Armostus Sharp, 1890

Hoshina, Hideto & Satô, Masataka, 2006, A Taxonomic Study of the Genus Armostus (Coleoptera: Hydrophilidae) from Japan, The Coleopterists Bulletin 60 (2), pp. 95-104 : 95-96

Genus Armostus Sharp, 1890

Armostus Sharp, 1890:358 (type species: Armostus optatus Sharp 1890 ); d’Orchymont 1926:208; d’Orchymont 1932:675; d’Orchymont 1942:1 (key to species); Hansen 1991:242; Hansen 1999 a:271; Hebauer 2001:37; Hebauer 2002:37.

Distribution. Oriental and Palaearctic Regions ( Japan).

Discussion. See Hansen (1991) for a review of the detailed generic morphological characters. In Japan, 16 genera belonging to the subfamily Sphaeridiinae were known to occur (d’Orchymont 1942; Satô 1985; Hansen 1999 b; Hori and Satô 2002; Hoshina and Satô 2004, 2005). The genus Armostus can be distinguished from other Japanese genera by having the following features: 1) dorsum strongly shining, 2) eyes not

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protuberant laterally and lateral margins of head simply and strongly curved, 3) pubescences of dorsum sparse, 4) pronotum simply convex, 5) elytral striae deep, 6) prosternum with antennal grooves, 7) prosternal plate highly or lowly carinate, 8), preepisternal elevation of mesothorax separated from metaventrite by a pronounced gap, 9), metaventrite with anterolateral ridges and lateral sutures, 10), both lateral sutures and episternum forming triangular areas, 11) or sutures running very close to episternum and hardly visible, 12) femoral line absent, 13) middle sclerite of genital segment relatively large, 14) medial lobe of aedeagus simple and sticky in ventral view.