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Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Antithamnieae
Selected citations: Athanasiadis 1996: 168, fig. 81. Maggs & Hommersand 1993: 6, fig. 1.
Thallus (Fig. 51A) medium to dark red-brown, densely tufted, 5–25 mm high, with limited prostrate axes bearing much branched erect axes with opposite, decussate, laxly branched, whorl-branchlets. Attachment by rhizoids (Fig. 51B) with digitate multicellular haptera, arising from basal cells of whorl-branchlets; epilithic. Structure. Apical cells 6–12 µm in diameter and L/D 1.5–2, within densely tufted apices, enlarging to mature axial cells 60–110 µm in diameter and L/D 2–4. Whorl-branchlets 700–1200 µm and 14–20 cells long, with opposite or unilateral, mostly erect, pinnules 200–500 µm long, pinnules simple or occasionally with a short gland cell bearing branch; rachis cells 25–35 µm in diameter and L/D 2–3 (basal cell isodiametric), tapering to subterminal cells 16–22 µm in diameter and L/D (1–) 1.5–2, terminal cells conical with rounded ends; pinnule cells 18–26 µm in diameter and L/D 1.2–1.8 (–2); gland cells (Fig. 51C) borne on short 2–4-celled branches on the pinnules, alongside 2 or 3 pinnule cells, ovoid when mature, 18–25 (–30) µm in diameter. Lateral branches arising on basal cells of whorl-branchlets. Cells uninucleate; rhodoplasts discoid in smaller cells, ribbon like in older cells.
Reproduction: Gametophytes unknown in Australian collections.
Tetrasporangia (Fig. 51D) pedicellate, ovoid, 55–80 µm in diameter, decussately divided; branching from the pedicel results in 2 (–3) adjacent tetrasporangia (Fig. 51E).
Type from Trieste, Italy; lectotype in Herb. Agardh, LD, 18774.
Selected specimens: Whyalla, S. Aust., in channel with tidal flow, 0.5 m deep (Harbison, 10.v.1994; 21.v.1994; 30.v.1994 and 24.viii.1994; AD, A63545, A63432, A63577 and A63581 resp.)
Distribution: Widespread in temperate Atlantic and European waters (see Athanasiadis 1996, p. 171).
In southern Australia, known only from Whyalla, S. Australia.
Taxonomic notes: These collections of a single population agree well with descriptions of A. cruciatum from Europe, and the identification has been supported by Dr Christine Maggs. Their locality is near a major industrial port and it is highly likely that they are adventive.
Previous records (e.g. Harvey 1863, synop.: liii) of A. cruciatum probably all apply to A. delicatulum.
References:
ATHANASIADIS, A. (1996). Morphology and classification of the Ceramioideae (Rhodophyta) based on phylogenetic principles. Opera Botanica No. 128, pp. 1–216.
HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)
MAGGS, C.A. & HOMMERSAND, M.H. (1993). Seaweeds of the British Isles. Vol. 1. Rhodophyta. Part 3A, Ceramiales. (HMSO: London.)
NÄGELI, C. (1847). Die neueren Algensysteme und Versuch zur Begründung eines eigenen Systems der Algen und Florideen. Neue Denkschr allg. schweiz. Ges. Naturwiss. 9, 1–275, Plates 1–10.
The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.
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. 51.
Figure 51 enlarge
Fig. 51. Antithamnion cruciatum (A, AD63581; B, C, AD, A63432; D, E, AD, A63577). A. Habit. B. Lower filament with attachment haptera and young erect branches. C. Gland cells alongside 2 or 3 pinnule cells. D. Branch with tetrasporangia. E. Pinnules with single or paired tetrasporangia.
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