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Order Bryopsidales

Family Bryopsidaceae

Genus Bryopsis J. V. Lamouroux

Thallus of gametophyte (conspicuous phase) of coenocytic filaments (siphons) forming turfs, tufts, or individual bushy plants from a few to 10 (-15) cm high. Individual thalli of erect uniaxial siphons, usually with small branches (ramuli) and rhizoidal holdfasts. Sexual reproduction involves formation of anisogametes in little-modified branches that are shed after release.

Life histories comprise alternation of generations. In one type, zygotes produce a sporophyte that is a creeping microthallus which produces zoospores. In another, zygotes develop directly into the characteristic macrothallus: the latter has been shown in culture for B. flanaganii (now included in B. myosuroides) from South Africa (Harper & Pienaar 1985).

The taxonomy of Bryopsis is problematic because molecular studies have shown that morphological characters appear to be unreliable in distinguishing between species (Krellwitz et al. 2001). In the absence of definitive studies, we provisionally accept six species on the south coast, based on morphological characters of the gametophytes.

Key to Bryopsis on south coast

1 a Short (up to 1 cm) compact turf of mainly unbranched siphons

B. pusilla

1 b Turf or bushy clumps of mainly branched siphons

2

2 a Main axes about 125 µm in diameter, plants very fine

B. caespitosa

2 b Main axes 150 µm or more in diameter

3

3 a Plants densely caespitose, often sand-binding, main axes usually with unbranched ramuli

B. africana

3 b Plants fairly open in habit; erect axes with 2-3 orders of branches

4

4 a Branching mainly polystichous (sometimes pinnate near apices); apices narrowly pyramidal in shape

B. hypnoides

4 b Branching distichous

5

5 a Main axes 300-450 µm in diameter; ramuli angled upwards and curving inwards, featherlike appearance

B. myosuroides

5 b Main axes up to 600 µm in diameter; ramuli decreasing in length towards apex of axis creating a narrowly pyramidal outline

B. plumosa

 

References Genus Bryopsis

Harper, I. S. and R. N. Pienaar 1985. Life history and cytological studies in Bryopsis flanaganii (Bryopsidales, Chlorophyceae) from the Natal coast. South African Journal of Botany 51: 401-407.

Krellwitz, E.C.,Kowallik, K. V. and P.S. Manos 2001. Molecular and morphological analyses of Bryopsis (Bryopsidales, Chlorophyta) from the western North Atlantic and Caribbean. Phycologia 40: 330-339.

 

Cite this record as:

Anderson RJ, Stegenga H, Bolton JJ. 2016. Seaweeds of the South African South Coast.
World Wide Web electronic publication, University of Cape Town, http://southafrseaweeds.uct.ac.za; Accessed on 20 November 2018.