Electronic Flora of South Australia Genus Fact Sheet

Genus APJOHNIA Harvey 1855a: 335

Phylum Chlorophyta – Order Cladophorales – Family Cladophoraceae

Thallus dendroid, with an erect, stipitate basal segment attached by rhizoids and increasing in diameter above, bearing apically a row, cluster or irregular whorl of similar branches, followed by several similar branch systems. Branch segments consisting of single or subdivided coenocytic segments with ultimate branchlets single or usually opposite; bases of all except juvenile segments with several annular constrictions; segments multinucleate, walls of cellulose microfibrils; cross walls complete, formed by ingrowth from the periphery; chloroplasts numerous, discoid, each containing a pyrenoid.

Reproduction: Reproduction by motile zooids.

Type species: A. lactevirens Harvey 1855a: 335.

Taxonomic notes: A genus of two species, the type from southern Australia, and A. scoparia (Kützing) Valet (1976) from New Caledonia.

Apjohnia was earlier placed in the Siphonocladales but is considered by Papenfuss & Chihara (1975) and van den Hoek (1963) to belong to the Cladophorales. The absence of any net formation indicates that it is best placed in the Cladophoraceae, where its size and branching pattern distinguish it from Cladophora.

References:

HARVEY, W.H. (1855a). Short characters of some new genera and species of algae discovered on the coast of the Colony of Victoria, Australia. Ann. Mag. nat. Hist. 15, 332–336.

PAPENFUSS, G.F. & CHIHARA, M. (1975). The morphology and systematic position of the green algae Ernodesmis and Apjohnia. Phycologia 14, 309–316.

VALET, G. (1976). Le Struvea scoparia Kützing (Chlorophycèe) de Nouvelle-Calédonie et sa position systématique. Phycologia 15, 421–424.

VAN DEN HOEK, C. (1963). Revision of the European species of Cladophora. (Brill: Leiden.)

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (31 May, 1984)
The Marine Benthic Flora of Southern Australia
Part I
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