Fauna and distribution of the bembidiine ground beetles (Coleoptera: Carabidae) in the investigated areas of the Yodogawa River system, central Japan

Bembidiine ground beetles in the investigated areas of the Yodogawa River system (Osaka, Kyoto and Hyogo Prefectures, central Japan) were surveyed, as a component of the general research project (2007-2010) conducted by the Osaka Museum of Natural History (OMNH). Thirty-six species of the subfamily Bembidiine (14 Tachyini species and 22 Bembidiini species) are recorded, including available species preserved in the OMNH from 1930s to 2006. The number of Tachyini species found in the project is almost the same number of preserved specimens. However, the number of Bembidiini species is reduced to 50-60% compared to the number of stored specimen records in both the trunk and branch of the Yodogawa river system. The distribution range of species is various and corresponded to each species inhabited areas such as mountains, flats and estuaries. Bembidiine adults are active from March to November though some species were collected during the winter season. Adults almost emerged from June to September in Tachyini species and from April to July in Bembidiini species. Chronological analysis of specimen records in ten year intervals showed gradual variations in Bembidiine fauna. These results show how the development of collection techniques and the environmental changes as river improvement projects and massive development of residential zones in and around the river-system have influenced these species.