Auxiliary Cell Ampullae Research Articles

Molecular phylogeny of foliose Halymenia and Austroepiphloea (Halymeniaceae, Rhodophyta) from the Indo-Pacific, with the description of Halymenia taiwanensis sp. nov.

ABSTRACT Many species of Halymenia from the Indo-Pacific have been described in the past decade, but their phylogenetic relationships are not well discussed. In this study, we inferred these relationships for the available species of Halymenia with an emphasis on the foliose species from the western Pacific Ocean and Western Australia based on rbcL and nuclear-encoded LSU rDNA sequence analyses. Our analyses show that most foliose Halymenia from the Indo-Pacific are clustered in a natural assemblage that also includes a new species (Halymenia taiwanensis sp. nov.) found in northern Taiwan, as well as the monospecific genus Austroepiphloea (single species A. bullosa) from Western Australia. The architecture of carpogonial branch (composed of a two-celled carpogonial branch and two orders of ampullar filaments, and a basal, nutritive cellular cluster) and auxiliary cell ampullae in Halymenia taiwanensis is similar to that found in the generitype H. floresii. We therefore propose the new combination Halymenia bullosa comb. nov. (basionym Schizymenia. bullosa), a species closely related to H. taiwanensis both genetically and morphologically. However, H. taiwanensis can be separated from H. bullosa by its thinner blades and surface bladelets, and by lacking a long cartilaginous stipe. Based on the rbcL phylogeny, most foliose Halymenia are seemingly more range-restricted than previously thought, except for a few species that are shown to have a wide distribution in the Western Pacific and Indian Oceans. In addition, H. dilatata, a species widely recorded in the Western Pacific Ocean, may include cryptic species and requires further investigation.

Revisiting the systematics of the genera Grateloupia, Phyllymenia, and Prionitis (Halymeniaceae, Rhodophyta) with a description of a new species-Prionitis taiwani-borealis.

The taxonomy of the genera Grateloupia, Phyllymenia, and Prionitis has been revised several times but remains controversial. The anatomy of female reproductive structures in combination with phylogenetic reconstructions is mostly used to define the genera. However, the architecture and behavior of the auxiliary cell ampullae before and after diploidization are not well documented for most species. To fill this knowledge gap, we examined the female reproductive structures of a new species (Prionitis taiwani-borealis sp. nov.) from Taiwan and compared our observations to the species currently placed in the Phyllymenia/Prionitis complex. The female reproductive structures of the Phyllymenia/Prionitis complex are characterized by (1) 2-celled carpogonial branches with the supporting cell being the basal cell of a third-order ampullar filament; (2) auxiliary cell ampullae composed of three orders of unbranched ampullar filaments before diploidization; (3) cells of auxiliary cell ampullar filaments forming a cellular cluster after diploidization and surrounding the developing gonimoblasts; (4) gonimoblast initials produced from the diploidized auxiliary cells before fusing with them; and (5) branched auxiliary cell ampullar and secondary medullary filaments involved in early pericarp formation. A monophyletic relationship of species possessing female structures similar to those of Pr. taiwani-borealis and related species was highly supported based on combined rbcL and LSU rDNA sequence analyses. The female reproductive structures of other species of Grateloupia sensu lato, phylogenetically closely related to the Prionitis and Phyllymenia assemblage, require reinvestigation as correct interpretations of pre- and post-fertilization events have proven to be informative for resolving the systematics of the Halymeniaceae.

Resurrection of the Family Grateloupiaceae Emend. (Halymeniales, Rhodophyta) Based on a Multigene Phylogeny and Comparative Reproductive Morphology

