Electronic Flora of South Australia Species Fact Sheet
Phylum Phaeophyta – Order Chordariales – Family Elachistaceae
Thallus (Fig. 21D) dark brown, tufted, with a pulvinate base surmounted by long, free, filaments, 0.5–5 mm high, epiphytic on basal leaves of Sargassum. Basal layer (Fig. 21E) 0.5–2 mm across, of radiating filaments 8–15 µm in diameter, with isodiametric cells. Medullary filaments (Fig. 21E,F) arising from each cell of the basal layer close to the margin, becoming 400–600 µm long, subdichotomous and densely aggregated, 20–45 µm in diameter with pyriform to subglobose cells L/B 2.5–4. Determinate cortical filaments (Fig. 21F) relatively few compared to the adjacent plurilocular sporangia, straight or slightly curved, 120–250 µm long with 15–25 cylindrical cells 4–6 (–8) µm in diameter and L/B (1–) 2–3. Long assimilatory
filaments (Fig. 21E,F) 2–4 mm long, with an indistinct lower meristem, cylindrical, (9–) 12–20 µ in diameter with cells L/B (1–) 1.5–2.5, each with numerous discoid phaeoplasts.
Reproduction: Plurilocular sporangia (Fig. 21F) in corymbose groups on medullary filaments or on long assimilatory filaments (sometimes subsecund), filiform, uniseriate (occasionally biseriate), simple or once (–2) branched, 4–8 pm in diameter and 75–100 (–120) pm long with 12–16 (–24) locules. Unilocular sporangia (Fig. 21G) on the same plants as plurilocular sporangia, arising from outermost medullary cells, ovoid to obpyriform, 50–70 µm long and 23–28 µm in diameter.
Type from Ocean Beach, Sorrento, Vic. (Clayton, 21.ix.1970): in ADU, A50809 (holotype) and MELU, 20520 (isotype).
Distribution: Only known from Port Phillip Heads, Vic.
Taxonomic notes: Elachista claytoniae is likely to be more widely distributed than indicated by the above records.
SKINNER, S. (1985). Australian and New Zealand species of Elachista and Halothrix (Elachistaceae, Phaeophyta). Trans. R. Soc. S. Aust. 109, 151–160.
The Marine Benthic Flora of Southern Australia Part II complete list of references.
Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
©Board of the Botanic Gardens and State Herbarium, Government of South Australia
Illustration in Womersley Part II, 1997: FIG. 21 D–G.
Figure 21 enlarge
Fig. 21. A–C. Elachista orbicularis (ADU, A50315). A. Thalli on lateral blade of Ecklonia. B. Diagrammatic representation of thallus with medulla, cortex with plurilocular sporangia, and long assimilatory filaments. C. Detail of basal layer, medulla bearing plurilocular sporangia, determinate cortical filaments and long assimilatory filaments. D–G. Elachista claytoniae (D–F, ADU, A50331; G, ADU, A50810). D. Thalli on Sargassum basal lateral. E. Diagrammatic representation of thallus with medulla, cortex with determinate cortical filaments and plurilocular sporangia, and long assimilatory filaments. F. Cortical filament (with basal layer and lower cells of filaments on right) continuing as a long assimilatory filament and bearing laterally determinate cortical filaments and plurilocular sporangia. G. Unilocular and plurilocular sporangia.
State Herbarium of South Australia