Assimilatory Filaments Research Articles

Sporochnus keyari sp. nov. (Sporochnales, Phaeophyceae) from Japan

ABSTRACT In the genus Sporochnus (Sporochnales, Phaeophyceae), Okamura reported S. radiciformis and S. scoparius in Japan in 1922; however, S. scoparius was later synonymized with S. radiciformis, as Okamura’s S. radiciformis was considered to be a young stage of S. scoparius. Therefore, only one species, S. radiciformis, has been recognized in Japan, until the reported occurrence of a second species, S. dotyi, and suggestion that the species identified as S. radiciformis in Japan was genetically distinct from true S. radiciformis described from Australia. We now report findings that based on molecular phylogeny (atpB, rbcL, atp6, cox3) and morpho-anatomical analyses confirming that the common Japanese Sporochnus species is distinct from true S. radiciformis, and we therefore describe a new species, S. keyari sp. nov. This new species differs from S. radiciformis in having less-branched erect thalli, longer terminal assimilatory filaments (trichothallic hairs), and larger unilocular zooidangia, and from S. bolleanus in having more robust thallus axes. In gross morphology, S. keyari is distinguished from S. dotyi, which is also distributed in Japan, in having more slender thalli and lacking greenish structural colour of the assimilatory filaments. In culture, unizoids (zoospores) released from unilocular zooidangia developed into monoicous gametophytes forming antheridia and oogonia at the distal ends of the filaments. Actual sexual fusion was not observed, but presumably fertilization occurred within oogonia and new sporophytes developed in situ within oogonia. Sporophytes were at first uniseriate, but later formed terete thalli by trichothallic growth, with terminal assimilatory filaments.

Structural colour in the brown algal genus Sporochnus (Sporochnales, Phaeophyceae)

ABSTRACT The colour produced by an object’s microstructure rather than by pigments is generally called structural colour. Various macroalgae have some mechanisms of structural colouration. The presence of structural colour in the brown algae is well known in the Dictyotales and Fucales but has recently been reported in the Sporochnales where Sporochnus dotyi has structures in the terminal assimilatory filaments (trichothallic hairs) that produce a pronounced green iridescence. Based on observations by light microscopy, the structural colour of this species was caused by iridescent bodies, 10–15 µm in diameter, within the cells of assimilatory filaments. In contrast, another Sporochnus species known as S. radiciformis in Japan (S. radiciformis auct. japon.) also contains iridescent bodies of 6–10 µm diameter in the assimilatory filaments, but no significant structural colour was observed. In epi-illumination observations using red, green and blue LED light sources, iridescent bodies of S. dotyi showed stronger reflection of green compared with red and blue, whereas the reflections were similar among those colours in S. radiciformis. Transmission electron microscopy (TEM) using a rapid freezing method revealed that homogeneous globules 130–160 nm in diameter were tightly packed inside the iridescent bodies of S. dotyi, whereas the sizes of the globules were markedly irregular in iridescent bodies of S. radiciformis. Therefore, we conclude that the structural colouration of S. dotyi is caused by the interference and diffraction of incident light caused by the crystal lattice-like structure of tightly packed and regularly arranged globules of homogeneous size in the iridescent bodies, which is similar to the mechanism causing iridescence in opal. A similar opal-like structure of iridescent bodies causing structural colouration was recently reported in Ericaria selaginoides, but that of S. dotyi lacked the dynamic shift of the globules shown in E. selaginoides that resulted in a change of the wavelength of reflected light.

