A NEW METHOD OF CYSTOCARP DEVELOPMENT IN THE RED ALGAL GENUS CALLOPHYLLIS (KALLYMENIACEAE) FROM CHILE1

Traditional studies suggest that the Kallymeniaceae can be divided into two major groups, a nonprocarpic Kallymenia group, in which carposporophyte formation involves an auxiliary cell branch system separate from the carpogonial branch system, and a procarpic Callophyllis group, in which the carpogonial branch system gives rise to the carposporophyte directly after fertilization. Based on our phylogenetic studies and unpublished observations, the two groups each contain both procarpic and nonprocarpic genera. Here, we describe a new method of reproductive development in Callophyllis concepcionensis Arakaki, Alveal et Ramírez from Chile. The carpogonial branch system consists of a supporting cell bearing both a three‐celled carpogonial branch with trichogyne and two‐lobed “subsidiary” cells. After fertilization, large numbers of secondary subcortical and medullary cells are produced. Lobes of the carpogonial branch system cut off connecting cells containing enlarged, presumably diploid nuclei that fuse with these secondary vegetative cells and deposit their nuclei. Derivative enlarged nuclei are transferred from one vegetative cell to another, which ultimately cut off gonimoblast initials that form filaments that surround the central primary medullary cells and produce carposporangia. The repeated involvement of vegetative cells in gonimoblast formation is a new observation, not only in Callophyllis, but in red algae generally. These results call for a revised classification of the Kallymeniaceae based on new morphological and molecular studies.     

REASSESSMENT OF THE LITTLE‐KNOWN CRUSTOSE RED ALGAL GENUS POLYSTRATA (GIGARTINALES), BASED ON MORPHOLOGY AND SSU rDNA SEQUENCES1

The taxonomic distinctiveness of the crustose red algal genus Polystrata Heydrich (Peyssonneliaceae) is confirmed on the basis of morphological and molecular data. The vegetative and reproductive morphology of the type species Polystrata dura Heydrich is newly described. Polystrata thalli are thick multi‐layered crusts, each crust of which is composed of a mesothallus, a superior perithallus, and an inferior perithallus. P. dura is characterized by a poorly developed inferior perithallus consisting of single‐celled perithallial filaments and each layer of multi‐layered crusts being closely adherent to the parental layer. This Polystrata species is identical to Peyssonnelia species, the type genus of the Peyssonneliaceae in the morphology of sexual reproductive organs: a carpogonial branch and an auxiliary cell branch are formed laterally on respective nemathecial filaments; the gonimoblasts are developed from connecting filaments and auxiliary cells; the spermatangia are produced in male and female nemathecia; and the spermatangial filament produces a series of one to four paired spermatangia that form a whorl surrounding each central cell (the Peyssonnelia dubyi‐type development). Polystrata fosliei (Weber‐van Bosse) Denizot is clearly distinguished from P. dura by an inferior perithallus as well‐developed as the superior perithallus, and each layer of multi‐layered crusts being loosely adherent to the parental layer. In our small subunit rDNA trees of the Peyssonneliaceae, these Polystrata species formed a clade with low to medium supports, although the phylogenetic position of Polystrata was unresolved in this family. Therefore, the thallus structure of Polystrata may be regarded as an important taxonomic character at the genus rank.     

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.     

Reproductive morphology of Gastroclonium pacificum (Champiaceae,Rhodymeniales) from Japan

Morphological studies were undertaken on Gastroclonium pacificum (E.Y. Dawson) C.F. Chang et B.M. Xia (Champiaceae, Rhodymeniales) from Japan. We describe the details of male reproductive structures, the procarp and early post‐fertilization stages. This species has a solid axis, with both tetrasporangia and polysporangia, spermatangia are cut off from spermatangial parent cells, and a procarp is composed of a 4‐celled carpogonial branch and two 2‐celled auxiliary cell branches. The mature cystocarp lacks a conspicuous ostiole, a characteristic of the genus Gastroclonium. The most distinctive characteristic of the species is the tela arachnoidea, which is lacking in other species of Gastroclonium.     

Tylotus laqueatus,a new species of Dicranemataceae (Gigartinales,Rhodophyta) from the Hawaiian Islands

