Non-photosynthetic predators are sister to red algae.

Rhodophyta (red algae) is one of three lineages of Archaeplastida1, a supergroup that is united by the primary endosymbiotic origin of plastids in eukaryotes2,3. Red algae are a diverse and species-rich group, members of which are typically photoautotrophic, but are united by a number of highly derived characteristics: they have relatively small intron-poor genomes, reduced metabolism and lack cytoskeletal structures that are associated with motility, flagella and centrioles. This suggests that marked gene loss occurred around their origin4; however, this is difficult to reconstruct because they differ so much from the other archaeplastid lineages, and the relationships between these lineages are unclear. Here we describe the novel eukaryotic phylum Rhodelphidia and, using phylogenomics, demonstrate that it is a closely related sister to red algae. However, the characteristics of the two Rhodelphis species described here are nearly opposite to those that define red algae: they are non-photosynthetic, flagellate predators with gene-rich genomes, along with a relic genome-lacking primary plastid that probably participates in haem synthesis. Overall, these findings alter our views of the origins of Rhodophyta, and Archaeplastida evolution as a whole, as they indicate that mixotrophic feeding-that is, a combination of predation and phototrophy-persisted well into the evolution of the group.

Of sea, rivers and symbiosis: Diversity, systematics, biogeography and evolution of the deeply diverging florideophycean order Hildenbrandiales (Rhodophyta).

The Hildenbrandiales, a typically saxicolous red algal order, is an early diverging florideophycean group with global significance in marine and freshwater ecosystems across diverse temperature zones. To comprehensively elucidate the diversity, phylogeny, biogeography, and evolution of this order, we conducted a thorough re-examination employing molecular data derived from nearly 700 specimens. Employing a species delimitation method, we identified Evolutionary Species Units (ESUs) within the Hildenbrandiales aiming to enhance our understanding of species diversity and generate the first time-calibrated tree and ancestral area reconstruction for this order. Mitochondrial cox1 and chloroplast rbcL markers were used to infer species boundaries, and subsequent phylogenetic reconstructions involved concatenated sequences of cox1, rbcL, and 18S rDNA. Time calibration of the resulting phylogenetic tree used a fossil record from a Triassic purportedly freshwater Hildenbrandia species and three secondary time points from the literature. Our species delimitation analysis revealed an astounding 97 distinct ESUs, quintupling the known diversity within this order. Our time-calibration analysis placed the origin of Hildenbrandiales (crown age) in the Ediacaran period, with freshwater species emerging as a monophyletic group during the later Permian to early Triassic. Phylogenetic reconstructions identified seven major clades, experiencing early diversification during the Silurian to Carboniferous period. Two major evolutionary events-colonization of freshwater habitats and obligate systemic symbiosis with a marine fungus-marked this order, leading to significant morphological alterations without a commensurate increase in species diversification. Despite the remarkable newly discovered diversity, the extant taxon diversity appears relatively constrained when viewed against an evolutionary timeline spanning over 800 million years. This limitation may stem from restricted geographic sampling or the prevalence of asexual reproduction. However, species richness estimation and rarefaction analyses suggest a substantially larger diversity yet to be uncovered-potentially four times greater. These findings drastically reshape our understanding of the deeply diverging florideophycean order Hildenbrandiales species diversity, and contribute valuable insights into this order's evolutionary history and ecological adaptations. Supported by phylogenetic, ecological and morphological evidence, we established the genus Riverina gen. nov. to accommodate freshwater species of Hildenbrandiales, which form a monophyletic clade in our analyses. This marks the first step toward refining the taxonomy of the Hildenbrandiales, an order demanding thorough revisions, notably with the creation of several genera to address the polyphyletic status of Hildenbrandia. However, the limited diagnostic features pose a challenge, necessitating a fresh approach to defining genera. A potential solution lies in embracing a molecular systematic perspective, which can offer precise delineations of taxonomic boundaries.

A multiscale analysis of coralline algae Lithophylloideae (Corallinophycidae, Rhodophyta) shedding new light on understanding cryptic diversity.