New record of Sporochnus dotyi (Sporochnales, Phaeophyceae) from Kii Peninsula, Japan

SUMMARYThe subtidal brown algal species Sporochnus dotyi Brostoff (Sporochnales, Phaeophyceae), which has been regarded as a Hawaiian endemic, is reported from Kushimoto, Kii Peninsula, Pacific coast of central Honshu, Japan, for the first time outside Hawai'i. The species grew on subtidal rocks ca. 5–20 m deep attached by a small conical holdfast. The erect thalli were 5–30 cm high, terete, robust and alternately branched in 1–2 orders. When mature, pedicellate receptacles developed on the branches, and formed elliptical sori 1 mm long with a pedicel 3–5 mm long. The apical parts of the thalli and the receptacles were terminated with a tuft of simple assimilatory filaments of up to 4 mm long and showed prominent green to yellow underwater iridescence. Reproductive filaments (paraphyses) were densely packed, simple, up to 200 μm long and bore 4–6 mostly unilateral unilocular zoidangia 20–22 μm long and 5–6 m in diameter. In the genetic analyses, the Sporochnus alga from Kushimoto had partial rbcL sequence identical to S. dotyi from Hawai'i. The cox3 phylogeny revealed that this alga formed a fully supported clade with S. dotyi. Therefore, we identified the alga from Kushimoto as S. dotyi. This finding of S. dotyi from Japan, together with the recent reports of the mesophotic macroalgae Ryuguphycus kuaweuweu (=Umbraulva kuaweuweu), Ulva iliohaha and Newhousia imbricata from various localities in the Pacific Ocean including Japan, suggest closer biogeographical connections of subtidal/mesophotic macroalgae in the Pacific than previously recognized.

Agrobacterium-Mediated Transient Transformation of Marchantia Liverworts.

Agrobacterium-mediated transient gene expression is a rapid and useful approach for characterizing functions of gene products in planta. However, the practicability of the method in the model liverwort Marchantia polymorpha has not yet been thoroughly described. Here we report a simple and robust method for Agrobacterium-mediated transient transformation of Marchantia thalli and its applicability. When thalli of M. polymorpha were co-cultured with Agrobacterium tumefaciens carrying β-glucuronidase (GUS) genes, GUS staining was observed primarily in assimilatory filaments and rhizoids. GUS activity was detected 2 days after infection and saturated 3 days after infection. We were able to transiently co-express fluorescently tagged proteins with proper localizations. Furthermore, we demonstrate that our method can be used as a novel pathosystem to study liverwort-bacteria interactions. We also provide evidence that air chambers support bacterial colonization.

Taxonomic revision of Saundersella (Ectocarpales s.l., Phaeophyceae) from the northwestern Pacific with description of Saundersella crassa sp. nov. and transfer of Heterosaundersella hattoriana to Saundersella

ABSTRACT Saundersella crassa sp. nov. (Ectocarpales s.l., Phaeophyceae) is newly described from cold-water regions of Japan and the northern Pacific. Saundersella crassa is similar to S. simplex (generitype) in morphology and has been identified as S. simplex in the area, but it has longer and thicker thalli, grows on different basiphytes (S. crassa on Chordaria spp vs S. simplex on Analipus spp) and is genetically distinct in the mitochondrial cox3 and chloroplast atpB, psaA, psbA and rbcL DNA sequences. The erect thalli of S. crassa were simple, filiform, soft and gelatinous, solid when young but later becoming hollow, cord-shaped, attenuated at the base to an indistinct stipe, at times twisted, yellowish to olive brown, and up to 50(–90) cm long and 5 mm wide. The erect thalli were composed of multiaxial colourless central medullary filaments and pigmented assimilatory filaments of 2–6 cells. Terminal cells of the assimilatory filaments were large and swollen, spherical or obovate. Unilocular zoidangia were sessile and obovate or irregular in shape, and were formed on erect thalli at the end of medullary cells or at the base of assimilatory filaments. In the molecular phylogeny, the type of the genus Heterosaundersella, H. hattoriana, was sister to S. crassa and was nested in the clade composed of S. simplex and S. crassa, irrespective of their differences in the habit and occurrence of basal prostrate thalli forming plurilocular zoidangia. Therefore, we propose the new combination S. hattoriana comb. nov. for H. hattoriana. Heterosaundersella thus becomes a taxonomic synonym of Saundersella.

