Taxonomic reassessment ofPolysiphonia foetidissima(Rhodomelaceae, Rhodophyta) and similar species, includingP. schneideri, a newly introduced species in Europe

Abstract

Morphological and molecular studies were carried out on two Polysiphonia with 6-9 pericentral cells from the Atlantic Iberian Peninsula. A detailed description is provided for P. foetidissima, a poorly known species originally described from the UK that is widespread and abundant in the Iberian Peninsula. Polysiphonia schneideri, originally described from Atlantic U.S.A. and Bermuda, is reported for the first time in Europe (Southern Spain). It was collected attached to man-made structures such as floating docks and artificial substrata for aquaculture and is believed to be a newly introduced species in Europe. In addition, the taxonomy of seven morphologically similar Polysiphonia was reassessed. A comparative study of type materials showed that the Mediterranean P. stuposa is morphologically different from its alleged synonym P. foetidissima. Instead, molecular and morphological evidence showed that P. foetidissima is a synonym of the widely reported (Atlantic and Pacific) P. tepida. Polysiphonia foetidissima was also shown to differ from P. brodiei, P. exilis, P. isogona and P. schneideri.

Widely distributed red algae often represent hidden introductions, complexes of cryptic species or species with strong phylogeographic structure

“…More than 200 red algal species have been considered as introduced or cryptogenic in one or several regions . Cryptic introductions are common in the red algae and non-native species often remain unnoticed until diversity surveys use molecular tools (McIvor et al 2001, Zuccarello et al 2002b, D ıaz-Tapia et al 2013b, 2017a. Considering the low dispersal ability of non-buoyant epilithic red algae, we hypothesize that the distribution of most truly cosmopolitan species can be explained by human-mediated transportwhich is frequently provided as a potential explanation for wide distributions of species (Zuccarello et al 2002a,b, Fraser et al 2013.…”

“…, Díaz‐Tapia et al. , ). Considering the low dispersal ability of non‐buoyant epilithic red algae, we hypothesize that the distribution of most truly cosmopolitan species can be explained by human‐mediated transport – which is frequently provided as a potential explanation for wide distributions of species (Zuccarello et al.…”