Floristic and Biogeographical Trends in Seaweed Assemblages from a Subtropical Insular Island Complex in the Gulf of California

Floristic and biogeographical trends of the seaweed assemblages in subtidial rocky areas were evaluated at 10 sites around Espiritu Santo Island in the Gulf of California. Seasonal sampling in two consecutive years with intensive surveys in a 500-m2 area at each site was done. An intensive search was made of previous records from the literature. We found 85 species in the field with an additional 69 species from the literature, for a total 116 species. Species composition was significantly different between sides of the island in the first year, but very similar in the second. Species composition was not influenced by the presence of epiphytes. Phenologically, most species were ephemeral or annual with a low reproductive effort. Biogeographically, tropical elements dominated, but there was an important contribution from temperate species. Our results indicate that Espiritu Santo Island is a dynamic system that is strongly influenced by local oceanographic conditions

Phylogenetic analysis of rhodolith formation in the Corallinales (Rhodophyta)

Although the ecological importance of rhodolith (maerl, free-living coralline algae) beds is well-known, rhodolith-forming species have been neglected in molecular phylogenetic studies. This is the first molecular systematic study aimed at understanding whether the rhodolith habit is a fixed feature in lineages and determining the relationship (phylogenetic vs. environmental) between rhodolith and crustose habits. Phylogenetic relationships of rhodolith-forming species and encrusting coralline algae at generic and species levels were analysed using SSU rDNA and psbA sequences. Extensive sampling in the European North Atlantic, Pacific and Caribbean Mexico of Phymatolithon, Lithothamnion, Lithophyllum and Neogoniolithon taxa forming rhodoliths and crusts was accompanied by examination of type or topotype material. Phylogenetic reconstruction showed that Neogoniolithon contained a monophyletic group of rhodolith-forming species whereas other rhodolith-formers were closely related to encrusting forms in the genera Phymatolithon, Lithothamnion, Mesophyllum, Hydrolithon, Spongites and Sporolithon. DNA analysis showed that the crust-forming Lithophyllum cf. incrustans/dentatum also forms rhodoliths with a stone nucleus that occur on rocky shores. In contrast, species that form beds of non-nucleate rhodoliths (e.g. Neogoniolithon spectabile, N. strictum, Lithophyllum cf. incrustans/dentatum or sp. 1 and Phymatolithon calcareum) rarely form crusts. The rhodolith habit cannot be used to delimit species for taxonomic or identification purposes. Extensive taxonomic revision will be required to deal with problems such as the position of specimens identified as Lithophyllum margaritae in two unrelated lineages

A taxonomic and distributional study of the rhodolith-forming species Lithothamnion muelleri (Corallinales, Rhodophyta) in the Eastern Pacific Ocean

Lithothamnion rnuelleri is reported for the first time as one of the main components of rhodolith beds along the Eastern Pacific Ocean based on samples from Washington State (USA), Pacific Baja California (Mexico), southern Nicaragua, and Costa Rica. Individual rhodoliths ranged from fruticose to lumpy in morphology, and bi-sporangial, tetrasporangial, and gametangial plants were similar to those described from Australia and Brazil. Our study revealed a surprisingly wide latitudinal distribution of this species along the American continent. Its documentation in the Eastern Pacific will facilitate a more accurate interpretation of the ecology, biology, and biogeography of rhodolith beds worldwide.Keywords: Coralline algae, Washington, Costa Rica, Mexico, Nicaragua, Taxonomy, Lithothamnion mueller

Hermatypic Corals Associated with Rhodolith Beds in the Gulf of California, Mexico

Subtidal surveys along the western Gulf of California coast revealed the presence of free-living hermatypic corals associated with rhodolith beds, the first record of this association in the gulf. Five coral species were found, as follows: Psammocora stellata Verrill, Porites panamensis Verrill, P. sverdrupi Durham, Fungia curvata Hoeksema, and F. distorta Michelin, with several new distributional records, Differences in relative abundance of species in our collections from those in other regions of the Pacific suggest that transport, light, and temperature play important roles in distribution and development of coral-rhodolith associations in the gulf

Analysis of the cox2-3 spacer region for population diversity and taxonomic implications in rhodolith-forming species (Rhodophyta: Corallinales)

