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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Cystocloniaceae
Thallus erect, complanately and subdichotomously branched, drying cartilaginous; branches flat, mostly 0.5–1 mm broad, with regular small marginal spines; holdfast discoid. Structure uniaxial, with an apical notch and each axial cell producing two periaxial cells, the lateral ones alternately extending into filaments, with the axial filament soon inconspicuous; medulla slight, of elongate cells and few rhizoids, cortex pseudoparenchymatous with large outer cells and groups of small cells, rosettes absent.
Reproduction: Sexual thalli probably dioecious; procarpic. Carpogonial branches 3-celled, laterally orientated on inner cells, with the basal cell of a filament on the supporting cell becoming the auxiliary cell, producing the gonimoblast initial outwardly. Carposporophyte with the basal auxiliary cell, other rounded cells, and radiating gonimoblast filaments with chains of carposporangia, with the cortex proliferating on both sides to form the pericarp, ostiolate. Spermatangia unknown.
Tetrasporangia scattered in the cortex, transformed from inner cortical cells, zonately divided.
Life history triphasic with isomorphic gametophytes and tetrasporophytes.
Type (and only) species: S. nitophylloides (Harvey) J. Agardh 1890a: 25.
Taxonomic notes: Stictosporum was placed by Kylin (1932, p. 53) in its own family, the Stictosporaceae, but was transferred to the Cystocloniaceae (Rhodophyllidaceae) by Searles (1968, p. 64) who investigated its structure and reproduction. It differs from other genera of the family in habit and in the gonimoblast initial developing outwardly, as well as in the absence of rosettes in surface view of the thallus. Further studies may indicate that it is best placed in its own family.
References:
AGARDH, J.G. (1890a). Till algemes systematik. Acta Univ. lund. 26(3), 1–125, Plates 1–3.
KYLIN, H. (1932). Die Florideenordnung Gigartinales. Lunds Univ. Årsskr. N.F. Avd. 2, 28 (8), 1–88, Plates 1–28.
SEARLES, R.B. (1968). Morphological studies of red algae of the order Gigartinales. Univ. Calif Pubis Bot. 43, vi + 1–86, Plates 1–12.
The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.
Publication:
Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.
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