The marine red algal order Halymeniales currently includes two families, the Halymeniaceae and Tsengiaceae, and consist of 38 genera and about 358 species. Phylogenetic analyses on specific taxa of the order are common, but not comprehensive, leaving the many intra-ordinal relationships within the Halymeniales unresolved. To reassess the phylogeny of the Halymeniales, we conducted extensive phylogenetic analyses based on 207 rbcL sequences and multigene analyses (rbcL, psaA, psbA, cox1, and LSU) using 47 taxa from the order. The combined data set fully supports the monophyly of the Grateloupia sensu lato clade. Phylogenetic assessment of the reproductive structures in the order using the type of auxiliary cell ampullae, pericarp origin, and tetrasporangial development characters, supports a Grateloupia sensu lato clade distinct from the Halymeniaceae exemplified by the generitype Halymenia. As a result, we propose to reinstate the family Grateloupiaceae Schmitz based on the Grateloupia sensu lato clade and including Grateloupia and eight other genera: Dermocorynus, Mariaramirezia, Neorubra, Pachymeniopsis, Kintokiocolax, Phyllymenia, Prionitis, and Yonagunia. The emended Grateloupiaceae is distinguished from the Halymeniaceae by the following three characteristics; (i) simple unbranched and unilateral type of auxiliary cell ampullae, (ii) pericarp formed densely by the fusion of secondary medullary filaments from subcortical cells and lateral ampullary filaments from a fusion cell complex, (iii) tetrasporangia originating laterally from the outer cortex. The Halymeniales comprises the monophyletic Grateloupiaceae, Halymeniaceae sensu lato (which requires further study), and the Tsengiaceae.

Systematics and Biogeography of the Red Algal Genus Yonagunia (Halymeniaceae, Rhodophyta) from the Indo-Pacific Including the Description of Two New Species from Taiwan.

Carpopeltis maillardii has been regarded as a widely distributed species in the Indo-Pacific region. In this study, we analyzed the genetic diversity of C. maillardii and related species collected from Taiwan and the Indian Ocean based on rbcL sequences, in order to elucidate species boundaries, diversity, and biogeographic patterns. Our analyses show that C. maillardii specimens are only distantly related to the genus Carpopeltis (type: C. phyllophora) but instead form a clade together with species of Yonagunia. We therefore propose the new combination Yonagunia maillardii comb. nov. In addition, two new species (Yonagunia palmata sp. nov. and Yonagunia taiwani-borealis sp. nov.) are described from Taiwan. The close relationship of Yonagunia to Grateloupia is corroborated by detailed observations of the female reproductive structures, which demonstrate that the development of auxiliary cell ampullae before and after diploidization is similar to that of Grateloupia sensu stricto. Namely, the ampullae are composed of only two orders of unbranched filaments in which only a few ampullar cells are incorporated into a basal fusion cell after diploidization of the auxiliary cell and the pericarp consists almost entirely of secondary medullary filaments. Of all Yonagunia species, Y. maillardii has the widest distribution in the Indo-Pacific, and can be identified in the field by its relatively thin, feathery, and highly branched morphology. Most other species, including those that occur in Taiwan, are seemingly more range-restricted. Our phylogenetic analyses resulted in a well-resolved phylogeny of Yonagunia, with an origin estimated in the Eocene-Oligocene, and diversification of species mainly in the Miocene.

The morphological, developmental and molecular landscape of Grateloupia qingdaoensis Li et Ding

The rhodophyte marine algal genus Grateloupia (Halymeniaceae, Halymeniales) is distributed worldwide, including in offshore southeastern China. Here, we investigated morphology, carpospore development, ecological habits, and molecular analyses of a rarely studied species, Grateloupia qingdaoensis. The carpogonial branch ampullae and auxiliary cell ampullae were the typical Grateloupia type (6cpb-5auxb type) and the type of spore development was “mediate discal type”. The life history included homotypic gametophytes (haploid), carposporophytes (diploid), and tetrasporophytes (diploid) and showed a typical isomorphic alternation of generations. By using single-factor and orthogonal experiments, we explored the effects of temperature, irradiance and seawater salinity on the early development of G. qingdaoensis. Each ecological factor showed distinct effect on the early development of G. qingdaoensis. Additionally, we found a significant interactive effect between temperature and irradiance on discord crust growth. The optimum conditions for the early growth of discoid crust and upright thalli were 20 °C, 80 μmol photons m−2 s−1 irradiance and 30‰ seawater salinity. To clarify its taxonomical status, we constructed the phylogenetic tree of rbcL gene sequences. Results showed that there was no pairwise divergence between G. qingdaoensis and G. asiatica from China. Our findings indicate that previous records without precise and comprehensive comparison and molecular analyses need to be re-examined to clarify the global distribution of this species.

