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Electronic Flora of South Australia Family Fact Sheet

Tribe POLYZONIEAE Schmitz & Falkenberg 1897: 461.

Phylum Rhodophyta – Family Rhodomelaceae

Thallus partly or largely prostrate, or erect, with indeterminate axes bearing determinate laterals in a regular pattern, these laterals often foliose and jungermanniaceous. Indeterminate apices dorsiventrally organised, with a large, usually curved, apical cell, with 6 (7 in Leveillea) pericentral cells; ecorticate or becoming corticated below; determinate laterals with three pericentrals, in some species absent. Determinate laterals arise exogenously, usually from alternate segments of the axes and in 2 slightly displaced ranks, and may be simple, branched, or foliose. Lateral indeterminate axes arise endogenously and subapically, at regular intervals or not. Trichoblasts absent or present on the determinate laterals. Attachment by rhizoids (usually paired, not cut off the parent cells, and with digitate haptera) or by fibrous holdfasts.

Reproduction: Procarps borne on basal cells of trichoblasts or directly on determinate laterals; carposporophytes with terminal carposporangia; cystocarps on determinate laterals, ovoid, pericarp ecorticate or corticate. Spermatangial organs spoon-shaped or tri-radiate, developed from determinate laterals, with marginal sterile cells to the flanges.

Tetrasporangia occur in the indeterminate axes or in special lateral indeterminate branches, cut off from lateral pericentral cells, relatively large, with 3 cover cells which divide to form a corticating layer over the tetrasporangia.

Type genus: Polyzonia Suhr 1834: 739.

Taxonomic notes: The tribe includes 5 genera, Polyzonia Suhr, Leveillea Decaisne, Dasyclonium J. Agardh, Cliftonaea (Harvey) Harvey and Echinosporangium Kylin, of which the last 3 occur on southern Australian coasts (and Leveillea only on warmer northern coasts). Polyzonia elegans Suhr was incorrectly ascribed to Australia by Lucas (1909, p. 44); Lucas & Perrin (1947, p. 289) and May (1965, p. 380).

Falkenberg (1901) and Scagel (1953 and 1962) have dealt comprehensively with some genera of the tribe.

References:

FALKENBERG, P. (1901). Die Rhodomelaceen des Golfes von Neapel und der angrenzenden Meeres-abschnitte. Fauna und Flora des Golfes von Neapel. Monogr. 26. (Friedländer: Berlin.)

LUCAS, A.H.S. & PERRIN, F. (1947). The Seaweeds of South Australia. Part 2. The Red Seaweeds. (Govt Printer: Adelaide.)

LUCAS, A.H.S. (1909). Revised list of the Fucoideae and Florideae of Australia. Proc. Linn. Soc. N.S.W. 34, 9–60.

MAY, V. (1965). A census and key to the species of Rhodophyceae (red algae) recorded from Australia. Contr. N.S. W. Natl Herb. 3, 349–429.

SCAGEL, R.F. (1953). A morphological study of some dorsiventral Rhodomelaceae. Univ. Calif. Pubis Bot. 27, 1–108.

SCAGEL, R.F. (1962). The genus Dasyclonium J. Agardh. Canadian J. Bot. 40, 1017–1040, Plates i-iv.

SCHMITZ, F. & FALKENBERG, P. (1897). Rhodomelaceae. In Engler, A. & Prantl, K., Die natürlichen Pflanzenfamilien. T.1. Abt. 2, pp. 421–480. (Englemann: Leipzig.)

SUHR, J.N. von (1834). Uebersicht der Algen, welche von Hrn. Ecklon an der südafrikanischen Küste gefunden worden sind. Flora 17, 737–744, 2 pls.

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

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.

KEY TO GENERA OF POLYZONIEAE

1. Indeterminate axes terete, ecorticate, without a keel, determinate laterals terete, branched; attachment by rhizoids

DASYCLONIUM

1. Indeterminate axes with a flat monostromatic keel, becoming heavily corticated below, determinate laterals terete or flat and scalpelliform; attachment by holdfasts

2

2. Determinate laterals terete, arising alternately from each axial segment; corticating cells over the tetrasporangia without cellular prolongations

CLIFTONAEA

2. Determinate laterals flat, scalpelliform, arising alternately from each second axial segment; corticating cells over the tetrasporangia have short cellular prolongations

ECHINOSPORANGIUM


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