A new taxonomic interpretation of the type ofPlocamium cartilagineum(Plocamiales, Florideophyceae) and its consequences

Abstract

A detailed study of the type specimen of Plocamium cartilagineum and other original material of European species of Plocamium revealed that the nomenclatural reorganization proposed by Saunders & Lehmkuhl in 2005 must be revised. The main consequences of the new interpretation are: (1) the use of Plocamium lyngbyanum to name their molecular entity EUR1 (previously considered to be equivalent to P. cartilagineum s.s.); and (2) adopting P. cartilagineum for their molecular entity EUR2, which renders P. subtile Ku¨tzing a taxonomic synonym. Using a combination of morphological, anatomical and molecular information (barcoding), we conclude that the colour and consistency of the thallus, the number of ramuli per series, the morphology and arrangement of the tetrasporangial stichidia, the length of the tetrasporangia, and the type of habitat are the most reliable characters of classical taxonomy for discriminating between the species of Plocamium occurring in northern Europe.

New features in the vegetative and reproductive morphology ofCystoclonium purpureum(Cystocloniaceae, Rhodophyta) from the North Atlantic Ocean

“…The species appears to be highly variable, and cryptic species may at some point in time be segregated from it, much as has recently occurred among species formerly included under Plocamium cartilagineum from Europe (Cremades et al, 2011). All of the samples we have looked at from Europe, Greenland and North America did, nonetheless, produce short-celled secondary gametophyte filaments that interacted with the gonimoblasts.…”

A revised check-list of the seaweeds of Britain

“…[Partly included in P. cartilagineum in Hardy & Guiry (2003) and earlier authors; see Saunders & Lehmkuhl (2005) and Cremades et al (2011). ]…”

Flora marina bentonica del Mediterraneo: Rhodophyta - Rhodymeniophycidae II. Halymeniales, Nemastomatales, Peysson-neliales, Plocamiales, Rhodymeniales, Sebdeniales

“…Nota -La descrizione riportata sopra è stata tratta da Cremades et al (2011) che hanno studiato il tipo di P. cartilagineum e il materiale originale di alcune altre specie europee considerate simili o sinonimi di P. cartilagineum. In particolare abbiamo preso soprattutto in considerazione la descrizione riportata per i campioni etichettati EUR2 (Cremades et al, 2011: 131 Tallo eretto, (3-)5-10(-15) cm alto, rosso porpora, a volte viola-brunastro (caratteristicamente blu iridescente in natura), di consistenza cartilaginea, leggermente carnosa negli esemplari di grande taglia, provvisto di corti stoloni fissati al substrato da piccoli dischi o apteri.…”