Species profile: Agapetus delicatulus

October 16, 2014

Agapetus delicatulus McLachlan, 1884

Agapetus delicatulus is one of five members of the Family Glossosomatidae found in Ireland, and one of three members of the genus Agapetus, along with Agapetus fuscipes and Agapetus ochripes. It is a species whose larvae can be found in stony rivers, streams and lake shores. Its substratum preference ranges from coarse gravel to bedrock. Agapetus delicatulus 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 water.

The reproductive cycle of Agapetus delicatulus is flexible, with a life duration of up to 1 year. In terms of feeding, this species is largely a grazer/scraper, though some gathering/collecting is evident.

Notable features of the larvae of Agapetus delicatulus 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 Glossosoma by the presence of more than seven setae along the anterior margin of each side of the pronotum and the presence of median sclerites on the mesodorsum and metadorsum. Separating it from other species of the genus is by the presence of an inconspicuous, pale posterior-lateral seta on the 8th abdominal segment, rather than a dark, conspicuous seta and by the form of the lateral mark on the pronotum, which is large.

Adults of Agapetus delicatulus can be found on the wing from (May) June to August.

Records for Agapetus delicatulus 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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