Cryptic diversity abounds in many biological species, posing challenges to our understanding of biological diversity, conservation and management. Taking the common coralline algae, the subfamily Lithophylloideae as an illustration, this study delved into the implications of cryptic diversity through global-level phylogenetic and geographical analysis based upon Lithophylloideae molecular data worldwide, as well as a multi-locus time-calibrated phylogeny to elucidate their possible evolutionary process. The multiscale analysis revealed the polyphyly in current concept of the genus Lithophyllum. Geographic isolation resulting from the Tethys terminal event (TTE) has led to two distinct distribution regions for this so-called cosmopolitan genus: one regionally distributed along European coasts/Mediterranean that should include the taxonomical Lithophyllum; others widely distributed, particularly among pan-tropic waters, suggesting at least five groups to be rediscovered within the subfamily Lithophylloideae. Meanwhile, the cryptic genus Titanoderma, lacking morphological identification features with Lithophyllum, exhibited differences in distribution and evolutionary patterns consistent with their ecological habits, thus supporting their separation. This study provided useful hints for cryptic diversity, which advocated an integrative thinking to investigating global cryptic diversity and exploring the broad linkages between phylogenetic relationships and evolutionary origin, biogeography, morphological and ecological traits to achieve a more comprehensive understanding of biodiversity.

Validation of the names Cavernulicolales, Cavernulicolaceae, Cavernulicola, and Cavernulicola chilensis (Rhodophyta).

A reclassification of Cyanidium chilense under the new genus Cavernulicola was recently proposed together with a new family (Cavernulicolaceae) and a new order (Cavernulicolales). Unfortunately, due to an error in the required citation of the basionym, the name "Cavernulicola chilensis" was invalid and cannot be accepted as the generitype of Cavernulicola. This means that Cavernulicola, Cavernulicolaceae, and Cavernulicolales are likewise invalid names under the provisions of the International Code of Nomenclature for algae, fungi, and plants (ICN, Shenzhen Code). In this contribution, each of these names is validated.

A revision of the genus Wrangelia (Wrangeliaceae, Ceramiales) in Bermuda resolves six new species including W. ryancraigii from the mesophotic zone.

Four species of the genus Wrangelia are presently known from the western Atlantic Ocean: W. argus, W. bicuspidata, W. penicillata, and W. gordoniae, with the first three historically being reported from Bermuda. Morphological and molecular barcode (COI-5P) and phylogenetic analyses used in this study (SSU, LSU, rbcL) indicated eight species groupings of Wrangelia in Bermuda, excluding two of the historically recognized species, retaining only W. argus while adding seven new species, of which six are formally described. What had been historically reported as W. penicillata from Bermuda was shown to be distinct from Mediterranean Sea specimens (type locality) and was shown to be a mixture of W. hesperia sp. nov. and W. incrassata sp. nov. Along with these two, three other new species (W. laxa sp. nov., W. ryancraigii sp. nov., and W. secundiramea sp. nov.) have complete rhizoidal cortication tightly covering axial cells of indeterminate axes below the apices, distinguishing them from the two local incompletely corticated congeners W. argus and W. abscondita sp. nov., the latter a morphologically cryptic sister species with W. bicuspidata from the Caribbean Sea. Only one of the new species, W. ryancraigii, has thus far been observed in the mesophotic zone off the Bermuda platform, and it is morphologically cryptic with the euphotic zone's W. laxa.

Characterization of the organellar genomes of Mazzaella laminarioides and Mazzaella membranacea (Gigartinaceae, Rhodophyta).

