Gyrinus cavatus Atton 1990

Gyrinus cavatus Atton, 1990

Gyrinus cavatus was reported from Nova Scotia by Atton (1990) and Roughley (1991). In Nova Scotia it has only been found on Cape Breton Island (Fig. 9). Prior to Atton’s (1990) description of the species, separating it from the Gyrinus minutus Fabricius, 1798 (a Holarctic species recorded by him in North America from northern sites in British Columbia and the Yukon Territories east to Labrador and northern Newfoundland), previous records of G. cavatus were reported under the name of G. minutus. Roughley (1991) appears to have confused Atton’s (1990) findings, reporting both species from Nova Scotia and treating G. cavatus in the subgenus Gyrinus (s. str.) rather than in Gyrinulus Zaitsev. Oygur and Wolfe (1991) were apparently unaware of Atton’s (1990) separation of G. minutus (sensu lato) into two species. Kenner (2000) subsequently reported G. cavatus from Ontario, Québec, and Maine.

Gyrinus minutus is consequently removed from the faunal list of New Brunswick and Nova Scotia. The ecology of this G. cavatus has not been documented, however, Oygur and Wolfe (1991) reported G. minutus from woodland pools, rocky pools, semi-peaty lakes, peat-ringed bogs, and dystrophic habitats. Presumably G. cavatus is found in similar habitats. We have not been able to find voucher specimens of this species from New Brunswick in any Canadian collection. Consequently, further research should be conducted to ascertain if this species actually occurs in the province as reported by Roughley (1991).