Acrothamnion J.Agardh, 1892

Holotype species: Acrothamnion pulchellum J.Agardh

Currently accepted name for the type species: Acrothamnion preissii (Sonder) E.M.Wollaston

Original publication and holotype designation: Agardh, J.G. (1892). Analecta algologica. Lunds Universitets ÅrsSkrift, Andra Afdelningen, Kongl. Fysiografiska Sällskapets i Lund Handlingar 28(6): 1-182, 3 pls.

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Description: Plant small, creeping, axes prostrate with erect branches bearing whorls of 2-4 equal or unequal branchlets (pinnae) and single gland cells terminal on rachides of pinnae. Pinnae variable in form, rachides always with small basal cell. Largest pinnae pinnately branched, distichous, flat, to 600 µm long. others reduced in form with shorter curved rachides and fewer (occasionally none) shorter outwardly-oriented pinnules. Uppermost pair of pinnules clasping the gland cell usually present. Most reduced pinnae towards base of thallus. Number of pinnae per axial cell varies from 2, as usual in A. butleriae, to 3-4 in A. preissii. Whorls of evenly spaced pinnae or opposite pairs of distichous-pinnate pinnae with 1-2 reduced pinnae side by side between them. Pinnules occasionally with short secondary branchlets. Procarp and carposporophyte as for Antithamnion with 4-celled carpogonial branches formed on basal (supporting) cells of 4-8 successive young pinnae near branch apices. Auxiliary cell, cut off from supporting cell, gives rise to gonimoblast cell with rounded groups of carposporangia. Spermatangial clusters on short pinnules usually towards base of pinnae. Tetrasporangia spherical, cruciate, borne in upward protrusions from basal cells of pinnae. Similar to Antithamnion in plant form, procarp and carposporophyte development and cruciate tetrasporangia. Distinct in pronounced morphological variation and gland cells terminal on rachides of pinnae.

Information contributed by: E.M. Wollaston. The most recent alteration to this page was made on 2017-01-25 by M.D. Guiry.

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

Most recent taxonomic treatment adopted: Athanasiadis, A. (1996). Morphology and classification of the Ceramioideae (Rhodophyta) based on phylogenetic principles. Opera Botanica 128: [1]-216, 108 figs.

Comments: Common in southern Australia. Also recorded from Japan, West Indies, Solomon Islands, southern Africa and the Mediterranean. Probably more widespread than at present recognized. Usually epiphytic on larger algae.

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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. 25 January 2017. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 18 April 2024

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