Female reproductive structures define the novel genus, Nesoia (Halymeniaceae, Rhodophyta)

ABSTRACTFemale reproductive structures, especially ampullae, play a significant role in defining generic boundaries in the family Halymeniaceae, despite recent advances in phylogenetic analyses aided by molecular data. Surveys of red algae from the Korean subtidal zone have revealed new evolutionary lineages within this family. We here propose a new genus in the Halymeniaceae, Nesoia H.W.Lee & M.S.Kim, gen. nov., with a description of N. delicatula sp. nov., N. pulchella sp. nov. and N. latifolia (P. Crouan & H. Crouan ex Kützing) comb. nov., based on Halymenia latifolia. Nesoia, which constitutes a distinct lineage of the Halymeniaceae in rbcL phylogenetic trees, has a foliose thallus with a single-layered cortex and medulla of anticlinal filaments. Carpogonial ampullae bear two-celled carpogonial branches and auxiliary cell ampullae have multiple orders of branching, mostly up to three or four. The auxiliary cell ampullary system of Nesoia is a unique type previously undescribed in the Halymeniaceae: each cell of the first-order ampullary filament produces bilateral second-order filaments, and the auxiliary cell is the basal cell of one of the two second-order filaments borne on the second or third cell of the first-order filament. Discovery of the new genus Nesoia suggests the need for more careful and systematic exploration of species diversity in this group of red algae.

Systematics of the red algal genus Halymenia (Halymeniaceae, Rhodophyta): characterization of the generitype H. floresii and description of Neofolia rosea gen. et sp. nov.

ABSTRACTMany traditional genera of the Halymeniaceae turn out to be poly- or paraphyletic based on molecular phylogenies. The genus Halymenia is no exception. In this study, we provide a detailed characterization of the vegetative and reproductive morphology of the generitype of Halymenia, H. floresii, based on specimens from the north-western Mediterranean Sea. In addition we describe a newly detected clade (Neofolia rosea gen. et sp. nov.) which was previously confused with ‘Halymenia latifolia’ from the north-eastern Atlantic Ocean and the western Mediterranean Sea. The development of auxiliary cell ampullae in Neofolia and Halymenia is similar, namely, ampullae consist of three orders of branched filaments after diploidization of the auxiliary cell and form a weak pericarp comprised only of elongated and branched ampullary filaments. The auxiliary cell is always differentiated from the first cell of the third-order ampullary filament. This pattern differs significantly from previous descriptions of the female reproductive system of Halymenia, in which the auxiliary cell is said to be the third cell of the primary ampullary filament and few secondary and tertiary ampullary filaments are produced from the primary ampullary filament before diploidization of the auxiliary cell. Neofolia primarily differs from Halymenia in the absence of a cellular cluster (= nutritive filaments), which is present in the basal parts of the carpogonial branch ampullae in Halymenia. Moreover, auxiliary cell ampullary filaments in Neofolia are much shorter (6–7 cells long) than those found in Halymenia (9–13 cells long), and the secondarily generated connecting filaments are issued from the basal cells of the ampullary filaments in Halymenia, whereas they are produced from the fusion cell in Neofolia. Resolving the polyphyly of Halymenia will require a re-examination of the species of ‘Halymenia’ that are not clustered with the generitype.

Grateloupia huanghaiensis sp. nov. (Halymeniaceae, Rhodophyta), a peculiar new species from China

Grateloupia huanghaiensis sp. nov. is newly described on the basis of morphological observations and molecular analyses. We document the vegetative and reproductive structures of G. huanghaiensis, which show that the carpogonial ampullae and auxiliary cell ampullae are of the simple Grateloupia-type. The new species can be distinguished from other Grateloupia species by (1) compressed and sword-like apices; (2) being single or double pinnately branched; (3) axes and branches densely covered with numerous short proliferations; (4) numerous distichous or lateral branchlets with proliferations from either end of the thalli; (5) two- to four-layered cellular cortex; (6) densely and irregularly intertwined medullary filaments; and (7) reproductive structures scattered over the surface of branches. Analysis showed this new species to be embedded within the Grateloupia clade in ribulose-1,5-bisphosphate carboxylase/oxygenase gene (rbcL) trees. Morphological observations and molecular analysis support G. huanghaiensis as a new species.

Neorubra decipiens gen. & comb. nov. and Phyllymenia lancifolia comb. nov. (Halymeniales, Rhodophyta) from South America

:The taxonomy of Grateloupia sensu lato from South America is still to be fully resolved. Based on the phylogeny of the rbcL and female reproductive structures, we described a new genus, Neorubra, to contain two Peruvian species previously known as Grateloupia denticulata and Prionitis decipiens. Neorubra was characterised by having five-celled carpogonial branches and four-celled auxiliary-cell branches, fusion of carpogonia and hypogynous cells that formed the basal cell or third cell of the carpogonial branch, a markedly elongated auxiliary-cell fusion cell and pericarps that were well developed on the basal side. Based on the carpogonial and auxiliary-cell ampullae and the formation of secondary connecting filaments, we transferred Grateloupia lancifolia to the genus Phyllymenia.

