Apjohnia Harvey, 1855

Holotype species: Apjohnia laetevirens Harvey

Original publication and holotype designation: Harvey, W.H. (1855). Short characters of some new genera and species of algae discovered on the coast of the colony of Victoria, Australia. Annals and Magazine of Natural History, Series 2 15: 332-336, Plate VIII.C.

Request PDF

Description: Thallus composed of one to may stipitate capitula, 10-25 cm tall including stipe. Apical orientation maintained throughout development. Stipe prominent, aseptate, unbranched, annulate near base, 2-3 m diameter, to 5 cm long; often encrusted with crustose coralline algae. Capitulum composed of 2-6 tiers of branched, filiform cells, each conspicuously annulated at base; initiated from apical end of stipe in which multiple, simultaneous, aseptate protrusions, elongate and later become septate. Central larger axial protrusion dominating and becoming septate first. Subsequent tiers of branches initiated from apices of subtending cells in identical fashion. Rhizoid well developed from which new uprights can arise. Structural reinforcement of branches achieved by specialized intracellular tenacular cells. Cell division by centripetal invagination. Cell multinucleate, with numerous discoid chloroplasts. The dendroid habit of Apjohnia resembles that of Chamaedoris, Struvea, and some species of Cladophora. Apjohnia is a warm-temperate to subtropical Australian endemic, although a second species has been described from New Caledonia. Plants are often highly epiphytized by crustose coralline algae on their stipes. The life history of Apjohnia is not known though it is presumed to have the standard cladophoralean, biphasic, alternation of generations. Motile cells have been observed. Cell wall ultrastructure is reviewed by Preston. The taxonomic history and putative phylogenetic position of the genus have been discussed by various authors.

Information contributed by: J.L. Olsen. The most recent alteration to this page was made on 2009-10-12 by Stephen Cusack.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Gender: This genus name is currently treated as feminine.

Verification of Data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.

Contributors
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.

Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.

Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=42969

Citing AlgaeBase
Cite this record as:
Stephen Cusack in Guiry, M.D. & Guiry, G.M. 12 October 2009. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024