First record of the Asian Antithamnion sparsum Tokida, 1932 (Ceramiales, Rhodophyta) in Nova Scotia, Canada

Abstract

We report the first record of a non-native species of Antithamnion detected on the eastern shore of Nova Scotia, Canada and assign these collections to the Asian Antithamnion sparsum based on available morphological and molecular data. Two collections of this non-native species were made at three sites in the subtidal (10 m) in August 2021, and it was observed as a dominant subtidal (10 m) turf at an additional four sites from April to August 2022. We describe here morphological traits that match the original type description of A. sparsum and generated rbc L 3P data (851 bp) for two 2021 collections which closely match a record in Genbank from South Korea that is likely A. sparsum (99.9% identity). These collections represent the first occurrence of A. sparsum in the Northwest Atlantic.