Description and distribution of Nemacystus howei (W.R. Taylor) Kylin (Chordariaceae) from the northern coast of the Yucatán peninsula

Background: There are few studies about Nemacystus on the Atlantic coast, and N. howei has been reported only once for Mexico; that record, however, did not provide a description of this species.
 Question: What are the morphological characteristics of Nemacystus howei and its distribution on the Yucatan coast?
 Species study: Macroalgae, Phaeophyceae, Nemacystus howei. 
 Study site and year of study: North coast of Yucatán Peninsula of Mexico. Dry and rainy seasons from 2017 to 2019.
 Methods: Sampling was carried out at five localities, at 5 and 10 m depths, with scuba equipment. Specimens were preserved in diluted formalin in sea water; silica gel and dried-pressed vouchers are housed at the UADY
 Results: Six samples were collected at the five localities. Each one contains a small mass of filamentous of specimens of Nemacystus howei , that were found only during dry season, at both depths sampled. This alga has a thallus of an entangled filamentous mass of cylindrical, mucilaginous axes, of a light brown color. Younger branches have a solid central axis. Branching is abundant. The main, older axes are hollow. The assimilatory filaments are branched a few times, producing uniseriate colorless hairs and with plurilocular sporangia arising from the base. Nemacystus howei is easily confused with Cladosiphon occidentalis Kylin due to their similar morphology, branching pattern, and size.
 Conclusion: The significant morphological similarities between these species as well as the paucity of specific works on the Phaeophyceae of the Yucatan Peninsula may explain why Nemacystus howei had not been previously reported.

Tinocladia sanrikuensis sp. nov. (Ectocarpales s.l., Phaeophyceae) from Japan

SUMMARYThe new species Tinocladia sanrikuensis sp. nov. H.Kawai, K.Takeuchi & T.Hanyuda (Ectocarpales s.l., Phaeophyceae) is described from the Pacific coast of the Tohoku region, northern Japan based on morphology and DNA sequences. The species is a spring–summer annual growing on lower intertidal to upper subtidal rocks and cobbles on relatively protected sites. T. sanrikuensis has a slimy, cylindrical, multiaxial erect thallus, slightly hollow when fully developed, branching once to twice, and resembles T. crassa in gross morphology. The erect thalli are composed of a dense medullary layer, long subcortical filaments, and assimilatory filaments of 11–35 cells, up to 425 μm long and curved in the upper portion. Unilocular zoidangia are formed on the basal part of assimilatory filaments. The species is genetically most closely related to T. crassa and has the same basic thallus structures but differs in having thinner and longer assimilatory filaments. DNA sequences of the mitochondrial cox1 and cox3, chloroplast atpB, psaA, psbA and rbcL genes support the distinctness of this species.

Cladosiphon takenoensis sp. nov. (Ectocarpales s.l., Phaeophyceae) from Japan

SUMMARYThe new brown algal species Cladosiphon takenoensis H. Kawai (Chordariaceae, Ectocarpales s.l.) is described from Takeno, Hyogo, Japan based on morphology and DNA sequences. The species is a spring annual, growing on subtidal rocks at more or less exposed sites. It resembles C. umezakii in its gross morphology, and the two often grow together, but is distinguishable from C. umezakii in having a more hairy appearance. Cladosiphon takenoensis has a slimy, cylindrical, multiaxial and sympodial erect thallus, branching once to twice, and is provided with long assimilatory filaments (up to 1.8 mm long, composed of up to 100 cells). Unilocular zoidangia are formed on the basal part of assimilatory filaments. The species is genetically most related to C. umezakii and has the same basic thallus structures, but differs from C. umezakii and other Cladosiphon species in lacking phaeophycean hairs and plurilocular zoidangia of the assimilatory filaments. DNA sequences of the mitochondrial cox1 and cox3, chloroplast atpB, psaA, psbA and rbcL genes and the nuclear rDNA ITS2 region support the distinctness of the species. The genus Cladosiphon was paraphyletic in our analyses because the clades of C. okamuranus/C. zosterae and C. takenoensis/C. umezakii were split by Mesogloia vermiculata. However, since the genus‐level taxonomy of Chordariaceae needs considerable revision, we suspend the genus‐level taxonomy of the new species, and tentatively describe it as C. takenoensis.

