Phylogeny and morphology of Nemalionopsis shawii (Thoreales,Rhodophyta), a new generic record from mainland China

The freshwater red alga Nemalionopsis shawii Skuja is first reported for mainland China from specimens collected in Guangdong and Yunnan Province. Morphological observations and molecular sequences of rbcL and cox1 genes were used to identify and analyze the phylogenetic position of the samples. Samples from China formed a monophyletic clade with other N. shawii samples from Japan, Indonesia, and Nepal with robust support values. The pairwise genetic distances for N. shawii between the samples from China and other samples were 0.2–1.5% and 1.0–2.4% for rbcL and cox1, respectively. Both male and female reproductive structures were observed in the specimens from Guangdong, but only monosporangia in the specimen from Yunnan. The samples from China increase the diversity of morphological measurements for N. shawii. The discovery of this genus in mainland China results in a new record of a freshwater red alga for this country.     

Phylogeography of the freshwater red alga Sirodotia (Batrachospermales,Rhodophyta) in Brazil

Considering the lack of knowledge on genetic variation on members of the freshwater red algal of the order Batrachospermales in tropical regions, phylogeographic patterns in Sirodotia populations were investigated using two mitochondrial regions: the cox2‐3 spacer and partial cox1 gene (barcode). Individuals identified as Sirodotia delicatula were analyzed from 14 stream segments across its distribution in Brazil. Phylogenetic analyses based on the ribulose‐1,5‐bisphosphate carboxylase/oxygenase large sub‐unit gene showed three clades, one representing S. delicatula, from all locations in southeastern Brazil and other regions from Brazil. The remaining samples formed two clades, which were highly divergent and distantly positioned from those of S. delicatula: 2.5–2.7% and 3.4–3.7%. This level of variation would warrant the species split of these taxa from mid‐western Brazil. A total of eight cox2‐3 spacer and nine cox1 haplotypes were observed among the 122 individuals studied. One location had two cox2‐3 haplotypes and three locations had two cox1 haplotypes; all others had a single dominant haplotype each. The existence of high intraspecific genetic variation among individuals of distinct locations (several haplotypes), but little variation within a location seems to be a pattern for the Batrachospermales. Haplotype networks showed low variation among the haplotypes from southeastern Brazil (10 locations with divergence of 0.3–1.1% for cox2‐3, 0.1–0.3% for cox1) and high variation among the haplotypes from the mid‐west region (four locations, 4.0–9.3% for cox2‐3, 6.2–8.4% for cox1). Thus, the present data clearly suggest the existence of cryptic species in Sirodotia in Brazil.     

Phenology and phylogenetic positioning of the Hawaiian endemic freshwater alga, Batrachospermum spermatiophorum (Rhodophyta, Batrachospermales)

The only known population of Batrachospermum spermatiophorum Vis et Sheath, located in a small stream on east Maui, Hawaii, was sampled from November 2001 to October 2002 to investigate its phenology. Additionally, the taxonomic status of the alga was examined. Phylogenetic analyses of the large subunit of the ribulose‐1,5‐bisphosphate carboxylase/oxygenase (rbcL) gene for B. spermatiophorum confirm its placement within the Section Contorta of the genus Batrachospermum. Comparisons with rbcL gene sequences for all other available Batrachospermum species, including 10 other members of the Section Contorta, illustrate that B. spermatiophorum is distinct in its rbcL nucleotide sequence and should be maintained as a separate species. The phenology of B. spermatiophorum differed from most studies of Batrachospermum reproduction in that the gametophytes were present year round, and no macroscopic chantran‐sia stages were identified at any point during the present study. Maximum plant length was highest in the late fall and early winter months, while gametangial production peaked in February and March. Carposporophyte abundance rose sharply in July and August, and the percentage of carposporophytes producing carpospores was highest in late summer and early fall months. Although significant correlations were determined among stream conditions and among phenological characteristics, only pH was associated with several of the reproductive characters, which is unusual for studies of Batrachospermum phenology. Timing of sexual reproduction for all macroalgal community members in the stream site was not coordinated, with some reproducing year round and others more sporadically. The year‐round presence of Batrachospermum gametophytes may be a result of a combination of smaller seasonal changes in cues such as day length and water temperature in the tropical environment than occur in temperate locations, and lack of extreme conditions that might inhibit the persistence of the gametophyte.     

