Hymenocladia J.Agardh, 1852
Holotype species: Hymenocladia usnea (R.Brown ex Turner) J.Agardh
Original publication and holotype designation: Agardh, J.G. (1852). Species genera et ordines algarum, seu descriptiones succinctae specierum, generum et ordinum, quibus algarum regnum constituitur. Volumen secundum: algas florideas complectens. Part 3, fasc. 1. pp. 701-786. Lundae [Lund]: C.W.K. Gleerup.
Request PDFDescription: Thallus with a discoid holdfast from which erect, lobed, regularly or irregularly pinnate or palmate, flattened or terete fronds arise. Construction multiaxial, cortex of 2-6 layers of small cells, the outermost of which are anticlinally elongated. Medulla consisting entirely of large axially elongated cells, often with smaller cells cut off from the cortical and medullary cells and ramifying between the larger cells, particularly in the older parts. Secretory cells absent in medulla, occasionally present in cortex. Gametangial plants monoecious or dioecious. Spermatangial sori superficial, scattered, spermatangia cut off terminally or laterally from modified cortical cells. Procarpic, carpogonial branches in cortex, 4-celled, formed on a large supporting cell with a 2-celled auxiliary cell branch, gonimoblast developing outwards from a fusion cell. Cystocarps ostiolate, scattered, never coronate, strongly protruding outwards, most cells forming carposporangia in 2-3 lobes of different ages, tela arachnoidea absent. Tetrasporangia formed in an intercalary position from cortical filaments, scattered, not grouped in nemathecia or sori. Spores regularly tetrahedrally 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: Some species of Hymenocladia resemble Hymenocladiopsis crustigena (q.v.), from which they differ in the absence of intercellular medullary spaces. Secretory cells are not produced in Hymenocladia species except for H. kallymenioides where they are formed exclusively in the cortex. Tetrasporangia are developed in an intercalary position in Hymenocladia but are terminal in Hymenocladiopsis. Both genera are, however, largely found in the colder waters of the Southern Hemisphere and are probably closely related. Species of Hymenocladia are known from the colder seas of Australia, New Zealand and South Africa where they occur mainly in the subtidal.
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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=35231
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 08 October 2010. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 30 December 2024
