Key to the species of Perissonemia occurring in Japan

1 Subcostal area of hemelytron 0.5 times as wide as discoidal area at widest part of each, with 3 rows of areolae (occasionally 4 rows in very small sections) throughout its length (Figs 5C, 6C); anterior margin of pygophore strongly concave in middle part of dorsum (Fig. 9C). ............................. P. yaeyamensis sp. nov.

– Subcostal area of hemelytron less than 0.5 times as wide as discoidal area at widest part of each, with 3 rows of areolae at apex and 2 rows (occasionally 3 rows in very small sections) in remaining parts (Figs 5A, B, 6A, B); anterior margin of pygophore weakly concave in middle part of dorsum (Figs 9A, B). ...... 2

2 Body length 3.7–4.1 mm (Figs 1A, B, 2A, B); rostrum not reaching beyond posterior margin of mesosternum (Fig. 7A); costal area of hemelytron more than 0.5 times as wide as subcostal area at widest part of each, with 2 rows of areolae in basal part and a single row in remaining parts (Figs 5A, 6A). .................................... ............................................. P. occasa Drake, 1942

– Body length 3.0– 3.5 mm (Figs 1C, D, 2C, D); rostrum reaching beyond posterior margin of mesosternum (Fig. 7B); costal area of hemelytron 0.5 times as wide as subcostal area at widest part of each, with a single row of areolae throughout its length (Figs 5B, 6B). .... ........................................... P. okinawensis sp. nov.