Key to genera and species of Japanese Tribelocephalinae

1 Interocular space narrower than eye in dorsal view; posterior pronotal lobe not sulcate along meson ( Opistoplatys)........ 2

- Interocular space wider than eye in dorsal view; posterior pronotal lobe sulcate along meson (Abelocephala)............. 3

2 Body approximately 6.7 mm long; antennal flagellum longer than antennal segment II; posterior pronotal lobe without yellow- ish longitudinal stripe or spot along meson................................................. Opistoplatys minimus

- Body approximately 7.6 mm long; antennal flagellum shorter than antennal segment II; posterior pronotal lobe with yellowish longitudinal stripe or spot along meson................................................ Opistoplatys flavolineatus

3 Head twice as long as width across eyes.................................................. Abelocephala longiceps

- Head 1.5 times or less as long as width across eyes........................................................... 4

4 Body length more than 3.8 mm; rostral segment I twice or more as long as segment II............................... 5

- Body length less than 3.6 mm; rostral segment I 1.7 times or less as long as segment II.............................. 6

5 Mandibular plates acutely angled at anterior corner and strongly projected anteriorly in dorsal view; outer (larger) cell of hem- elytral membrane acutely angled apically; posterior process of pygophore narrow in dorsal view.. Abelocephala yaeyamensis

- Mandibular plates nearly right-angled at anterior corner and weakly projected anteriorly in dorsal view; outer (larger) cell of hemelytral membrane rounded apically; posterior process of pygophore wide in dorsal view........... Abelocephala major

6 Mandibular plates acutely angled at anterior corner and strongly projected anteriorly in dorsal view; outer (larger) cell of hem- elytral membrane rounded apically; posterior process of pygophore narrow in dorsal view; lateral projections of female abdominal tergite IX long and gently constricted at middle.................................... Abelocephala nakatai

- Mandibular plates nearly right-angled at anterior corner and weakly projected anteriorly in dorsal view; outer (larger) cell of hemelytral membrane acutely angled apically; posterior process of pygophore wide in dorsal view; lateral projections of

female abdominal tergite IX short and not constricted at middle................................................. 7 7 Head approximately 1.4 times in male and 1.5 times in female longer than width across eyes; corial cell more or less fuscous in macropterous form; posterior process of pygophore with straight apical margin in dorsal view; valvula I with 4 setae............................................................................................ Abelocephala albula

- Head approximately 1.6 times in male and 1.7 times in female longer than width across eyes; corial cell evenly pale in macropterous form; posterior process of pygophore with weakly curved apical margin in dorsal view; valvula I with 2 setae.................................................................................... Abelocephala araiorum