Electronic Flora of South Australia Genus Fact Sheet

Genus SCYTOTHALIA Greville 1830: xxxiv

Phylum Phaeophyta – Order Fucales – Family Seirococcaceae

Thallus 0.5–2 m long, much branched laterally and essentially complanately, with long axes or primary branches, slightly flexuous, bearing marginally, alternately distichous, simple laterals (2–) 3–6 mm broad; vesicles absent; stipe simple, with a discoid and marginally hapteroid holdfast. Growth from 1–2 four-sided apical cells in an apical depression. Structure with a medulla of elongate cells with hyphae, and a cortex of isodiametric cells with a surface meristoderm.

Reproduction: Thalli monoecious. Receptacles clustered along the adaxial margins of laterals and spreading to the margin of the parent branch, strongly compressed, ensiform to lanceolate, often rostellate, 10–15 mm long and (1–) 2–5 mm broad. Conceptacles unisexual or bisexual, scattered over the flat surfaces; oogonia sessile, with a mesochiton collar and a single egg; antheridia on branched paraphyses.

Type and only species: S. dorycarpa (Turner) Greville.

Taxonomic notes: Scytothalia is distinguished from Seirococcus by the form of the receptacles; in habit the thalli are similar. Scytothalia is a western genus, but overlaps with the eastern Seirococcus.

Nizamuddin (1968, p. 86) reported a three-sided apical cell in developing receptacles, in contrast to the normal four-sided apical cell in vegetative parts.

References:

GREVILLE, R.K. (1830). Algae Britannicae. (Edinburgh.)

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

Author: H.B.S. Womersley

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