The value of regular monitoring and diverse sampling techniques to assess aquatic non-native species: a case study from Orkney Author Kakkonen, Jenni E. * & Marine Services, Harbour Authority Building, Scapa, Orkney, KW 15 1 SD, United Kingdom Author Worsfold, Tim M. APEM Ltd., Diamond Centre, Works Road, Letchworth Garden City, SG 6 1 LW, United Kingdom Author Ashelby, Christopher W. APEM Ltd., Diamond Centre, Works Road, Letchworth Garden City, SG 6 1 LW, United Kingdom Author Taylor, Andrea * & Marine Services, Harbour Authority Building, Scapa, Orkney, KW 15 1 SD, United Kingdom Author Beaton, Katy * & Marine Services, Harbour Authority Building, Scapa, Orkney, KW 15 1 SD, United Kingdom text Management of Biological Invasions 2019 2018-10-17 10 1 46 79 http://dx.doi.org/10.3391/mbi.2019.10.1.04 journal article 299406 10.3391/mbi.2019.10.1.04 a53d05d0-2083-4f05-a83c-8f418fdc5468 1989-8649 11969078 (24) Ascidiella scabra (Müller, 1776) Status in U.K. – cryptogenic. Ascidiella scabra has been recorded from many monitoring programme sites, each year since 2012, from scrape, settlement panel and rapid assessment samples. Genetic studies ( Nishikawa et al. 2014 ) have confirmed the distinction between this species and A. aspersa , to which it is very similar and the two species share the same type locality. It is likewise considered invasive in Japan but has been listed as cryptogenic in the Mediterranean ( López-Legentil and Legentil 2015 ). It should be considered cryptogenic in British waters until its origin has been determined. NMS voucher reference number: NMS .Z.2017.144.120.