A rarely collected shallow‐subtidal Hawaiian macroalga has been determined anatomically and molecularly to belong to an undescribed species of Tylotus J. Agardh, the most widely distributed genus of the small, mostly Australian‐endemic family Dicranemataceae. Thalli are repent and imbricate on calcareous boulders at the type locality on O‘ahu, and are anchored both basally and by haptera arising marginally and ventrally on the (sub‐)dichotomous, linear axes. Simple or forked terete haptera can be a means of perennation by the occasional direct issuing of adventitious blades. Fronds are multiaxial and consist of a broad pseudoparenchymatous medulla of thick‐walled cells surrounded on both sides by a two‐ or three‐layered small‐celled pigmented cortex in which numbers of ‘glandular’ hairs are embedded. Tetrasporangia are zonate, and gametophytes are monoecious. Carpogonial branches are three‐celled, directed to the thallus surface, and borne laterally on inner‐cortical supporting cells; cystocarps are prominently protuberant and scattered sparingly on dorsal frond surfaces, the carposporophytes directed outwardly beneath an ostiolate pericarp and connected to the parent gametophyte across a broad placental base in which the remnant auxiliary cell persists centrally. The inner surface of the pericarp is unusual in producing extensive patches or isolated islands of short gonimoblast filaments with terminal carposporangia as an apparent result of the implantation of gonimoblasts into the tissue of the lining. Anatomy indicates that the new species is more closely related to the East‐Asian Tylotus lichenoides Okamura than to the only other described member of the genus, the type species T. obtusatus (Sonder) J. Agardh from southern Australia. An rbcL phylogeny supports placement of sequences for Hawaiian specimens within the genus Tylotus but distinct from all previously recorded sequences of Tylotus. As is widely reported in other molecular‐phylogenetic analyses of the Gigartinales, we find that support for generic and familial relationships within the order is strong whereas that for between‐family relationships is low.     

LEACHIELLA PACIFICA,GEN. ET SP. NOV., A NEW PARASITIC RED ALGA FROM WASHINGTON AND CALIFORNIA

Leachiella pacifica, gen. et sp. nov., a marine alloparasitic red alga is described from Washington and California. Several species of Polysiphonia and Pterosiphonia are hosts for this parasite. The thallus is a white, multiaxial, unbranched pustule with rhizoidal filaments that ramify between host cells, forming numerous secondary pit connections with host cells. All reproductive structures develop from outer cortical cells. Tetrasporocytes, situated on stalk cells, undergo simultaneous, tetrahedral cleavage to form tetraspores. Spermatia are formed continuously by oblique cleavages of the elongate spermatial generating cells. This results in spermatial clusters consisting of 4–8 spermatia in an alternate arrangement. Carposporophyte development is procarpial. The carpogonium is part of a six-celled branch including a sterile cell that is formed by the basal cell. The carpogonial branch is attached laterally to an obovate supporting cell that also forms an auxiliary cell, presumably formed prior to fertilization. After fertilization the carpogonium temporarily fuses with the auxiliary cell apparently to transfer the diploid nucleus and initiate further fusion with the subtending supporting cell to form an incipient fusion cell. The auxiliary cell portion of this fusion cell divides to form gonimoblast initials that continue to divide, forming gonimoblast filaments whose terminal cells differentiate into carpospores. The remainder of the fusion cell enlarges by continual fusion with adjacent vegetative cells. The resultant carposporophyte consists of a basal, multinucleate fusion cell supporting a hemispherical cluster of gonimoblast filaments with terminally borne carpospores. Vegetatively, Leachiella resembles several other parasitic red algae but it is clearly separated by the procarp, carposporophyte development and structure, and tetrasporocyte cleavage.     

Grammephora peyssonnelioides gen. et sp. nov. (Rhodophyta, Rhodymeniaceae) from the Solomon Islands, South Pacific

A new genus and species of red alga in the Rhodymeniaceae, Grammephora peyssonnelioides, is described from both shallow and deepwater habitats in the Solomon Islands, South Pacific. The new genus and species is characterized by prostrate overlapping lobes with a strongly cartilaginous flexible texture, distinct surface linear markings perpendicular to the growing margins, and a compact three to four celled medulla of relatively small refractive cells. Tetrasporangia are elongate and decussately divided, and occur in large scattered dorsal surface sori. Cystocarps are prominent and conical, on the dorsal surface of the blade, with a network of nutritive filaments and basal nutritive tissue around the suspended, centrally located carposporophyte, with all gonimoblast initials becoming carposporangia. The columnar fusion cell is uniquely crowned by a ring of discoid cells of nonalgal origin.     

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.     

MORPHOLOGY OF PLACENTOPHORA (SOLIERIACEAE,GIGARTINALES: RHODOPHYTA), A NEW GENUS BASED ON SARCODIOTHECA COLENSOI FROM NEW ZEALAND1

The only member of the red algal family Solieriaceae known from New Zealand is the endemic Sarcodiotheca colensoi (Hook. & Harv.) Kylin. This study shows that it differs in several respects from the type S. furcata (Setch. & Gard.) Kylin; thus a new genus Placentophora is created for the New Zealand alga. Although P. colensoi nov. comb. is retained in the Solieriaceae on the basis of vegetative, spermatangial, tetrasporangial, carpogonial-branch and early gonimoblast features, it differs from typical members of that family in its pattern of later carposporophyte development. After a single gonimoblast initial is cut off from the auxiliary cell towards the center of the thallus, further gonimoblasts develop from the initial as ramifying, radiating filaments. These filaments enter an extensive “nutritive-cell” region surrounding the auxiliary cell, form, numerous connections to the “nutritive” cells, and incorporate most of them into a central placenta of interconnected, and variously-fused vegetative and gonimoblast cells. Carpo-sporangia then form in short chains around the periphery of the placenta. The cystocarp lacks both a central fusion cell and a sterile-celled investment, or “Faserhülle.” The distinctive carposporophyte of Placentophora is compared to patterns of gonimoblast development, known in other members of the Solieriaceae.     

