior seta sometimes reduced. Five dorsocentral setae. Acrostichal setulae in four scattered rows	A.orbitalis (Melander)