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Callithamnion byssoides Arnott ex Harvey in W.J. Hooker 1833: 342.

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Callithamnieae

Selected citations: Dixon & Price 1981: 116. Harvey 1851: pl. 262.


Aglaothamnion byssoides (Arnott ex Harvey in W.J. Hooker)L'Hardy-Halos & Rueness 1990: 352, figs 2–9,19–21,31–41. Maggs & Hommersand 1993: 92, fig. 30. Silva et al. 1996: 373.

Aglaothamnion furcellariae (J. Agardh) Feldmann-Mazoyer 1941: 454, figs 178–180.

Thallus (Figs 116A) erect and spreading, medium red-brown, tufted, 5–15 mm high, main axes weakly defined apically, clearer below, bearing radially shorter lateral branchlets which are branched 2–4 times, ecorticate. Attachment by spreading rhizoids from basal cells of erect axes (Fig. 116B), sometimes producing further erect axes; epiphytic on gelatinous Rhodophyta (e.g. Gloiosaccion, Platoma foliosa, Tsengia comosa). Structure. Apical cells 3–6 µm in diameter and L/D 2–5, ends of apical cells rounded, increasing to 8–12 µm in diameter and L/D 2–4 at 2–3 cells below their apices, increasing gradually to 30–40 µm and L/D 3–5 in mid cells and in lower axes 80–120 µm in diameter, cells L/D (1–) 1.5–2 (–6), with thick gelatinous walls; lateral branchlets branched 3–4 times, lower cells 20–30 (–35) µm in diameter and L/D 2–3 (–4). Cells uninucleate; rhodoplasts discoid to elongate.

Reproduction: Gametophytes dioecious. Procarps borne on mid cells of the upper axes or main branches, with two periaxial cells one of which (the supporting cell) bears the 4-celled carpogonial branch; post-fertilization each periaxial cell cuts off an auxiliary cell which produces a branched carposporophyte (Fig. 116C, D) with tapering lobes of ovoid carposporangia (10–) 15–30 µm in diameter. Spermatangia (Fig. 116E) borne on short branched filaments 3–4 cells long, ovoid, 1.5–3 µm in diameter.

Tetrasporangia (Figs 116F) sessile on cells of the lateral branchlets, subspherical, 25–45 µm in diameter, tetrahedrally to decussately divided.

Type from Cornwall, England (Arnott); lectotype in TCD (L'Hardy-Halos & Rueness 1990, p. 353).

Selected specimens: Esperance, W. Aust., 13 m deep on Gibsmithia womersleyi on pilings (Kraft, 20.xii.1980; AD, A67274). Topgallant I., Investigator Group, S. Aust., on Platoma foliosa, 27 m deep (Turner, 29.iii.1982; AD, A53064). Pearson I., S. Aust., on Gloiosaccion, 10–15 m deep (Shepherd, 28.iii.1982; AD, A53026). Port Noarlunga, S. Aust., on tyre reef, on Gloiosaccion, 19 m deep (Branden, 26.iii.1987; AD, A57452). American R. inlet, Kangaroo I, S. Aust., on Gloiosaccion, 2–3 m deep (Kraft, Wickes & Johnson, 16.iv.1973; AD, A43748). Snapper Point, Kangaroo I., S. Aust., on Kallymenia cribrosa, 20 m deep (Lavers, 24.iii.1996; AD, A64863). Port MacDonnell, S. Aust., on Tsengia comosa, drift (Kraft, 30.x.1986; AD, A57325).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: Europe.

In southern Australia, from Esperance, W. Aust., to Port MacDonnell, S. Aust.

Taxonomic notes: These specimens appear to agree well with C. byssoides in Europe; all collections have been on gelatinous red algae. However, interfertility should be checked following the study of L' Hardy-Halos & Rueness (1990).


DIXON, P.S. & PRICE, J.H. (1981). The genus Callithamnion (Rhodophyta, Ceramiaceae) in the British Isles. Bull. Br. Mus. nat. Hist. (Bot.) 9(2), 99–141.

FELDMANN-MAZOYER, G. (1941). Recherches sur les Céramiacées de la Méditerranée occidentale. (Algiers.)

HARVEY, W.H. (1851). Phycologia Britannica, Plates 301–360. (Reeve: London.)

HOOKER, W.J. (1833). The British Flora. Edn 4, Vol. 2. (Longman: London.)

L'HARDY-HALOS, M.-Th. & RUENESS, J. (1990). Comparative morphology and crossability of related species of Aglaothamnion (Rhdophyta). Phycologia 29, 351–366.

MAGGS, C.A. & HOMMERSAND, M.H. (1993). Seaweeds of the British Isles. Vol. 1. Rhodophyta. Part 3A, Ceramiales. (HMSO: London.)

SILVA, P.C., BASSON, P.W. & MOE, R.L. (1996). Catalogue of the Benthic Marine Algae of the Indian Ocean. (University of California Press: Berkeley, Los Angeles & London.)

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

Author: H.B.S. Womersley & E.M. Wollaston

Publication: Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia

Illustration in Womersley Part IIIA, 1998: FIG. 116.

Figure 116 image

Figure 116   enlarge

Fig. 116. Callithamnion byssoides (AD, A57452). A. Frond with tetrasporangia. B. Base of male thallus. C. Branches with branched, tapering carposporophytes. D. Twinned carposporophytes with residual supporting cells. E. Branch cells with spermatangia. F. Branches with tetrasporangia.

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