MORPHOLOGY OF THE SUBANTARCTIC RED ALGA CENACRUM SUBSUTUM GEN. ET SP. NOV. (RHODYMENIALES) FROM MACQUARIE ISLAND1

The red alga Cenacrum subsutum gen. et sp. nov. is described from material collected at Macquarie Island in the subantarctic between November 1977 and February 1978. The habit and carposporophyte development are similar to members of the family Rhodymeniaceae (Rhodymeniales), but certain vegetative features are unique. The frond is a variously incised or lobed foliose blade with hollow apices above and a medulla which becomes progressively filled basipetally with ingrowing rhizoidal filaments. Details of carpogonial branch, auxiliary cell, connecting cell and gonimoblast anatomy are given, as well as observations on the habitats and distribution of the species.     

Morphology and reproduction of Bostrychia pinnata (Rhodomelaceae, Ceramiales) in laboratory culture

In unialgal culture, isolates of vegetative plants of Bostrychia pinnata often developed tetrasporangial stichidia and released viable tetraspores. Most tetra‐sporelings developed normal branching before reproduction, however, some sporelings developed procarps, and later, spermatangia on juvenille unbranched stages (< 1 mm). Most normally branched gametophytes (> 2 mm) were initially female before becoming bisexual when older and larger (> 5 mm). Unisexual male gametophytes were not seen in culture. Carposporophytes developed slowly (40–70 days) and were sometimes abortive or produced reduced numbers of carpo‐sporangia (10–15 in cultures compared with 40–50 in field material). Carpospores germinated more slowly than tetraspores and the tetrasporophytes required up to 6 months to reach reproductive maturity. The Polysi‐phonia‐type life‐history was completed in 9–12 months in the laboratory. Peripherohaptera were absent in cultured plants. The isolates from Florida, Guatemala and Peru did not reproduce sexually, but regularly underwent lower branch abscission as a means of vegetative reproduction. After several years in culture, most individual isolates became self‐incompatible. In the female, 1 or 2 procarps formed on each axial segment and most were 4‐celled with a few having 3 cells. A single branched sterile group of 3–7 cells was also present. After fertilization, the diploid nucleus in the carpogonium divided twice, isolating the capping element and trichogyne and establishing the connecting element adjacent to the auxiliary cell. In mature normal cystocarps the sterile group persisted and secreted mucilage into the central cavity. The mature pericarp was four layers thick (one layer of axial filaments and three cortical cell layers). Pseudocystocarps were common, produced no carpo‐sporangia, contained elongate sterile cells, and were enclosed with a partially developed pericarp. Carpogonia in which 4 nuclei were usually seen may indicate developmental failure resulting in pseudocystocarps.     

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 DEVELOPMENT1

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.     

ACROSYMPHYTON FIRMUM SP. NOV. (RHODOPHYTA,CRYPTONEMIALES), A NEW SUBTIDAL RED ALGA FROM NEW ZEALAND; DEVELOPMENTAL MORPHOLOGY AND DISTRIBUTION OF THE GAMETOPHYTE1

Acrosymphyton firmum sp. nov., is described from the northeastern coast of North 1., New Zealand. Gametophytes are spring–summer annuals which grow subtidally on cobbles. Thalli are uniaxial; each axial cell bears a whorl of four indeterminate and one determinate branchlets. Indeterminate branchlets are alternately arranged giving the thallus a distichous and feather-like appearance. Numerous corticating rhizoidal filaments are produced from the periaxial and lower whorl branchlet cells. These rhizoids entwine and obscure the main axis as the thallus develops until in the mature plant the axes have a firm consistency and lubricous texture. The carpogonial branch bearing short lateral filaments and auxiliary cell branch with terminal auxiliary cell place this new species in the genus Acrosymphyton Sjöstedt. Of the three described species in the genus, A. firmum is most similar to A. taylori. This is the first report of the genus Acrosymphyton and the only confirmed report of the family Dumontiaceae in New Zealand waters.     