Taxonomic revision of Papenfussiella species (Chordariaceae, Phaeophyceae) in the Northern Hemisphere

:Using mitochondrial cox3 and chloroplast rbcL-rbcS DNA sequences, molecular phylogeny of Papenfussiella species that were collected from various localities in Japan revealed considerable species diversity in the genus. Although only P. kuromo has been recognized in Japan, in the molecular phylogeny Japanese Papenfussiella formed four distinct clades (clades 1, 2, 3 and 4) with high statistical supports. Specimens of clade 1 corresponded to P. kuromo because the morphology agreed well with the reported descriptions of the species, and the DNA sequences agreed with the lectotype specimen. Clade 2 comprised the syntype specimens of P. kuromo f. densa Inagaki, having distinctively narrow and well-branched thalli. Papenfussiella kuromo f. gracilis was not distinguishable from P. kuromo f. densa in morphology, nor in the DNA sequences. Specimens of clade 3 were collected from Shikoku and were similar to P. kuromo in gross morphology but were anatomically different from P. kuromo in having a subcortical layer. Specimens comprising clade 4 were collected from Akkeshi, eastern Hokkaido, and resembled P. callitricha in gross morphology but were distinct in having longer assimilatory filaments and isodiametric medullary cells. In summary, we propose the establishment of two new species, P. shikokuensis sp. nov. for clade 3 and P. iemasae sp. nov. for clade 4, and to reappraise P. kuromo f. densa and f. gracilis as an independent species, P. densa stat. nov. In addition, preliminary genetic study of the Southern Hemisphere Papenfussiella species suggested the occurrence of several cryptic species in the genus.

Molecular phylogeny of two unusual brown algae, Phaeostrophion irregulare and Platysiphon glacialis, proposal of the Stschapoviales ord. nov. and Platysiphonaceae fam. nov., and a re-examination of divergence times for brown algal orders.

The molecular phylogeny of brown algae was examined using concatenated DNA sequences of seven chloroplast and mitochondrial genes (atpB, psaA, psaB, psbA, psbC, rbcL, and cox1). The study was carried out mostly from unialgal cultures; we included Phaeostrophion irregulare and Platysiphon glacialis because their ordinal taxonomic positions were unclear. Overall, the molecular phylogeny agreed with previously published studies, however, Platysiphon clustered with Halosiphon and Stschapovia and was paraphyletic with the Tilopteridales. Platysiphon resembled Stschapovia in showing remarkable morphological changes between young and mature thalli. Platysiphon, Halosiphon and Stschapovia also shared parenchymatous, terete, erect thalli with assimilatory filaments in whorls or on the distal end. Based on these results, we proposed a new order Stschapoviales and a new family Platysiphonaceae. We proposed to include Phaeostrophion in the Sphacelariales, and we emended the order to include this foliose member. Finally, using basal taxa not included in earlier studies, the origin and divergence times for brown algae were re‐investigated. Results showed that the Phaeophyceae branched from Schizocladiophyceae ~260 Ma during the Permian Period. The early diverging brown algae had isomorphic life histories, whereas the derived taxa with heteromorphic life histories evolved 155–110 Ma when they branched from the basal taxa. Based on these results, we propose that the development of heteromorphic life histories and their success in the temperate and cold‐water regions was induced by the development of the remarkable seasonality caused by the breakup of Pangaea. Most brown algal orders had diverged by roughly 60 Ma, around the last mass extinction event during the Cretaceous Period, and therefore a drastic climate change might have triggered the divergence of brown algae.

Reproductive morphology and DNA sequences of the brown alga Platysiphon verticillatus support the new combination Platysiphon glacialis.

