Mychodea gracilaria (Sond.) Kraft
Australian Journal of Botany 528 (1978)
Conservation Code:
Not threatened
Naturalised Status: Native to Western Australia
Name Status:
Current
Scientific Description
John Huisman & Cheryl Parker,
Monday 20 June 2011
Habit and structure. Thallus dark red to yellow-brown, 10–25 cm high, irregularly radially branched with spreading subterete laterals and ramuli tapering gradually to acute apices, not constricted basally. Holdfast crustose, thin, 1–3 mm across, bearing one to several axes; epiphytic on Amphibolis and occasionally on Posidonia or stalked tunicates. Structure uniaxial, developing similarly to M. carnosa; cortex with outer cells evenly distributed, not forming rosettes, ovoid, 3–6 µm in diameter. Rhodoplasts discoid to elongate, ribbon like in inner cells.
Reproduction. Sexual thalli monoecious; procarpic; polycarpogonial. Carpogonial branches 3-celled, 2–6 borne on inner cortical (supporting) cells which become auxiliary cells, producing gonimoblast initials mainly inwardly, forming chains of irregularly maturing ovoid carposporangia 14–22 µm in diameter, with slight filamentous enveloping tissue; ostiole absent. Spermatangia in scattered clusters on basal cells in the outer cortex, with 4–6 initials each cutting off two spermatangia 1–2 µm in diameter. Tetrasporangia scattered, intercalary, transformed from mid cortical cells and each bearing two groups of outer cortical cells, ovoid, 47–55 µm long and 30–35 µm in diameter, zonately divided.
Distribution. Rottnest I., W. Aust., to Phillip I., Vic., and northern Tas., usually on the seagrass Amphibolis (or Posidonia).
[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 454–456 (1994)]
