Electronic Flora of South Australia Genus Fact Sheet

Genus AUSTROCLONIUM Min-Thein & Womersley 1976: 131

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Cystocloniaceae

Thallus erect, terete, segmented with verticillate branching; epiphytic and attached mainly by recurved tendrils. Structure uniaxial, each axial cell with two periaxial cells in alternating pairs, developing a medulla of elongate cells and rhizoids with a persistent axial filament, and a 1–2 layered cortex with some small outer cells forming slight rosettes.

Reproduction: Sexual thalli dioecious; procarpic. Carpogonial branches 3-celled, laterally orientated on outer medullary cells with the auxiliary cell next outwardly from the supporting cell, producing the gonimoblast initial laterally or inwardly. Carposporophyte with a basal fusion cell connected to the periaxial filament, and radiating gonimoblast filaments with short chains of carposporangia, surrounded by lax filamentous enveloping tissue. Cystocarps swelling the branchlets, with an ostiolate pericarp formed by anticlinal rows of cortical cells. Spermatangia in scattered groups, cut off via initials from outer cortical cells.

Tetrasporangia scattered, pit-connected laterally to outer cells of periaxial filaments and extending through the cortex and medulla, zonately divided.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Type (and only) species: A. charoides (Harvey) Min-Thein & Womersley 1976: 131.

Taxonomic notes: Austroclonium differs from other genera of the Cystocloniaceae in habit, being terete, segmented, and with verticillate branching, but is similar to other genera in reproductive features though a small-celled nutritive tissue is not formed.

References:

MIN-THEIN, U. & WOMERSLEY, H.B.S. (1976). Studies on southern Australian taxa of Solieriaceae, Rhabdoniaceae and Rhodophyllidaceae (Rhodophyta). Aust. J. Bot. 24, 1–166.

The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.

Author: H.B.S. Womersley

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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