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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Heterothamnieae
Thallus erect, distantly branched with short laterals above, main axes becoming subdichotomous, axial cells bearing distally 4 (–5) short whorl-branchlets 2–5 cells long, subequal or with 1 slightly larger; branching lateral, independent of or from the basal cell of whorl-branchlets; gland cells present. Attachment by rhizoids from basal axial cells; epiphytic. Cells uninucleate.
Reproduction: Gametophytes dioecious. Carpogonial branches borne on the basal cell of 2-celled whorl-branchlets near apices; post-fertilization the carposporophyte forms 1–3 gonimolobes with the basal cells fusing, and the fertile axis does not develop further leaving the carposporophyte terminally situated and loosely surrounded by 3–4 branches developed from the lower axial cell. Spermatangia on cell clusters borne on the cells of whorl-branchlets.
Tetrasporangia occur on whorl-branchlet cells, sessile, ovoid, decussately divided.
Type species: L. elongatum (Wollaston) Athanasiadis (1996: 183) [=L. fastigiatum (Harvey) Womersley, comb. nov.].
Taxonomic notes: Athanasiadis (1996, pp. 183, 184) distinguished Leptoklonion on the occurrence of carpogonial branches on 2-celled whorl-branchlets, the development of secondary axes in place of a whorl-branchlet, and the development of tetrasporangia on protrusions from basal cells of whorl-branchlets.
Most whorl-branchlets are only 2- (occasionally 3-) celled near apices where carpogonial branches arise, and those bearing carpogonial branches cannot be considered to be reduced. Lateral branches develop mostly independently of the whorl-branchlets but some probably from basal cells of whorl-branchlets. Separation from Amoenothamnion needs to be further assessed and is probably doubtfully justified.
References:
ATHANASIADIS, A. (1996). Morphology and classification of the Ceramioideae (Rhodophyta) based on phylogenetic principles. Opera Botanica No. 128, pp. 1–216.
The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.
Publication:
Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia
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