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Electronic Flora of South Australia Species Fact Sheet

Pterothamnion flexile (Wollaston) Athanasiadis & Kraft 1994: 130.

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Pterothamnieae

Synonym

Glandothanmus flexilis Wollaston 1981: 119, figs 31–36, 43.

Thallus (Figs 58E, 61D) rose-red, 4–8 cm high, slender, much branched with upper parts complanately branched with laterals 5–8 axial cells apart, flexuous near apices, ecorticate throughout, basally attached by rhizoids; on shells or hard substrates. Structure. Apical cells 6–9 µm in diameter and L/D 1–1.5 in curved apices with unilateral development (Fig. 66A) of whorl-branchlets, enlarging to 50–100 µm in diameter and L/D 3–4 in mid parts, and to 200–400 µm in diameter and L/D 1.5–2 in lower axes, with (2 or) 4 whorl-branchlets of similar size. Whorl-branchlets 0.5–1.5 mm long, adaxially branched above, oppositely branched below, branches long and slender, unbranched or occasionally with terminal rhizoids (Fig. 66B); basal cells 35–55 µm in diameter and L/D 2–3, tapering gradually to mid and upper cells 15–20 µm in diameter and L/D (2–) 3–4 (–6), apical cells terminally rounded; gland cells (Fig. 66B, C) prominent, sessile on mid cells of the whorl-branchlets, ovoid and oblique, 18–25 µm in diameter. Lateral branches arise from axial cells or the basal cells of whorl-branchlets (Fig. 66C). Cells uninucleate; rhodoplasts elongate in smaller cells, ribbon like in larger cells.

Reproduction: Gametophytes unknown.

Tetrasporangia (Fig. 66D) borne on inner cells of whorl-branchlets, sessile or usually stalked, subspherical, 20–30 µm in diameter, decussately divided.

Type from 20 km WSW of Outer Harbor, S. Aust., 22–25 m deep on shells (McFarlane, l1.ix.1975); holotype in AD, A46637.


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

Distribution: Known from the type and Fitzgerald Bay (Point Lowly), Spencer Gulf, S. Aust., 14 m deep on artificial reef (Branden, 13.ix.1987; AD, A59341).

References:

ATHANASIADIS, A. & KRAFT, G.T. (1994). Description of Pterothamnion squarrulosum (Harvey) comb. nov. from south-eastern Australia and southern New Zealand, with a taxonomic re-assessment of the genera Pterothamnion, Platythamnion & Glandothamnus (Ceramiaceae, Rhodophyta). Eur. J. Phycol. 29, 119–133.

WOLLASTON, E.M. (1981). Descriptions of two new genera, Scageliopsis and Glandothamnus (Ceramiaceae, Rhodophyta), including five previously undescribed species from southern Australia. Pacific Sci. 34, 109–127.

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


Illustrations in Womersley Part IIIA, 1998: FIGS 58E, 62D, 66 A–D.

Figure 58 image

Figure 58   enlarge

Fig. 58. A. Pterothamnion nodiferum (AD, A31499). B. Pterothamnion squarrulosum (AD, A48820). C. Pterothamnion ramulentum (MEL, 10258). D. Pterothamnion manifestum (AD, A41641). E. Pterothamnion flexile (AD, A46637). Habit of each species.

Figure 62 image

Figure 62   enlarge

Fig. 62. A, B. Pterothamnion francisianurn (AD, A38087). A. Upper slightly flexuous branches. B. Branches with pinnae hearing tetrasporangia. C. Pterothamnion aciculare (AD, A46154). Upper branches with tetrasporangia. D. Pterothamnion flexile (AD, A59341). Upper branches.

Figure 66 image

Figure 66   enlarge

Fig. 66. A–D. Pterothamnion flexile (AD, A46637). A. Branch apices with unilateral development of whorl-branchlets. B. Attachment rhizoid developed by elongation of a branch axis. C. Lateral branch arising from basal cell of a whorl-branchlet, with gland cells. D. Tetrasporangia on a whorl-branchlet cell. (As in Wollaston 1981, courtesy of Pacific Science, Univ. Hawaii Press.) Ballia callitricha (AD, uncertain). E. Branch apex with large apical cell. F. Lateral whorl-branchlets with extended rachides. G. Part of an indeterminate branch with a lateral whorl-branchlet and basal cells of others. H. Junction of two axial cells. L Tetrasporangial branches on basal cell of a whorl-branchlet. J, K. Ballia pennoides (AD, uncertain). I. Whorl-branchlet with simple pinnules. K. Rhizoidal filament on basal cell of a whorl-branchlet. (E–K, as in Wollaston 1968, courtesy of Aust. J. Bot.)


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