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Hirsutithallia tincta Wollaston & Womersley, sp. nov.

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Callithamnieae

Thallus (Fig. 120A) erect, 5–10 (–13) cm high, with a main axis bearing radially numerous alternate to irregular laterals with a more or less pyramidal form, cortication commencing close to apices. Holdfast 0.5–1 mm across; epilithic. Structure. Ecorticate determinate branchlets (Fig. 120C, G) 500–1500 µm long, subdichotomous, basal cells 50–90 µm in diameter and L/D 1–2, decreasing over 6–15 cells to small ovoid, rounded, terminal cells 4–9 µm in diameter and L/D 1.5–2, often with hairs. Axial cells of corticate branches increasing to 150–450 µm in diameter and L/D 1.5–2, becoming densely corticated (Fig. 120B) by descending rhizoids from the basal cells of ecorticate branchlets, and bearing profuse anticlinal filaments 3–4 (–5) cells and 45–50 (–60) µm long, occasionally branched near their ends and with terminal hairs. Cells uninucleate but with numerous darkly staining globules; rhodoplasts small, irregularly discoid in young cells, more elongate in older cells.

Reproduction: Gametophytes dioecious. Procarps borne on mid cells of ecorticate branchlets. Carpogonial branches borne on one of two opposite periaxial cells, with the carpogonium enlarging transversely post-fertilization and dividing longitudinally prior to fusion via connecting cells with the two auxiliary cells cut off from the periaxial (one the supporting) cells. Each auxiliary cell produces a gonimoblast initial which forms irregular, branched, tapering gonimolobes (Fig. 120C, D), with later tapering lobes being produced from the first, forming a much branched carposporophyte; carposporangia irregularly ovoid, 20–28 µm in diameter; involucre absent. Spermatangial clusters (Fig. 120E, F) are 45–55 µm across, borne on cells of the ecorticate branchlets, with a stalk cell which branches 2–4 times with terminal spermatangia.

Tetrasporangia (Fig. 120G) are borne singly on outer cells of ecorticate branchlets, sessile, subspherical, 40–55 µm in diameter, tetrahedrally divided.

Type from Elliston, S. Aust., 7 m deep (Shepherd, 21.x.1970); holotype in AD, A37575.

Selected specimens: Safety Bay, W. Aust., drift (Womersley, 29.ix.1979; AD, A50730). Point Avoid, S. Aust., epiphytic, drift ( Womersley, 2.xii.1975; AD, A46885). Almonte Beach, SE of Point Avoid, S. Aust., on Codium galeatum (Lawrence, 21.i.1977; AD, A47853). Seal Bay, Kangaroo I., S. Aust., on Codium galeatum, drift ( Womersley, 29.x.1966; AD, A31031). Pennington Bay, Kangaroo I., S. Aust., drift (Womersley, 28.x.1966; AD, A30853). Stanley Beach (E of Pennington Bay), Kangaroo I., S. Aust., on Posidonia, drift (Womersley, 27.i.1957; AD, A20820). Port MacDonnell, S. Aust., on Tsengia, drift (Kraft, 30.x.1986; AD, A57327).

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

Distribution: Safety Bay, W. Aust., to Port MacDonnell, S. Australia.

Taxonomic notes: H. tincta is closest to H. abaxialis, differing in lacking the abaxial branching, in having more branched carposporophytes, each with several tapering lobes, and in having smaller carposporangia.

References: The Marine Benthic Flora of Southern Australia Part IIIC

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. 120.

Figure 120 image

Figure 120   enlarge

Fig. 120. Hirsutithallia tincta (AD, A37575). A. Habit. B. Cortication with anticlinal filaments. C. Upper branches with corticate axis and carposporophytes. D. Branched and twinned carposporophytes. E. Spermatanigal clusters, surface view. F. Spermatangial clusters on stalk cells. G. Branch with tetrasporangia.

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