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Electronic Flora of South Australia Species Fact Sheet

Homoeostrichus canaliculatus (J. Agardh) J. Agardh 1894a: 16.

Phylum Phaeophyta – Order Dictyotales – Family Dictyotaceae – Tribe Zonarieae


Zonaria canaliculata J. Agardh 1872: 49. Womersley 1967: 225.

Thallus (Fig. 85A) medium brown to grey-brown, usually farinaceous, (5–) 10–20 cm long, multifid and much branched, branches complanate but becoming irregularly twisted below, with long, densely stupose, lower axes 2–5 mm thick and a matted rhizoidal holdfast 2–20 mm across and 5–20 (–25) mm long; epilithic. Fronds (Fig. 84E) subdichotomously to alternately branched by apical splitting, branches more or less linear, (0.5–) 1–1.5 (–2) mm broad throughout, sometimes drying slightly canaliculate. Structure 6–7 cells (Fig. 84G,H) and 150–200 gm thick throughout with cells in regular rows; cortical cells the same size as medullary cells (or occasionally paired) in transverse section, 4–8 to each medullary cell lengthwise, 16–24 (–28) µm across in surface view (Fig. 84F) and L/B (0.5–) 0.7–1.5. Hairs apparently absent.

Reproduction: Reproduction unknown.

Type from Port Fairy, Vic. (Harvey); in Herb. Agardh, LD, 48186.

Selected specimens: Stinky Bay, Nora Creina, S. Aust., drift ( Womersley, 19.viii.I 957; ADU, A21201). Off Cape Northumberland, S. Aust., 15 m deep (Shepherd, 13.ii.1976; ADU, A46997). Port MacDonnell, S. Aust., drift (Womersley, 19.viii.1953; ADU, A18976). Peterborough, Vic., drift (Pope & Bennett, 17.viii.1949; ADU, Al2147). Port Phillip, Vic. ("Alg. Muell."; MEL 16897).

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

Distribution: From Stinky Bay (Nora Creina), S. Aust., to Port Phillip, Vic.

Taxonomic notes: H. canaliculata is retained in Homoeostrichus since the cortical cells are mostly not paired; sporangia are unknown. ft appears to be restricted to deep water on rough-water coasts of S.E. South Australia and western Victoria, and is characterised by the narrow, linear branches and farinaceous surface appearance.


AGARDH, J.G. (1872). Till algernes systematik. Ada Univ. lund. 9(8), 1–71.

AGARDH, J.G. (1894a). Analecta Algologica. Cont. I. Acta Univ. lund. 29, 1–144, Plates 1, 2.

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 84 E–H, 85A.

Figure 84 image

Figure 84   enlarge

Fig. 84. A–D. Taonia australasica (ADU, A50866). A. Upper part of thallus showing marginal apical cells, lines of hairs, and scattered sporangia. B. Longitudinal section showing apical cell and segmentation. C. Transverse section of thallus with an undivided sporangium. D. Longitudinal section of thallus with sporangia and phaeophycean hairs. E–H. Homoeostrichus canaliculatus (ADU, A18976). E. Upper branches. F. Surface view of cortical cell rows. G. Longitudinal section from apex to mature thallus showing segmentation. H. Transverse section with three rhizoids.

Figure 85 image

Figure 85   enlarge

Fig. 85. A. Honweostrichus canaliculatus (ADU, A 18976). B. Homoeostrichus sinclairii (ADU, A19171). C. Homoeostrichus olscnii (ADU, A55409, holotype).

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