Key to species of the genus Taiwanhormius

1. Parallel vein (CU1a) of fore wing not interstitial to cubital vein (2-CU1), arising from anterior third of the vein (3-CU1) closed brachial (subdiscal) cell distally. Antenna with 23 antennomeres.—POL equal to OD. Ovipositor sheath about 0.7 × as long as metasoma. Body length 2.3 mm.— China (Taiwan) .................................. T. affinis Belokobylskij, 1988

- Parallel vein (CU1a) of fore wing interstitial to cubital vein (2-CU1) (Figs 2A; 4A). Antenna with 17–19 antennomeres (Figs 1A; 3A) ............................................................................................ 2

2. Malar space 1.5 × larger than basal width of mandible (Fig. 3B). Prescutellar depression almost entirely smooth (Fig. 3G). Brachial (subdiscal) cell of fore wing distally closed on level of recurrent vein (m-cu) or rarely weakly before it (Fig. 4A). Nervulus (cu-a) of fore wing distinctly postfurcal to basal vein (1-M). First metasomal tergite weakly rugulose-granulate (Fig. 4B). Body length 1.5–1.9 mm.— China (Taiwan), Japan .......................... T. granulosus Belokobylskij, 1988

- Malar space almost equal to or only weakly larger than basal width of mandible (Fig. 1B). Prescutellar depression rugulose (Fig. 1F). Brachial (subdiscal) cell of fore wing distally closed distinctly before recurrent vein (m-cu) (Fig. 2A). Nervulus (cu-a) of fore wing subinterstitial to basal vein (1-M) or sometimes even weakly antefurcal. First metasomal tergite entirely coarsely rugulose-reticulate and without granulation (Figs 1F; 2B). Body length 1.3–1.8 mm.— South Korea .................................................................................................. T. austrokoreanus sp. nov.