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Order Gigartinales

Family Cystocloniaceae

Hypnea Lamouroux

Plants bushy or caespitose; thalli terete or slightly compressed, either attached basally or with hooked branches or apices and entangled in other algae. Apices uniaxial, structure pseudoparenchymatous throughout, central axis obscure except in young axes. Generations isomorphic. Tetrasporangia zonately divided and arranged in nemathecia or sori on ultimate or penultimate branches (stichidia). Cystocarps in ultimate or penultimate branches, protruberant, ostiolate or non-ostiolate, comprising central sterile tissue of large cells with radiating gonomiblasts ending in single carposporangia. Hypnea currently includes 60 species worldwide (Guiry & Guiry 2015), of which seven are recorded in our area. We note that some species are very difficult to tell apart, and often differ only in size: this genus in South Africa is the subject of a current molecular and morphological study.

Key to south coast species (provisional; March 2015)

1a. Thallus of stiff uprights, 1-2 mm in diameter, green to dark purple

H. spicifera

1b. Thallus 1 mm or less in diameter

2

2a. Thallus ca. 180 µm in diameter, less than 5 mm tall

H. arenaria

2b. Thallus 200 µm to 1 mm in diameter, a few to many cm tall

3

3a. Thallus iridescent blue in situ, without hooked tips

H. viridis

3b.Thallus pink, red or brown-yellow, tips sometimes or often hooked

4

4a. Main axes 200-400 µm in diameter, branching mostly second

H. tenuis

4b. Main axes between 400 µm and 1 mm in diameter, branching irregular

5

5a. Thallus brownish-red to straw coloured

H. musciformis

5b.Thallus pink to bright red

6

6a. Main axes about 1 mm in diameter

H. rosea

6b. Main axes about 0.5 mm in diameter

H. intricata

 

References Hypnea

Guiry, M.D. & Guiry, G.M. 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 31 March 2015.

 

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 23 September 2018.