Acanthosoma, CURTIS, 1824

Key to Japanese species of the genus Acanthosoma View in CoL

1 Maxillary plate without tubercle; posterolateral comer of abdominal segment VII angulate in male; posterior margin of abdominal segment VII with a pair of concave black spot in female....................................................... A. expansum HORVATH, 1905 Maxillary plate with a small tubercle; posterolateral comer of abdominal segment VII not angulate in male; posterior margin of abdominal segment VII without concave spot in female............................................................................................................... 2

2 Posterior margin of pronotum and inner margin of corium with broad red bands...... 3 Pronotum and corium without red marking................................................................. 4

3 Body slender; humeral angle weakly projected, blackish; mesostemal carina not reaching head................................................................. A. spinicolle JAKOVLEV, 1880 Body broader; humeral angle strongly projected, reddish; mesostemal carina reaching head................................................... A. haemorrhoidale angulatum JAKOVLEV, 1881

4 Humeral angle distinctly spinous............................ A. giganteum MATSUMURA, 1913 Humeral angle not spinous.......................................................................................... 5

5 Scutellum with reddish mark; humeral angle triangular, blackish.............................. ................................................................................... A. denticaudum JAKOVLEV, 1880 Scutellum without markings; humeral angle round, or triangular and reddish........... 6

6 Posterolateral comers of pronotum with a pair of small, triangular extensions; a pair of posterior projections of male pygophore stout, with round apex.............................. ................................................................................. A. crassicaudum JAKOVLEV, 1880 Posterior margin of pronotum without above structure; a pair of posterior projections of pygophore long and slender.................................................................................... 7

7 Humeral angle round, orange to yellowish red; posterior end of female genitalia not arcuate ( Fig. 6b); male genitalia as in Fig. 3b................. A.fmficula JAKOVLEV, 1880 Humeral angle triangular, brightly red; female genitalia biarcuate caudally.............. 8

8 Antennal segments IV and V dark brown, segment III blackish on apical half; Male genital projections produced in parallel, densely with apical hairs ( Fig. 3c); posterior end of female genitalia strongly arcuate as in Fig. 6c.................................................... ................................................................................... A. labiduroides JAKOVLEV, 1880 Antenna! segments II to V blackish; male genital projections widely divergent without apical hairs ( Fig. 3a); posterior end of female genitalia weakly arcuate as in Fig. 6a............................................. A. ishiharai YAMAMOTO et M. HAYASHI , sp. nov.

Remarks. Acanthosoma giganteum MATSUMURA, 1913 had been transferred into the genusAnaxandra STAL by MATSUMURA (1931), but HASEGAWA (1966) pointed out that it should be included in the Acanthosoma . Recently, GOLLNER-SCHEIDING (2006) followed the former proposal in the "Catalog of the Heteroptera of the Palaearctic Region Vol. 5".