Octactis J.Schiller, 1926

Holotype species: Octactis octonaria (Ehrenberg) Hovasse

Original publication and holotype designation: Schiller, J. (1926). Die planktonischen Vegetationen des Adriatischen Meeres. B. Chrysomonadina, Heterokontae, Cryptomonadina, Eugleninae, Volvocales. 1. Systematischer Teil. (Nach den Ergebnissen der österreichischen Adriaforschung in den Jahren 1911-1914). Archiv für Protistenkunde 53: 59-123, 30 figures, plates 3-6.

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Description: Skeleton-bearing is the prevalent form. Naked, amoeboid and sometimes mucocyst-bearing forms also present. Typically the external basket-like skeleton consisting two conspicuous rings; an apical ring supported by short, struts that are attached to a larger basal ring. Pikes may or may not occur on the abapical surface of the basal ring. The generally large window enclosed by the apical ring is undivided. Both skeleton-bearing and naked cells showing one long flagellum under LM. Mucocysts sometimes found on the periphery of the skeleton-bearing cell but absent in the naked form. Pyrenoid embedded internally within the chloroplast with short thylakoid intrusion. Containing 6–8 Golgi bodies in the skeleton-bearing form. Life cycle consisting of a multinucleate stage. With all three accessory chlorophylls, c1 + c2, c3. Main carotenoids: fucoxanthin, with diadinoxanthin and one or two oxyfucoxanthin derivatives. Lutein absent.

Information contributed by: Emended descritpion by Chang et al. (2017). Comments by Ø. Moestrup from 1990s.. The most recent alteration to this page was made on 2023-07-25 by E.A. Molinari Novoa.

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

Gender: This genus name is currently treated as feminine.

Most recent taxonomic treatment adopted: Chang, F.H., Sutherland, J. & Bradford-Grieve, J. (2017). Taxonomic revision of Dictyochales (Dictyochophyceae) based on morphological, ultrastructural, biochemical and molecular data. Phycological Research 65: 235–247, 22 figs.

Comments: Schiller (1925) erected this genus for silicoflagellates which have a silicified skeleton of two octoradiate rings interconnected by short silicified elements, of which one ring is very thin. Later, Gemeinhardt (1930) referred the type species ofOctactis to Distephanus as D.speculum (Ehrenberg) Haeckel var.octonarius (Ehrenberg) Jørgensen. Hovasse (1946) retained Octactis as a separate genus and established the combination Octactis octonaria. Octactis or Dictyocha octonaria is a widely distributed silicoflagellate known from most seas, but usually considered a warm water species. It has not been studied by transmission electron microscopy, and therefore cytoplasmic details are lacking. Some workers have referred the 3 well-known extant silicoflagellates to Dictyocha or split them into 3 genera (Dictyocha, Distephanus, Octactis.).

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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=44780

Citing AlgaeBase
Cite this record as:
E.A. Molinari Novoa in Guiry, M.D. & Guiry, G.M. 25 July 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 June 2024

 
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