Electronic Flora of South Australia Genus Fact Sheet

Genus RHODOPHYLLIS Kützing 1847: 23, nom. cons.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Cystocloniaceae

Thallus compressed to flat, complanately and irregularly to alternately marginally branched; holdfast discoid. Structure uniaxial with a sunken apical cell, axial filament usually apparent for some distance from the branch apex; medulla filamentous but slight, cortex 1–2 (–4) cells thick with weakly developed surface rosettes of small outer cortical cells around large inner cells; some cortical cells developing dense refractive contents ("gland cells").

Reproduction: Sexual thalli dioecious; procarpic. Carpogonial branches 3 (–4)-celled, with the auxiliary cell adjacent to the supporting cell and nearby cells enlarging, becoming darkly staining and producing a small-celled nutritive tissue inwards to the auxiliary cell. Carposporophytes with a central fusion cell and radiating gonimoblast filaments with terminal chains of carposporangia and a few sterile filaments passing to the pericarp; cystocarps protuberant, with a cortical pericarp, usually non-ostiolate. Spermatangia cut off from outer cortical cells, scattered over young branches.

Tetrasporangia in the outer cortex, scattered, zonately divided.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Type species: R. bifida (Lamouroux) Kützing 1847: 23 [= R. divaricata (Stackhouse) Papenfuss].

Taxonomic notes: A genus of about 10 species, mostly southern hemisphere, but the type species is from Europe and further comparative studies are needed between the type and other species.

Rhodophyllis in southern Australia is most similar to Craspedocarpus, differing from the latter in having weakly developed rosettes and vein system and a central fusion cell.

References:

KÜTZING, F.T. (1847). Diagnosen and Bemerkungen zu neuen oder kritischen Algen. Bot. Zeit. 5, 1–5, 22–25, 33–38, 52–55, 164–167, 177–180, 193–198, 219–223.

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.

KEY TO SPECIES OF RHODOPHYLLIS

1. Lower branches mostly 5–15 (–20) mm broad, upper laterals mostly 2–4 mm broad with broad apices when young, or tapering to branches 1–2 mm broad with narrow apices; gland cells usually abundant; cystocarps marginal

R. membranacea

1. Lower branches 2–5 (–6) mm broad, of uniform width or tapering slightly and evenly from base to apex, with or without small marginal, proliferous, laterals; gland cells occasional or absent; cystocarps marginal or scattered on the surface

2

2. Thallus usually 10–25 cm high, subdichotomously to subpinnately branched, tapering evenly and gradually from base to apex, 3–5 mm broad below, 1–2 mm broad just below apices; gland cells usually absent; cystocarps marginal

R. multipartita

2. Thallus usually 5–10 cm high, 2–4 (–6) mm broad throughout with small, marginal, basally constricted lateral proliferations; gland cells absent; cystocarps scattered on branches or laterals, not marginal

R. volans


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