Electronic Flora of South Australia Family Fact Sheet

FAMILY SEIROCOCCACEAE Nizamuddin

Phylum Phaeophyta – Order Fucales

Thallus usually 0.5–2 m long, with a single, short, stipe and essentially complanate, much branched, fronds with long main branches bearing simple, flat, ecostate, entire or serrate, distichous, laterals; holdfast with a discoid-conical centre usually with a marginal, thickened rim, from which laterally appressed haptera extend, the whole holdfast usually 2–10 cm across. Vesicles present or absent. Growth from a short series of four-sided apical cells in an apical depression. Structure of a medulla of elongate cells, and a cortex of isodiametric cells with a surface meristoderm; extensive development of hyphae occurs in the medulla and inner cortex.

Reproduction: Thalli monoecious or dioecious. Receptacles developed from laterals, or discrete, terete or flattened, structures borne on the adaxial margins of laterals, often spreading to the parent branch margin. Conceptacles with ostioles on the flat surface of receptacles, or scattered on terete receptacles; oogonia sessile, with an apical mesochiton collar, containing a single egg; antheridia sessile or on branched paraphyses.

Type genus: Seirococcus Greville.

Taxonomic notes: A family of 5 genera (3 from southern Australia, Marginariella Tandy from New Zealand and Cystosphaera Skottsberg from the Antarctic), characterised by the four-sided apical cells, of which often more than one appear to remain active in an apex, the mesochiton oogonial collar, the marginal receptacles to the branches, and the discoid holdfast with marginal haptera. The latter three features now characterise the family, since McCully (1966) has shown that a group of 4–8 four-sided apical cells (rather than a single apical cell) exist in Fucus vesiculosus and F. edentatus; other taxa of Fucaceae may, however, have a single apical cell.

The Seirococcaceae was proposed as a family by Nizamuddin (1962a, p. 193), but only validated by a Latin diagnosis in Nizamuddin (1987). Nizamuddin (1962a, p. 195) also recognised two subfamilies, but this is scarcely warranted in this small family. The family corresponds to the tribe Phyllosporeae (Schmidt 1938, p. 225) of the Fucaceae.

References:

NIZAMUDDIN, M. (1962a). Classification and the distribution of the Fucales. Bot. Mar. 4, 191–203.

NIZAMUDDIN, M. (1987). Observations on the family Seirococcaceae. Willdenowia 16, 527–529.

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

KEY TO GENERA OF SEIROCOCCACEAE

1. Axes and primary branches bearing marginal, serrate, flat, leafy laterals 5–15 (–25) cm long and 3–12 (–20) mm broad, which become receptacles with scattered conceptacles; vesicles elongate-ovoid, 2–4 (–5) cm long

PHYLLOSPORA

1. Axes or primary branches bearing alternate, entire, flat laterals, which bear either short and terete or compressed and ensiform receptacles in a marginal-adaxial position; vesicles absent

2

2. Receptacles terete, torulose, 2–5 (–8) mm long

SEIROCOCCUS

2. Receptacles compressed, ensiform to lanceolate and often rostellate, 10–15 mm long and (1–) 2–5 mm broad

SCYTOTHALIA


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