Re-identifying Grateloupia yangjiangensis (Rhodophyta, Halymeniaceae) based on morphological observations, life history and rbcL sequence analyses

On the basis of morphological observations, life history and molecular phylogeny, Grateloupia yangjiangensis, which is similar to G. filicina, G. orientalis, G. catenata, and G. ramosissima in appearance, was re-examined. The results are as follows: (1) the auxiliary-cell ampullae of G. yangjiangensis were of Grateloupia type, thalli was fleshy and gelatinous in texture, and the erect axes were compressed; the cortex was 0.25–0.30 mm thick, consisting of five to seven outer layers, and there were five inner layers of triangular or stellate cells; (2) there was no filamentous stage in the development of the carpospores; (3) the ribulose-1,5-bisphosphate carboxylase/oxygenase gene (rbcL) sequence of four G. yangjiangensis examined showed that there was no intergeneric divergence among them, and for the phylogenetic tree, four sequences of G. yangjiangensis formed a single monophyletic subclade within the large Grateloupia clade of Halymeniaceae. In conclusion, G. yangjiangensis was a single species within the genus Grateloupia. This research provided criterion for identification and cultivation of G. yangjiangensis.

A Re-Assessment of Reproductive Anatomy and Postfertilization Development in the Systematics ofGrateloupia(Halymeniales, Rhodophyta)

The red algal family Halymeniaceae has been recently the subject of taxonomic revisions based strictly on molecular data. As a result, the number of genera ascribed to it has been decreasing and many generic definitions changed profoundly owing to inconsistencies in diacritical vegetative and particularly reproductive characters in standard literature. Reproductive uniformity within this family has been claimed since the late 19th century and is generally supported by recent authors. In this study we report on consistent significant differences in the architecture of carpogonial and auxiliary cell ampullae, as well as in early postfertilization events, among Mediterranean species currently assigned to the genus Grateloupia C. Agardh and provide new interpretations of these features. We recognize several distinct types of ampullae and postfertilization events that distinguish groups of species, these groups proving to be strongly supported by rbcL phylogenies. As a result we conclude that the genus Grateloupia as presently circumscribed should be segregated into multiple genera. In addition to Grateloupia sensu stricto, we resurrect Dermocorynus P.L. Crouan et H.M. Crouan, Pachymeniopsis Y. Yamada ex S. Kawabata, Phyllymenia J. Agardh and Prionitis J. Agardh, all of which have been subsumed in Grateloupia by previous authors. New genera based on our anatomical and rbcL results for G. doryphora (Montagne) M. Howe, G. subpectinata Holmes and G. proteus Kützing will be described in subsequent papers.

Grateloupia tenuisWang et Luan sp. nov. (Halymeniaceae, Rhodophyta): A New Species from South China Sea Based on Morphological Observation andrbcL Gene Sequences Analysis

Grateloupia tenuis Wang et Luan sp. nov. is a new species described from Lingshui, Hainan Province, South China Sea. Based on the external form and internal structure, combined with rbcL gene sequence analysis, Grateloupia tenuis is distinct from other Grateloupia species as follows: (1) thalli is slippery and cartilaginous in texture; possess fewer branches, relatively slight main axes, and two or three dichotomous branches; (2) cortex is 5-6 layers; medulla is solid when young, but hollow in old branches; reproductive structures are dispersed in main axes of thalli and lower portions of branchlets; exhibits Grateloupia-type auxiliary cell ampullae; (3) the four studied G. tenuis sequences were positioned in a large Grateloupia clade of Halymeniaceae, which included sister group generitype G. filicina with 68 bp differences; G. tenuis was determined to be a sister taxon to the G. catenata, G. ramosissima, G. orientalis, and G. filiformis subclade. The pairwise distances between G. tenuis and these species were 39 to 50 bp. The sequences of G. tenuis differed by 81–108 bp from the sequences of other samples in Grateloupia; there are 114–133 bp changes between G. tenuis and other genera of Halymeniaceae. In final analysis, we considered Grateloupia tenuis Wang et Luan sp. nov. to be a new species of genus Grateloupia.

