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

2007·1.1 MB·English

by  Robert A Cannings

J.Entomol.Soc.Brit.Columbia 104,December2007 89
SCIENTIFIC NOTE
The Helicopsychidae, a caddisfly family new
to British Columbia (Insecta: Trichoptera)
ROBERT A. CANNINGS^ ^ and GINA ROBERTS^
The Helicopsychidae is a small but dis- 1983, Wiggins 1996a). The larvae feed on
tinctive family of the Trichoptera contain- diatoms andplant detritus on the surfaces of
ing 10 genera (Morse 2007). It is found in the rocks or in the spaces between them
most faunal regions around the world (Williams etal 1983).
(Wiggins 1996a). The cosmopolitan genus This note records the first specimens of
Helicopsyche consists of about 238 de- H. borealis and the family Helicopsychidae
scribed species (Morse 2007) andis the sole from BC. The main material examined was
North American genus in the family. Al- collected by Gina Roberts from the San
though this genus is mostly tropical in dis- Jose River, 2.4 km east ofits mouth in Wil-
tribution, it contains five known species liams Lake (52"05'50"N x 12r59'52"W)
north ofMexico (Morse 2007). on 9 November 1998. The water at the col-
Helicopsyche borealis (Hagen) is the lection site was up to 50 cm deep and
only species ranging north into Canada. flowed at about 0.3 to 0.5 m/sec. During
Despite its name, it is not a typical trans- springrun-off, the river's water level rises 1
continental boreal species but is only dis- to 1.5 m. Larvae were abundant; over the 3
m
tributed northerly relative to other species or 4 of river examined, there were sev-
in the genus. It is widespread and common eral hundred larvae per square decimetre.
over much of North America (Wiggins The specimens, about 100 in total, are
1996a) but has not been recorded from the housed in three ethanol lots in the Royal
Yukon (Wiggins and Parker 1999) orprevi- British Columbia Museum (ENTOOl-
ously in British Columbia (BC) (Nimmo 000978, 79, 80).
and Scudder 1978, 1983). It prefers clear, In addition, two small collections of
fast-flowing streams, but also inhabits the specimens from the Chilcotin River were
littoral zone of lakes (Wiggins 1996a, deposited as vouchers at the Royal BC Mu-
Schmid 1998) and is among the caddisflies seum as part ofEnvironment Canada's Era-
most tolerant of high water temperatures ser River Action Plan. Although the larval
(Wiggins 1996a), perhaps areflection ofthe specimens were labeled and identified to
tropical origin ofthe genus (Williams et al. family in the project, the Helicopsychidae
1983). was not listed in the benthic invertebrate
The most striking feature of almost all report describing the collections and their
species in the family is the larval case, analysis (Rosenberg et al 1999). The data
which, finely built of sand grains and silk, for the two sites on the Chilcotin River are:
strongly resembles a tightly coiled snail 52«12'41"N X 123'^50'50"W, 21.x. 1994,
shell. Indeed, H. borealis was originally 3040' asl, T.B. Reynoldson; and
described as a gastropod (Lea 1834). This 52°18'52"N X 123°58'35"W, 22.x.1994,
distinctive, compact and consolidated case 3180' asl, T.B. Reynoldson. These sites are
probably is an adaptation for a larval life in northwest of Redstone between Puntzi
beds of gravel and stones (Williams et al. Creek andChilcotin Lake.
' Correspondingauthor.
^ Royal British Columbia Museum, 675 Belleville Street, Victoria, British Columbia V8W 9W2, (250)
356-8242,[email protected]
^ 2002GrebeDrive,WilliamsLake,BritishColumbia V2G5G3
90 J.Entomol. Soc.Brit.Columbia 104,December2007
Wiggins (1996a) illustrated the larva with various shades of brown. They lack
and case. The mean maximum diameter of ocelli, the mesotibiae do not have preapical
30 cases from the San Jose River sample spurs and the costa of the hindwing is
was 2.7 mm (range 2.2-3.3 mm). According broadly angled and bears a row ofhooks on
to Ross (1944) and Wiggins (1996a) the the basal half (Schmid 1998). The vertex
diameter of the case of a full-grown larva has large setal warts extending from the
ranges from about 5 to 7 mm, suggesting mesal margins ofthe eyes to the mid-dorsal
that these specimens were about half line and anteriorly to the middle ofthe head
grown. Williams et al. (1983) summarized (Wiggins 1996b).
what little is known about the species' life We thank Claudia Copley (Royal BC
history. They indicated that an Ontario Museum, Victoria, BC) for locating the
population they studied was probably Chilcotin River specimens; and David
univoltine, with the adults emerging in the Rosenberg (Department of Fisheries and
lasthalfofJune. Oceans, Winnipeg, Manitoba), Trefor Rey-
No adult Helicopsyche specimens were noldson (Acadia University, Wolfville,
collected at the San Jose or the Chilcotin Nova Scotia) and Stephanie Strachan
River sites. Adults ofH. borealis should be (Environment Canada, Vancouver, BC) for
mm
looked for in BC. They are about 5-7 information aboutthem.
long and typically are pale yellow washed
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