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.     

Patterns of genetic diversity of the cryptogenic red alga Polysiphonia morrowii (Ceramiales,Rhodophyta) suggest multiple origins of the Atlantic populations

The red alga Polysiphonia morrowii, native to the North Pacific (Northeast Asia), has recently been reported worldwide. To determine the origin of the French and Argentine populations of this introduced species, we compared samples from these two areas with samples collected in Korea and at Hakodate, Japan, the type locality of the species. Combined analyses of chloroplastic (rbcL) and mitochondrial (cox1) DNA revealed that the French and Argentine populations are closely related and differ substantially from the Korean and Japanese populations. The genetic structure of P. morrowii populations from South Atlantic and North Atlantic, which showed high haplotype diversity compared with populations from the North Pacific, suggested the occurrence of multiple introduction events from areas outside of the so‐called native regions. Although similar, the French and Argentine populations are not genetically identical. Thus, the genetic structure of these two introduced areas may have been modified by cryptic and recurrent introduction events directly from Asia or from other introduced areas that act as introduction relays. In addition, the large number of private cytoplasmic types identified in the two introduced regions strongly suggests that local populations of P. morrowii existed before the recent detection of these invasions. Our results suggest that the most likely scenario is that the source population(s) of the French and Argentine populations was not located only in the North Pacific and/or that P. morrowii is a cryptogenic species.     

Phylogeography of the freshwater red alga B atrachospermum viride‐brasiliense (Rhodophyta,Batrachospermales)

Phylogeography of B atrachospermum viride‐brasiliense was investigated using two mitochondrial regions: the cox2‐3 spacer and the barcode region of cox1 gene. Eighty‐seven individuals were analyzed from nine stream segments throughout its distribution in Brazil. Ten cox2‐3 spacer and nine cox1 haplotypes were observed among the individuals studied (87 vs. 43, respectively). Divergences among haplotypes were relatively low (≤2.4% for cox2‐3 and ≤1.8% for cox1). Most locations have a single haplotype, whereas only two locations had two haplotypes for both markers. The haplotype network for cox2‐3 showed a phylogeographic trend from the south towards the southeast with haplotypes from the southeast more closely related. For cox1 a trend from the southeast spreading towards the south and north was revealed, with the southern haplotypes more closely associated. Results clearly indicated that B . viride‐brasiliense represents a single species and the phylogeographic pattern consisted of a closely connected group of haplotypes from southern and southeastern Brazil. Levels of intra‐ and inter‐population variation were similar for the two markers with slightly higher values for cox2‐3. The trend observed in this study is similar to that in other members of Batrachospermales with little variation within a stream segment (one or two haplotypes) and more distant haplotypes showing higher divergences. This pattern could be attributed to the fact that colonization of a site might be rare by a single event with subsequent proliferation of the population. The geographic distribution of B . viride‐brasiliense was interpreted according to the biogeographic models proposed for South America being limited to three morpho‐climatic domains or biogeographic provinces: tropical Atlantic rainforest, sub‐tropical rainforest and cerrado (Brazilian savannah).     

