Two species of Dasya (Ceramiales, Rhodophyta) from Bonin Islands, southern Japan, with the description of Dasya boninensis sp. nov.

Two species of Dasya in the Dasyaceae (Ceramiales, Rhodophyta) are reported from Bonin Islands, southern Japan. Dasya murrayana Abbott et Millar, new to Japan, is characterized by the following set of features: the tufted habit (up to 30 erect axes developing from a basal disc), small‐sized (6–10 mm high and 350–500 μm in diameter in the middle region), thinly but completely corticated axes, rigid and incurved pseudolaterals forming corymbose heads at the apices of axes and branches, the absence of adventitious monosiphonous filaments, a large number of tetrasporangial stichidia and spermatangial branches per fertile pseudolateral and slender spermatangial branches (35–45 μm in diameter). Dasya boninensis Masuda, Kurihara et Kogame, sp. nov. is characterized by short but thick (10–30 mm high and 600–1000 μm in diameter at the middle portion), heavily corticated axes, indistinct pericentral cells except for the upper portion in transverse sections, soft, straight pseudolaterals and adventitious monosiphonous filaments densely covering the axis and branches, a small number of tetrasporangial stichidia and spermatangial branches per fertile pseudolateral, thick spermatangial branches (65–90 μm in diameter), and short‐necked cystocarps. A dichotomous key to the taxa found in Japanese waters is given.     

Dasya adela sp. nov. (Rhodophyta,Ceramiales), an enigmatic new Dasya from a landlocked fjord in southwest Norway

We here report a new Dasya species found in a landlocked fjord or poll in southwestern Norway; Dasya adela sp. nov. The thallus of this species is small (1–3 cm), normally sparsely branched, and its axes are completely covered with cortex cells. The species is set with long (3–4 mm) and flaccid monosiphonous pseudolaterals, and during autumn it showed high growth of adventitious monosiphonous branches. Only a few individuals with tetrasporangia have been recorded, and no sexual reproductive structures have been observed in field collections. In culture stichidia readily developed on the pseudolaterals, with four tetrasporangia per section. The spores showed high mortality. A few sporelings survived in culture, and developed into small and loosely organized filaments with no upright axes. After 2 years in culture a few plants bearing spermatangial branches were observed, but no individuals with carpogonia. The monosiphonous branches are readily shed in culture, attach themselves by rhizoids and rapidly develop into new thalli, some of which have produced tetrasporangial stichidia. Sequences analyses of partial COI and the rbc L gene showed that the new taxon belongs within Dasyoideae. However, no close relationship was found with other European species of Dasya. The new taxon was compared to other Dasya taxa with which it shared a number of selected characters, but none of these taxa shared all characters of the new Dasya.     

DASYA ROSLYNIAE SP. NOV. (DASYACEAE,RHODOPHYTA), WITH A DISCUSSION ON GENERIC DISTINCTIONS AMONG DASYA,EUPOGODON, RHODOPTILUM,AND POGONOPHORELLA1

Dasya roslyniae sp. nov. (Dasyaceae, Rhodophyta) is described from subtidal habitats at Split Solitary Island (30°14′S, 153°11′E), New South Wales, Australia. The new species is distinct within the genus due to its strongly compressed and secondarily bilaterally branched axes, differing from the majority of Dasya species that are terete and secondarily radially organized. Pseudolaterals are quickly caducous on ventral and dorsal (transverse) surfaces but are persistent on lateral surfaces for short distances from the apex, leaving the bulk of the plants flattened and denuded. Its gross morphological characters are thus similar to those displayed by the genera Pogonophorella, Eupogodon (formerly known as Dasyopsis), and Rhodoptilum. Characters used for separating these genera and Dasya are, in some cases, overlapping and in need of critical evaluation. To the primarily radially organized taxa, determined by examination of divisions of the apical cell, are placed species of Dasya, six species now included in Eupogodon, and the type and only species of Pogonophorella californica. Examination of the activity of the apical cells of Eupogodon planum and Rhodoptilum plumosum, the type species of their genera, confirms the primary bilaterality of these two genera, and the traditional defining feature of Eupogodon (lack of discernible pericentral cells in cross-section of indeterminate axes) is shown to be untenable. A secondary character that would separate Eupogodon and Rhodoptilum is the polysiphonous bases of otherwise monosiphonous laterals (pseudolaterals) in Eupogodon and the monosiphonous bases in Rhodoptilum.     

