Electronic Flora of South Australia Genus Fact Sheet

Genus ACROCARPIA Areschoug 1854: 335

Phylum Phaeophyta – Order Fucales – Family Cystoseiraceae

Thallus usually 10–100 cm long, with one to few much branched primary branches from a lacerate to sub-hapteroid holdfast. Primary branches more or less straight, with dense, tristichously and spirally arranged laterals, becoming irregular below, usually basally denuded and with irregular branch residues. Laterals with simple or once branched ramuli, tristichously and spirally arranged, dense. Vesicles absent. Growth from a three-sided apical cell. Structure of a central medulla, cortex of isodiametric cells and surface meristoderm developing a thick cortex on lower axes.

Reproduction: Receptacles terminal on upper ramuli, pedicellate, short (up to 1 cm long), terete-torulose. Conceptacles bisexual, with scattered ostioles, with or without a basal columella; oogonia with a single egg.

Type species: A. paniculata (Turner) Areschoug.

Taxonomic notes: A genus of two species, confined to southern Australia. Acrocarpia is characterised by the lacerate, sometimes almost hapteroid, holdfast, by the radial (basically tristichous) branching throughout, and by development of receptacles from the ends of upper ramuli. It is probably most closely related to Caulocystis, but differs in lacking vesicles, in its tristichous branching pattern, and in the holdfast.

References:

ARESCHOUG, J.E. (1854). Phyceae novae et minus cognitae in maribus extraeuropaeis collectae. Ada Reg. Soc. Sci. Upsala, Ser. III, 1, 329–372.

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 SPECIES OF ACROCARPIA

1. Laterals densely to loosely branched, with simple or branched (above their base) ramuli of uneven length, mostly 1–3 (–5) cm long

A. paniculata

1. Laterals 1–4 (–6) cm long, clothed with numerous, basally bifurcate, ramuli of similar length (2–6 mm long)

A. robusta


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