Key for distinguishing Phymatocera from other Japanese genera of Blennocampinae (excluding former Heterarthrinae)

1 All tarsi with plantar lobe on tarsomeres 1–4 (Fig. 3A); in Onychostethomostus, fore and middle tarsi with plantar lobe on tarsomeres 1–4, but hind tarsus with plantar lobe only on tarsomere 4 (Fig. 3B, C).................................. 2

- All tarsi with plantar lobe only on tarsomeres 3 and 4 (Fig. 3D).............................. Esehabachia, Halidamia

2(1) In fore wing, proximal part of vein 2A+3A usually distally separated from vein 1A (Fig. 4A–D), if fused with vein 1A or very close to it (Fig. 4B, E), cell 1A about 1/2 as long as cell 2A (Fig. 4E) or epicnemium present (Fig. 4G, I)................ 3

- In fore wing, proximal part of vein 2A+3A distally fused with vein 1A and cell 1A about 3/4 or more as long as cell 2A (Fig. 4F). Epicnemium absent (Fig. 4H)............................................................ Hoplocampoides

3(2) Fore wing with proximal part of vein 2A+3A not sinuate (Fig. 4A, C–E). If epicnemium present, epicnemial groove wide depression formed by elevation of epicnemium and usually seamlessly fused with anterior marginal ridge (Fig. 4G). In some species, either epicnemium or anterior marginal ridge, or both absent............................................. 4

- Fore wing with proximal part of vein 2A+3A sinuate (Fig. 4B), but often distally faint. Epicnemium present, with epicnemial groove linear, and completely separated from anterior marginal ridge (Fig. 4I)............................ Tomostethus

4(3) In fore wing, section of vein M between its junctions with vein Rs and crossvein 1m-cu shorter than 1/2 vein Rs+M (Fig. 4A); proximal part of vein 2A+3A simple and straight. Flagellomere 2 0.4–0.5 × flagellomere 1 in dorsal length.... Nipponocampa

- In fore wing, section of vein M between its junctions of vein Rs and crossvein 1m-cu longer than 1/2 vein Rs+M (Fig. 4B, F); proximal part of vein 2A+3A of fore wing various (Fig. 4C–E). Flagellomere 2 usually more than 0.5 × flagellomere 1 in dorsal length............................................................................................... 5

5(4) Dorsal tentorial pit widely and deeply open ventrally (Fig. 5A–C). Proximal part of vein 2A+3A of fore wing various (Fig. 4A, C–E). Epicnemium present or absent (Fig. 4G, H)............................................................ 6

- Dorsal tentorial pit isolated (Fig. 5D) or shallowly or narrowly and shallowly open ventrally (Fig. 5E, F). Proximal part of vein 2A+3A of fore wing distally curved anteriorly (Fig. 4C), rarely straight (Fig. 4A). Epicnemium absent (Fig. 4H)................................................................... Apareophora, Ardis, Monardis, Pareophora, Periclista

6(5) Mesoscutellum without distinct punctures and microsculptures (Fig. 6A), or mostly or entirely covered with minute punctures of similar size (Fig. 6B). Notaulus not changing size abruptly near middle (Fig. 6E) or slightly so (Fig. 6F). Apical maxillary palpomere longer than torulus height (Fig. 6I). Flagellomere 2 0.7 × or more flagellomere 1 in dorsal length.............. 7

- Mesoscutellum usually posteriorly with large punctures or distinct microsculptures (Fig. 6C, D), if as above, notaulus changing size abruptly near middle (Fig. 6G, H) or apical maxillary palpomere shorter than torulus height. Flagellomere 2 sometimes less than 0.7 × flagellomere 1 in dorsal length........ “ Cladardis hartigi ” (Naito 2019, 2020, not Liston, 1995; genus and species wrong), Eutomostethus, Habachia, Lagonis, Masaakia, Megatomostethus, Monophadnoides, Monophadnus, Nesotomostethus, Nipponostethus, Onychostethomostus, Phymatoceropsis, Stethomostus, Zaphymatocera

7(6) Tarsal claws without inner tooth (Fig. 7A) or with one inner tooth (Fig. 7B, C). Gena in lateral view with breadth about 1/2 or more basal thickness of mandible (Fig. 7E)................................................................. 8

- Tarsal claws with two inner teeth (Fig. 7D). Gena in lateral view with breadth less than 1/2 basal thickness of mandible (Fig. 7F)............................................................ Paracharactus leucopodus (genus questionable)

8(7) Ovipositor sheath 0.4–0.5 × as long as abdomen (Fig. 8A). Genal orbit without pit (Fig. 8C) or with one pit (Fig. 8D). Male flagellum with setae various in length, but if genal orbit with pit, setae as long as or longer than middle width of flagellum 1 in dorsal view (Fig. 8F)......................................................................... Phymatocera

- Ovipositor sheath 0.6–0.7 × as long as abdomen (Fig. 8B). Genal orbit with one to three pits (Fig. 8E). Male flagellum with setae shorter than 1/2 middle width of flagellum 1 (Fig. 8G)........................................ Phymatoceriola