The Helicopsychidae, a caddisfly family new to British Columbia (Insecta: Trichoptera)

The Helicopsychidae is a small but distinctive family of the Trichoptera containing 10 genera (Morse 2007). It is found in most faunal regions around the world (Wiggins 1996a). The cosmopolitan genus Helicopsyche consists of about 238 described species (Morse 2007) and is the sole North American genus in the family. Although this genus is mostly tropical in distribution, it contains five known species north of Mexico (Morse 2007). Helicopsyche borealis (Hagen) is the only species ranging north into Canada. Despite its name, it is not a typical transcontinental boreal species but is only distributed northerly relative to other species in the genus. It is widespread and common over much of North America (Wiggins 1996a) but has not been recorded from the Yukon (Wiggins and Parker 1999) or previously in British Columbia (BC) (Nimmo and Scudder 1978, 1983). It prefers clear, fast-flowing streams, but also inhabits the littoral zone of lakes (Wiggins 1996a, Schmid 1998) and is among the caddisflies most tolerant of high water temperatures (Wiggins 1996a), perhaps a reflection of the tropical origin of the genus (Williams et al. 1983). The most striking feature of almost all species in the family is the larval case, which, finely built of sand grains and silk, strongly resembles a tightly coiled snail shell. Indeed, H. borealis was originally described as a gastropod (Lea 1834). This distinctive, compact and consolidated case probably is an adaptation for a larval life in beds of gravel and stones (Williams et al. 1983, Wiggins 1996a). The larvae feed on diatoms and plant detritus on the surfaces of the rocks or in the spaces between them (Williams et al. 1983). This note records the first specimens of H. borealis and the family Helicopsychidae from BC. The main material examined was collected by Gina Roberts from the San Jose River, 2.4 km east of its mouth in Williams Lake (52o05’50”N x 121o59’52”W) on 9 November 1998. The water at the collection site was up to 50 cm deep and flowed at about 0.3 to 0.5 m/sec. During spring run-off, the river’s water level rises 1 to 1.5 m. Larvae were abundant; over the 3 or 4 m of river examined, there were several hundred larvae per square decimetre. The specimens, about 100 in total, are housed in three ethanol lots in the Royal British Columbia Museum (ENT001000978, 79, 80). In addition, two small collections of specimens from the Chilcotin River were deposited as vouchers at the Royal BC Museum as part of Environment Canada’s Fraser River Action Plan. Although the larval specimens were labeled and identified to family in the project, the Helicopsychidae was not listed in the benthic invertebrate report describing the collections and their analysis (Rosenberg et al. 1999). The data for the two sites on the Chilcotin River are: 52o12’41”N x 123o50’50”W, 21.x. 1994, 3040’ asl, T.B. Reynoldson; and 52o18’52”N x 123o58’35”W, 22.x.1994, 3180’ asl, T.B. Reynoldson. These sites are northwest of Redstone between Puntzi Creek and Chilcotin Lake.

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