Pyrobotrys Arnoldi, 1916

Holotype species: Pyrobotrys incurvus Arnoldi

Currently accepted name for the type species: Pyrobotrys incurvus Arnoldi

Description: Colonies star- or mulberry-shaped, containing 4, 8 or 16 cells arranged in two or four tiers, without encompassing gelatinous matrix. Cells spherical, subspherical, ovoid, ellipsoidal, pear-shaped or irregularly pear-shaped, each with two equal flagella, two contractile vacuoles at the base of the flagella and a massive cup-shaped chloroplast without pyrenoids. A stigma may be present in each cell of the colony. Cell walls delicate with a papilla at base of flagella. Asexual reproduction by autocolony formation, each cell of the colony dividing to form a daughter colony. In sexual reproduction, all cells divide into 4, 8, 16 or 32 small, biflagellate isogametes that fuse to form planozygotes. Mature planozygotes quadriflagellate with a large stigma and a species dependent form. Mature aplanozygotes spherical with a heavy wall. On germination, zygotes give rise to four biflagellate gone cells released separately. Pyrobotrys is cosmopolitan and found in freshwater rich in organic matter. Pringsheim compared the morphology of Pyrobotrys based on cultures from various habitats of Europe, South Africa and USA, but did not distinguish species because of limited morphological differences between strains and a great morphological variation within one clone. Using anaerobic culture conditions, morphological studies of 54 clones from Japan distinguished these clones into four species on the basis of differences in cell shape, colony cell number and planozygote form. Physiology of P. stellata includes weak oxygen evolving capacity in light, and photosynthetic pathway with photoassimilation of acetate. Ultrastructurally flagellar apparatuses of P. stellata and P. elongata asymmetrical, but generally typical of Chlorophyceae.

Information contributed by: H. Nozaki. The most recent alteration to this page was made on 2021-03-06 by Eduardo Antonio Molinari Novoa.

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

Gender: This genus name is currently treated as masculine.

Most recent taxonomic treatment adopted: Masjuk, N.P. & Lilitska, G.G. (2011). Volvocales. In: Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Volume 3: Chlorophyta. (Tsarenko, P.M., Wasser, S.P. & Nevo, E. Eds), pp. 218-225. Ruggell: A.R.A. Gantner Verlag K.-G..

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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=43496

Citing AlgaeBase
Cite this record as:
Eduardo Antonio Molinari Novoa in Guiry, M.D. & Guiry, G.M. 06 March 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 16 April 2024