The Fine Structure of Photoreceptor Terminals in the Compound Eye of Pandalus borealis (Crustacea)

Seven of the photoreceptor axons of each ommatidium in the compound eye of the prawn Pandalus borealis end in two layers in the optic lamina. They have expanded terminals in the optic cartridges; four distally and three proximally in each cartridge. All seven receptor terminals are presynaptic to one lamina monopolar neuron (M₂) of the cartridge. This monopolar neuron is situated centrally in the cartridge and has a thick axis fibre with radially arranged branches, and its axon has a terminal in medulla externa. At the synapses, an arrowlike presynaptic bar is found facing three postsynaptic profiles. The receptor terminals have several characteristics. Their cytoplasm is filled with empty and coated vesicles, and contains numeorus large mitochondria and clusters of tubular elements. There is a longitudinally arranged fascicle of filaments partly surrounded by electron-dense amorphous material in the terminals. Centrally towards M₂, numerous neural spines invaginate into the terminal. Along the entire terminal periphery, there are invaginations from the glial cells. The terminals also form small knoblike protrusions extending into the surrounding glial cells.     

Taxonomic notes on three species of Herposiphonia (Ceramiales, Rhodophyta) found in Japan

Three species of the red algal genus Herposiphonia (Ceramiales, Rhodomelaceae) found in Japan are described, and taxonomic features of the genus are discussed. Herposiphonia crassa Hollenberg is reported from Japan for the first time and is characterized by thick axes (200–350 µm in diameter) and determinate branches (100–200 µm in diameter), relatively short determinate laterals (400–1200 µm in length) with a large number of periaxial cells (15–19 per segment) and three (occasionally two or four) vigorously developed (1.8–2.5 mm in length by 50–75 µm in diameter basally) trichoblasts on each determinate lateral. Herposiphonia elongata Masuda et Kogame is also reported from Japan for the first time and is characterized by the conspicuous thickening growth of cystocarp‐bearing branches and spermatangial branches with an elongated sterile tip. Some newly found features of Herposiphonia fissidentoides (Holmes) Okamura are presented: the rhizoid production from the central portion of parental periaxial cells in addition to the distal end, virtual absence of vegetative trichoblasts, production of procarpial trichoblasts and spermatangial branches on fertile determinate branches on short indeterminate laterals, cystocarps sometimes with a short spur, and extremely large tetrasporangia.     

Segregative cell division and the cytoskeleton in two species of the genus Struvea (Cladophorales,Ulvophyceae, Chlorophyta)

The detailed segregative cell division (SCD) processes and changes in the arrangement of cortical microtubules and actin filaments were examined in two species of Struvea. SCD was initiated by the appearance of annular constrictions along the lateral side of a mother cell. The constrictions decreased in diameter, became thin, tubular in shape, and pinched the protoplasm of the mother cell into several protoplasmic sections. The protoplasmic sections expanded and developed into daughter cells, which appressed each other, and were arranged in a single row. Lateral branches protruded from the upper parts of the daughter cells. The protoplasm of the lateral branches was divided by secondary SCDs and was distributed amongst the new daughter cells. SCD and lateral branch formation were essential for morphogenesis in Struvea. Cortical microtubules were arranged parallel and longitudinally to the cell axis before SCD. When SCD was initiated, there was considerable undulation of the cortical microtubules and several transverse bundles appeared in the cytoplasmic zone where annular constrictions occurred. A microtubule‐disrupting drug (amiprophos methyl) inhibited SCD. Actin filaments maintained reticulate patterns before and during SCD. These results demonstrated that SCD in Struvea species was quite distinct from that in Dictyosphaeria cavernosa reported previously.     