SCHMITZIA EVANESCENS SP. NOV. (RHODOPHYTA,GIGARTINALES) A NEW SPECIES OF CALOSIPHONIACEAE FROM THE NORTHEASTERN NEW ZEALAND COAST1

A new red alga, Schmitzia evanescens sp. nov. (Gigartinales), is described from the northeastern coast of North I., New Zealand. Gametophytes are diminutive, delicate, mucilaginous spring annuals which grow subtidally on cobble substrata. The uniaxial construction and carposporophyte development place this new taxon in the Calosiphoniaceae, a family of only two genera, Calosiphonia H. M. Crouan et P. L. Crouan and Schmitzia P. C. Silva. This is the first report of this family in New Zealand. The new species has vegetative features of both these genera, but is assigned to Schmitzia on the basis of its unusual carposporophyte development in which the gonimoblast initial arises directly from the connecting filament at some distance from the undifferentiated intercalary auxiliary cell. Because recent investigators of other red algal genera with a similar carposporophyte development have questioned the validity of site of gonimoblast initiation as a generic criterion it is suggested that the separation of Schmitzia and Calosiphonia should be re-evaluated. These and several other genera in the Gymnophlaeaceae, Pseudoanemoniaceae, Dumontiaceae and Gloiosiphoniaceae, can be considered, on morphological and reproductive grounds, to be relatively simple and therefore perhaps primitive members of the Rhodophyta.     

A MORPHOLOGICAL STUDY OF HOMMERSANDIA MAXIMICARPA GEN. ET SP. NOV. (KALLYMENIACEAE,RHODOPHYTA) FROM THE NORTH PACIFIC1

A new foliose red alga, common subtidally from British Columbia to the Aleutian Islands, is described and given the name Hommersandia maximicarpa. The lobed perennial thallus, which can reach a height of 23 cm, is distinguished by its vegetative structure and by its unique pattern of nonprocarpic carposporophyte development. In transverse section, the blades consist of a narrow filamentous medullary layer sandwiched on either side by large ellipsoidal subcortical cells and a thin outer cortex. The monocarpogonial branch and auxiliary cell systems of the female plants are typical of many members of the Kallymeniaceae. However, after the carpogonialfusion cell forms, a distinctive developmental pattern begins. The connecting filaments radiate outward into the surrounding tissue, branch abundantly, and become septate. They then contact, in addition to auxiliary cells, many small moniliform accessory branches. These branches appear to act as initiation points for the gonimoblast filaments. The large diffuse carposporophytes produced are unknown in any other member of the Cryptonemiales. The vegetative and reproductive anatomy of Hommersandia is compared to other Kallymeniaceae, and similar patterns of postfertilization development are examined in the Rhodophyta.     

Taxonomic revision of the genus Cutleria proposing a new genus Mutimo to accommodate M. cylindricus (Cutleriaceae,Phaeophyceae)

Molecular phylogenetic analyses of representative Cutleria species using mitochondrial cox3, chloroplast psaA, psbA and rbcL gene sequences showed that C. cylindrica Okamura was not included in the clade composed of other Cutleria species including the generitype C. multifida (Turner) Greville and the related taxon Zanardinia typus (Nardo) P.C. Silva. Instead, C. cylindrica was sister to the clade composed of the two genera excluding C. cylindrica. Cutleria spp. have heteromophic life histories and their gametophytes are rather diverse in gross morphology, from compressed or cylindrical‐branched to fan‐shaped, whereas the sporophytes are rather similar. In contrast, the monotypic species Z. typus has an isomorphic life history and resembles fan‐shaped Cutleria in morphology. Morphological comparisons of these taxa revealed that C. cylindrica is morphologically distinct from other Cutleria spp. and Z. typus in having cylindrical gametophytes with multiseriate trichothallic filaments instead of uniseriate filaments (hairs) characteristic of Cutleriales (or Cutleriaceae, Tilopteridales), and in lacking rhizoidal filaments in the crustose sporophytes. Therefore, based on the molecular and morphological data, the establishment of a new genus Mutimo to accommodate C. cylindrica, and the new combination of M. cylindricus, is proposed.     

STRUCTURE AND DEVELOPMENT OF THE CARPOSPOROPHYTE OF NEMALION HELMINTHOIDES (NEMALIONALES,RHODOPHYTA)1

Following fertilization, the carposporophyte of Nemalion helminthoides (Velley in With.) Batters differentiates into four distinct regions: the fusion cell, the sterile gonimoblast cells, the carposporangial mother cells and the carposporangia. The gonimoblast is formed by apically dividing, monopodial filaments of limited growth which may later become pseudodichotomous. Upon differentiation of a terminal carposporangium, a gonimoblast filament may continue to grow sympodially. A single carposporangial mother cell may produce carposporangia in several different directions as well as proliferate successive carposporangia within the sporangial walls that remain after carpospore liberation. As the carposporophyte matures, the gonimoblast initial, the stalk cell, the hypogynous and subhypogynous cells fuse. Except for the fusion cell, all cells of the carposporophyte show organelle polarity and contain a distally located, lobed chloroplast and proximal nucleus.