Mazzaella, a genus with no genomic resources available, has extensive distribution in the cold waters of the Pacific, where they represent ecologically and economically important species. In this study, we aimed to sequence, assemble, and annotate the complete mitochondrial and chloroplast genomes from two Mazzaella spp. and characterize the intraspecific variation among them. We report for the first time seven whole organellar genomes (mitochondria: OR915856, OR947465, OR947466, OR947467, OR947468, OR947469, OR947470; chloroplast: OR881974, OR909680, OR909681, OR909682, OR909683, OR909684, OR909685) obtained through high-throughput sequencing for six M. laminarioides sampled from three Chilean regions and one M. membranacea. Sequenced Mazzaella mitogenomes have identical gene number, gene order, and genome structure. The same results were observed for assembled plastomes. A total of 52 genes were identified in mitogenomes, and a total of 235 genes were identified in plastomes. Although the M. membranacea plastome included a full-length pbsA gene, in all M. laminarioides samples, the pbsA gene was split in three open reading frames (ORFs). Within M. laminarioides, we observed important plastome lineage-specific variations, such as the pseudogenization of the two hypothetical protein-coding genes, ycf23 and ycf45. Nonsense mutations in the ycf23 and ycf45 genes were only detected in the northern lineage. These results are consistent with phylogenetic reconstructions and divergence time estimation using concatenated coding sequences that not only support the monophyly of M. laminarioides but also underscore that the three M. laminarioides lineages are in an advanced stage of divergence. These new results open the question of the existence of still undisclosed species in M. laminarioides.

Morphological and Chemical Diversity within Japanese Laurencia Complex (Rhodomelaceae, Ceramiales, Rhodophyta).

Seaweeds of the red algal genus Laurencia are distributed worldwide in tropical, subtropical to temperate zones, growing in Japan from Hokkaido to Okinawa. Laurencia is highly difficult to classify morphologically because of a high degree of morphological variation within individual species. Nevertheless, Laurencia investigation is favored by organic chemists as it produces uniquely structured compounds. Halogenated secondary metabolites are considered to be used as chemical markers for chemical systematics (chemotaxonomy) of this troublesome genus. As a "weedy seaweed", Laurencia is not effectively utilized, yet it produces a variety of metabolites and thus, holds good potential for containing compounds with specific activity, especially in aspects of secondary metabolites. In this review, we reported significant morphological features to distinguish species in this genus, and the morphological features, habitat, distribution, and chemical composition that help discriminate Japanese Laurencia species.

Trophic control of cryptic coralline algal diversity.

Understanding how trophic dynamics drive variation in biodiversity is essential for predicting the outcomes of trophic downgrading across the world's ecosystems. However, assessing the biodiversity of morphologically cryptic lineages can be problematic, yet may be crucial to understanding ecological patterns. Shifts in keystone predation that favor increases in herbivore abundance tend to have negative consequences for the biodiversity of primary producers. However, in nearshore ecosystems, coralline algal cover increases when herbivory is intense, suggesting that corallines may uniquely benefit from trophic downgrading. Because many coralline algal species are morphologically cryptic and their diversity has been globally underestimated, increasing the resolution at which we distinguish species could dramatically alter our conclusions about the consequences of trophic dynamics for this group. In this study, we used DNA barcoding to compare the diversity and composition of cryptic coralline algal assemblages at sites that differ in urchin biomass and keystone predation by sea otters. We show that while coralline cover is greater in urchin-dominated sites (or "barrens"), which are subject to intense grazing, coralline assemblages in these urchin barrens are significantly less diverse than in kelp forests and are dominated by only 1 or 2 species. These findings clarify how food web structure relates to coralline community composition and reconcile patterns of total coralline cover with the widely documented pattern that keystone predation promotes biodiversity. Shifts in coralline diversity and distribution associated with transitions from kelp forests to urchin barrens could have ecosystem-level effects that would be missed by ignoring cryptic species' identities.

Extensive cryptic diversity in the widely distributed Polysiphonia scopulorum (Rhodomelaceae, Rhodophyta): Molecular species delimitation and morphometric analyses.

Our knowledge of seaweed diversity and biogeography still largely relies on information derived from morphological identifications, but the use of molecular tools is revealing that cryptic diversity is common among algae. Polysiphonia scopulorum is a turf-forming red alga widely reported in tropical and temperate coasts worldwide. The only study based on material collected from its Australian type locality and the Iberian Peninsula indicates that it is a species complex, but the extent of cryptic diversity across its geographical range is not known. To investigate the species diversity in P. scopulorum, the geographical distribution of species-level lineages and their morphological characterization, we collected 135 specimens from Australia, South Africa and southern Europe. Two gene datasets (cox1 and rbcL) were used to delimit species using three methods (GMYC, PTP, ABGD), leading to a consensus result that our collections of the P. scopulorum complex comprise 12 species. Five of these species were resolved in a highly supported clade, while the other seven species were related to other taxonomically accepted species or in unresolved parts of the tree. Morphometric and statistical analysis of a set of ten quantitative characters showed that there are no clear morphological correlates of species boundaries, demonstrating true cryptic diversity in the P. scopulorum complex. Distribution patterns of the 12 species were variable, ranging from species only known from a single site to species with a wide distribution spanning three continents. Our study indicates that a significant level of undiscovered cryptic diversity is likely to be found in algal turfs, a type of seaweed community formed by small entangled species.

