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Abstract:Morphological characterization, together with phylogenetic and DNA barcoding analyses on the basis of rbcL and COI-5P, conducted on some species of the Laurenciacomplex in South Florida confirmed the occurrence of Laurencia intricataand supported the presence and recognition of Laurenciellain the United States. Samples of L. intricatafrom Florida grouped with full support with the species from the type locality (Antilles). The intraspecific divergence within the L. intricataclade ranged from 0.0% to 1.3%; the samples from Florida diverged by only 0.06% to 0.20%, the sample from Mexico (EF658643 – Puerto Morelos, Quintana Roo) being the most divergent. The two new species of Laurenciellafrom Florida, La. mayaimiiand La. sp., formed an assemblage with La. marilzaewith full support, and the interspecific divergence was high for both molecular markers. Laurenciella mayaimiiis characterized mainly by its brownish-yellow main axis and cylindrical, alternate to subopposite branchlets, anastomoses between branches in the basal portions, and a single ‘corps en cerise’ present in each cortical cell and in trichoblasts. In addition, the walls of the cortical cells near the apices project, and lenticular thickenings are absent. The finding of Laurenciellain Biscayne Bay and Key Largo, South Florida expands its geographic distribution to western Atlantic lower subtropical waters.

Abstract:Phylogeographic studies can contribute to our understanding of the evolutionary forces acting on the patterns of genetic variation and the evolutionary history of species. The Hydropuntia cornea/Hydropuntia usneoidesspecies complex consists of two common species of red algae in the Gulf of Mexico and Caribbean Sea. Both species exhibit high phenotypic plasticity and total overlap in morphological characters and are only distinguished genetically (group GI, assigned to H. usneoidesand group GII, assigned to H. cornea). In the Yucatan Peninsula, where they are abundant, they have a sympatric distribution. In order to understand the historical events and their influence on the current distribution patterns of these species around the Yucatan Peninsula and compare them with some populations from Venezuela and Brazil, we analyzed variation in the plastid-encoded RuBisCo spacer. A total of 133 individuals collected from 14 sites were sequenced. The analyses revealed 12 haplotypes (R1–R12). The haplotype network revealed two major groups (GI and GII) separated by three mutational steps. Group I was found in almost all sampled sites (n= 13), while GII was found in six sites but was absent from the Gulf of Mexico (Campeche). Haplotype R1 was the most abundant in GI, and haplotype R4 was dominant in GII. Genetic variation was higher in GI than in GII. Mismatch distribution suggests that GI may be in a period of demographic equilibrium, and GII experienced a recent demographic expansion and may have come from the south when the northern portion of the peninsula emerged (2.8 million years ago). Our results revealed that the Yucatan Peninsula is a mix of southern and northern floristic influences, which can be explained by the geological events in the area.

Abstract:Species recognition in algae is often extremely difficult due to the paucity of morphological characters and high environmental plasticity. If environment is important to morphology, then related species growing in sympatry are good candidates to discover diagnostic characters. We studied algae collected in sympatric populations in tropical Atlantic Mexico. Hydropuntia corneaand H. usneoideshave high morphological variation and have been difficult to diagnose morphologically. We used four molecular markers (RuBisCo spacer, cox2–3 spacer, rbcL and COI) to investigate the genetic relationship between samples that correspond to either H. corneaor H. usneoides; in addition, we determined if molecular-characterized groups were morphologically distinguishable. RuBisCo and cox2–3 spacers revealed low genetic variation but showed two genetic groups: groups I and II. rbcL and COI phylogenies also showed a separation into two groups, corresponding with cox2–3 spacer groups I and II. Group I matched sequences in GenBank of H. usneoidesand group II with H. cornea. Populations were mixed for these genetic groups, with group I prominent in Quintana Roo populations. Morphological analysis of samples in both genetic clades showed that they are not distinguishable. As the difference between the two groups is only genetic, they are, consequently, cryptic species. While the extremes of morphology in allopatric populations may be distinguishable, we do not feel that in most cases these species can be recognized. Therefore, we propose that these two ‘species’ should be designated as a species complex (the Hydropuntia cornea/H. usneoides complex).

V. Cassano, J. Díaz-Larrea, A. Sentíes, M.C. Oliveira, M. CandelariaGil-RodríguezandM.T. Fujii. 2009. Evidence for the conspecificity of Palisada papillosawith P. perforata(Ceramiales, Rhodophyta) from the western and eastern Atlantic Ocean on the basis of morphological and molecular analyses. Phycologia48: 86–100. DOI: 10.2216/08-22.1.Morphological and molecular studies were carried out on Palisada papillosaand P. perforatafrom the Canary Islands (type locality of P. perforata), Mexico and Brazil. The two species have been distinguished by features of their external morphology such as size and degree of compactness of the thalli, presence or absence of arcuate branches, branching pattern and basal system. A detailed morphological comparison between these taxa showed that none of the vegetative anatomical or reproductive characters was sufficient to separate these species. The presence or absence of cortical cells in a palisade-like arrangement, also previously used to distinguish these species, is not applicable. The species present all characters typical of the genus, and both share production of the first pericentral cell underneath the basal cell of the trichoblast, production of two fertile pericentral cells (the second and the third additional, the first remaining sterile), spermatangial branches produced from one of two laterals on the suprabasal cell of trichoblasts, and the procarp-bearing segment with four pericentral cells. Details of the procarp are described for the species for the first time. The phylogenetic position of these species was inferred by analysis of the chloroplast-encoded rbcL gene sequences from 39 taxa, using one other Rhodomelacean taxon and two Ceramiaceae as outgroups. Relationships within the clade formed by P. papillosaand P. perforatahave not been resolved due to the low level of genetic variation in their rbcL sequences (0–0.4%). Considering this and the morphological similarities, we conclude that P. papillosais a taxonomic synonym of P. perforata. The phylogenetic analyses also supported the nomenclatural transfer of two species of Chondrophycusto Palisada, namely, P. patentiramea(Montagne) Cassano, Sentíes, Gil-Rodríguez & M.T. Fujii comb. nov. and P. thuyoides(Kützing) Cassano, Sentíes, Gil-Rodríguez & M.T. Fujii comb. nov.