New red alga Meristotheca imbricata (Solieriaceae, Gigartinales) from Japan

A new red alga Meristotheca imbricata Faye et Masuda (Solieriaceae, Gigartinales) was described on the basis of specimens collected from southern Japan. Although this species might have been for a long time included in the concept of M. coacta Okamura, until recently a very poorly known alga, it is distinguished from the latter by the following features: (i) each thallus consists of one primary blade and several secondary blades, the latter arising from the apical or subapical portion of terminal segments of the primary blade; (ii) the individual blades are repeatedly dichotomously divided into linear segments of which margins are neither undulate nor crispate, and are fleshy, imbricate, frequently anastomosing and often acervate; (iii) each tetrasporangial initial is attached by a basal pit-connection to the parental cell, and the position of the pit-connection changes from basal to lateral by inward growth of the tetrasporangium; and (iv) the carpogonial branches sometimes have a one-celled sterile lateral.     

Phenology,irradiance and temperature characteristics of a freshwater red alga,Nemalionopsis tortuosa (Thoreales), from Kagoshima,southern Japan

Phenology, irradiance and temperature characteristics of a freshwater benthic red alga, Nemalionopsis tortuosa Yoneda et Yagi (Thoreales), were examined from Kagoshima Prefecture, southern Japan for the conservation of this endemic and endangered species. Field surveys confirmed that algae occurred in shaded habitats from winter to early summer, and disappeared during August through November. A net photosynthesis–irradiance (P–E) model revealed that net photosynthetic rate quickly increased and saturated at low irradiances, where the saturating irradiance (E_k) and compensation irradiance (E_c) were 10 (8–12, 95% credible interval (CRI)) and 8 (6–10, 95% CRI) μmol photon m^?2 s^?1, respectively. Gross photosynthesis and dark respiration was determined over a range of temperatures (8–36°C) by dissolved oxygen measurements, and revealed that the maximum gross photosynthetic rate was highest at 29.5 (27.4–32.0, 95%CRI) °C. Dark respiration also increased linearly when temperature increased from 8°C to 36°C, indicating that the increase in dark respiration at higher temperature most likely caused decreases in net photosynthesis. The maximum quantum yield (Fv/Fm) that was determined using a pulse amplitude modulated‐chlorophyll fluorometer (Imaging‐PAM) was estimated to be 0.51 (0.50–0.52, 95%CRI) and occurred at an optimal temperature of 21.7 (20.1–23.4, 95%CRI) °C. This species can be considered well‐adapted to the relatively low natural irradiance and temperature conditions of the shaded habitat examined in this study. Our findings can be applied to aid in the creation of a nature‐reserve to protect this species.     

Taxonomic features of the red alga Meristotheca coacta (Solieriaceae, Gigartinales)

Vegetative and reproductive structures of the little‐known red alga, Meristotheca coacta Okamura (Solieriaceae, Gigartinales) were described on the basis of specimens collected from three localities in southern Japan, including an island close to the lectotype locality. Meristotheca coacta was shown to be a strongly supported monophyletic clade in our rbcL analyses. The taxonomic features of this species were reassessed. This species is characterized as follows: (i) the thalli consist of relatively thick (300–1400 μm from the uppermost to basal regions), elastic and rose‐red blades; (ii) the blades are irregularly lobed and branched into variously shaped segments with undulate and crispate margins; (iii) tetrasporangial initials are laterally attached to their parental cells and the lateral pit‐connections remain in mature tetrasporangia; (iv) gametophytes are dioecious; (v) carpogonial branches are three‐celled (occasionally two‐ or four‐celled); (vi) a darkly staining auxiliary cell complex is present and recognizable prior to diploidization; and (vii) cystocarps are produced along (or near) the margins of the blades and on the marginal proliferations and lack spinous outgrowths.     

Rhodenigma contortum,an obscure new genus and species of Rhodogorgonales (Rhodophyta) from Western Australia

An unknown microscopic, branched filamentous red alga was isolated into culture from coral fragments collected in Coral Bay, Western Australia. It grew well unattached or attached to glass with no reproduction other than fragmentation of filaments. Cells of some branch tips became slightly contorted and digitated, possibly as a substrate‐contact‐response seen at filament tips of various algae. Attached multicellular compact disks on glass had a very different cellular configuration and size than the free filaments. In culture the filaments did not grow on or in coral fragments. Molecular phylogenies based on four markers (rbcL, cox1, 18S, 28S) clearly showed it belongs to the order Rhodogorgonales, as a sister clade of Renouxia. Based on these results, the alga is described as the new genus and species Rhodenigma contortum in the Rhodogorgonaceae. It had no morphological similarity to either of the other genera in Rhodogorgonaceae and illustrates the unknown diversity in cryptic habitats such as tropical coral rubble.     