Radiation of the coralline red algae (Corallinophycidae, Rhodophyta) crown group as inferred from a multilocus time-calibrated phylogeny.

The subclass Corallinophycidae is the only group of red algae characterized by the presence of calcite crystals in their cell walls. Except for the Rhodogorgonales, the remaining orders - collectively called corallines - are diverse and widely distributed, having calcified cell walls and highly variable morphology. Corallines constitute the group with the richest fossil record among marine algae. In the present study, we investigate the evolutionary history of the subclass Corallinophycidae and provide a time-calibrated phylogeny to date the radiation of the crown group and its main lineages. We use a multi-locus dataset with an extensive taxon sampling and comprehensive collection of fossil records, carefully assigned to corallines, to reconstruct a time-calibrated phylogeny of this subclass. Our molecular clock analyses suggest that the onset of crown group diversification of Corallinophycidae started in the Lower Jurassic and sped up in the Lower Cretaceous. The divergence time of the oldest order Sporolithales is estimated in the Lower Cretaceous followed by the remaining orders. We discuss the long period of more than 300 million years between the early Paleozoic records attributed to the stem group of Corallinophycidae and the radiation of the crown group. Our inferred phylogeny yields three highly-supported suprageneric lineages for the order Corallinales; we confirm the family Mastophoraceae and amend circumscription of the families Corallinaceae and Lithophyllaceae. These three families are distinguished by a combination of vegetative and reproductive features. In light of the phylogeny, we discuss the evolutionary trends of eleven morphological characters. In addition, we also highlight homoplasious characters and selected autapomorphies emerging in particular taxa.

Chemotaxonomic Study of Bostrychia spp. (Ceramiales, Rhodophyta) Based on Their Mycosporine-Like Amino Acid Content.

This study presents a chemotaxonomic investigation of the genus Bostrychia through the quantitation of the major mycosporine-like amino acids (MAAs). The presence of some cryptic species had been suggested in the B. moritziana/B. radicans complex and MAA-profiling in respective samples revealed different chemotypes within this species complex. Another possibly polyphyletic species is Bostrychia simpliciuscula; previous molecular phylogenetic analyses showed four genetic lineages within this species, one of which was recently distinguished as a new species. Phytochemical profiling of those samples used for DNA analyses revealed four different chemotypes, corresponding to the above four lineages and it supports the re-circumscription of the other three B. simpliciuscula lineages. Therefore, mycosporine-like amino acids are considered as suitable chemotaxonomic markers for the reassessment of the classification of B. simpliciuscula. The determination of the MAA patterns in these algae was possible after developing and validating a suitable high-performance liquid chromatography-diode array detector (HPLC-DAD) method.

Algae metabolites: from in vitro growth inhibitory effects to promising anticancer activity.

Covering: 1957 to 2017 Algae constitute a heterogeneous group of eukaryotic photosynthetic organisms, mainly found in the marine environment. Algae produce numerous metabolites that help them cope with the harsh conditions of the marine environment. Because of their structural diversity and uniqueness, these molecules have recently gained a lot of interest for the identification of medicinally useful agents, including those with potential anticancer activities. In the current review, which is not a catalogue-based one, we first highlight the major biological events that lead to various types of cancer, including metastatic ones, to chemoresistance, thus to any types of current anticancer treatment relating to the use of chemotherapeutics. We then review algal metabolites for which scientific literature reports anticancer activity. Lastly, we focus on algal metabolites with promising anticancer activity based on their ability to target biological characteristics of cancer cells responsible for poor treatment outcomes. Thus, we highlight compounds that have, among others, one or more of the following characteristics: selectivity in reducing the proliferation of cancer cells over normal ones, potential for killing cancer cells through non-apoptotic signaling pathways, ability to circumvent MDR-related efflux pumps, and activity in vivo in relevant pre-clinical models.

