Pseudodichotomosiphon Yamada, 1934

Holotype species: Pseudodichotomosiphon constricta (Yamada) Yamada

Original publication and holotype designation: Yamada, Y. (1934). The marine Chlorophyceae from Ryukyu, especially from the vicinity of Nawa. Journal of the Faculty of Science, Hokkaido Imperial University Ser. 5, 3: 33-88, 55 figures.

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Description: Thalli forming clumps to 1-2 cm in height comprised of simple to sparsely branched monosiphonous axes arising from filamentous basal system with slender rhizoids, 20-80 _m in diameter, that extend into the substratum. Plants without septations but with numerous irregular constrictions scattered along all axes. Erect axes simple or branched to one or two orders with axes 120-270 _m diameter. Filaments coenocytic with numerous nuclei, 1.5-2.5 _m diameter with single nucleolus. Chloroplasts numerous and rod shaped, in parietal cytoplasm. Pyrenoid single, forming a slightly swollen end to each chloroplast; traversed by multiple parallel bands of thylakoids, these continuous with thylakoid bands along the long axis of the organelle. Pyrenoid core with DNA nucleoid. Asexual reproduction not described. Sexual reproduction oogamous with plants bisexual and gametangia sessile and produced laterally on filaments. Oogonia solitary, almost spherical and 250-300 _m diameter with papillate appendage at apex. Antheridia rarely single, mostly aggregated in groups away from filament apices. Antheridia fusiform to bottle shaped, 170-220 _m long and 80-120 _m long. During antheridial development only outer portion of cytoplasm develops into spermatozoids with hundreds of sperm produced in each gametangium. Spermatozoids 3-4 _m long and 1.5 _m wide and biflagellate with anterior and posterior directed flagella, anterior flagellum hair like appendages. Pseudodichotomosiphon in marine intertidal zone on muddy sand; known only from tropical regions of Japan. Taxonomic position of Pseudodichotomosiphon in Tribophyceae based on ultrastructural studies of vegetative cells and antherizoids as well as pigment composition which is similar to Vaucheria. The occurrence of diadinoxanthin and cellulosic cell walls supports placement in Tribophyceae. Within Tribophyceae genus is similar to Vaucheria, however, phylogenetic relationships of these genera to each other and to the related genus Botrydium remain to be established.

Information contributed by: D. Garbary. The most recent alteration to this page was made on 2021-10-07 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Gender: This genus name is currently treated as feminine.

Most recent taxonomic treatment adopted: Kawai, H. & Nakayama, T. (2015). Introduction (Heterokontobionta p.p.), Cryptophyta, Dinophyta, Haptophyta, Heterokontophyta (except Coscinodiscophyceae, Mediophyceae, Fragilariophyceae, Bacillariophyceae, Phaeophyceae, Eustigmatophyceae), Chlorarachniophyta, Euglenophyta. In: Syllabus of plant families. Adolf Engler's Syllabus der Pflanzenfamilien. Ed. 13. Phototrophic eukaryotic Algae. Glaucocystophyta, Cryptophyta, Dinophyta/Dinozoa, Haptophyta, Heterokontophyta/Ochrophyta, Chlorarachnniophyta/Cercozoa, Chlorophyta, Streptophyta p.p. (Frey, W. Eds), pp. 11-64, 103-139. Stuttgart: Borntraeger Science Publishers.

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Contributors
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.

Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.

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Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 07 October 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 03 May 2024