We evaluated the relationships among species in the genus Gelidiella using 47 rbcL and 29 COI sequences, including those from 18 specimens collected in Madagascar. Molecular analyisis revealed the presence of three major lineages among Magalasy Gelidiella which were assigned, based on morpho-anatomical observation, to Gelidiella acerosa, G. ligulata and a so far not described species for which we here proposed the name G. incrassata. Both molecular and morphological data demonstrated the presence of three species in Madagascar: the G. acerosa complex, G. ligulata, and G. incrassata sp. nov., described here. Gelidiella incrassata was collected on small gravel from the intertidal down to a depth of 14 m on the southeast coast of Madagascar. It is distinguished by its large size (up to 7 cm), opposite to alternate ramuli, thick-walled cortical and medullary cells, and stalked tetrasporangial stichidia with irregular arrangement of tetrasporangia. Phylogenetic analyses of rbcL and COI sequences revealed the sister relationship between G. incrassata and G. fanii from southeast Asia and Hawaii. Gelidiella acerosa comprised three genetic groups in Madagascar, each being genetically distinct (pairwise distances, 4.9–8.3% for COI and 1.2–2.3% for rbcL). Further sampling of G. acerosa is needed before taxonomic revisions can be proposed. The distribution of G. ligulata is expanded to include the southwest Indian Ocean.

ATIMO VATAE

The present study documents species of coralline algae that form maerl and rhodoliths in Guadeloupe, Caribbean using an integrative systematic approach of combining molecular (COI-5P, psbA) and morphological/anatomical data. Maerl and rhodoliths were collected by SCUBA and dredging from six localities in Guadeloupe during the Karubenthos Expedition, which was coordinated by the Parc National de la Guadeloupe and the Muséum National d´Histoire Naturelle. Of the twelve maerl and rhodolith specimens collected and sequenced, eight specific entities were delimitated based on the analysis of molecular data: Lithothamnion cf. ruptile, five species of the genus Lithothamnion, one species of the genus Spongites, and the remaining one was either assigned to the genus Lithoporella or Mastophora. Morphological/anatomical data are presented for each of these species. Molecular analyses revealed that Lithothamnion. cf ruptile and other four species (Lithothamnion spp.1–4) were resolved in a distinct lineage than the other Lithothamnion species examined. Nevertheless, these five species were provisionally remained in the genus Lithothamnion based on the presence of flared epithallial cells. Previously, only three species of Lithothamnion have been cited in the Caribbean. Till this study species belonging to the genus Spongites have not been hitherto reported for this region. The specimen identified as either Lithoporella or Mastophora shared anatomical features with both genera. Further examination of reproductive material is required to identify this specimen to a lower taxonomical rank. This study is the first to report the occurrence of maerl and rhodoliths belonging to the genus Lithothamnion at 110 m depth; this record being the deepest for the genus in the Caribbean Sea. Our results have revealed that species diversity of Caribbean maerl has been underestimated and further surveys coupled with an integrative taxonomic approach on this biodiversity hotspot are necessary.

KARUBENTHOS 2012

The systematics of the Laurencia complex was investigated using a taxon-rich data set including the chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene only and a character-rich data set combining mitochondrial cytochrome oxidase 1 (COI-5P), the rbcL marker, and the nuclear large subunit of the ribosomal operon (LSU). Bayesian and ML analyses of these data sets showed that three species hitherto placed in the genus Laurencia J.V.Lamour. were not closely related to Laurencia s. str. Laurencia caspica Zinova & Zaberzhinskaya was the sister group of the remaining Osmundea Stackh. species, L. crustiformans McDermid joined Palisada and L. fl exilis Setch. consisted of an independent lineage. In light of these results a new genus, Ohelopapa F.Rousseau, Martin-Lescanne, Payri & L.Le Gall gen. nov., is proposed to accommodate L. fl exilis. This new genus is morphologically characterized by four pericentral cells in each vegetative axial segment; however, it lacks ‘corps en cerise’ in cortical cells and secondary pit connections between cortical cells, which are characteristic of Laurencia. Three novel combinations are proposed to render the classifi cation closer to a natural system: Ohelopapa fl exilis (Setch.) F.Rousseau, Martin-Lescanne, Payri & L.Le Gall comb. nov., Osmundea caspica (Zinova & Zaberzhinskaya) Maggs & L.M.McIvor comb. nov. and Palisada crustiformans (McDermid) A.R.Sherwood, A.Kurihara & K.W.Nam comb. nov.

KARUBENTHOS 2012