A molecular phylogeny of the bladed Bangiales (Rhodophyta) in China provides insights into biodiversity and biogeography of the genus Pyropia.

A molecular taxonomic study was undertaken for the first time of the bladed Bangiales of the mainland coast of China (Northwest Pacific) based on sequence data of 201 plastid rbcL and 148 nuclear 18S sequences of historical and contemporary specimens. The results revealed that only one genus of bladed Bangiales, Pyropia, was present along Chinese coast. Species delimitation was determined using two empirical methods: the Automatic Barcode Gap Discovery (ABGD) and General Mixed Yule Coalescence (GMYC) coupled with detection of monophyly in tree reconstruction. At least fourteen species of Pyropia were recovered. Six species were confirmed that had been recorded previously based on morphology (Py. suborbiculata, Py. yezoensis, Py. haitanensis, Py. katadae, Py. tenera and Py. acanthophora), three species were recorded from China for the first time (Py. kinositae, Py. pseudolinearis and Py. tanegashimensis), and five cryptic species that did not match any molecular sequences were also discovered. The phylogeny of the concatenated rbcL and 18S dataset resolved three singletons and four clades. Each clades has a strong trend towards occupying a biogeographic region, but they are not confined to them. A transoceanic and antitropical pattern of distribution was found for Pyropia at both the subgeneric and species level. This together with high biodiversity (ca. 30% of all known Pyropia species) indicates that the Northwest Pacific might act as a centre of origin for modern distribution of Pyropia since the early Cenozoic.

Phylogenetic analyses of transcriptome data resolve familial assignments for genera of the red-algal Acrochaetiales-Palmariales Complex (Nemaliophycidae).

Phylogenetic analyses of transcriptome data for representatives of the red algal Acrochaetiales-Palmariales Complex provided robust support for the assignment of genera to the constituent families. In the Acrochaetiales, the genera Acrochaetium, Grania, and an unnamed genus-level lineage (Acrochaetiac sp._1Aus) were assigned to the Acrochaetiaceae, while Audouinella is placed in a resurrected Audouinellaceae and Rhodochorton and Rhododrewia constitute the resurrected Rhodochortonaceae. For the Palmariales, transcriptome data solidly support the inclusion of Camontagnea and Rhodothamniella in the Rhodothamniellaceae, Meiodiscus and Rubrointrusa in the Meiodiscaceae, Rhodonematella and Rhodophysema in the Rhodophysemataceae, while Devaleraea and Palmaria remained in the Palmariaceae. These analyses, however, questioned the monophyly of Palmaria, which prompted a second round of analyses using eight common red algal phylogenetic markers and including a broader sampling of red algal genera in our analyses. These results supported transfer of Palmaria callophylloides and P. mollis to the genus Devaleraea necessitating new combinations, and further added the genus Halosaccion to the Palmariaceae and the genera Kallymenicola and Rhodophysemopsis to the Meiodiscaceae. Finally, DNA barcode (mitochondrial COI-5P) and ITS data were explored and supported the continued recognition of Palmaria palmata as a single species in the North Atlantic.

Cryptic dispersal of Cyanidiophytina (Rhodophyta) in non-acidic environments from Turkey.

Cyanidiophytina are a group of polyextremophilic red algae with a worldwide, but discontinuous colonization. They are restricted to widely dispersed hot springs, geothermal habitats, and also some human-altered environments. Cyanidiophytina are predominant where pH is prohibitive for the majority of eukaryotes (pH 0.5-3). Turkey is characterized by areas rich in volcanic activity separated by non-volcanic areas. Here we show that Cyanidiophycean populations are present in thermal baths located around Turkey on neutral/alkaline soils. All known genera and species within Cyanidiophytina were detected in Turkey, including Galdieria phlegrea, recorded up to now only in Italian Phlegrean Fields. By phylogenetic analyses, Turkish G. sulphuraria strains are monophyletic with Italian and Icelandic strains, and with Russian G. daedala strains. G. maxima from Turkey clustered with Icelandic, Kamchatka, and Japanese populations. The discovery of Cyanidiophytina in non-acidic Turkish soils raises new questions about the ecological boundaries of these extremophilic algae. This aids in the understanding of the dispersal abilities and distribution patterns of this ecologically and evolutionarily interesting group of algae.

