Electronic Flora of South Australia Species Fact Sheet

Antithamnion uniramosum Athanasiadis 1996: 157, fig. 74.

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Antithamnieae

Thallus (Fig. 50A) with prostrate and erect axes 2–7 mm long, more or less complanately branched with whorl-branchlets distichously or decussately arranged, with each axial cell producing a single or usually two opposite and equal whorl-branchlets each 500–1000 µm and 8–11 cells long and bearing short, opposite, 1–2 celled branches in 2 rows (Fig. 50C, D). Lateral axes arising from basal cells of whorl-branchlets, without an opposite branchlet. Attachment by rhizoids with terminal digitate pads, arising from basal cells of whorl-branchlets on prostrate axes; probably epiphytic. Structure. Apical cells 5–8 µm in diameter and L/D 0.8–1.2, enlarging to axial cells 20–80 µm in diameter and L/D 4–8. Whorl-branchlets (Fig. 50A, B) with lower and mid cells 20–25 µm in diameter and L/D 3–6, basal cell isodiametric and markedly shorter than upper cells, sub-terminal cells 8–12 µm in diameter and L/D 3–4, terminal cells with rounded ends; short lateral branches opposite on upper rachis cells, 10–15 µm long and 3–4 µm in diameter, often with terminal hairs; gland cells borne on the short lateral branches, lateral and touching both cells or occasionally terminal, ovoid, 15–20 µm in diameter. Lateral branches replacing a whorl-branchlet and without an opposite whorl-branchlet. Cells uninucleate; rhodoplasts discoid, becoming ribbon like in older cells.

Reproduction: Gametophytes unknown.

Tetrasporangia (Fig. 50B) borne on unicellular pedicels, on lower cells of pinnules or on short, gland cell bearing, branches, ovoid, 50–75 µm in diameter, cruciately or decussately divided.

Type from Arno Bay, S. Aust., drift (Kraft 4215, 12.xi.1971; holotype in GB, isotypes in MELU and AD, A67213).

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

Distribution: Only known from the type.

Some data for the type collection given by Athanasiadis (1996, p. 158) are incorrect (see above), and the specimen in AD has been presented by Kraft.

References:

ATHANASIADIS, A. (1996). Morphology and classification of the Ceramioideae (Rhodophyta) based on phylogenetic principles. Opera Botanica No. 128, pp. 1–216.

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

Author: E.M. Wollaston & 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
©State Herbarium of South Australia, Government of South Australia

Illustration in Womersley Part IIIA, 1998: FIG. 50.

Figure 50   enlarge

Fig. 50. Antithamnion uniramosum (A, AD, A67213; B–D, MELU, 4215). A. Thallus branching, with terminal hairs. B. Branches with apical group, small lateral cells and tetrasporangia. C. Upper branches, with paired short branches on cells of whorl-branchlets. D. Whorl-branchlet cells with paired, short, unicellular branches.

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