(23) Ascidiella aspersa (Müller, 1776) Status in U.K. – cryptogenic. Ascidiella aspersa (“fluted sea squirt”) has been recorded from many monitoring programme sites, each year since 2012, from scrape, settlement panel and rapid assessment samples. It has also been recorded from renewable energy structures in Orkney (Want et al. 2017). This species has been listed as “introduced” in the Mediterranean (López-Legentil and Legentil 2015) and is considered invasive in Japan and elsewhere (Nishikawa et al. 2014). Its type locality is southern Norway (Skagerrak) and it is widely considered to be native to northern Europe: however, it should be regarded as cryptogenic in the U.K. until its native range can be confirmed. NMS voucher reference number: NMS.Z.2017.144.117.

Published as part of Kakkonen, Jenni E., Worsfold, Tim M., Ashelby, Christopher W., Taylor, Andrea & Beaton, Katy, 2019, The value of regular monitoring and diverse sampling techniques to assess aquatic non-native species: a case study from Orkney, pp. 46-79 in Management of Biological Invasions 10 (1) on page 62, DOI: 10.3391/mbi.2019.10.1.04, http://zenodo.org/record/11969078