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Coralline red algae in the non-geniculate genera Clathromorphum, Phymatolithon and Lithothamnion are important benthic ecosystem engineers in the photic zone of the Arctic and Subarctic. In these regions, the systematics and biogeography of Clathromorphum and Phymatolithon have mostly been resolved whereas Lithothamnion has not, until now. Seventy-three specific and infraspecific names were given to Arctic and Subarctic Lithothamnion specimens in the late 19th and early 20th century by Frans R. Kjellman and Mikael H. Foslie. DNA sequences from 36 type specimens, five historical specimens, and an extensive sampling of recent collections resulted in the recognition of four Arctic and Subarctic Lithothamnion species, L. glaciale, L. lemoineae, L. soriferum and L. tophiforme. Three genes were sequenced, two plastid-encoded, rbcL and psbA, and the mitochondrial encoded COI-5P; rbcL and COI-5P segregated L. glaciale from L. tophiforme but psbA did not. Partial rbcL sequences obtained from type collections enabled us to correctly apply the earliest available names and to correctly place the remainder in synonymy. We were unable to sequence another 22 type specimens, but all of these are more recent names than those that are now applied. It is difficult to identify these species solely on morpho-anatomy as they can all occur as encrusting corallines or as maerl (rhodoliths). We demonstrate the importance of sequencing historical type specimens by showing that the recently proposed North-east Atlantic L. erinaceum is a synonym of one of the earliest published Arctic species of Lithothamnion, L. soriferum, itself incorrectly placed in synonymy under L. tophiforme based on morpho-anatomy. Based on sequenced specimens, we update the distributions and ecology of these species. [ABSTRACT FROM AUTHOR]

A constant effort in sequencing an extensive number of specimens originating from comprehensive sampling had return an unprecedented amount of information fostering our understanding of diversity, evolution and distribution of coralline algae; however, many sequences lack reliable assignation of a taxonomic name, specially at the species level. Recently, the sequencing of type material allowed to bridge this gap by providing a direct link between the DNA sequence and the type bearing name. For instance, in the genus Lithophyllum, the identity of three species, generally abundant along the European Atlantic and the Mediterranean, was demonstrated by including sequences of the type material. Nevertheless, for less conspicious species, such as Lithophyllum nitorum, data are still needed to assess distribution, anatomy, phylogenetic affinities and taxonomic status. Using DNA sequences recovered from the type material of L. nitorum, further recent collections were resolved as conspecific and used to improve the description and refine the distribution of this species. Lithophyllum nitorum consisted of subtidal, thin crusts overgrowing fragments of dead maerl, pebbles and drifted fragments of fishing lines. The presence of uniporate conceptacles markedly protruding can be considered an external morphological feature useful to identify L. nitorum from other subtidal Lithophyllum species with similar habitat. Lithophyllum nitorum is reported for the Mediterranean Sea and confirmed in the North East Atlantic, a similar distribution as for L. incrustans and L. hibernicum. [ABSTRACT FROM AUTHOR]

Plastid-encoded rbcL and psbA sequences from branched, Caribbean Sea Lithophyllum specimens indicate that four species are present, not one. Short (263 base pairs) rbcL sequences from an isolectotype of L. kaiseri (Gulf of Suez) and the holotypes of L. congestum, L. daedaleum and L. platyphyllum (Caribbean Sea) show that L. congestum and L. daedaleum are conspecific with L. kaiseri, the last having nomenclatural priority. Lithophyllum platyphyllum, currently considered a synonym of L. congestum, is recognised as a valid species. Lithophyllum stictaeforme, originally described from the Mediterranean Sea, is not conspecific with L. kaiseri (as L. congestum) as previously suggested. Lithophyllum neocongestum sp. nov. and L. pseudoplatyphyllum sp. nov. are proposed. Together with L. platyphyllum, these three branched species are so far endemic to the Caribbean Sea. This is the first report, documented by DNA sequence data, of a coralline species ( L. kaiseri) widespread through the tropical Indo-West Pacific Oceans, Red Sea and Caribbean Sea. [ABSTRACT FROM AUTHOR]