Platysiphon verticillatus, a brown alga endemic to the Arctic, was described based on vegetative specimens collected at Inglefield Bay, West Greenland. The species is distinctive in having a lanceolate blade-like thallus terminated by a terete portion, both covered with hair-like assimilatory filaments. Punctaria glacialis was described from Eastern Greenland, and the species differs from other Punctaria species in lacking hairs and plurilocular zoidangia. Unilocular zoidangia were reported, but instead of zoids being released they formed cell walls insitu developing the appearance of plurilocular zoidangia. However, the fate of the zoids, as well as the walled cells was not traced, and the life history of the alga has remained unclear. By comparing DNA sequences (cox1, cox3, and rDNA ITS2) of specimens morphologically referable to Platysiphonverticillatus and Punctaria glacialis collected at Baffin Island, as well as re-examining morphology and studying crude cultures, we concluded that they are the same taxonomic entity. Furthermore, their cox3 sequence and vegetative morphology agreed with those of the type specimen of Punctaria glacialis. Consequently, we propose Platysiphon glacialis comb. nov. The life cycle could not be completed in culture, but we hypothesize that insitu germination of the unizoids produces reduced gametophytes housed in peripheral tissue of erect sporophytic thalli.

Revisiting the systematics of Ganonema (Liagoraceae, Rhodophyta) with emphasis on species from the northwest Pacific Ocean

:The genus Ganonema was distinguished from the other genera in the Liagoraceae morphologically by several reproductive and vegetative features, including spermatangia formed in dense, dendroidal clusters; carpogonial branches remaining unfused after fertilisation, having compact gonimoblasts; and medullary filaments being relatively broad. In addition, the generitype G. farinosum was uniquely characterised by its carpogonial branches being borne on small, specialised branches arising from the basal part of assimilatory filaments, a feature not seen in other species of Ganonema. Our molecular analyses, incorporating several species currently attributed to Ganonema, showed that the genus was polyphyletic and represented in three independent lineages, one including the generitype G. farinosum, a second including ‘G’ dendroideum, and a third containing three ‘Ganonema’ (‘G.’ clavatum, ‘G.’ borowitzkae and ‘G.’ samaense) from the northwest Pacific Ocean. We have therefore proposed two segregate genera, Gloiocallis gen. nov. for ‘G.’ dendroideum and Hommersandiophycus gen. nov. for ‘G.’ clavatum, ‘G.’ borowitzkae and ‘G.’ samaense. Morphologically, Gloiocallis differed from Ganonema and Hommersandiophycus in having only a few involucral filaments produced from the cortical cells above the supporting cell and most cells of the gonimoblasts differentiating into carposporangia. Hommersandiophycus can be separated from related genera by a combination of unfused carpogonial branches, involucral filaments produced from the cortical cells above and below the supporting cell and its neighbouring cells, carposporangia differentiating sequentially in chains of two to three and gonimoblasts being hemispherical to spherical. The taxonomy of other species currently placed in Ganonema but not analysed in this study requires further work.

First Record of Cladosiphon umezakii (Ectocarpales, Phaeophyceae)in Korea

The genus Cladosiphon Kutzing (1843) is classified into the Chordariaceae in Ectocarpales sensu lato and includes 13 species in the world (Sanson et al. 2006; Ajisaka et al. 2007). Although most of the species of Cladosiphon have been reported in Europe and Africa (Guiry and Guiry 2009), only two species, C. okamuranus Tokida and C. umezakii Ajisaka, are reported in Japan (Tokida 1942; Ajisaka et al. 2007). Cladosiphon okamuranus is very famous for foods in Japan as well as a resource of fucoidan (Nagaoka et al. 1999) and cultivate massively in Okinawa. Recently C. umezakii has been established as a new species based on morphological and molecular data in Japan (Ajisaka et al. 2007). This species is annual, growing on lower intertidal to subtidal regions along the south part of Japan. Cladosiphon umezakii is distinguished by long assimilatory filaments up to 840 μm from the other taxa of the genus (Ajisaka et al. 2007). It is most similar with C. filum (Harvey) Kylin from Australia having long assimilatory filaments up to 800 μm, however it differs from C. umezakii on the basis of its habitus (mainly epiphytic) and cell number of assimilatory filaments (Womersley 1987; Ajisaka et al. 2007). In this study, we encountered Cladosiphon umezakii on the southern coast of Korea. Both morphological characters and plastid rbcL regions of the species confirmed its identity. Two slimy chordariacean species, Tinocladia crassa (Suringar) Kylin and Papenfussiella kuromo (Yendo) Inagaki in Korea were also included for comparison.