Morphological observation and rbcL gene sequences studies of two new species, Grateloupia dalianensis H.W.Wang et D.Zhao, sp. nov. and G. yinggehaiensis H.W.Wang et R.X.Luan, sp. nov. (Halymeniaceae, Rhodophyta) from China

A few species in the genus Grateloupia (Halymeniaceae, Rhodophyta) have been investigated in detail with respect to morphological observations and molecular analyses. In this study, the authors document the vegetative and reproductive structures of two new species of Grateloupia, G. dalianensis H.W.Wang et D.Zhao, sp.nov. and G. yinggehaiensis H.W.Wang et R.X.Luan, sp.nov. They both have the morphological character that carpogonial ampullae and auxiliary cell ampullae are the simple Grateloupia-type. The two species can be distinguished from other species of the genus by their distinctive morphological features respectively. Based on ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) gene sequences, the phylogenetic tree obtained in the study indicated that they are both embedded within the Grateloupia clade. G. dalianensis clusters a subclade with G. asiatica, and G. yinggehaiensis forms a single monophyletic subclade with G. hawaiiana.

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

Abstract 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 two genera had most morphological characteristics in common, including the Grateloupia type auxiliary cell ampullae. Sinotubimorpha hitherto was distinguished from Grateloupia by: (i) the hollow axis; (ii) the presence of secondary filaments in ampullae; (iii) 1- to 3-celled carpogonial branch; and (iv) the occasional production of 1- to 4-celled flanking filaments on carpogonium. However, when these features were re-examined among 37 Chinese species of genera described in Flora Algarum Marinarum Sinicarum and one newly reported species, Grateloupia orientalis, we found that it was difficult to draw a clear-cut distinction between the two genera based only on morphological differences. In rbcL sequence analysis, all the species of Sinotubimorpha with G. catenata formed a single monophyletic subclade within the large Grateloupia clade of the Halymeniaceae. It is therefore suggested that all the Chinese species of Sinotubimorpha, S. catenata, S. guangdongensis, S. qingdaoensis, S. claviformis, and S. ramosissima should be synonymous with G. catenata, and that Sinotubimorpha should be included in synonymy under Grateloupia.

Grateloupia huangiae (Halymeniaceae, Rhodophyta), a new species from Taiwan previously confused with Polyopes lancifolius, with emphasis on the development of the auxiliary-cell ampullae

Lin S.-M., and Liang H.-Y. 2011. Grateloupia huangiae (Halymeniaceae, Rhodophyta), a new species from Taiwan previously confused with Polyopes lancifolius, with emphasis on the development of the auxiliary-cell ampullae. Phycologia 50: 232–240. DOI: 10.2216/10-29.1Grateloupia huangiae S.-M. Lin & H.-Y. Liang sp. nov. was previously recorded as G. okamurae Yamada [currently recognized as Polyopes lancifolius (Harvey) Kawaguchi & H.W. Wang] in Taiwan. Molecular phylogenetic analysis shows that G. huangiae is unrelated to P. lancifolius but is closely related to Grateloupia taiwanensis S.-M. Lin & H.-Y. Liang. Although G. huangiae superficially resembles P. lancifolius in having a leafy thallus and short proliferations borne on the thallus surface, the structure of the auxiliary-cell ampulla is very different. The auxiliary-cell ampulla of G. huangiae is composed of three orders of unbranched filaments before diploidization, each of which is 11–13 cells long. The auxiliary cell is the first cell of the third-order ampullar filament, which is cut off from the first cell of the second-order ampullar filament. This type of auxiliary-cell ampulla is the same as that found in G. taiwanensis. On the other hand, P. lancifolius has a more complex auxiliary-cell ampulla in which the ampullar filaments may bear up to five to six orders of branches before diploidization. A detailed study of the development of auxiliary-cell ampullae before and after diploidization is needed in other species and genera within the Halymeniaceae to better delineate generic concepts in the family.