Lachemilla jaramilloi and L. talamanquensis spp. nov. (Rosaceae) from Ecuador and Costa Rica

Two new species of Lachemilla (Rosaceae) are described and illustrated. Lachemilla jaramilloi Romoleroux &Morales‐Briones from Ecuador is characterized by its decumbent habit, villous‐hirsute pubescence, long basal petiole, and deeply tri‐parted leaf blades. The flowers are sessile to subsessile and subtended by episepals, and the hypanthia elongated and glabrescent. Lachemilla talamanquensis Romoleroux & Morales‐Briones from Costa Rica is distinguished by its sericeous‐villous, ascending branches, sub‐sessile distal leaves, tri‐lobed leaf blades, forming whorls with the stipule. The flowers are solitary or arranged in few‐flowered inflorescences, with big, dark, villous hypanthia, containing several achenes.     

Developmental morphology of Odonthalia floccosa (Ceramiales, Rhodophyta) in laboratory culture

Material of the red alga Odonthalia floccosa (Esper) Fal-kenberg (Rhodomelaceae, Ceramiales), collected from California, was cultured in the laboratory and its life-history was completed. Tetraspores grew into bipolar sporelings that differentiated into a colorless rhizoidal portion and a pigmented upright shoot. The sporelings became compressed apically and formed lateral branches in a regularly distichous manner that were congenitally fused with the main axis. These tetraspore germlings grew into diecious gametophytes. Male ga-metophytes produced numerous spermatangia on modified fertile branchlets (male trichoblasts) that possessed three to four monosiphonous, proximal segments. Female gametophytes formed a single pro-carp on the suprabasal segment of unbranched female trichoblasts. Cystocarps developed on the female gametophytes cocultured with male gametophytes and released viable carpospores that developed into fertile te-trasporophytes. Tetrasporangia were produced from the third and fourth periaxial cells in each of 12–45 successive fertile segments and provided three (two lateral and one basal) cover cells. The occurrence of both spermatangia and procarps on fertile trichoblasts in O. floccosa suggests that the alga is the most derived in these two characters among the species of the genus Odonthalia. This species is distributed in cold temperate regions in the North Pacific, and it should be excluded from the North Atlantic marine algal flora.     

Cladosiphon umezakii sp. nov. (Ectocarpales, Phaeophyceae) from Japan

The new species Cladosiphon umezakii Ajisaka (Ectocarpales, Phaeophyceae) is described from Japan based on morphology and DNA sequences. The species resembles Cladosiphon okamuranus Tokida in its gross morphology; somewhat slimy, cylindrical, multiaxial and sympodial erect thallus, arising from a small disc‐shaped holdfast, and branching once to twice. However, C. umezakii has considerably longer assimilatory filaments (up to 840 μm long, composed of up to 90 cells) than any known taxa of the genus. The species is a winter to spring annual, growing on lower intertidal to subtidal rocks of more or less exposed sites on the north‐eastern coast of Kyushu and on both the Pacific and the Sea of Japan coasts of Honshu. Specimens from the Sea of Japan coast had both unilocular and plurilocular zoidangia, whereas those from Kyushu and from the Pacific had only unilocular zoidangia. Unilocular zoidangia were formed on the basal part of assimilatory filaments, and plurilocular ones were transformed from the distal part of assimilatory filaments. DNA sequences of the Rubisco‐spacer (rbc‐spacer) region and the nuclear rDNA ITS region (ITS1, 5.8S and ITS2) supported the distinctness of the species.     