Coralline red algae demonstrate phenotypic plasticity related to environmental factors, rendering their identification difficult. The cox2-3 spacer is a mitochondrial marker widely used for phylogeographic studies and discrimination between closely related species in red algae; however, cox2-3 spacer sequence data for coralline algae are still limited. In this study we substantially increase the number of cox2-3 spacer sequences available for coralline algae, exploring their usefulness for different types of molecular investigations in coralline algae (DNA barcoding and phylogeography), with emphasis on rhodolith-forming species. Specimens from North Atlantic Europe, the Caribbean region and the Gulf of California (Mexico) were sequenced and two datasets were built, one for the subfamily Lithophylloideae and one for the Melobesioideae. Our results suggest the utility of cox2-3 spacer as barcoding marker for coralline algae with a slight variation in the barcode gap depending in the way gaps in the alignment are treated. Analyses on both datasets found a barcode gap or separation between intra and interspecific divergence (p distance and ABGD analysis) while some inconsistencies were evident when the results were compared with morphology-based classification. Using the cox2-3 spacer region, the morphospecies Lithophyllum margaritae from the Gulf of California revealed the existence of two well-supported clades, with the possibility of respectively five and two additional species; haplotype networks for Phymatolithon calcareum and P. purpureum revealed similar patterns when Mediterranean and NW Europe specimens were analysed, and P. calcareum was shown to consist of a single population in NW Europe. Based on our analyses the marker cox2-3 spacer has strong potential applications for studies of phylogeography and DNA barcoding in coralline algae after understanding its variation

Branched Halymenia species (Halymeniaceae, Rhodophyta) in the Indo-Pacific region, including descriptions of Halymenia hawaiiana sp. nov.andH. tondoana sp. nov.

Several species in the red algal genus Halymenia from the Indo-Pacific have been described with branched thalli, toothed margins, spinose proliferations on the blade, and a firm gelatinous texture. Previous works have synonymized many of these morphologically similar species with H. durvillei. Our increased taxon sampling and molecular data indicate that the taxonomy of the Indo-Pacific Halymenia species is in need of revision, and that several aspects of taxonomies proposed by previous authors now seem unlikely. Thus, the aim of the present work was to analyse species delimitation in branched Halymenia species. Molecular and morphological data for specimens from the coral triangle and peripheral Indo-Pacific localities (East African coast, Hawaii) were used to understand species delimitation for selected branched Halymenia spp. Phylogenetic analyses based on 29 rbcL gene sequences grouped the specimens in four well-supported clusters at the species level with high p-distances (2.7-5.3%). After the morphological analysis, five features were retained as diagnostic to identify the four species studied. Our analyses led to the recognition and description of two new species, H. hawaiiana from the Hawaiian Islands (previously erroneously called H. formosa) and H. tondoana from the Philippines. In addition, H. harveyana (currently treated as a subspecies of H. floresii in Australia) is reassessed and recognized at the species level. Specimens with seven orders of branching and a thick cortex (70-150 μm) formed a monophyletic group, including sequences from previous work, with mostly well-supported branches and with high p-distances at the species level. We propose to call this group the H. durvillei complex until further reassessment is completed. None of the sequences studied here grouped with H. floresii from the Mediterranean, suggesting that previous Indo-Pacific reports of the species were erroneou

Branchedhalymeniaspecies (halymeniaceae, rhodophyta) in the indo-pacific region, including descriptions ofhalymenia hawaiiana sp. nov.andh. tondoana sp. nov.

Several species in the red algal genus Halymenia from the Indo-Pacific have been described with branched thalli, toothed margins, spinose proliferations on the blade, and a firm gelatinous texture. Previous works have synonymized many of these morphologically similar species with H. durvillei. Our increased taxon sampling and molecular data indicate that the taxonomy of the Indo-Pacific Halymenia species is in need of revision, and that several aspects of taxonomies proposed by previous authors now seem unlikely. Thus, the aim of the present work was to analyse species delimitation in branched Halymenia species. Molecular and morphological data for specimens from the coral triangle and peripheral Indo-Pacific localities (East African coast, Hawaii) were used to understand species delimitation for selected branched Halymenia spp. Phylogenetic analyses based on 29 rbcL gene sequences grouped the specimens in four well-supported clusters at the species level with high p-distances (2.7-5.3%). After the morphological analysis, five features were retained as diagnostic to identify the four species studied. Our analyses led to the recognition and description of two new species, H. hawaiiana from the Hawaiian Islands (previously erroneously called H. formosa) and H. tondoana from the Philippines. In addition, H. harveyana (currently treated as a subspecies of H. floresii in Australia) is reassessed and recognized at the species level. Specimens with seven orders of branching and a thick cortex (70-150 mm) formed a monophyletic group, including sequences from previous work, with mostly well-supported branches and with high p-distances at the species level. We propose to call this group the H. durvillei complex until further reassessment is completed. None of the sequences studied here grouped with H. floresii from the Mediterranean, suggesting that previous Indo-Pacific reports of the species were erroneous