Reproductive ecology of the freshwater red alga Batrachospermum delicatulum (Batrachospermales, Rhodophyta) in three tropical streams

Batrachospermum delicatulum specimens from three stream segments were analyzed from a tropical region in south‐ eastern Brazil (20°18′– 20°49′S, 49°13′– 49°46′W). Physical and chemical parameters and the spatial placement of thalli were investigated along with the reproductive characteristics of the gametophytic phase. Sequence data of the cox 2‐ 3 spacer region was also utilized to evaluate genetic variation in individuals within and among stream segments. Gametophyte occurred under relatively diverse environmental conditions, whereas thalli abundance was weakly or not correlated to environmental variables within the stream segments. All specimens examined were dioecious. The ratio of male/female plants was relatively low (0.5 to 1.3) and male plants tended to occur as clumps (two or three plants together). High reproductive success was observed, as indicated by the occurrence of 100% fertilized (carposporophytic) female plants. This is similar to previous reports for this and other dioecious species, which is remarkable considering the relatively low proportion of male/female plants. Results support the two hypotheses to explain the high reproductive success in dioecious species. The occurrence of male plants in clumps was evidence for a strict spatial relationship (i.e. male plants located in upstream position of female plants in order to release spermatia, which would be carried by eddies through female plants). In contrast, the occurrence of male and female plants adjacent to each other allowed outcrossing among neighboring plants with intermingled male and female branches, which seemed more applicable to some situations (low turbulence habitats). The cox 2‐ 3 spacer region from the 18 individuals sequenced was 376 bp and the DNA sequence was identical with no base pair substitutions. Likewise, a previous study of another Batrachospermum species showed that the same haplotypes were present in all stream segments from the same drainage basin, even though the stream segments were a considerable distance apart. Short distance dispersal either by small birds or waterway connectivity might explain these findings.     

Reinstatement of Grateloupia subpectinata (Rhodophyta, Halymeniaceae) based on morphology and rbcL sequences

Morphological observations and molecular analyses of the north‐western Pacific species of the red algal genus Grateloupia (Halymeniaceae) indicate the presence of an entity, which is somewhat similar in gross morphology to G. asiatica Kawaguchi et Wang but is distinguished from the latter species by some morphological features. These include: (i) a somewhat fleshy texture; (ii) wider and much thicker (4.5–10 mm wide and up to 1300 μm thick) axes, of which an inner cortex consists of more (6–9) cells; (iii) generally longer (up to 17 cm), marginal and surface proliferations that are clearly constricted (terete) at bases; and (iv) much elongated, oblong auxiliary cells. Phylogenetic analysis using the ribulose‐l,5‐bisphosphate carboxylase/ oxygenase (rbcL) gene of G. asiatica and the alga in question shows them to be distantly related and strongly supports the differentiation of these two entities at the species level. Judging from the literature, this entity is actually Grateloupia subpectinata Holmes, which has been placed into synonymy under G. asiatica [as G. filicina (Lamouroux) C. Agardh] or G. prolongata J. Agardh in previous reports, and therefore the Holmes name is reinstated.     

