Diversity of aquatic and riparian Coleoptera of the Philippines: checklist,state of knowledge,priorities for future research and conservation

The diversity of the aquatic and strictly riparian beetles of the Philippines is reviewed. A checklist (with 317 species and subspecies) of the aquatic and riparian Coleoptera of the Philippines is provided for the first time herein. This checklist covers the following families (number of species and subspecies in parentheses): Hydroscaphidae (1), Gyrinidae (15), Dytiscidae (65), Noteridae (4), Haliplidae (2), Hydraenidae (15), Hydrochidae (2), Spercheidae (1), Hydrophilidae (72), Scirtidae (49), Elmidae (23), Dryopidae (2), Psephenidae (16), Eulichadidae (1), Limnichidae (20), Heteroceridae (5), Malachiidae (5), Lampyridae (15), Nitidulidae (4). A total of 201 species and subspecies (63%) are considered to be endemic to the Philippines. Aquatic/riparian beetle genera and families that are still unrecorded but likely to occur in this country are briefly discussed. Based on estimates at the genus level, it is concluded that about 850 aquatic and riparian species can be expected to occur in the Philippines. The implication of the Philippine biogeographic history for this diversity is discussed. The potential of aquatic/riparian beetles as bioindicators is briefly examined. The dilemma of aquatic invertebrate conservation is analysed and priorities for future research are outlined.