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Genus PLATYCLINIA J. Agardh 1898: 103

Phylum Rhodophyta – Family Delesseriaceae

Thallus complanately and irregularly branched, margin entire to crisped or spinous; veins absent but central thallus slightly thicker than wings; holdfast discoid, becoming divided. Structure. Growth marginal, without distinct apical cells, intercalary divisions frequent, blades monostromatic near apices, soon tristromatic and polystromatic, especially in centre of blades, with first and second cortical layers equivalent or dimidiate.

Reproduction: Gametophytes dioecious. Procarps scattered, with the primary cells cutting off a cover cell and supporting cell with a 4-celled carpogonial branch and 2 sterile cells. Carposporophyte with a weft of slender radiating filaments (with cells fusing) over the layer of primary cells, producing numerous erect filaments of 3–5 carposporangia. Cystocarps slightly protuberant, pericarp thick, ostiolate. Spermatangial sori scattered, with the outer cortical cells producing initials with elongate spermatangia.

Tetrasporangial sori scattered, raised, with cortical cells producing paraphyses 3–4 cells long and tetrasporangia laterally from their lower cells.

Lectotype species: P. stipitata J. Agardh 1898: 106.

Taxonomic notes: Wynne (1983, p. 446) discussed the type species of Platyclinia, advocating lectotypification of the genus on P. stipitata, on which the generic description is largely based.

Platyclinia is characterised by habit, sectional view of regular dimidiate or equivalent cortical cells, and especially by the carposporophyte in which a weft of slender, radiating filaments (with cells fusing) spreads over the layer of primary cells in the cystocarp, producing numerous erect filaments with clusters or rows of 3–5 carposporangia which mature simultaneously. While further detailed studies are needed, this structure appears distinctive within the Delesseriaceae.


AGARDH, J.G. (1898). Species Genera et Ordines Algarum. Vol. 3, Part 3 - De dispositione Delesseriearum. (Gleerup: Lund.)

WYNNE, M.J. (1983). The current status of genera in the Delesseriaceae (Rhodophyta). Bot. Marina 26, 437–450.

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

Author: H. B. S. Womersley

Publication: Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.


1. Thallus branches 5–15 mm broad; cortex where polystromatic dimidiate

P. stipitata

1. Thallus lateral branches 2–6 mm broad; cortex with cells equivalent to primary cells


2. Margins and apices crenulate with frequent projecting cells; tetrasporangial sori linear (or in lines) between centre and margin of blades

P. crenulata

2. Apices and margins not crenulate; tetrasporangial sori ovate and scattered

P. ramosa

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