Molecular systematics of the genus Actinotrichia (Galaxauraceae, Rhodophyta) from Taiwan, with a description of Actinotrichia taiwanica sp. nov.

Three species of Actinotrichia from Taiwan (Galaxauraceae, Rhodophyta) are described on the basis of morphological and molecular evidence, including A. fragilis, the generitype, A. robusta, a new record for Taiwan, and A. taiwanica sp. nov. Actinotrichia fragilis can be distinguished from the other two species by having a wider branching angle (usually > 40°), persistent and distinctly whorled assimilatory filaments and paraphyses issuing from the pericarp, which do not intermix with the gonimoblasts. Actinotrichia robusta can be distinguished from A. taiwanica by its narrower branches, thinner cortex, more obvious whorled assimilatory filaments and smaller fusion cell that is usually indistinguishable in the mature cystocarp. Recognition of these three species was also supported by rbcL sequence analysis. While A. fragilis is distributed in the pantropical regions of the Indian and Pacific oceans, A. robusta and A. taiwanica sp. nov. are only found along the Kuroshio Current in the northwestern Pacific Ocean.

Cladosiphon umezakiisp. nov. (Ectocarpales, Phaeophyceae) from Japan

SUMMARYThe new speciesCladosiphon umezakiiAjisaka (Ectocarpales, Phaeophyceae) is described from Japan based on morphology and DNA sequences. The species resemblesCladosiphon okamuranusTokida 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. umezakiihas 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.

Studies in the Liagoraceae (Nemaliales, Rhodophyta) I. The genus Trichogloea

The calcified, though strongly mucosoid gametophytes of Trichogloea (Nemaliales, Liagoraceae) usually appear seasonally for a short period in tropical and subtropical regions. Vegetative and reproductive characteristics of the presently recognized species, Trichogloea requienii (Mont.) Kutzing (the generitype), Trichogloea lubrica J. Agardh, and Trichogloea herveyi W. R. Taylor, are described and compared. In addition, the identities of two previously synonymized species, Trichogloea jadinii Borgesen and Trichogloea javensis B0rgesen are clarified. Species of the genus display considerable variation in habit and branching patterns, necessitating an assessment of reproductive structures for accurate identification. Reliable features of Trichogloea include the structure of the medulla and the cortical (assimilatory) filaments, location and structure of carpogonial branches and spermatangia, and the nature of sterile filaments in the vicinity of the cystocarp. Secondary features include both external and internal branching pattern, and the proportion of calcium carbonate to lubricous material, the latter having to be assessed from fresh collections. The present study provides a comparative morphological account of the species of Trichogloea. As a result, T. requienii, T. lubrica, T. herveyi are confirmed as independent species; T. jadinii is removed from synonymy with T. lubrica and placed in that of T. requienii, and T. javensis is confirmed as a synonym of Izziella orientalis (J. Agardh) Huisman et Schils.

Elachistiella leptonematoides gen. et sp. nov. (Elachistaceae, Phaeophyceae) from Brazil

