Key to subgenera of Dacnusa and related species in Palaearctic China

1. Vein 1-SR +M of fore wing absent (Figs A7, 8); veins 3-CU1 and CU1b of fore wing strongly widened, wider than vein m-cu (Subgenus Aphanta Förster) ............................................................................ 2

- Vein 1-SR +M of fore wing present (Figs C4, D8); veins 3-CU1 and CU1b of fore wing slender, not or slightly wider than vein m-cu............................................................................................... 3

2. First metasomal tergite beyond pair of spiracles parallel-sided, 1.8–2 times as long as apically wide; fore wing with pterostigma distinctly longer than vein 1-R1; mesoscutum almost entirely smooth.... D. (Ap.) sasakawai Takada, rec. nov.

- First metasomal tergite evenly widened towards its apex, 1.1–1.3 times as long as apiclly wide; fore wing with pterostigma as long as, or less than, vein 1-R1; mesoscutum with central lobe strongly sculptured anteriorly.... .. D. (Ap.) hospita (Förster)

3. Vein r of fore wing absent and basal part of vein 3-SR+SR1 of fore wing lined along pterostigma (Fig. B4) (Subgenus Agonia Förster) ............................................................... D. (Ag.) adducta (Haliday), rec. nov.

- Vein r of fore wing present and basal part of vein 3-SR+SR1 of fore wing separate to pterostigma......................4

4. First metasomal tergite strongly widened towards its apex (Fig. C7), often not longer than wide, its surface almost smooth or finely sculptured and usually covering with fairly dense pubescence; pubescence of metapleuron and propodeum always very dense and usually long; pterostigma narrow and long, goes over the vein 3-SR; marginal cell usually reaching or almost reaching the wing apex (Subgenus Dacnusa s.str.) ................................................................5

- First metasomal tergite not strongly widened towards its apex, usually long and much longer than wide (Fig. D6), always sculptured and usually sparsely pubescent; metapleural and propodeal pubescence usually not dense; pterostigma of fore wing variable, but rarely elongate; characterized by a sharp sexual dimorphism in shape and colour (Subgenus Pachysema Förster) ....................................................................................................6 5. Pterostigma conspicuously widened towards its apex, vein 1-R1 0.4 times length of pterostigma............................................................................................. D. (D.) maculipes Thomson, rec. nov.

- Pterostigma not or only very slightly widened toward its apex, vein 1-R1 0.5 times length of pterostigma.................................................................................................. D. (D.) confinis Ruthe

6. First mandibular tooth almost absent; notaulus complete; medio-posterior depression of mesoscutum nearly extends to anterior edge of mesoscutum......................................................... .. D. (P.) heterodentatus, sp. nov.

- First mandibular tooth normal; notaulus only restricted to declivous fore part of mesoscutum; medio-posterior depression extends to middle of mesoscutum................................................... D. (P.) megastigma Tobias