Electronic Flora of South Australia Species Fact Sheet

Platyclinia ramosa Womersley, sp. nov

Phylum Rhodophyta – Family Delesseriaceae

Thallus (Fig. 47A) light to medium red to yellow-red, 4–10 cm high, much branched marginally, main axes 5–15 mm broad, laterals 3–6 mm broad, tapering to 1–2 mm broad, margins crisped to convolute, apices rounded; veins absent. Base of main axes tapering to a short, slender stipe. Holdfast discoid; epiphytic. Structure. Growth marginal with numerous very small apical cells (Fig. 47B, C), segmenting to irregularly arranged cells with frequent intercalary divisions (Fig. 47C), mature cells angular, isodiametric to slightly elongate, 20–35 µm across; blades monostromatic near margins, becoming tristromatic and 30–90 µm thick, cortical cells equivalent, polystromatic near the base. Cells multinucleate; rhodoplasts discoid.

Reproduction: Gametophytes dioecious. Procarps scattered, details not observed. Carposporophytes (Fig. 47D) with a central fusion cell and a weft of gonimoblast filaments over the cystocarp floor, producing numerous erect chains of 2–4 ovoid carposporangia 20–40 µm in diameter. Cystocarps scattered, 1–1.5 mm across, hemispherical and with a collar; pericarp ostiolate, 3–5 cells thick, thicker at the collar. Spermatangial sori (Fig. 47E) scattered, relatively small and irregular in shape, some becoming confluent, with cortical initials producing elongate spermatangia in blocks corresponding to the primary cells.

Tetrasporangial sori (Fig. 47F) scattered, ovate, with tetrasporangia cut off from primary cells and lying largely in one layer of mixed ages, with outer cover cells; tetrasporangia subspherical, 40–70 µm in diameter.

Type from Elliston, S. Aust., 25 m deep outside bar (Shepherd, 25.x.1971); holotype in AD, A42565.

Selected specimens: Point Peron, W. Aust., drift (Kraft 7473, 7.xii.1980; MELU). Elliston, S. Aust., drift (Womersley, 13.i.1951; AD, A13537) and 5 m deep in bay (Shepherd, 13.v.1971; AD, A38682). Point Avoid, S. Aust., drift (Womersley, 2.xii.1975; AD, A46948 and A46949).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: Only known from Point Peron, W. Aust., Elliston, and Point Avoid, Yorke Pen., S. Australia.

Taxonomic notes: P. ramosa (named from the much branched thallus compared to the type species), has the distinctive carposporophyte of Platyclinia but differs from P. stipitata in habit, dimensions, and in having equivalent cortical cells. It is closely related to P. crenulata, as is discussed under the latter species.

References: The Marine Benthic Flora of Southern Australia Part IIID

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.

Illustration in Womersley Part IIIA, 2003: FIG. 47.

Figure 47   enlarge

Fig. 47. Platyclinia ramosa (AD, A42565). A. Habit, type sheet. B. Apex of a branch. C. Apex of a branch showing slight apical cells and segmentation. D. Section of a cystocarp, carposporophyte with erect chains of carposporangia. E. Spermatangial sori. F. Tetrasporangial sorus.

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