A morphological and phylogenetic study of Glaphyrosiphon gen. nov. (Halymeniaceae, Rhodophyta) based on Grateloupia intestinalis with descriptions of two new species: Glaphyrosiphon lindaueri from New Zealand and Glaphyrosiphon chilensis from Chile

Hommersand M.H., Leister G.L., RamÍrez M.E., Gabrielson P.W. and Nelson W.A. 2010. A morphological and phylogenetic study of Glaphyrosiphon gen. nov. (Halymeniaceae, Rhodophyta) based on Grateloupia intestinalis with descriptions of two new species: Glaphyrosiphon lindaueri from New Zealand and Glaphyrosiphon chilensis from Chile. Phycologia 49: 554–573. DOI: 10.2216/09-106.1A new genus, Glaphyrosiphon Hommersand & Leister gen. nov., is proposed to contain the generitype Glaphyrosiphon intestinalis (Harvey) Leister & W.A. Nelson comb. nov., a species known in New Zealand under the name Grateloupia intestinalis (Hooker. f. & Harvey) Setchell ex P.G. Parkinson, and two additional species: Glaphyrosiphon lindaueri W.A. Nelson & P.W. Gabrielson sp. nov. from the northern part of New Zealand and Glaphyrosiphon chilensis M.E. Ramírez, Leister, and P.W. Gabrielson sp. nov. in the southern part of Chile from Valdivia (Región de Los Ríos), to Punta Arenas in the Strait of Magellan (Región de Magallanes). Thalli are borne singly or in clusters from a small discoid holdfast and consist of simple or one- to three-times-branched slippery tubes that are copiously filled with mucilage. The medulla consists of a one- to several-layered network inside the cortex composed of stellate cells that interconnect by short to long extensions linked by pit connections. Primary rhizoidal filaments are absent. Spermatangia are superficial on terminal cortical cells. Carpogonial and auxiliary-cell ampullae are formed separately and link by unsegmented tubular connecting filaments, as in other Halymeniaceae. The auxiliary-cell ampulla consists of a basal cell and four unilaterally branched filaments in which the auxiliary cell is the basal cell of one of the four filaments. The auxiliary cell and inner ampullar filaments unite forming a fusion cell. Ampullar filaments connect terminally to inner cortical cells and laterally with one another by short filaments and pit connections that form an involucral network surrounding the gonimolobes. Tetrasporangia are cruciately divided and borne laterally on filaments produced secondarily from surface cortical cells. Sequence analyses of the rbcL gene place Glaphyrosiphon sister to Polyopes in the Halymeniaceae. The two New Zealand species consist of southern and northern clades separated by 1.2% to 1.7% base-pair distances in rbcL analyses and a Chilean species that forms a single clade separated from the New Zealand clades by 3.9% to 4.4% base-pair distances. Records of Grateloupia intestinalis from Tasmania have not been studied.

TWO TYPES OF AUXILIARY CELL AMPULLAE IN GRATELOUPIA (HALYMENIACEAE, RHODOPHYTA), INCLUDING G.TAIWANENSIS SP. NOV. AND G.ORIENTALIS SP. NOV. FROM TAIWAN BASED ON rbcL GENE SEQUENCE ANALYSIS AND CYSTOCARP DEVELOPMENT(1).

Few species in the genus Grateloupia have been investigated in detail with respect to the development of the auxiliary cell ampullae before or after diploidization. In this study, we document the vegetative and reproductive structures of two new species of Grateloupia, G.taiwanensis S.-M. Lin et H.-Y. Liang sp. nov. and G.orientalis S.-M. Lin et H.-Y. Liang sp. nov., plus a third species, G.ramosissima Okamura, from Taiwan. Two distinct patterns are reported for the development of the auxiliary cell ampullae: (1) ampullae consisting of three orders of unbranched filaments that branch after diploidization of the auxiliary cell and form a pericarp together with the surrounding secondary medullary filaments (G.taiwanensis type), and (2) ampullae composed of only two orders of unbranched filaments in which only a few cells are incorporated into a basal fusion cell after diploization of the auxiliary cell and the pericarp consists almost entirely of secondary medullary filaments (G.orientalis type). G.orientalis is positioned in a large clade based on rbcL gene sequence analysis that includes the type species of Grateloupia C. Agardh 1822, G.filicina. G. taiwanensis clusters with a clade that includes the generitype of Phyllymenia J. Agardh 1848, Ph.belangeri from South Africa; that of Prionitis J. Agardh 1851, Pr.lanceolata from Pacific North America; and that of Pachymeniopsis Y. Yamada ex Kawab. 1954, Pa.lanceolata from Japan. A reexamination of the type species of the genera Grateloupia, Phyllymenia, Prionitis, and Pachymeniopsis is required to clarify the generic and interspecific relationships among the species presently placed in Grateloupia.

