Elachista orbicularis (Ohta) Skinner
Brit.Phycol.J. 98 (1983)
Conservation Code:
Not threatened
Naturalised Status: Alien to Western Australia
Name Status:
Current
Scientific Description
John Huisman & Cheryl Parker,
Monday 20 June 2011
Habit and structure. Thallus dark brown, tufted, with a pulvinate base surmounted by long, free, exserted filaments, 2–8 mm across and high, epiphytic on Ecklonia radiata. Basal layer of radiating, closely adjacent filaments, 1–3 mm across, more or less circular, with filaments 8–12 µm broad, cells L/B 1.5–3, sometimes with short projections between the host cells. Medullary filaments arising from each cell of the basal layer close to the margin, of two types: subdichotomous filaments 100–200 µm long with cells 2–6 µm in diameter and L/B 3–10, producing the determinate cortical filaments and sporangia, and unbranched filaments with cells 5–15 µm in diameter and L/B 3–5 which continue as the long assimilatory filaments. Determinate cortical filaments 80–120 µm long, with 4–6 narrow, cylindrical to ovoid, cells below and slightly inflated or cylindrical upper cells 8–15(–20) µm in diameter and L/B 1.5–3, each with several phaeoplasts. Long assimilatory filaments 2–6 µm long, indeterminate, with an indistinct meristem a few cells above the medulla, cylindrical, 18–26 µm in diameter with cells L/B (l–)1.5–2.5, containing numerous discoid to irregularly shaped phaeoplasts, each with a pyrenoid.
Reproduction. Plurilocular sporangia forming a dense stratum above the cortex, borne in clusters on branched determinate cortical filaments, filiform, uniseriate, 80–120(–150) µm long and 3–5 µm in diameter, with 16–35(–50) locules. Unilocular sporangia unknown. Life history direct.
Distribution. In southern Australia, known from Rottnest I., W. Aust., from Port Noarlunga to Port Elliot, S. Aust., and from Garie Beach, N.S.W.
Habitat. E. orbicularis is common throughout the year on Ecklonia within the above range.
[After Womersley, Mar. Benthic Fl. Southern Australia II: 78 (1987)]