Elachistiella leptonematoides Cassano, Yoneshigue-Valentin & M.J. Wynne gen. et sp. nov. is described from regions of upwelled colder waters in Brazil. This new brown algal genus is characterized by the presence of two types of plurilocular structures: the multiseriate ‘ectocarpoid’ type, which is developed from the tips of filaments at the periphery of the medullary layer, and the intercalary type, which is usually in long series in the assimilatory filaments. Arguments are presented to circumscribe the new species from Brazil as lacking paraphyses because the shorter assimilatory filaments are not dimorphic from the longer assimilatory filaments and furthermore the former filaments can become fertile, producing clusters of ectocarpoid plurilocular structures. Elachista endarachnae Stegenga, J.J. Bolton & R.J. Anderson, described from South Africa, is transferred to the new genus because it also has two types of plurilocular structures: multiseriate ectocarpoid and intercalary types. Elachistiella endarachnae (Stegenga, J.J. Bolton & R.J. Anderson) Cassano, Yoneshigue-Valentin & M.J. Wynne comb. nov. is distinguished from the Brazilian species by the possession of more obvious paraphyses. The new genus has a disjunct distribution and lends further support to a biogeographic connection between the benthic algal floras of South Africa and Brazil.

Elachista endarachnae sp. nov. (Phaeophyceae, Elachistaceae), a peculiar representative of the genus in South Africa

The genus Elachista (Phaeophyceae, Elachistaceae), which has a very low presence in the Indian Ocean, is recorded from the South African south coast for the first time, with the description of E. endarachnae Stegenga, J.J. Bolton & R.J. Anderson, sp. nov. The most striking feature of this species is the possession of multiseriate plurilocular sporangia, otherwise unknown in the genus. Conical, ectocarpoid sporangia develop at the base of assimilatory filaments, but plurilocular sporangia also develop by the transformation of intercalary cells in assimilatory filaments and even of paraphyses.

Neoleptonema yongpilii E.-Y. Lee & I.K. Lee, gen. et sp. nov. (Phaeophyceae), based on morphological characters and RuBisCO spacer sequences

An elachistacean epiphyte, Neoleptonema yongpilii E.-Y. Lee & I.K. Lee, gen. et sp. nov., is reported from Korean coasts. The plants are distinguished by having unbranched assimilatory filaments with intercalary plurilocular sporangia as well as lateral plurilocular sporangia from the cortex. The new genus differs from the genera Leptonematella P. Silva and Halothrix Reinke by having pod-shaped plurilocular sporangia on the medulla, and from Elachista Duby and Proselachista Y.P. Lee & Garbary by having intercalary plurilocular sporangia and a poorly developed medulla. The phylogenetic relationships of Neoleptonema yongpilii were inferred from the spacer sequences between the genes coding for the large and small subunits of the RuBisCO gene. The new genus is a member of a poorly resolved clade consisting of several genera within the Elachistaceae, within which it is more closely related to Halothrix and Elachista nipponica than to Leptonematella.

The reproductive development of the red alga Actinotrichia fragilis (Galaxauraceae, Nemaliales)

The reproductive structures in Actinotrichia fragilis (Forsskål) Børgesen are described, including the first report of the structure and development of the carpogonial branch and cystocarp for the genus. Tetrasporangia usually arise in a terminal position on assimilatory filaments; occasionally they are formed laterally and in a secund manner. In male thalli, conceptacles are initiated from the apical pit of a thallus branch. Filaments bearing spermatangia issue from the inner face of the conceptacle wall. In female thalli, a carpogonial branch consists of a carpogonium, hypogynous cell and basal cell. Carpogonial branches may arise in two ways, either replacing a vegetative branch or rarely as a third branch between vegetative dichotomous branches. Before fertilization, the hypogynous cell divides to produce four cells. Subsequently, the basal cell produces branched filaments that eventually form the pericarp, which envelops the carpogonial branch and developing gonimoblast. After fertilization, the carpogonium divides transversely into two cells. The upper progeny cell retains its cytoplasmic connection to the trichogyne. The lower cell produces a lateral gonimoblast initial. Primary gonimoblast filaments form a compact pseudoparenchymatous mass at the base of the carposporophyte. Carposporangia are produced singly from the tips of the secondary gonimoblast filaments, which develop from the primary gonimoblast mass. Many simple or little-branched sterile paraphyses issue from the inner face of the pericarp and grow into the cavity. A comparison of the reproductive structures of Actinotrichia with those of the other genera of the Galaxauraceae suggests that the genus is closely related to Tricleocarpa Huisman et Borowitzka and Galaxaura Lamouroux.