Irvinea Guiry, 1999

Holotype species: Irvinea ardreana (J.Brodie & Guiry) Guiry

Original publication and holotype designation: Saunders, G.W., Strachan, I.M. & Kraft, G.T. (1999). The families of the order Rhodymeniales (Rhodophyta): a molecular-systematic investigation with a description of Faucheaceae fam. nov. Phycologia 38: 23-40.

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Description: Thallus consisting of erect branched stipes bearing inflated, ovoid, branched or unbranched vesicles formed sympodially and irregularly arranged, arising from a branched stoloniferous holdfast coalescing to form a discoid structure emitting further axes. Structure multiaxial, cortex of 2-3 layers of small cells, forming initially a discontinuous layer over the medullary cells, medulla of 1-2 layers of axially-elongated , rounded cells forming a compact tissue. Vesicles filled with a weak mucilage apparently from secretory cells borne in groups of 1-6 exclusively on morphologically differentiated cells formed on the inner faces of the medullary cells. Filamentous medulla absent. Life history a sequence of tetrasporangial gametangial and carposporangial phases, the gametophytes and tetraporophytes isomorphic. Gametangial plants dioecious; spermatangia in sori covering most of the mature vesicles, cut off from elongate initials formed from cortical cells. Procarpic, carpogonial branches 4-celled, borne on inner cortical supporting cells also bearing a 2-celled auxiliary cell branch, carposporophyte directed outwardly from a basal fusion cell, forming 2-3 synchronously developing lobes of carposporangia in different stages of maturity; a few, slender, stretched cells, perhaps with a nutritive function, persisting in the mature cystocarp. Cystocarps protruding strongly outwards, ostiolate with a thick pericarp. Tetrasporangia in ill-defined sori borne on the mature vesicles, formed in an intercalary position from cortical filaments. Spores regularly or irregularly cruciately arranged.

Information contributed by: M.D. Guiry. The most recent alteration to this page was made on 2010-10-08 by M.D. Guiry.

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

Most recent taxonomic treatment adopted: Schneider, C.W. & Wynne, M.J. (2007). A synoptic review of the classification of red algal genera a half a century after Kylin's "Die Gattungen der Rhodophyceen". Botanica Marina 50: 197-249.

Comments: Irvinea ardreana was initially included in the genus Botryocladia by Brodie and Guiry (1988) with some reservations. A subsequent molecular-systematic investigation of this species and others referred to Botryocladia resulted in this entity being referred to a segregate genus, Irvinea. Strongly protruding cystocarps, the formation of cortical cells in rosettes, and, possibly, the formation of secretory cells on special initials circumscribe Irvinea and separate it from other Rhodymeniacean genera. Detailed investigations of other Botryocladia are required. Brodie and Guiry (1988) found that cultured plants of Irvinea ardreana from Portugal would not grow at 5°C, did not reproduce at 10°C, formed tetrasporangia and gametangial at 15°C, long days and short days, but grew and reproduced most rapidly at 20°C, long days, completing a life history cycle in about one year.

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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.

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M.D. Guiry in Guiry, M.D. & Guiry, G.M. 08 October 2010. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 16 July 2024

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