Electronic Flora of South Australia Species Fact Sheet

Elachista australis J. Agardh 1882: 13.

Phylum Phaeophyta – Order Chordariales – Family Elachistaceae

Selected citations: Skinner 1985: 154, fig. 1G–I.

Synonyms

Philippia australis (J. Agardh) Kuckuck ex Oltmanns 1922: 34, fig. 327. Kuckuck 1929: 19, fig. 8.

Philippiella australis (J. Agardh) Silva 1959: 63. Lindauer et al. 1961: 216, fig. 42. Womersley 1967: 229.

Portphillipia australis (J. Agardh) Silva 1970: 944.

Thallus (Fig. 22A) medium to dark brown, forming dense but soft, globose, mucoid, tufts 0.5–6 mm high, epiphytic on Xiphophora with the base becoming endophytic, usually within the host conceptacles. Basal layer at first of radiating filaments, soon replaced by an irregular mass of entangled rhizoids, partly endophytic, with cells 3–5 in diameter. Medullary filaments (Fig. 22B,C) slender, 2–4 mm long, laterally separated, 7–12 µ in diameter with cells cylindrical and mostly L/B 5–8, branched at intervals of 3–8 cells, with occasional to frequent transverse filaments present mainly in the lower medulla or throughout, arising from the lower end of medullary cells. Determinate cortical filaments (Fig. 22B,C) curved to recurved, 150–300 µm long with 15–30 cells 4–7 µm in diameter and L/B (2–) 3–7. Long assimilatory filaments (Fig. 22B,C) 3–6 mm long, meristem indistinct, 8–12 µm in diameter with cells L/B (1–) 2–3, each with several discoid to irregular phaeoplasts and physodes.

Reproduction: Unilocular sporangia (Fig. 22B,C) usually sessile, occasionally with a unicellular pedicel, arising from outer medullary cells near the base of cortical filaments, shortly ovoid to elongate-ovoid, often slightly asymmetrical, 40–60 long and 20–50 (–55) in diameter when mature. Plurilocular sporangia unknown.

Type from Port Phillip Heads, Vic. (Harvey, Alg. Aust. Exsicc. 101); holotype in Herb.
Agardh, LD, 45972; isotype in NSW.

Selected specimens: Apollo Bay, Vic., on Xiphophora chondrophylla in low eulittoral pools (Womersley, 10.xii.1969; ADU, A34809-"Marine Algae of southern Australia" No, 45, as Philippiella australis). Point Lonsdale, Vic., on X. chondrophylla, upper sublittoral (Skinner, 4.i.1978; ADU, A49067) and lower eulittoral pools (Gordon-Mills, 3.xii.1983: ADU, A55449-"Marine Algae of southern Australia" No. 45a). Bicheno, Tas., on X. gladiata, upper sublittoral in harbour (Womersley, 3.xi.1982: ADU, A56451). Tesselated Pavement, Eaglehawk Neck, Tas., on X. gladiata, upper sublittoral (Parsons & Womersley, 30.x.1982; ADU, A53981).

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

Distribution: From Apollo Bay to Port Phillip Heads, Vic. and around Tasmania. New Zealand (Waihi, Bay of Plenty, and Stewart I.)

Taxonomic notes: The presence of occasional to frequent lateral-growing ("transverse") filaments from medullary cells scarcely warrants placing E. australis in a separate genus. These filaments give little if any "support" to the medullary tissue.

References:

AGARDH, J.G. (1882). Till algernes systematik. Acta Univ. lund. 17, 1–136, Plates 1–3.

KUCKUCK, P. (1929). Fragmente einer Monographie des Pheosporeen. Biol. Anst. Helgol. 17, 1–93.

LINDAUER, V.W., CHAPMAN, V.J. & AIKEN, M. (1961). The marine algae of New Zealand. II. Phaeophyceae. Nova Hedwigia 3, 129–350, Plates 57–97.

OLTMANNS, F. (1922). Morphologie and Biologie der Algen. Vol. 2. (Jena.)

SILVA, P.C. (1959). Remarks on algal nomenclature. II. Taxon 8, 60–64.

SILVA, P.C. (1970). Remarks on algal nomenclature. IV. Taxon 19, 941–945.

SKINNER, S. (1985). Australian and New Zealand species of Elachista and Halothrix (Elachistaceae, Phaeophyta). Trans. R. Soc. S. Aust. 109, 151–160.

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 22, 27A.

Figure 22   enlarge

Fig. 22. Elachista australis (A, ADU, A34809; B,C, ADU, A53981). A. Thalli on Xiphophora chondrophylla. B. Diagrammatic representation of thallus growing from host conceptacle, with long medullary filaments, curved determinate cortical filaments and unilocular sporangia, and long assimilatory filaments. C. Medullary filaments (with a transverse filament) bearing determinate cortical filaments and unilocular sporangia, with two long assimilatory filaments.

Figure 27   enlarge

Fig. 27. A. Elachista australis on Xiphophora chondrophylla (ADU, A34809). B. Corynophlaea cystophorae on Cystophora tnoniliformis (ADU, A46767). C. Leathesia difformis (ADU, A44619). D. Leathesia intermedia on Gelidium australe (ADU, A49179).

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