Water Beetles of the Kermadec Islands (Dytiscidae and Hydrophilidae)

Abstract

A map of the Kermadecs could lead one to believe that freshwater habitats are extensive but they are in fact very limited. Dr J. C. Watt (pers. comm.) informs me that on his visit to Raoul Island in 1967 he noted that Blue Lake was polluted by the last volcanic eruption, Green Lake was both hot and saline, leaving Tui Lake as the best aquatic habitat, although both Blue and Green Lakes do contain some beetles. The Denham Bay Lagoon has been another good source of specimens and there are also two springs (one near Lava Point, the other west of Bell's Flat: see Watt 1975) which apparently do not support water beetles, and a couple of cattle troughs. .is early as 1908 Dr W. R. B. Oliver collected water beetles from the Denham Bay Lagoon and more recently the extensive collecting done by J. C. Watt and G. A. Samuelson indicates that the water beetle fauna is limited to one endemic and t\vo widely distributed dytiscids, and one equally widespread hydrophilid.