Haemescharia Kjellman, 1883
Holotype species: Haemescharia polygyna Kjellman
Original publication and holotype designation: Kjellman, F.R. (1885 '1883'). The algae of the Arctic Sea. A survey of the species, together with an exposition of the general characters and the development of the flora. Kongliga Svenska Vetenskaps-Akademiens Handlingar 20(5): 1-351, 31 pls.
Request PDFPrecise date of publication: None
Description: Crusts reach 5 cm in diam. and have soft but firm textures. Erect filaments produce one to a few non-pigmented laterals of unknown function. Hypogynous cells sometimes bear a single sterile lateral cell, although some possibly non functional carpogonia are sessile on supporting cells. Tetrasporangia are cuboidal in shape.
Information contributed by: G.T. Kraft. The most recent alteration to this page was made on 2017-01-23 by M.D. Guiry.
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: 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: The identity of this long-debated genus (Denizot 1968) has finally been established by Wilce and Maggs (1989). The catenate, cruciate sporangia, division of the fertilized carpogonium, emission of numerous connecting filaments, and initiation of goniomoblasts from the fusion site of the connecting filament adjacent to the auxiliary cell distinguish the genus from superficially similar non-calcified crusts belonging to the Peyssonneliaceae, Cruoriaceae, Ganiaceae and Blinksiaceae, as well as from foliose genera with encrusting tetrasporophytes belonging to the Gigartinaceae, Petrocelidaceae and Phyllophoraceae. Distribution: The type species appears to be circumpolar, having been recorded in Greenland, adjacent Canadian islands and Siberia. Plants are generally collected from 3-10 m depths, with exceptional records coming from 46 m. The second species, H. hennedyi (Harvey) Wilce and Maggs, occurs from Norway to the British Isles and in northeastern Canada, and has long been known as Petrocelis hennedyi. In Ireland it occurs intertidally down to 10 m depths. Family of one genus and two species. Plants are uncalcified crusts on rocks, encrusting Corallinaceae, or frondose algae and consist of a basal horizontal layer of cells from each of which one or two erect filaments arise dorsally. Rhizoidal anchoring filaments may or may not be present. Cell fusions and secondary pit connections are lacking. Spermatangia are very elongate (to 24 um in length) and borne in clusters on intercalary mother cells in monoecious gametophytes. Supporting cells are intercalary and bear single or pairs of 2-celled carpogonial branches directed towards the frond surface. Auxiliary cells are intercalary in positions comparable to supporting cells. Following fertilization the carpogonium divides into two uninucleate derivative cells which, together with the hypogynous cell, initiate up to 8 branched, septate or non-septate, connecting filaments. Auxiliary cells fuse to connecting filaments at a protrusion on the auxiliary cell, the connecting filaments then growing on to effect further diploidizations. One or two goninmoblast initials arise thallus-outwardly from the fusion site adjacent to the auxiliary cell and develop into an ovoid to linear cluster of 32-64 carposporangia borne on few if any inner sterile gonimoblast cells. Gametangaia and tetrasporangia are both aggregated into indistinct soral areas. Tetrasporangia form as single or chains of up to 8 intercalary initials that divide irregularly cruciately.
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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=37708
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 23 January 2017. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024
