Expansion of the Known Range of Two Bog-Dwelling Beetles into Nova Scotia

Abstract

Two species of aquatic beetle are reported from northern Cape Breton Island, Nova Scotia. Helophorus lineatus Say (Hydrophilidae) was not known from Atlantic Canada (except New Brunswick) whereas Dytiscus alaskanus Balfour-Browne (Dytiscidae) has not previously been reported from the Maritime Provinces. Both were collected in boggy barrens, the former found in streams and the latter in ponds. Two legs of an expedition to the Caribou Barrens, Cape Breton Highlands National Park, were undertaken in June and July of 1996 to investigate species of flora and fauna considered rare in Nova Scotia. Two beetle species, Helophorus lineatus Say (Hydrophilidae) and Dytiscus alaskanus Balfour-Browne (Dytiscidae) were collected which had not been recorded in Nova Scotia before. All specimens from this project have been deposited in the Nova Scotia Museum of Natural History. The Caribou Barrens (46°43' N, 60041' W) is a boggy barrens bor- dered by boreal forest which went through a spruce budworm (Choristoneura fumiferana (Clemens)) defoliation in the late 1970s and early 1980s (Fig. 1). The only older trees around the barrens are white birches (Betula papyrifera), although conifers are regrowing. The Bar- rens is dotted with many ombrotrophic ponds. These were of diverse sizes from quite small, having less than one meter square surface area, to quite large, well over 500 m2. Dwarf birches (Betula michauxii) and several herbaceous plants (e.g. Carex spp., Eriophorum tenellum Nutt) occupied the upper littoral zone. The streams which drain the barren (Fig. 2) flow into the North Aspy River. The banks of the streams and ponds are sometimes steep, with the stream banks often displaying a half-meter or more of exposed peat. Three specimens of Helophorus lineatus were collected in July in the lotic waters of the barrens. The streams were rarely over a meter wide and reasonably fast flowing (no flow measurements were taken). The