Recently, the writer examined the specimens of Dinoderus befoueolatus (WOLLASTON) from imported rattan desk and chair in Tokyo and Heterobostrychus aequalis (WATERHOUSE) from seasoned wood of imported lauan timber in Naha, Okinawa. These two tropical bostrychid beetles are firstly founded in Japan. Now, Japanese bostrychid fauna consists of the following 16 species, belonging to 9 genera : Eudecatomus lanatus LESNE, Rhizopertha dominica (FABRICIUS), Dinoderus minutus (FABRICIUS), D. bifoveolatus (WOLLASTON), D. japonica LESNE, D. speculifer LESNE, Sinoxylon japonicum LESNE, Lichenophanes carinipennis (LEWIS), Heterobostrychus aequalis (WATERHOUSE), H. hamatipennis (LESNE), Bostrychopsis affinis LESNE, Xylothrips flavipes (ILLIGER), Xylopsocus bicuspis LESNE, X.capucinus (FABRICIUS), X. castanopterus (FABRICIUS), and X. galloisi LESNE. A number of exotic species, intercepted from time to time in imports from tropical countries are not mentioned in above species. Amony them, serious pests are Dinoderus minutus injurious to dried bamboo and Rhizopertha dominica to all kinds of stored grains. Sometimes Dinoderus japonicus damage to bamboo at the local level.
The biological notes and distinguishable characters of each species of genera Dinoderus and Heterobostrychus from Japan were given in this paper. New discovered species, Dinoderus befoueolatus may be distinguished from other Japanese species of Dinoderus by the following key:
1. Elytra with an impunctate and glabrous part on declivity; antennae 10-segmented. Body length 3.5-4.0 mm ......... D.speculifer LESNE
1'. Elytra without impunctate and glabrous part on declivity ......... 2
2. Antennae 10-segmented; 1st tarsal segment shorter or nearly as long as the 2 nd ; a median pair of tubercles on the pronotal anterior margin not so larger than others on its lateral sides ......... 3
2'. Antennae 11-segmented ; 1st tarsal segment longer than the 2nd ; a median pair of tubercles on pronotal anterior margin distinctly larger than others on its lateral sides. Body length 3.0-3.8 mm ...... D.japonicus LESNE
3. Body slightly stout and large ; anterior margin on pronotum sinuate with nearly triangular teeth ; the teeth not contiguous to each other at the base. Body length 2.5-3.5 mm ......... D. minutus (FABRICIUS)
3'. Body slender and small ; anterior margin of pronotum serrate with semicircular teeth ; the teeth contiguous to each other at the base. Body length 2.4-2.7 mm ......... D. bifoveolatus (WOLLASTON)
Heterobostrychus aequalis may be distinguished from H.hamatipennis only hitherto known species of this genus from Japan by the following characters ; weakly impressed frontoclypeal suture, numerous and strong punctures on basal half of pronotum, smooth and glabrous scutellum, glabrous elytra, and in male two distinct horns on each elytral declivity.

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