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Choreonema thuretii (Bornet) F.Schmitz

Reference
Thuret & Bornet, Flora 455 (1889)
Conservation Code
Not threatened
Naturalised Status
Native to Western Australia
Name Status
Current

Scientific Description

Habit and structure. Thallus largely unconsolidated, mostly 0.3–2 mm in greatest extent, vegetative portions endophytic but conceptacles produced external to the host. Structure filamentous to partly pseudoparenchymatous; construction diffuse, consisting of several-celled simple or branched filaments with cells mostly 5–20 µm in diameter and 20–65 µm long; cell elongation characteristics uncertain; cell-fusions and secondary pit-connections absent; epithallial cells, haustoria, and trichocytes unknown.

Reproduction.Vegetative reproduction unknown. Gametangia and tetrasporangia formed in uniporate conceptacles produced external to the host. Bisporangia unknown. Gametangial thalli dioecious. Carpogonia terminating 2-celled filaments arising from the female conceptacle chamber floor. Mature female-carposporangial conceptacle roofs protruding above the host surface, 15–20 µm thick, composed of one layer of cells above the chamber, conceptacle chambers 75–80 µm in diameter and 50–60 µm high. Mature carposporophytes composed of a conspicuous central fusion cell and several-celled gonimoblast filaments bearing terminal carposporangia 15–30 µm in diameter. Spermatangial filaments unbranched, arising from the floor, walls and roof of male conceptacle chambers, mature male conceptacle roofs protruding above the host surface, 15–20 µm thick, composed of one layer of cells above the chamber, conceptacle chambers 55–70 µm in diameter and 50–60 µm high. Tetrasporangial conceptacle roofs protruding above the host surface, 15–20 µm thick above the chamber and composed of one layer of cells, conceptacle chambers 60–80 µm in diameter and 50–55 µm high; tetrasporangia scattered across the conceptacle chamber floor; each mature sporangium 8–20 µm in diameter and 35–50 µm long, containing zonately arranged tetraspores and possessing an apical plug that helps to block the single conceptacle pore prior to spore release.

Distribution.Widespread. In western and southern Australia, Kalbarri, W. Aust., to Gabo I., Vic., and around Tas.

Habitat. C. thuretii has been found on the geniculate corallines Haliptilon roseum and less often on Jania verrucosa and J. micrarthrodia in southern Australia; host thalli containing the endophyte have been collected intertidally from pools and rock platforms and subtidally to depths of 25 m.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 212–214 (1996)]