Morphology and molecular relationships of Leptofauchea rhodymenioides (Rhodymeniales,Rhodophyta), a new record for Japan

Leptofauchea rhodymenioides Taylor (Faucheaceae, Rhodymeniales) is reported from Japan for the first time, based on detailed morphological studies and molecular phylogenetic analyses of nuclear‐encoded small subunit ribosomal RNA (SSU rRNA) and plastid‐encoded rbcL gene sequences. This is the first report of male gametophytes and detailed carposporophyte development in the genus Leptofauchea. This species is characterized as follows: (i) flat, membranous, and regularly and dichotomously branched thalli; (ii) the older blades are constricted below the apices; (iii) the cortex is composed of a continuous layer with an irregularly arranged outer layer, and the medulla of two to three incomplete layers; (iv) gametophytes are dioecious; (v) in males, the cortical cells cut off two to three spermatangial mother cells, which produce terminal spermatangia; (vi) in females, the procarp is composed of a three‐celled carpogonial branch and a two‐celled auxiliary cell branch; (vii) upon fertilization, the carpogonium directly contacts the auxiliary cell; (viii) the auxiliary mother cell fuses with vegetative cells, and forms a large trunk‐like fusion cell; (ix) gonimoblast filaments develop outwardly, and transform completely into carposporangia; (x) the carposporophyte is covered with a pericarp with a well‐defined tela arachnoidea; (xi) the mature cystocarp is spherical, has an ostiole, and protrudes from the blade margins; and (xii) the cruciately divided tetrasporangia are formed in nemathecia, produced laterally from paraphyses or terminally on short filaments. Molecular analyses suggest that Leptofauchea forms a strong sister alliance with the genus Webervanbossea. The families Faucheaceae and Lomentariaceae, and the genera Leptofauchea and Webervanbossea are monophyletic, but the latter two genera are not included in the Faucheaceae.     

Neorhodomela enomotoi sp. nov. (Ceramiales, Rhodophyta) from Japan

The red alga Neorhodomela enomotoi Masuda et Kogame (Rhodomelaceae, Ceramiales) is described as a new species from Japan. It is characterized by the following combination of features: (i) thalli reddish-brown and slightly rigid; (ii) first-order branches mostly indeterminately branched; (iii) adventitious branches infrequent, determinately branched and formed chiefly in the axils of lateral branches; (iv) vegetative trichoblasts abundant; (v) tetrasporangia produced on paniculate ultimate and penultimate branches; and (vi) cystocarps flask-shaped (urceolate). This species has been found growing only in the upper subtidal zone in the warm temperate waters of Japan.     

Gracilaria corallicola and G. multipartita (Gracilariales,Rhodophyta), two related flattened European species

Two European species of Gracilaria possess flattened blades borne on cylindrical axes, namely, G. multipartita, known primarily from the Atlantic coast, and G. corallicola from the Mediterranean Sea. They are sister species that cluster with G. armata, G. bursa-pastoris and G. longa in rbcL analyses with strong bootstrap support. Blades of G. multipartita taper towards the tips, whereas those of G. corallicolla have broadly rounded tips. Spermatangia of G. corallicola are borne in shallow conceptacles (textorii-type) and data from the literature indicate that the same is true of G. multipartita. Cystocarp morphology is similar, with the gonimoblast filaments initially elongated, narrow and densely filled with cytoplasm, and with tubular nutritive cells issuing initially from lower gonimoblast cells and fusing with cells in the lowermost regions of the outer pericarp. Tetrasporangia are initiated terminally and displaced laterally with the production of side branches from the subterminal cell. The diagnostic characters of the Gracilariaceae are reviewed from a developmental perspective.     

Erysiphe corylopsidis sp. nov., a new powdery mildew fungus found on Corylopsis spicata and C. pauciflora

A powdery mildew fungus occurring on leaves of Corylopsis pauciflora and C. spicata in Japan is described as a new species, Erysiphe corylopsidis. This species is characterized by fewer than 15 appendages on a chasmothecium, primary branches of the appendages occasionally elongated, and a relatively small number (2–5) of ascospores per ascus. Molecular phylogenetic analyses based on rDNA ITS and 28S rDNA sequences indicate that this fungus forms an independent lineage in the genus Erysiphe.     