Three gene phylogeny of the Thoreales (Rhodophyta) reveals high species diversity.

The freshwater red algal order Thoreales has triphasic life history composed of a diminutive diploid "Chantransia" stage, a distinctive macroscopic gametophyte with multi-axial growth and carposporophytes that develop on the gametophyte thallus. This order is comprised of two genera, Thorea and Nemalionopsis. Thorea has been widely reported with numerous species, whereas Nemalionopsis has been more rarely observed with only a few species described. DNA sequences from three loci (rbcL, cox1, and LSU) were used to examine the phylogenetic affinity of specimens collected from geographically distant locations including North America, South America, Europe, Pacific Islands, Southeast Asia, China, and India. Sixteen species of Thorea and two species of Nemalionopsis were recognized. Morphological observations confirmed the distinctness of the two genera and also provided some characters to distinguish species. However, many of the collections were in "Chantransia" stage rather than gametophyte stage, meaning that key diagnostic morphological characters were unavailable. Three new species are proposed primarily based on the DNA sequence data generated in this study, Thorea kokosinga-pueschelii, T. mauitukitukii, and T. quisqueyana. In addition to these newly described species, one DNA sequence from GenBank was not closely associated with other Thorea clades and may represent further diversity in the genus. Two species in Nemalionopsis are recognized, N. shawii and N. parkeri nom. et stat. nov. Thorea harbors more diversity than had been recognized by morphological data alone. Distribution data indicated that Nemalionopsis is common in the Pacific region, whereas Thorea is more globally distributed. Most species of Thorea have a regional distribution, but Thorea hispida appears to be cosmopolitan.

Revision of Corallinaceae (Corallinales, Rhodophyta): recognizing Dawsoniolithon gen. nov., Parvicellularium gen. nov. and Chamberlainoideae subfam. nov. containing Chamberlainium gen. nov. and Pneophyllum.

A multi-gene (SSU, LSU, psbA, and COI) molecular phylogeny of the family Corallinaceae (excluding the subfamilies Lithophylloideae and Corallinoideae) showed a paraphyletic grouping of six monophyletic clades. Pneophyllum and Spongites were reassessed and recircumscribed using DNA sequence data integrated with morpho-anatomical comparisons of type material and recently collected specimens. We propose Chamberlainoideae subfam. nov., including the type genus Chamberlainium gen. nov., with C. tumidum comb. nov. as the generitype, and Pneophyllum. Chamberlainium is established to include several taxa previously ascribed to Spongites, the generitype of which currently resides in Neogoniolithoideae. Additionally we propose two new genera, Dawsoniolithon gen. nov. (Metagoniolithoideae), with D. conicum comb. nov. as the generitype and Parvicellularium gen. nov. (subfamily incertae sedis), with P. leonardi sp. nov. as the generitype. Chamberlainoideae has no diagnostic morpho-anatomical features that enable one to assign specimens to it without DNA sequence data, and it is the first subfamily to possess both Type 1 (Chamberlainium) and Type 2 (Pneophyllum) tetra/bisporangial conceptacle roof development. Two characters distinguish Chamberlainium from Spongites: tetra/biasporangial conceptacle chamber diameter (<300 µm in Chamberlainium vs. >300 µm in Spongites) and tetra/bisporangial conceptacle roof thickness (<8 cells in Chamberlainium vs. >8 cells in Spongites). Two characters also distinguish Pneophyllum from Dawsoniolithon: tetra/bisporangial conceptacle roof thickness (<8 cells in Pneophyllum vs. >8 cells in Dawsoniolithon) and thallus construction (dimerous in Pneophyllum vs. monomerous in Dawsoniolithon).

