Electronic Flora of South Australia Genus Fact Sheet

Genus CLADOSIPHON Kützing 1843: 329

Phylum Phaeophyta – Order Chordariales – Family Chordariaceae

Thallus simple or branched, cylindrical, mucoid, usually 10–20 cm long and 2–4 mm in diameter. Medulla multiaxial, often becoming hollow, of more or less parallel longitudinal filaments (with relatively slight production of hyphae), often with slightly narrower longitudinal filaments with shorter cells on the periphery. Subcortex slight, usually of one to 3 cells at right angles to medulla. Cortex of simple, determinate, assimilatory filaments arising in groups from outer subcortical cells or occasionally directly from outer medullary cells, filaments usually 20–40 cells long, curved to recurved above with the upper cells ovoid or extended on their upper side. Phaeophycean hairs arising from outer subcortical cells.

Reproduction: Reproduction by plurilocular sporangia formed laterally from upper cells of cortical filaments, and by unilocular sporangia borne on outer subcortical cells and lying within the inner cortex.

Life history unknown.

Type species: C. mediterraneus Kützing.
A genus with some 12–15 species.

Taxonomic notes: The two southern Australian species were placed by J. Agardh (1882, p.24) in his newly described genus Bactrophora, characterised by the lack of hyphal filaments overlying the medulla (as in Cladosiphon). However, both the Australian species and the type species, Cladosiphon mediterraneus, show relatively slight development of "hyphae"-i.e. somewhat slenderer longitudinal filaments-on the periphery of the medulla, and from which some subcortical filaments arise, and it is not possible to recognise a separate genus (Bactrophora) as a segregate from Cladosiphon. The Australian species are similar in construction to C. mediterraneus [based on Feldmann 11.171 from Villefranche-sur-Mer, France (12.v.1966; ADU, A46354)] with a subcortex mostly only one cell high, but differ in having much longer cortical filaments (only 8–12 cells long in C. mediterraneus) and the plurilocular sporangia differ in form in the latter species.

References:

AGARDH, J.G. (1882). Till algernes systematik. Acta Univ. lund. 17, 1–136, Plates 1–3.

KÜTZING, F.T. (1843). Phycologia generalis. (Leipzig.)

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
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

KEY TO SPECIES OF CLADOSIPHON

1. Thallus simple or with a very few long branches; phaeophycean hairs (16–) 20–25 (–30) µm in diameter; epiphytic, mainly on Posidonia and Amphibolis

 1. C. filum

1. Thallus usually much branched, with a main axis bearing numerous relatively long laterals; phaeophycean hairs 10–12 p.m in diameter; epilithic

C. vermicularis


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