Electronic Flora of South Australia Genus Fact Sheet

Genus CHORDARIA C. Agardh 1817: XII, nom. cons.

Phylum Phaeophyta – Order Chordariales – Family Chordariaceae

Thallus with one to a few main axes bearing long laterals which may or may not be much branched irregularly radially with branches of several orders, not or only slightly mucoid, usually 5–20 (–100) cm long and 1–2 (–3) mm in diameter, attached by a small, discoid holdfast. Medulla multiaxial, of closely appressed (pseudoparenchymatous) longitudinal filaments, either solid or with the inner medulla of loosely arranged filaments and becoming hollow; narrow medullary hyphae usually present. Cortex dense, borne directly on the peripheral medullary filaments of shorter cells, consisting of short, 2–6 celled, usually clavate filaments. Phaeophycean hairs scattered in the cortex, arising from outer medullary cells. Growth subapical, with lateral filaments arising 1–3 cells below the apical cells.

Reproduction: Plurilocular sporangia (in C. cladosiphon) uniseriate, borne on a unicellular pedicel from peripheral medullary cells, within the cortex. Unilocular sporangia clavate to ovoid, sessile on outer medullary cells or on the basal cell of cortical filaments, reaching almost to the surface.

Life history (in C. flagelliformis) heteromorphic with zooids from unilocular sporangia producing macrothalli directly, or microthalli at low temperatures; gametophytes doubtful (Kornmann 1962a).

Type species: C. flagelliformis (Mueller) C. Agardh.

Taxonomic notes: A genus of some 6 or 7 species (Kylin 1940, p. 40), largely confined to cold temperate waters. Chordaria is characterised by the multiaxial medulla of closely associated filaments showing monopodial growth and giving rise directly to the cortex of short, usually clavate, few-celled filaments, without a subcortex.

References:

AGARDH, C.A. (1817). Synopsis Algarum Scandinaviae. (Lund.)

KORNMANN, P. (1962a). Die Entwicklung von Chordaria flagelliformis. Helga wiss. Meeresunters. 8, 276–279.

KYLIN, H. (1940). Die Phaeophyceenordnung Chordariales. Acta Univ. lund. N.F. Avd. 2, 36(9), 1–67, Plates 1–8.

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

Author: H.B.S. Womersley & A. Bailey

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
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