The discovery of the Window-winged sedge (Hagenella clathrata) in Ireland

June 25, 2018

Hagenella clathrata at Ower, Co. Galway. Photograph by Caitriona Carlin

Hagenella clathrata at Ower, Co. Galway. Photograph by Caitriona Carlin

The story of the discovery of Hagenella clathrata in Ireland began with a post to the Insects/Invertebrates of Ireland Facebook group on the 26 June 2017 by Tina Claffey looking for a species identification. The image was of an adult caddisfly with black and orange mottled wings photographed on Abbeyleix Bog, Co. Laois on 22 May 2016. At first glance, due to a superficial similarity, the possibility that it was Philopotamus montanus was considered; however, the habitat was all wrong – woodland on a raised bog, rather than a fast-flowing, rocky mountain stream. It was Dr Martin Gammell of GMIT who first suggested Hagenella clathrata as a contender; a species that has never been recorded in Ireland. A brave suggestion based on a photo, I thought. Brave, but as it turned out, correct. Further expertise was brought to bear on the issue to great effect, with Graham Vick confirming that it was indeed the Window winged sedge H. clathrata, a Biodiversity Action Plan (BAP) species in UK and a species that was not previously known from Ireland.

Haganella clathrata_Tina Claffey

The first encounter with Hagenella clathrata in Ireland at Abbeyleix Bog, Co. Laois. Photograph by Tina Claffey – www.TinaClaffey.com

The next step, according to Irish expert Dr Jim O’Connor, was to take at least a single adult specimen for confirmation before the species could be added to the Irish list. Unfortunately, attempts to relocate the species on Abbeyleix Bog in 2017 were unsuccessful and so more visits in 2018 were planned.

As the presumed flight period for H. clathrata approached, the eyes of those with an interest in caddisflies in Ireland turned once again to Abbeyleix Bog, but at this point luck (or fate, for those who hold with such ideas) intervened. While out surveying for the protected butterfly Marsh Fritillary (Euphydryas aurinia) on 1 June 2018 at Ower, Co. Galway, Dr Gammell and Dr Caitriona Carlin spotted some dark-winged caddisflies and took the opportunity to capture one. On getting it under a microscope, it was discovered to be male H. clathrata. From photographs of the genitalia, Dr O’Connor was able to confirm the identification and with an adult in hand, the species can now be added to the Irish list.

Irish entomology continues to throw up new species across many groups, with some being new arrivals, while others might well have been there all along, but avoided detection. No doubt there will be further additions to the Irish Trichoptera list in the future, so keep your eyes open and your net in hand.

References

Gammell, M.P., Carlin, C.M., O’Connor, J.P., O’Connor, M.A. and Brophy, J.T. (2018) The window winged sedge Hagenella clathrata (Kolenati, 1848) confirmed as an Irish species. Bulletin of the Irish Biogeographical Society 42: 45-57.

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