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Perithalia caudata (Labillardière) Womersley 1967: 239.

Phylum Phaeophyta – Order Sporochnales

Selected citations: Müller et al. 1985: 467, figs 1–25.


Fucus caudatus Labillardière 1806: 113, pl. 259 fig. 1.

Carpomitra inermis (Turner) Kützing. Harvey 1862: pl. 238.

Perithalia inermis (Turner) J. Agardh 1890: 4.

Thallus (Fig. 104A) dark brown, 20–50 (–100) cm long, fastigiate, with numerous percurrent axes with long erect laterals irregularly radially arranged and ending in blunt or capitate apices (Fig. 105B,C), occasionally with an apical tuft of assimilatory filaments (Fig. 105A); holdfast at first irregularly discoid, lobed and verrucose, becoming massive with age (to 10 cm across and 2 cm thick); epilithic. Growth apical (Fig. 105C), with a convex branch meristem covered by a cupulate cap formed of the bases of laterally adherent and basally branched trichothallic filaments which spread laterally down around the apex, with the central filaments occasionally continuing as a tuft of free filaments 1–3 mm long, each with a meristem 12–15 cells above their base, 16–20 µm in diameter above with cells L/B 3–8. Fronds (Fig. 105A) terete (often flat sided on drying), wiry, robust, branches mostly 2–10 mm apart, 0.5–1 (–4) mm in diameter in lower axes, decreasing gradually to 200–400 µm in diameter in upper parts. Structure haplostichous and pseudoparenchymatous, with a medulla of elongate cells, broader outwardly, and a cortex increasing in diameter by periclinal (and occasional anticlinal) divisions of the outer cells; surface cells 4–8 µm across, L/B 0.6–1.2 (–2).

Reproduction: Sporangial sori surrounding lesser lateral branches, several mm below the apices, usually 5–10 mm long and 300–600 in diameter. Paraphyses (Fig. 105D,E) simple above their basal cell, 80–130 µm and 5–6 cells long, slightly clavate with the upper 3 (–4) cells slightly larger, apical cell 6–10 µm in diameter and L/B 1–1.5, oblong with a rounded end; unilocular sporangia borne on the basal cell, clavate, 30–40 µm long and 8–10 µm in diameter, with 16 to 32 meiospores.

Selected specimens: West Bay, Kangaroo I., S. Aust., drift (Womersley, 6.i.1946; ADU, A3292). Seal Bay, Kangaroo I., S. Aust., drift (Womersley, 29.x.1966; ADU, A30978). Pennington Bay, Kangaroo I., S. Aust., 0.5 m over reef edge ( Womersley, 15.i.1946; ADU, A2854). Amphitheatre Rock, West I., S. Aust., 10–15 m deep (Shepherd, March 1966; ADU, A30478). Robe, S. Aust., slipway reef pools ( Womersley, 20.viii.1966; ADU, A30801). Point Lonsdale, Vic., upper sublittoral ( Womersley, 21.i.1967; ADU, A31693). Wilsons Prom., Vic. (Mueller; MEL, 15852). Rocky Cape, Tas., drift (Gordon, 18.i.1966; ADU, A29948). Low Head, Tas. (Perrin, Aug. 1948; ADU, A9320). Bicheno, Tas., 0–5 m deep (Olsen, 29.xii.1963; ADU, A27072). Lady Bay, Southport, Tas., 3–5 m deep (Brown & Womersley, 28.x.1982; ADU, A56499).

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

Distribution: From West Bay, Kangaroo I., S. Aust., to Wilsons Prom., Vic., and around Tasmania.

Taxonomic notes: Gametophytes (Müller et al. 1985) microscopic, filamentous, dioecious, oogamous. Type from Cape van Diemen (S.E. Tasmania); in FI.

P. caudata is often common in shaded areas just below low tide level on rough-water coasts, and extends to 15 m deep. Apical tufts of free filaments are unusual, but occasionally occur on the side of branches as laterals start to develop.


AGARDH, J.G. (1890). Till algernes systematik. Ada Univ. lund. 26(3), 1–125, Plates 1–3.

HARVEY, W.H. (1862). Phycologia Australica. Vol. 4, Plates 181–240. (Reeve: London.)

LABILLARDIÈRE, J.J. (1806–1807). Novae Hollandiae Plantarum Specimen. Vol. 2. (Plates 231–265 in 1807). (Huzard: Paris.)

MÜLLER, D.G., CLAYTON, M.N. & GERMANN, I. (1985). Sexual reproduction and life history of Perithalia caudata (Sporochnales, Phaeophyta). Phycologia 24, 467–473.

WOMERSLEY, H.B.S. (1967). A critical survey of the marine algae of southern Australia. II. Phaeophyta. Aust. J. Bot. 15, 189–270.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

Illustrations in Womersley Part II, 1997: FIGS 104A, 105 A–E.

Figure 104 image

Figure 104   enlarge

Fig. 104. A. Perithalia caudata (ADU, A27072). B. Bellotia eriophorum (ADU, A41298). C. Encyothalia cliftonii (ADU, A46855).

Figure 105 image

Figure 105   enlarge

Fig. 105. A–E. Perithalia caudata (A, ADU, A30978; B,C, ADU, A29948; D,E, ADU, A30801). A. Upper branches with apical (and lateral) tufts of filaments. B. Apex of a branch with the terminal cap. C. Longitudinal section (diagrammatic) of a branch apex with a terminal cap formed from filament bases (tufted filaments occasionally present from central area). D. Paraphyses with unilocular sporangia. E. Paraphyses with mature and young unilocular sporangia and phaeoplasts in upper cells. F. Bellotia eriophorum (ADU, A41298). Paraphyses with unilocular sporangia. G–I. Encyothalia cliftonii (ADU, A56365). G. A fertile branch with short branchlets. H. Paraphyses with unilocular sporangia. I. Longitudinal section of branch apex with apical meristem and trichothallic filaments.

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