Nemastoma J.Agardh, 1842, nom. cons.

Lectotype species: Nemastoma dichotomum J.Agardh

Original publication: Agardh, J.G. (1842). Algae maris Mediterranei et Adriatici, observationes in diagnosin specierum et dispositionem generum. pp. [i]-x, 1-164. Parisiis [Paris]: Apud Fortin, Masson et Cie.

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Type designated in: Schmitz, F. (1889). Systematische Übersicht der bisher bekannten Gattungen der Florideen. Flora oder Allgemeine botanische Zeitung 72: 435-456, pl. XXI.

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Description: Thallus erect and uncalcified, mucilaginous, compressed to subterete with subdichotomous to irregular branching. Structure multiaxial, with a medulla of entwined filaments and a cortex of discrete subdichotomous branches; refractive gland cells usually present, terminal on cortical filaments. Carpogonial branches 3-4 celled, lacking a sterile-cell branchlet and borne on adventitious filaments. Auxiliary cell borne on adventitious filament, and lacking subsidiary cells. Gonimoblast outwardly developing, issued from connecting filament; nutritive cells absent. Carposporophyte lacking an ostiole. Spermatangia cut off from cortical cells; tetrasporophytes unknown (Ardré 1980; Masuda & Guiry 1994).

Information contributed by: G.T. Kraft; Robert Wilkes; A.D.R. N'Yeurt. The most recent alteration to this page was made on 2021-08-10 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 neuter.

Most recent taxonomic treatment adopted: Cormaci, M., Furnari, G. & Alongi, G. (2021). Flora marina bentonica del Mediterraneo: Rhodophyta - Rhodymeniophycidae II. Halymeniales, Nemastomatales, Peyssonneliales, Plocamiales, Rhodymeniales, Sebdeniales. Bollettino dell'Accademia Gioenia di Scienze Naturali di Catania 54(384): 9-342.

Comments: The present widely held concept of Nemastoma defines it as containing linear to foliose plants in which gland cells are present and connecting filaments issue directly from carpogonia to fuse with generative auxiliary cells (Kraft and John 1976). Recent detailed study of the type species by Athanasiadis (1988) and Robins (pers. comm.), however, confirms the generally overlooked observations of Berthold (1884) that the carpogonial branches are restricted to adventitious rhizoids. In rare cases, gonimoblasts arise presumably auxiliary cells, that subtend the carpogonial branches and are not in contact with connecting filaments. Where connecting filaments are present, gonimoblasts arise from auxiliary carpogonial branches. Robins (pers. comm.) is of the opinion that only 2 or 3 species, possibly including Adelophycus, belong to Nemastoma as defined by the type species. Distribution: The type species occurs subtidally in the Mediterranean Sea, with a rarely collected second species, N. canariensis J. Agardh, from an unknown habitat in the Canary Islands.

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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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M.D. Guiry in Guiry, M.D. & Guiry, G.M. 10 August 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 09 December 2022

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