Key to species of the noctuabundus group

1 Left mandible in frontal view markedly narrowed apically, blunted at tip (Fig. 53). Apical margin of labrum almost straight, at most only slightly concave medially...................................................................... 2

- Left mandible in frontal view at most only moderately narrowed apically, truncate or subtruncate at tip (Figs. 54 & 55). Apical margin of labrum almost straight or markedly concave medially................................................ 4

2 Median lobe of aedeagus (Figs. 47–52) in lateral view arcuate, narrow, angularly bent ventrally just at apex and slightly swollen at tip forming a small apical capitulum. Internal sac without distinct spiny patches.......... T. doiinthanonensis Ito, 1997

- Median lobe of aedeagus not as above, with apex bent dorsally. Internal sac with spiny patches apically................ 3

3 Median lobe of aedeagus (Figs. 59–64) in lateral view rather evenly arcuate, slightly bent dorsally just at apex; internal sac with two (dorsal and ventral) wide spiny patches apically. Microsculpture on head more distinct, consisting of obliterated meshes. Apex of last visible abdominal sternite (VII) subtruncate in male and widely rounded in female. Gonocoxite (Figs. 65 & 66) with relatively wider base. Smaller: body length 7.3–8.4 mm ..................................... T. schmidti sp. n.

- Median lobe of aedeagus (Figs. 68–70) in lateral view slightly arcuate, with almost straight apical half; apex thin, hooked ventrally; internal sac with a large curved spiny patch apically. Meshes on head almost not recognized. Apex of last visible abdominal sternite (VII) rounded in both sexes. Gonocoxite (Figs. 71 & 72) with relatively narrower base. Larger: body length 8.5–9.1 mm .......................................................................... T. fedorenkoi sp. n.

4 Left mandible in frontal view moderately narrowed apically, subtruncate at tip (Fig. 54). Apical margin of labrum almost straight, at most only slightly concave medially. Median lobe of aedeagus (Figs. 89–91) in lateral view more robust, with relatively large basal bulb, with apex slightly protruding dorsally forming there a very small apical capitulum; internal sac with a spiny formation apically. Female genitalia as in Figs. 92 & 93........................... T . noctuabundus Habu, 1954

- Left mandible in frontal view wide and truncate at tip (Fig. 55). Labrum more or less markedly concave anteriorly. Median lobe of aedeagus (Figs. 77–81) in lateral view slenderer, with apex thin, not protruding dorsally or ventrally; internal sac with narrow spiny patches along sides apically. Female genitalia as in Figs. 82 & 83...................... T . subangulatus Ito, 2021