Linda M. Irvine

A REAPPRAISAL OF PORPHYRA AND BANGIA (BANGIOPHYCIDAE, RHODOPHYTA) IN THE NORTHEAST ATLANTIC BASED ON THE rbcL–rbcS INTERGENIC SPACER

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. “miniata”, B. atropurpurea s.l. from Denmark and B. atropurpurea s.l. from Wales, P. drachii, P. leucosticta (includes a British record of P. “miniata var. abyssicola”), and P. “insolita” (includes P. “yezoensis” from Helgoland). Of these, data obtained for P. purpurea, P. dioica, P. amplissima, P. linearis, P. umbilicalis, P. drachii, 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 confirm 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 Atlantic group, containing P. purpurea, P. dioica, P. amplissima, P. linearis, P. umbilicalis, P. “miniata”, and B. atropurpurea, and a Pacific group, containing P. “pseudolinearis”, P. drachii, P. leucosticta, P. “yezoensis” (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.

Molecular and morphological characters distinguishing two Porphyra species (Rhodophyta: Bangiophycidae)

Definition of species limits within the rhodophyte genus Porphyra is hampered by the lack of reliable morphological markers; confusion in the taxonomy has serious implications for ecological studies. We report the results of a combined morphological and molecular analysis of plants variously referred to as P. purpurea, P. purpureo-violacea, P. umbilicalis f. laciniata and P. laciniata. All plants examined fell into one of two distinct groups: P. purpurea—monoecious with reproductive fronds divided into two distinct, but often unequal, male and female parts; P. laciniata—dioecious with fronds folding in half longitudinally when hanging vertically. All plants within a group were found to share a common nucleotide sequence for the chloroplast-borne rbcL-S spacer; a single nucleotide transition separates the two groups.

AN SEM-BASED ANALYSIS OF THE MORPHOLOGY, ANATOMY, AND REPRODUCTION OF LITHOTHAMNION TOPHIFORME (ESPER) UNGER (CORALLINALES, RHODOPHYTA), WITH A COMPARATIVE STUDY OF ASSOCIATED NORTH ATLANTIC ARCTIC/SUBARCTIC MELOBESIOIDEAE1

Lithothamnion tophiforme (Esper) Unger is a dominant, arctic, saxicolous species that extends southward, albeit with reduced cover, into the deeper colder waters of the North Atlantic subarctic, where it also occurs in significant rhodolith deposits with L. glaciale. The external appearance of L. tophiforme is distinctive, but typification, anatomy, reproduction, ecology, and biogeography have not been previously analyzed. These topics are now addressed, with extensive use of SEM, in comparison with other North Atlantic arctic and subarctic melobesioid genera and species. The species considered in this article comprise 95% of the coralline biomass of the colder North Atlantic and adjacent arctic (i.e. less than 12° C summer and less than 0° C winter). In the outer thallus region of coralline algae, crust extension proceeds, calcification develops, surface sloughing and grazing occur, and reproductive structures are initiated. Analysis of the ultrastructure of the outer thallus region (epithallium, meristem, and perithallium) of L. tophiforme shows distinctive generic similarities and specific differences from the other Lithothamnion species discussed here. Considerable generic differences from the Clathromorpum and Leptophytum species also encountered in the region considered are highlighted as well. We discuss the functional and taxonomic implications of these distinguishing features and recommend that they be more widely considered in future research on coralline algae to understand more fully the ecology and evolution of the Corallinales.

Epitypification and Redescription of Corallina officinalis L., the Type of the Genus, and C. elongata Ellis et Solander (Corallinales, Rhodophyta)

Abstract Corallina L. is the type genus of the subfamily Corallinoideae (Aresch.) Foslie and Corallina officinalis L. is the type species of the genus. This name has been applied worldwide, particularly in temperate waters. An attempt to obtain sequence data from the lectotype specimen was not successful. In order to establish a species concept for C. officinalis based on molecular sequence data as well as morphology, an epitype was selected from Devon, England within the vague type locality ‘in O [Oceano] Europaeo’, and from which mitochondrial (cox1) and plastid (rbcL) data were obtained. A second species, Corallina elongata Ellis et Solander (type locality Cornwall, England), was shown previously to include at least two species based on DNA sequences. The lectotype of C. elongata is an illustration and therefore an epitype was selected to provide molecular sequence data, using the same markers as for C. officinalis. These molecular sequences for C. officinalis and C. elongata are compared with those of a third, recently described species from Great Britain, Corallina caespitosa R.H. Walker, J. Brodie et L.M. Irvine: these data provide an example for studying Corallina species taxonomy and diversity in other parts of the world. The implications of this work are discussed in relation to concepts of species distribution.

Toward resolution of species diversity and distribution in the calcified red algal genera Corallina and Ellisolandia (Corallinales, Rhodophyta)

Abstract: Cryptic species diversity and the misapplication of names have restricted an understanding of species boundaries in the tribe Corallineae of the calcified red algal order Corallinales. Recent DNA sequencing of type material provided a framework facilitating further examination of genera within the tribe. A phylogenetic study of the genera Corallina and Ellisolandia, based on cytochrome c oxidase subunit 1 and ribulose-bisphosphate carboxylase gene sequences, was undertaken using Natural History Museum herbarium collections and contemporary samples to explore species diversity, geographic distributions and the extent to which names have been misapplied. Twenty Corallina clades likely corresponding to species were resolved, of which C. officinalis and C. caespitosa were confirmed, four were clades newly identified during the present study and 14 had been reported by other workers in previous studies. These data indicated considerable genetic diversity within the genus that was not readily apparent on the basis of morphology. The generitype C. officinalis was shown to have a predominantly North Atlantic Ocean, cool-temperate distribution, whereas the global distribution of C. caespitosa is confirmed for the first time, with samples from Asia, Australasia, Europe, Africa and America. Widespread misidentification of Corallina species was documented, as was the need for sequencing of type specimens to correctly apply names and for comparison with historical collections. The phylogeny reported here serves both as a baseline for future phylogenetic positioning of Corallina species and highlights the degree to which species concepts within this genus remain unresolved.

The genus Mesophyllum (Hapalidiaceae, Corallinales, Rhodophyta) : typification update

W.J. Woelkerling and L.M. Irvine. 2007. The genus Mesophyllum (Hapalidiaceae, Corallinales, Rhodophyta): typification update. Phycologia 46: 230–231. DOI: 10.2216/06-71.1 The 1986 neotypification of Mesophyllum lichenoides (J. Ellis) Me. Lemoine, type species of Mesophyllum (Hapalidiaceae, Corallinales, Rhodophyta), has to be superseded because the International Code of Botanical Nomenclature rules governing the selection of types have changed, and the new rules are retroactive. In accordance with the present rules, an illustration in the original account of the species is designated here as lectotype, and the superseded neotype is designated here as epitype. Relevant historical information and nomenclatural details associated with these changes are presented.