Schizymenia jonssonii sp. nov. (Nemastomatales, Rhodophyta): a relict or an introduction into the North Atlantic after the last glacial maximum?

Karl Gunnarsson,Juliet Brodie,Stephen Russell

doi:10.1111/jpy.12957

Karl Gunnarsson, Juliet Brodie + Show 1 more

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https://doi.org/10.1111/jpy.12957

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Abstract

North‐Atlantic records of Schizymenia dubyi extend along the eastern shores of the North Atlantic from Morocco to southern Britain and Ireland, and the species is also recorded from Iceland. A study was undertaken to confirm the identity of the specimens from Iceland that were geographically separate from the main distribution of S. dubyi and in contrast to other species of the genus did not have gland cells. We analyzed rbcL and COI molecular sequence data from Icelandic specimens and compared the results with those for Schizymenia specimens available in GenBank. For both markers, Schizymenia was shown to be a monophyletic genus. The Icelandic specimens were clearly genetically distinct from S. dubyi and formed a well‐supported clade with Schizymenia species from the Northern Pacific. Based on these results, we have described a new species, Schizymenia jonssonii, which can be distinguished by molecular phylogeny, its lack of gland cells and by being strictly intertidal. Crustose tetrasporophytes with identical COI and rbcL sequences were found at the same locations as foliose plants. Schizymenia apoda is reported for the first time in the UK, its identity confirmed by rbcL sequence data. In light of these findings, it is likely that by further molecular analysis of the genus Schizymenia in the north‐eastern Atlantic and the Mediterranean, a higher diversity of Schizymenia spp. will be discovered in this region.

Highlights

Schizymenia was erected by J. Agardh (1851) to accommodate several species of foliose red algae
We have described a new species, Schizymenia jonssonii, which can be distinguished by molecular phylogeny, its lack of gland cells and by being strictly intertidal
The results from the present analysis of Cytochrome c oxidase I gene (COI) and rbcL data reveal a new species of Schizymenia in the Atlantic, S. jonssonii K.Gunnarsson & J.Brodie, which adds a third species of Schizymenia to the North Atlantic seaweed flora

Summary

Stephen Russell and Juliet Brodie

A similar pattern is encountered by species that have their main distribution area south of Iceland and their northern limit of distribution along the Icelandic coast (as e.g., Chondrus crispus, Corallina officinalis, and Pelvetia canaliculata) These species are common in the Faeroes, southern Scandinavia, and Scotland, whereas Schizymenia, except for unconfirmed records (due to a lack of specimens) from northern Scotland, is not found in these areas (Rueness 1977, Nielsen et al 1995, Nielsen and Gunnarsson 2001, Hardy and Guiry 2003). The disjunct distribution of Schizymenia in the northern North Atlantic, the lack of gland cells in the specimens collected in Iceland, and the observation that they have only been found in the intertidal zone evoked suspicion that the Schizymenia found in Iceland might be genetically separated from the more southern relatives.

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