Dicranema cincinnalis Kraft (1977 b , p. 228)

Dicranema cincinnalis Kraft (1977 b, p. 228)

Thalli are confined to the stems of the seagrass Amphibolis antarctica and recorded from western Yorke Peninsula, South Australia to Westernport, Victoria. The erect axes form tightly curled, ball-like clusters of slender (200–250 μm in diameter) dichotomous filaments ( Fig. 1 b, c View Fig , 3 d View Fig ). Vegetative structure is basically that of D. revolutum but layers encircling the medullary filaments are fewer and somewhat laxer in these much thinner axes ( Fig. 2 b View Fig ). Tetrasporangia form in slightly swollen and hooked ends of branch forks ( Fig. 3 d View Fig ), the cells basally pit-connected and at maturity borne on inner-cortical mother cells similarly inset from the surface as in D. revolutum ( Fig. 3 e View Fig ). Deeply inset clusters of catenate spermatangia ( Fig. 3 f View Fig ) are also similar to but smaller than those of the generitype species. Carpogonial branches, fusion-cell formation and gonimoblast initiation are much as in D. revolutum ( Kraft 1977 b, fig. 4F, G) but placental size and depth ( Fig. 4 m View Fig ; Kraft 1977 b, fig. 5B) are much reduced owing to the thinness of the axes. Mature cystocarps take virtually the whole interior of the bearing axis and no ostiole has been observed although filaments to one side of the surrounding pericarp ( Fig. 4 n View Fig , arrow) are much laxer and may be where the pericarp splits to release carpospores. On rare occasions, two carposporophytes originating from opposite sides of the bearing branch meet in the middle and completely fill the centre of the axis ( Kraft 1977 b, fig. 13E).