Phymatolithon lusitanicum is a new maerl species described based on an integrative systematic approach including molecular (COI-5P, psbA) and morphological data obtained from recent collections, as well as comparison of type material from the morphologically and ecologically alike NE Atlantic species P. lamii and P. laevigatum. Molecular analyses including type material of P. lamii and P. laevigatum were congruent in delimiting P. lusitanicum as an independent lineage from these crustose species. The three species shared a common external morphology of multiporate asexual conceptacles, but P. lusitanicum has been detected only unattached as maerl while P. lamii and P. laevigatum are crustose. Phymatolithon lusitanicum is particularly abundant in subtidal maerl beds of the Atlantic Iberian Peninsula (Galicia and the Algarve); however it has also been detected northwards in Ireland intertidally and in Western Mediterranean Sea (Alborán Sea, Balearic Islands) down to 64 m. Phymatolithon lusitanicum differs from other Phymatolithon species reported for the European coasts mainly by the external shape of the multiporate asexual conceptacles (pore plate flush with surface or slightly sunken without a conspicuous thick raised rim) and its unattached habit as maerl/rhodolith. In addition, the lectotype of Lithothamnion hamelii turned out to be conspecific to Phymatolithon calcareum, therefore this taxon is proposed as a heterotypic synonym of P. calcareum. Finally, our molecular analyses detected cryptic diversity within the European collections of Phymatolithon, while collections identified as P. lenormandii from Canada or P. repandum from New Zealand were resolved as unrelated to the remaining Phymatolithon. In the light of these results, it is clear that further work is necessary to resolve species diversity within the genus Phymatolithon and its relationship with related genera. [ABSTRACT FROM AUTHOR]

The red algal genus Stenogramma (Gigartinales, Phyllophoraceae) was not recorded in the Indian Ocean. In this study, we used molecular assisted alpha taxonomy to assess the algal diversity of the algal flora of the southern coasts of Madagascar. Using COI-5P sequences as barcode marker and LSU and rbcL sequences to infer phylogenetic relationships, a novel species of Stenogramma has been uncovered at Manantenina, Anosy, Madagascar, which is here described. The species diversity within the genus Stenogramma is discussed and in light of our phylogenetic inference we hypothesized that species of northern and southern hemispheres may have diversified separately. This novel species, being found on subtidal rocks surrounded by sands, the habitat preference of the genus is discussed. [ABSTRACT FROM AUTHOR]

For the first time, a comprehensive assessment ofMesophyllumspecies diversity and their distribution in Atlantic Europe and the Mediterranean Sea is presented based on molecular (COI-5P,psbA) and morphological data. The distribution ranges were redefined for the four species collected in this study:M. alternans, M. expansum, M. macroblastumandM. sphaericum. Mesophyllum sphaericum,which was previously known only from a single maerl bed in Galicia (NW Spain), is reported from the Mediterranean Sea. The known range ofM. expansum(Mediterranean and Macaronesia) was extended to the Atlantic Iberian Peninsula. The occurrence ofM. alternanswas confirmed along the Atlantic French coast south to Algarve (southern Portugal).Mesophyllum lichenoideswas only recorded from the Atlantic, whereasM. macroblastumappears to be restricted to the Mediterranean Sea. A positive correlation was observed between maximum Sea Surface Temperature (SSTmax) and the depth at whichM. expansumwas collected, suggesting that this species may compensate for higher SST by growing in deeper habitats where the temperature is lower. The latter indicates that geographic shifts in the distribution of coastal species as a result of global warming can possibly be mitigated by changes in the depth profile at which these species occur.Mesophyllum expansum, an important builder of Mediterranean coralligenous habitats, may be a good target species to assess its response to climate change. [ABSTRACT FROM PUBLISHER]

Fertile gametangial plants of Phymatolithon calcareum, which are seldom reported in the Atlantic European coasts, were collected as encrusting, epilithic plants in a subtidal maerl bed in Brittany (France). Based on their morphological features, the plants were identified as P. calcareum. This identification was further confirmed by DNA barcodes using as a reference COI-5P sequences obtained from the neotype together with recent collections from the Atlantic European maerl beds. The reproductive structures were empty but they were regarded as mature female conceptacles. Compared to the two previous records of gametangial plants of P. calcareum for the Atlantic European waters, the uniporate conceptacles observed in this study are larger, and were collected at a different time of the year. To our knowledge, this is the first time that the occurrence of gametangial plants of P. calcareum is corroborated with molecular tools (DNA barcodes). [ABSTRACT FROM AUTHOR]

Cladophora rhodolithicola sp. nov., a small green macroalgal epiphyte on rhodoliths, is described from the Atlantic coasts of the British Isles, France and Spain, based on morphological and molecular evidence. Molecular phylogenetic analyses reveal that the rhodolith epiphyte is closely related to C. pygmaea, a dwarf species that also grows on maerl and small stones and whose systematic position was previously uncertain. The fact that both species, along with two other distinct Cladophora species (C. echinus and C. battersii), are resolved among species traditionally assigned to the Cladophora section Longi-articulatae, has implications for our understanding of the evolution of the genus. The section Longi-articulatae is one of the most distinctive groups in Cladophora, being characterized by coarse thalli with conspicuous basal cells, strict acropetal growth and the lack of intercalary rhizoids. Here we show that deviant character states such as reduced and irregular growth, and intercalary rhizoids have evolved independently several times within this clade. [ABSTRACT FROM AUTHOR]