Species profile: Glossosoma boltoni

November 3, 2014

Glossosoma boltoni Curtis, 1834

Glossosoma boltoni is one of five members of the Family Glossosomatidae found in Ireland, and one of two members of the genus Glossosoma, along with Glossosoma conformis. It is a species whose larvae can be found in large streams and rivers with a substratum preference ranging from coarse gravel to boulders and bedrock. Glossosoma boltoni has a case made of sand grains held together by silk, but spaces remain between the grains that allow oxygenated water to pass through. The species has no preference with regard to pH of the water.

In temperate areas, Glossosoma boltoni has a flexible reproductive cycle, with a bivoltine (two generations per year) noted, and lives for up to one year. In terms of feeding, this species is largely a grazer/scraper, though some gathering/collecting is evident.

Notable features of the larvae of Glossosoma boltoni include the passing similarity to uncased species in that they lack case-bearing protuberances on the first abdominal segment and also have elongate lateral sclerites on the anal prolegs. The species is separated from the genus Agapetus by the presence of no more than seven setae along the anterior margin of each side of the pronotum and the absence of median sclerites on the mesodorsum and metadorsum. Separating it from Glossosoma conformis is by a number of features including the presence of a dark, conspicuous posterior-lateral seta on the 8th abdominal segment, rather than an inconspicuous, pale seta, while the band of pigmentation at the posterior margin of the pronotum, closest to the median suture, is never entirely black, with brown coloration, similar to the colour of the pronotum anterior to the dark band, particularly notable towards the rear and also towards the median suture.

Adults of Glossosoma boltoni can be found on the wing from (March) April to October.

Records of Glossosoma boltoni on the National Biodiversity Data Centre mapping system can be found here.

References

Barnard, P. and Ross, E. (2012) The Adult Trichoptera (Caddisflies) of Britain and Ireland. RES Handbook Volume 1, Part 17.

Graf, W., Murphy, J., Dahl, J., Zamora-Muñoz, C. and López-Rodríguez, M.J. (2008) Distribution and Ecological Preferences of European Freshwater Species. Volume 1: Trichoptera. Astrid Schmidt-Kloiber & Daniel Hering (eds). Pensoft, Sofia-Moscow.

O’Connor, J.P. (2015) A Catalogue and Atlas of the Caddisflies (Trichoptera) of Ireland. Occasional Publication of the Irish Biogeographical Society, No. 11.

Wallace, I.D., Wallace, B. and Philipson, G.N. (2003) Keys to the Case-bearing Caddis Larvae of Britain and Ireland. Scientific Publication of the Freshwater Biological Association No. 61.

Last updated: 31/05/2016

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