(3) Bonnemaisonia hamifera Hariot, 1891

Status in U.K. – non-native.

Bonnemaisonia hamifera (“Bonnemaison’s hook weed”) was introduced to Europe from Japan and was first found in southern England in 1890 (Maggs and Stegenga 1999); it has been recorded from the monitoring programme each year since 2012, at many sites from both rapid assessment and scrape samples. It has previously been recorded from Orkney by Wilkinson (1975), who found it at Skatelan Skerry, Burray Ness and the Bay of Kirkwall; Nall et al. (2015) summarised other Orkney records from (Marine Nature Conservation Review (MNCR) surveys.