Electronic Flora of South Australia Family Fact Sheet

Tribe COMPSOTHAMNIEAE Schmitz 1889: 450

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae

Thallus erect, 5–20 cm high, much branched complanately, largely or partly distichously, usually with long lateral branches on the axes, with a single, lateral, determinate branchlet on each cell, some of which become indeterminate; apical cells dividing alternately obliquely or more or less transversely; axes and branches corticated below with loose rhizoids from the basal cells of lateral branches; one genus (Haloplegma) net like, flat and irregularly complanately branched; gland cells absent. Cells multinucleate.

Reproduction: Gametophytes dioecious. Procarps borne on 2–3 cells of short lateral axes, 2–5 or more cells below the apex which may develop further, with 2 or 3 periaxial cells, one bearing a 4-celled carpogonial branch and another a short 1–3-celled sterile branch; supporting cell with or without a sterile cell. Post-fertilization the auxiliary cell produces 2–5 gonimolobes becoming rounded groups of carposporangia. Carposporophyte with some fusion of basal cells but not a distinct fusion cell, surrounded by simple or branched involucral filaments derived from the axial cell(s) below the carposporophyte or sterile cells of the procarp. Spermatangial heads borne on cells of the determinate branchlets, sessile or pedicellate, ovoid to elongate, with an axial filament (sometimes with a terminal hair) producing whorls of initials and ultimate spermatangia.

Tetrasporangia borne on cells of the determinate branchlets, sessile or pedicellate, ovoid to subspherical, tetrahedrally divided with occasional octosporangia.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Taxonomic notes: The Compsothamnieae includes four or five genera, two (Dasythamniella, including Compsothamnionella, and Haloplegma) in southern Australia, Compsothamnion in the Northern Hemisphere, and probably Antarcticothamnion which Moe & Silva (1979) referred to a separate tribe but Gordon-Mills & Wollaston (1980) consider should be placed in the Compsothamnieae. Gymnophycus Huisman & Kraft (1983) is also considered a probable member of the tribe. The tribe is characterised by procarps borne on somewhat unlimited apices 3 to many cells long, with such apices often lengthening slightly after procarp formation. The procarps have 2 or 3 periaxial cells with a single carpogonial branch and usually a short sterile filament on one periaxial cell. The spermatangia are typically formed in heads. Norris (1985, p. 61), following Itono (1977, p. 43), mistakenly stated that Compsothamnionella has a "Pleonosporium-type of procarp structure". The latter is distinct in this respect and is placed in the Spongoclonieae.

References:

HUISMAN, J.M. & KRAFT, G.T. (1983). Gymnophycus, a new genus of Ceramiaceae (Rhodophyta) from eastern Australia. Phycologia 22, 285–294.

ITONO, H. (1977). Studies on the Ceramiaceous algae (Rhodophyta) from southern parts of Japan. Bibliotheca Phycologia 35, 1–499.

MOE, R.L. & SILVA, P.C. (1979). Morphological and taxonomic studies on Antarctic Ceramiaceae (Rhodophyceae). I. Antarcticothamnion polysporum gen. et sp. nov. Br. phycol. J. 14, 385–405.

NORRIS, R.E. (1985). Studies on Pleonosporium and Mesothamnion (Ceramiaceae, Rhodophyta) with a description of a new species from Natal. Br phycol. J. 20, 59–68.

SCHMITZ, F. (1889). Systematische Ubersicht der bisher bekannten Gattungen der Florideen. Flora, Jena 72, 435–456, Plate 21.

The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
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KEY TO GENERA OF COMPSOTHAMNIEAE

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