Pycnothamnion P.J.L.Dangeard, 1953

Holotype species: Pycnothamnion crustaceum (P.J.L.Dangeard) P.J.L.Dangeard

Description: Polysiphonous thalli with dorsiventral prostrate and erect radially organized branches; 7-9 pericentral cells, uncorticated. Rhizoids, often in groups, attaching dorsiventral prostrate branches; upright branchlets of two types, exogenously or endogenously formed; exogenous upright branches up to ~1mm long, dichotomously branched and with unbranched trichoblasts, often formed opposite rhizoid cluster; endogenous branchlets develop on segments between the exogenous ones, they are smaller, often unbranched and bent toward the prostrate branch apex in early stages of development. In later stages they may resemble the exogenous branchlets. Reproductive structures on upright branches. Tetrasporangia in a single straight series in unmodified or slightly curved branch tips. Cystocarps near the branch apex, urceolate to ovoid. Male capitula cylindrical, borne in place of trichoblasts near branch tips.

Information contributed by: R.E. Norris. The most recent alteration to this page was made on 2010-10-07 by M.D. Guiry.

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

Most recent taxonomic treatment adopted: Schneider, C.W. & Wynne, M.J. (2007). A synoptic review of the classification of red algal genera a half a century after Kylin's "Die Gattungen der Rhodophyceen". Botanica Marina 50: 197-249.

Comments: Known only on intertidal rocks, on the Dakar, west African coast. Pycnothamnion closely resembles Stichothamnion Boergesen but in the latter genus upright branches are only endogenously developed and in a single row compared with the exogenous and endogenous upright branches in Pycnothamnion borne in 2 rows. Lophosiphonia also is similar but produces only endogenous upright branches in 2 rows, and all upright branches have similar form, even in early stages.

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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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in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.

Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=42878

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 07 October 2010. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 19 April 2024