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Genus ELISIELLA Womersley, gen. nov.

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Heterothamnieae

Thallus with or without prostrate axes, with numerous lateral erect branches, radially or distichously branched, axial cells each with 4 or 5 similar or dissimilar whorl-branchlets usually over 200 mm long, closely arranged along the axes. Attachment by rhizoids from basal axial cells (just penetrating the host cortex) or from prostrate filaments. Lateral branches arising on the basal cells of whorl-branchlets. Structure. Subapical cells in short series of small cells then enlarging rapidly. Whorl-branchlets branched from their basal cells, with several successive di- or trichotomies, terminal cells mucronate or with rounded ends; gland cells on outer cells of whorl-branchlets. Cells uninucleate.

Reproduction: Gametophytes dioecious. Carpogonial branches borne on adjacent whorls close to apices, on normal or reduced whorl-branchlets; carposporophytes with 1–3 gonimolobes, surrounded by whorl-branchlets from below. Spermatangia borne on branched clusters developed adaxially on lower cells of whorl-branchlets.

Tetrasporangia occur terminally on cells of special branch clusters borne adaxially on lower cells of whorl-branchlets, subspherical, tetrahedrally divided.

Type species: E. arhuscula (J. Agardh) Womersley, comb. nov.

Taxonomic notes: The two species here placed in a separate genus, Elisiella, were placed by Wollaston (1968) in Perithamnion, and transferred to Tetrathamnion by Athanasiadis (1996). They differ from both these genera in having tetrasporangia borne on branched filaments of small cells developed adaxially on lower whorl-branchlet cells, in contrast to sessile tetrasporangia in both the above genera. They also differ from Perithamnion in having spermatangia borne on adaxial clusters on lower whorl-branchlet cells.

The genus Elisiella is named after Dr Elise Wollaston, for her significant contributions to studies on tribes of the Ceramiaceae.


ATHANASIADIS, A. (1996). Morphology and classification of the Ceramioideae (Rhodophyta) based on phylogenetic principles. Opera Botanica No. 128, pp. 1–216.

WOLLASTON, E.M. (1968).Morphology and taxonomy of southern Australian genera of Crouanieae Schmitz (Ceramiaceae, Rhodophyta). Aust. J. Bot. 16, 217–417.

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

Author: H.B.S. Womersley & E.M. Wollaston

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


1. Axial cells with 4 whorl-branchlets, the two lateral ones often developing longer branches. Terminal whorl-branchlet cells rounded

E. arhuscula

1. Axial cells with 4 or 5 whorl-branchlets, usually uneven in length. Terminal whorl-branchlet cells mucronate

E. dispar

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