Towards the resolution of taxonomic and nomenclatural problems concerning the typification of Acrosorium uncinatum (Delesseriaceae: Rhodophyta)

Abstract

Evidence is presented that the lectotype of Fucus laceratus var. uncinatus Turner is a hook-producing form of Cryptopleura ramosa, in confirmation of the taxonomic judgement expressed by earlier workers. Two hook-forming delesseriacean taxa occur in the British Isles: Cryptopleura ramosa (Hudson) Kylin ex Newton var. uncinata (Turner) Newton and Acrosorium venulosum (Zanardini) Kylin. The latter name should be applied to the alga with a worldwide distribution that is currently known as Acrosorium uncinatum.