Phylogeographic analysis of the brown alga Cutleria multifida (Tilopteridales,Phaeophyceae) suggests a complicated introduction history

In depth genetic comparisons of populations of Cutleria multifida (Tilopteridales, Phaeophyceae) collected from Europe, the northwestern Pacific Ocean, Australia and New Zealand using the DNA sequences of four gene regions (the mitochondrial cox2 and cox3 genes, the intergeneric spacer region adjacent to cox3, and the open reading frame) suggested that the northwestern European and Japanese populations were considerably greater in terms of their genetic divergence than Mediterranean, Australian or New Zealand populations. The haplotypes of the populations in northwestern European (distribution range including the type locality, seven haplotypes) and Japanese populations (seven haplotypes) were unique except for one shared haplotype. There were weak but positive correlations between the geographical distance and the genetic divergence among northwestern European and Japanese populations. Moreover, both female and male gametophytes occurred in eight of the nine Japanese localities, suggesting Japanese populations showed normal sexual heteromorphic life history of the species. In light of these results, it appears that Japanese populations were native to the area despite earlier hypothesis. In contrast, Australian and New Zealand populations were composed of only one haplotype that is very close to those found in northwestern Europe and Japan, suggesting a recent introduction history from Europe (or from northeastern Asia via Europe) by ship transport to Australia and New Zealand. The Mediterranean populations included two haplotypes identical to those found in northwestern Europe and Japan, and it is suggestive of transoceanic introductions of some populations between Mediterranean and Japanese coasts.     

New species of freshwater Ulva, Ulva limnetica (Ulvales, Ulvophyceae) from the Ryukyu Islands, Japan

Ulva limnetica Ichihara et Shimada, sp. nov. (Ulvales, Ulvophyceae) is described from the Ryukyu Islands, Japan, and is characterized by thalli that are: (i) branched, tubular, fragile and wrinkled; (ii) up to 80 cm in height and up to 2 cm in diameter; (iii) light to yellowish green in color; and (iv) having an asexual reproduction by means of quadriflagellate swarmers. Rhizoidal cells bear tubular extensions on the outside of the cell layer in the stipe. Ulva limnetica is distinguished from species with similar thalli by chloroplast disposition, branching pattern, number of pyrenoids per cell and gross morphology. It is also distinguished by sequences of the nuclear-encoded 18S ribosomal RNA gene, internal transcribed spacer 2 region and the plastid-encoded large subunit of ribulose-1,5-bisphosphate carboxylase/oxgenase gene ( rbc L). Ulva limnetica was clustered with other Ulva species in an early diverging lineage within the genus.     

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.     

A morphological and molecular assessment of the genus Sinotubimorpha (Halymeniaceae, Rhodophyta)

A critical reassessment of the morphological features of two closely related red algal genera,Grateloupia C.Agardh and Sinotubimorpha W.X.Li & Z.F.Ding (Halymeniaceae),pointed out that members of the t...     

Phylogeny of extant genera in the family Characeae (Charales,Charophyceae) based on rbcL,sequences and morphology

Extant genera of Characeae have been assigned to two tribes: Chareae (Chara, Lamprothamnium, Nitellopsis, and Lychnothamnus) and Nitelleae (Nitella and Tolypella), based on morphology of the thallus and reproductive structures. Character analysis of fossil and extant oogonia suggest that Tolypella is polyphyletic, the genus comprising two sections, one in each of the two tribes. Eleven morphological characters and sequence data for the Rubisco large subunit (rbcL) were used to reconstruct the phylogeny of genera, including the two sections of Tolypella. Parsimony analysis of the rbcL data, with all positions and changes weighted equally, strongly supports the monophyly of the Characeae. The two Tolypella sections form a robust monophyletic group basal to the family. Transversion weighting yielded the same tree but with a paraphyletic Tolypella. The rbcL data strongly support monophyly of tribe Chareae but tribe Nitelleae is paraphyletic. Parsimony analysis of morphological data produced one unrooted tree consistent with monophyly of the two tribes; on this tree the Tolypella sections were paraphyletic. Combining morphological with rbcL data did not change the results derived from rbcL sequences alone. The rbcL data support the monophyly of the Characeae and Coleochaete, which together form a monophyletic sister group to embryophytes.