Morphology and life history of four Japanese species of Elachista (Elachistaceae, Phaeophyceae), including a new record of E. fucicola

Elachista fucicola (Velley) Areschoug (Elachistaceae, Phaeophyceae) is newly recorded from Japan, and compared with three previously described species, Elachista coccophorae Takamatsu, Elachista mollis Takamatsu and Elachista okamurae Yoshida. All species showed direct‐type life histories in culture without sexual fusion. Prostrate filaments of E. fucicola formed globular plurilocular zoidangia similar to those reported from Atlantic isolates of this species. However, these were different from uniseriate plurilocular zoidangia of the three Japanese species. Furthermore, the position of a meristematic region in assimilatory filaments and the morphology of paraphyses can easily distinguish these from E. fucicola. Previously emphasized differences in cell length : width ratios in assimilatory filaments showed only slight differences. Elachista coccophorae is characterized by thick‐walled assimilatory filaments and curved paraphyses, and the absence of downwardly growing rhizoidal filaments. Elachista mollis and E. okamurae are very similar. However, germlings from plurizoids formed on erect filaments of E. mollis showed characteristic pseudodiscoid growth in culture. Halothrix coccophorae Ohta and Elachista zosterae Noda are reduced to synonyms of E. coccophorae and E. mollis, respectively.     

MESOPHYLLUM SPHAERICUM SP. NOV. (CORALLINALES,RHODOPHYTA): A NEW MAËRL‐FORMING SPECIES FROM THE NORTHEAST ATLANTIC1

Mesophyllum sphaericum sp. nov. is described based on spherical maërl individuals (up to 10 cm) collected in a shallow subtidal maërl bed in Galicia (NW Spain). The thalli of these specimens are radially organized, composed of arching tiers of compact medullary filaments. Epithallial cells have flattened to rounded outermost walls, and they occur in a single layer. Subepithallial initials are as long as, or longer than the daughter cells that subtend them. Cell fusions are abundant. Multiporate asexual conceptacles are protruding, mound‐like with a flattened pore plate, lacking a peripheral raised rim. Filaments lining the pore canal and the conceptacle roof are composed of five to six cells with straight elongate and narrow cells at their base. Carposporangial conceptacles are uniporate, protruding, and conical. Spermatangial conceptacles were not observed. Molecular results placed M. sphaericum near to M. erubescens, but M. sphaericum is anatomically close to M. canariense. The examination of the holotype and herbarium specimens of M. canariense indicated that both species have pore canal filaments with elongate basal cells, but they differ in number of cells (five to six in M. sphaericum vs. four in M. canariense). Based on the character of pore canal filaments, M. canariense shows similarities with M. erubescens (three to five celled). The outermost walls of epithallial cells of M. canariense are flared compared to the round to flattened ones of M. erubescens, the latter being widely accepted for the genus Mesophyllum. The addition of M. sphaericum as new maërl‐forming species suggests that European maërl beds are more biodiverse than previously understood.     

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.     

First record of Asteronema rhodochortonoides (Phaeophyceae) for the Pacific Ocean

Morphological observations of a minute, filamentous, branched brown alga epiphytic on Sargassum thun‐bergii (Mertens ex Roth) Kuntze were made on material collected at Tsuyazaki (33°48′N, 130°27′E), Fukuoka Prefecture, southern Japan. This alga was assignable to Asteronema rhodochortonoides (Børgesen) Möller et Parodi in having stellately arranged chloroplasts with several pyrenoids grouped in the center, predominantly apical growth, narrow filaments, and elliptical or broadly elliptical plurilocular zoidangia that are apically or laterally formed on upright filaments. A comparison of partial nuclear small subunit rDNA sequences between the Japanese material and A. rhodochortonoides from the Canary Islands showed only two or three nucleotide differences. This supports our assignment of the Japanese material to this species as a first report for the Pacific Ocean. In laboratory cultures, zoids released from plurilocular zoidangia developed into plants with morphology similar to the field‐collected plants. This cycle repeated without production of unilocular zoidangia in our cultures.