Systematic reassessment of the red algal genus Phyllymenia (Halymeniaceae, Rhodophyta)

A systematic reassessment of the sole representative of the South African genus Phyllymenia, P. belangeri, indicates a lack of clear-cut diagnostic characters to separate it from Grateloupia. The morphology of the auxiliary cell ampullae, widely regarded as a key generic character in the Halymeniaceae, is almost identical in both genera. The autapomorphic character that has traditionally separated Phyllymenia from Grateloupia is the formation of pronounced lateral cytoplasmic protuberances on inner cortical cells. However, the establishment of protuberances is correlated with the presence of large intercellular spaces between neighbouring cortical cell files, coupled with narrow intercalary cortical cells. Thus, in order to establish secondary pit connections to more distant neighbouring cells, cortical cell protuberances may have become more prominent in P. belangeri than in species of Grateloupia with smaller intercellular spaces. Phylogenetic analyses of chloroplast-encoded rbcL sequences for a dataset including four representatives of P. belangeri and 32 other species, currently placed in Grateloupia or Prionitis, resolve (with high support) P. belangeri as a sister taxon of G. longifolia from South Africa. Based on morphological and molecular evidence, it is therefore proposed that Phyllymenia be reduced to a synonym of Grateloupia.

THE NEW GENUS YONAGUNIA KAWAGUCHI ET MASUDA (HALYMENIACEAE, RHODOPHYTA), BASED ON Y. TENUIFOLIA KAWAGUCHI ET MASUDA SP. NOV. FROM SOUTHERN JAPAN AND INCLUDING Y. FORMOSANA (OKAMURA) KAWAGUCHI ET MASUDA COMB. NOV. FROM SOUTHEAST ASIA1

Yonagunia Kawaguchi et Masuda, gen. nov. (Halymeniaceae, Rhodophyta) is proposed to accommodate a new species, Yonagunia tenuifolia Kawaguchi et Masuda and the species currently known as Prionitis formosana (Okamura) Kawaguchi et Nguyen. Based on auxiliary cell ampullar features, Yonagunia is included in the group of genera with the simplest type of ampulla (the Grateloupia type) that comprises Dermocorynus, Grateloupia, Kintokiocolax, Phyllymenia, and Zymurgia. However, Yonagunia differs from these genera in the behavior of cells in the ampullar filaments immediately after diploidization, most cells of the primary and secondary filaments simultaneously dividing to form grape‐like clusters of small globular cells that subsequently elongate and produce involucral filaments to laxly surround the maturing carposporophyte. Yonagunia is resolved by our rbcL gene sequence analyses as one of five monophyletic clades within the Halymeniaceae (an Aeodes/Pachymenia, a Polyopes, a Carpopertis/Cryptonemia/Halymenia, a Yonagunia, and a Grateloupia clade) that is positioned as sister to the Grateloupia clade. Carpogonial branch apparatuses are identified as a potential taxonomic significance on the same level as auxiliary cell ampullae.

Rejection of Sinkoraena and transfer of some species of Carpopeltis and Sinkoraena to Polyopes (Rhodophyta, Halymeniaceae)

Three red algal species of the Halymeniaceae from Japan, Carpopeltis affinis, C. prolifera and Polyopes polyideoides, all have frequently branched, bushy auxiliary-cell ampullae of the Aeodes type, with a cup-shaped outline. The auxiliary-cell ampullae are similar to those of the generitypes of Polyopes and Sinkoraena, P. constrictus and S. lancifolia. In ribulose-1,5-bisphosphate carboxylase-oxygenase gene sequence analysis, the five species of Carpopeltis, Polyopes and Sinkoraena, together with another species of Sinkoraena, S. tasmanica form a distinct and monophyletic clade (with high bootstrap support) in the Halymeniaceae. Carpopeltis affinis and C. prolifera are therefore transferred to Polyopes as P. affinis (Harvey) Kawaguchi & Wang, comb. nov. and P. prolifer (Hariot) Kawaguchi & Wang, comb. nov. The genus Sinkoraena is congeneric with Polyopes, and S. lancifolia and S. tasmanica are transferred to Polyopes as P. lancifolius (Harvey) Kawaguchi & Wang, comb. nov. and P. tasmanicus (Womersley & J.A. Lewis) Kawaguchi & J.A. Lewis, comb. nov.