1069 J. Phycol. 34, 1069–1074 (1998) A REAPPRAISAL OF PORPHYRA AND BANGIA (BANGIOPHYCIDAE, RHODOPHYTA) IN THE NORTHEAST ATLANTIC BASED ON THE rbcL–rbcS INTERGENIC SPACER 1 Juliet Brodie 2 Faculty of Applied Sciences, Bath Spa University College, Newton Park, Newton St. Loe, Bath BA2 9BN, United Kingdom Paul K. Hayes, Gary L. Barker School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, United Kingdom Linda M. Irvine Botany Department, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom and Inka Bartsch Biologische Anstalt Helgoland, Zentrale Hamburg, Notkestrasse 31, D22607 Hamburg, Germany ABSTRACT Sequence data of the rbcL–rbcS noncoding intergenic spacer of the plastid genome for 47 specimens of Porphyra and Bangia from the northeast Atlantic reveal that they fall into 11 distinct sequences: P. purpurea, P. dioica (includes a sample of P. ‘‘ochotensis’’ from Helgoland), P. amplissima (includes P. thulaea and British records of P. ‘‘miniata’’), P. linearis, P. umbilicalis, P. ‘‘min- iata’’, B. atropurpurea s.l. from Denmark and B. atro- purpurea s.l. from Wales, P. drachii, P. leucosticta (in- cludes a British record of P. ‘‘miniata var. abyssicola’’), and P. ‘‘insolita’’ (includes P. ‘‘yezoensis’’ from Hel- goland). Of these, data obtained for P. purpurea, P. dioi- ca, P. amplissima, P. linearis, P. umbilicalis, P. dra- chii, and P. leucosticta were based on type specimens or material compared with types. Comparison of sequence data for Porphyra spp. and Bangia atropurpurea s.l. (including B. fuscopurpurea, the type species of Bangia) confirms that the species are congeneric. The data also con- firm that the number of layers that make up the Porphyra thallus are not taxonomically significant. Comparison of sequence data for species from the northeast Atlantic with those for material of two species from the Pacific reveals that the species fall into two distinct groupings: an Atlan- tic group, containing P. purpurea, P. dioica, P. am- plissima, P. linearis, P. umbilicalis, P. ‘‘miniata’’, and B. atropurpurea, and a Pacific group, containing P. ‘‘pseudolinearis’’, P. drachii, P. leucosticta, P. ‘‘ye- zoensis’’ (including a sample of P. ‘‘tenera’’), and P. ‘‘insolita’’ (including P. ‘‘yezoensis’’ from Helgoland). The possibility of alien species in the northeast Atlantic is discussed. Key index words: Atlantic; Bangia; introduced species; Pacific; Porphyra; Rhodophyta; RUBISCO spacer; tax- onomy Abbreviation: s.l., sensu lato 1 Received 21 October 1997. Accepted 1 September 1998. 2 Corresponding author; e-mail j.brodie@bathspa.ac.uk The red algal family Bangiaceae currently has two genera assigned to it, Porphyra and Bangia, but in this paper we now have good evidence that the type species are congeneric. Species of Porphyra occur in the intertidal and shallow subtidal zones in cool- to warm-temperate regions of the world and at certain times of the year can be the dominant algae in some shore regions. Some species are economically im- portant, being harvested from the wild or grown commercially as food; for example, laver and nori. Bangia occurs mainly in the intertidal zone in cool to tropical regions. Despite being the subject of much study over at least the last 100 years, the taxonomy within the fam- ily remains problematic, mainly because of the high- ly variable morphology and lack of easily recogniz- able characters. Molecular techniques have been used to assist in the discrimination of species of Por- phyra (Lindstrom and Cole 1992a, b, Stiller and Waaland 1993, 1996, Oliveira et al. 1995), and an analysis of nucleotide sequence data of the plastid- borne rbcL–rbcS intergenic spacer (RUBISCO spac- er) has proved useful in differentiating between two often confused species of Porphyra (Brodie et al. 1996): Porphyra dioica Brodie et L. Irvine (as P. laci- niata) was distinguished from P. purpurea using this technique, and sound morphological characters confirmed it as a distinct species (Brodie and Irvine 1997). In this paper, species-level taxonomy based on analysis of the RUBISCO spacer data is explored for specimens of Porphyra and Bangia from the northeast Atlantic. We also compare sequence data for three Pacific samples of Porphyra. Six species of Porphyra, as well as Bangia atropur- purea, were recognized for the coasts of Britain, Ire- land, and adjacent waters by Parke and Dixon (1976). A further five species were reported for the northeast Atlantic by South and Tittley (1986) and five more by Guiry (1997) (Table 1). We have tested specimens purporting to belong to all these species except for P. helenae; although we have been able to