Widely distributed red algae often represent hidden introductions, complexes of cryptic species or species with strong phylogeographic structure.

Despite studies suggesting that most seaweeds are poor dispersers, many red algal species are reported to have circumglobal distributions. Such distributions have mostly been based on morphological identifications, but molecular data have revealed a range of issues with morphologically defined species boundaries. Consequently, the real distribution of such reportedly circumglobal species must be questioned. In this study, we analyzed molecular data sets (rbcL gene) of nine species in the Rhodomelaceae for which samples were available from widely spaced geographical locations. Three overall patterns were identified: (i) species showing strong phylogeographic structure (i.e., phylogenetic similarity correlates with geographical provenance), often to the point that populations from different locations could be considered as different species (Lophosiphonia obscura, Ophidocladus simpliciusculus, Polysiphonia villum, and Xiphosiphonia pinnulata); (ii) species with a broad distribution that is explained, in part, by putative human-mediated transport (Symphyocladia dendroidea and Polysiphonia devoniensis); and (iii) non-monophyletic complexes of cryptic species, most with a more restricted distribution than previously thought (Herposiphonia tenella, Symphyocladia dendroidea, and the Xiphosiphonia pennata complex that includes the species Xiphosiphonia pinnulata and Symphyocladia spinifera). This study shows that widely distributed species are the exception in marine red algae, unless they have been spread by humans.

Ottia meiospora (Ottiaceae, Rhodophyta), a new genus and family endophytic within the thallus of Nothocladus (Batrachospermales, Rhodophyta).

A new genus, Ottia, and family, Ottiaceae, are proposed within the Acrochaetiales to accommodate the uniseriate red algal endophyte of batrachspermalean taxa previously named Balbiania meiospora. Prior to this study, Balbiania investiens was transferred to its own family and order (Balbianiales) based on comparative DNA sequence data and a distinctive reproductive morphology. However, the second species described in this genus, B. meiospora, continued to be treated as a species of Audouinella (A. meiospora) pending further investigation. Phylogenetic analyses of sequence data confirmed only a distant relationship between the two endophytes, and a closer alliance of B. meiospora to Acrochaetiales. The data also showed that Ottia meiospora was the deepest diverging lineage in the Acrochaetiales, sister to all of the currently recognized genera and families. In this study, we review the classification of what we now call O. meiospora - reported from Australia, New Zealand and Brazil - based on sequence and morphological data. Morphological observations provided little clarity around the reproductive morphology or the life cycle of this endophyte of Nothocladus s. lat. found commonly in mainland Australia but, to date, less so in New Zealand.

Phylogenetic relationships and biogeography of Ptilophora (Gelidiales, Rhodophyta) with descriptions of P. aureolusa, P. malagasya, and P. spongiophila from Madagascar.

The genus Ptilophora currently includes 16 species occurring mostly in subtidal habitats of the Indo-Pacific Ocean, but its global diversity and biogeography are poorly understood. We analyzed mitochondrial cox1, plastid rbcL and plastid psbA sequences from specimens collected in southern Madagascar during the 2010 Atimo Vatae expedition and studied their morphologies. Both morphological and molecular data sets demonstrated the presence of five species in southern Madagascar: Ptilophora hildebrandtii, P. pterocladioides, and three new species described here, P. aureolusa, P. malagasya, and P. spongiophila. Ptilophora aureolusa is distinguished by its compound pinnae with uniformly spaced pinnules. Ptilophora malagasya has an indistinct midrib and irregularly spaced pinnules. Ptilophora spongiophila, heavily coated with sponges, has cylindrical to flattened main axes, lateral and surface proliferations, and spatulate tetrasporangial sori. The species of Ptilophora found in Madagascar are endemic, except P. hildebrandtii, which also occurs in eastern Africa. Ptilophora comprises four phylogenetic groups that map to eastern Australia, Japan, western Australia/Southeast Asia/Madagascar/eastern Africa, and Madagascar/eastern Africa/Aegean Sea. Biogeographical analysis revealed that the ancestor of Ptilophora originated in Australia, but most of the species radiated from Madagascar.