Volume 67, Issue 6

Understanding of non-geniculate coralline algal (NGCA) diversity, prevalence, and distribution in the tropical western North Atlantic is currently limited by reliance on morphological and anatomical features that are inadequate for species identifications. Reef surveys from two study sites, the Florida Keys (Florida, USA) and Roatán (Honduras), provided prevalence data for the main benthic organisms as well as relative abundance for NGCA genera. NGCA collected during these surveys and from additional sites and depths were identified using DNA sequences from two plastid genes, psbA and rbc L, and two nuclear genes, SSU and LSU, and supported by morphological and anatomical descriptions. Bayesian and Maximum Likelihood phylogenetic analyses, along with species delimitation and genetic distance methods, resolved 11 genera within two orders. Within the Corallinales, the genera Dawsoniolithon , Porolithon and Spongites each had one species, Harveylithon and Lithophyllum had two, Titanoderma three, Hydrolithon four, Neogoniolithon eight, and an unknown genus within the subfamily Neogoniolithoideae had 11 putative species. Within the Hapalidiales, the genera Phymatolithon and Roseolithon each had one species. This study reinforces the inability of morphological and anatomical features to distinguish NGCA species in the tropical western North Atlantic, resulting in substantial underestimations of species richness and diversity.

Lithothamnion mirabile is currently considered a heterotypic synonym of L. muelleri. Three of the 14 specimens and additional fragments comprising the holotype of L. mirabile were selected for DNA sequencing as they best matched the protologue. The three 263-base pair rbc L sequences were distinct from each other, and were classified in the order Hapalidiales, but none were resolved in Lithothamnion. One sequenced specimen belongs in Roseolithon and was selected as the lectotype; thus we propose R. mirabile (Foslie) comb. nov . Another sequenced specimen groups with Phymatolithopsis and the third is well resolved in an undescribed genus of Hapalidiales sister to Boreolithothamnion .

Palisada corallopsis has a widely reported distribution in the western and eastern Atlantic and some areas of the Indo-Pacific Ocean, whereas P. furcata has a more restricted distribution, reported only from Brazil and Cuba. Palisada corallopsis and P. furcata were collected from their type localities, Havana, Cuba and Ceará, Brazil, respectively, and compared by morphological and molecular analyses using rbc L and COI-5P genes. The molecular results placed the sequences from the type locality of both species in the same clade, showing low genetic divergence, 0.95 % for rbc L and 1.6 % for COI-5P. Morphologically, the species share similar habits, with branchlets bi-to trifurcated, cortical cells that may be arranged as a palisade and connected by secondary pit-connections. Our detailed morphological observations, including examination of the type specimens, and molecular analyses demonstrate that P. corallopsis and P. furcata are conspecific, P. furcata being a later taxonomic synonym of P. corallopsis .

The genus Gelidium is a representative element of the Mexican Tropical Pacific. The recent use of molecular tools has allowed us to resolve the taxonomic problems of some species and to increase the knowledge regarding this group of red algae in the region. The present study aimed to evaluate specimens collected in the southern Mexican Tropical Pacific using molecular markers and morphological characters. Samples were collected from four locations along the coast of Oaxaca state. They were characterised morphologically and molecularly using rbc L and COI–5P. Phylogenetic analysis classified the examined specimens into three independent clades, representing taxonomic entities different from what has been described previously for the genus. With the support of morphological data and genetic distances, we propose three new species for the Mexican Tropical Pacific: Gelidium dawsonii sp. nov., Gelidium longisporophyllum sp. nov., and Gelidium rubruparvum sp. nov. Some of the distinct characteristics of these species are based on little size of G. rubruparvum , the branching pattern of G. longisporophyllum and G. dawsonii , the number of layers of medullary cells in G. dawsonii and  G. rubruparvum , and the tetrasporangial sorus in G. longisporophyllum . We also highlight the relationship between Asian and Mexican species and the value of using different tools in the evaluation of the taxonomic status of the genus Gelidium .

The cryptophytes of the Black Sea are a poorly studied group that has yet to be fully resolved using comprehensive taxonomic approaches, including electron microscopy and molecular genetics. This study describes Proteomonas agilis sp. nov. belonging to a marine cryptophyte genus formerly thought to be monotypic. The morphological characters of the new species align with those currently used to delineate the genus Proteomonas , and are similar to those of the haplomorph P. sulcata , the type species, with minor morphological and molecular modifications. Phylogenetic relationships inferred from nuclear-encoded SSU, LSU, and ITS2 rDNA datasets confirmed that the new species belongs to the monophyletic genus Proteomonas , which is divided into two unequal branches. The largest and relatively long branch contains 18 strains, including P. agilis sp. nov. Comparison of ITS2 rRNA secondary structures using the compensatory base changes approach confirmed the distinction of P. agilis sp. nov. from the other Proteomonas strains. Our findings revealed that the cryptophyte genus Proteomonas is not monotypic but includes a range of unstudied species besides the type species P. sulcata and P. agilis sp. nov. described in this study. Therefore, an integrated approach is required for a careful revision of the genus.

The resting spore stage of Cerataulina bicornis has been reported sporadically from the Indian Sundarbans, with one sediment core record that dates back to ∼2000 yrs. BP, but its vegetative stage has remained elusive during this entire period. The present report of its vegetative stage is a new record from this estuarine system. A comprehensive morphometric description along with molecular data of rbc L and 18s rDNA of the vegetative stage of C. bicornis is presented. The morphological and morphometric characters observed in the light microscope (LM) and scanning electron microscope (SEM) studies, along with a detailed description of the copulae, establish its distinction from other Cerataulina spp. described from different parts of the world.

Agar, a phycocolloid naturally extracted from Gracilariopsis heteroclada is strongly influenced by salinity. Wild stocks of G. heteroclada were exposed to varying salinities (20, 30, 40, 50, 60) for 6 days, and subsequently processed for agar extraction using 5 % NaOH. The extracted agar was evaluated regarding yield, gel rheology, colour composition, chemical properties, and infrared spectra. Results highlighted that hypersaline conditions (salinity 50) could produce high agar yield (4.77 %) and viscosity (10.67 mPa s), while agar samples at salinity 40 exhibited gels with high cohesiveness (6.35 mm), gel breaking strength (3.01 N), and gel strength (390.61 g cm −2 ) while having a rather high 3,6-anhydrogalactose content (7.49 %). All samples exhibited FTIR signature peaks at 930 cm −1 , confirming the identity of extracted agar from G. heteroclada . Exposure at increasing hypersalinity increased the sulphate levels of agar from G. heteroclada , which implies synthesis of sulphated polysaccharides. Moreover, high 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities were obtained in acid hydrolysed agars at salinities of 40 (74.09 %) and 50 (75.57 %), suggesting that G. heteroclada agars from hypersaline conditions potentially offer antioxidative roles beyond its traditional food use.