Devaleraea Guiry, 1982

Holotype species: Devaleraea ramentacea (Linnaeus) Guiry

Original publication and holotype designation: Guiry, M.D. (1982). Devaleraea, a new genus of the Palmariaceae (Rhodophyta) in the North Atlantic and North Pacific. Journal of the Marine Biological Association of the United Kingdom 62: 1-13.

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Description: Thallus erect with one or several stipitate hollow fronds arising from a basal disc, blades saccate or tubular, flattened or terete, not filled with a watery mucilage, becoming cartilaginous with age, simple or irregularly divided, frequently with marginal, adventitious proliferations; construction multiaxial, cortex of 2-3 layers of small pigmented cells increasing in number rather than size as the thallus matures, medulla compact with 2-3 layers of large, rounded, loosely coherent, almost colourless cells with bead-like chloroplasts; secretory cells absent. Gametangial plants dioecious; spermatangia formed in large, irregular, tortuous sori over most of the surface of erect, frondose blades similar in morphology to the tetrasporangial plants; carpogonia occurring as single cells on young plantlets only; tetrasporangial plant developing directly from the fertilized carpogonium and overgrowing the carpogonial plant, carposporophyte lacking. Tetrasporangia in large, irregular tortuous sori generally covering much of the surface of the young frond when mature, formed in a terminal position from cortical cells, interspersed with highly modified, pigmented, sterile filaments, regenerating repeatedly from a basal generative stalk cell, spores regularly cruciately arranged. Revised description (Skriptsova et al., 2023: [9].

Information contributed by: M.D. Guiry. The most recent alteration to this page was made on 2023-09-01 by G.M. 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: Skriptsova, A.V. & Kalita, T.L. (2020). A re-evaluation of Palmaria (Palmariaceae, Rhodophyta) in the North-West Pacific . European Journal of Phycology 55(3): 266-274.

Comments: Anatomically and reproductively, species of Devaleraea are anatomically identical to species of Palmaria, the only notable difference being that species of Devaleraea are hollow. Unlike hollow entities in the Rhodymeniaceae, hollow members of the Palmariaceae are not filled with a watery mucilage and do not have the secretory cells that produce this mucilage. Species of Halosaccion, which are also hollow, are easily distinguished from species of Devaleraea by the stellate cells contents of the latter and the gradual size transition of cortical and medullary cells (Guiry 1982; Klochkova and Selivanova 1989). The life history of Devaleraea ramentacea, which is identical to that of Palmaria palmata, was established by van der Meer (1981) who also demonstrated that meiosis occurred in the tetrasporangia and that there was Mendelian transmission of a recessive colour mutation. The chromosome number of these Canadian plants were n = ~ 24 in the gametophytes and 2n = ~ 48 in the tetrasporophytes. Jónsson and Chesnoy (1982), however, reported 2n =16 in tetrasporophytes from Iceland and 8 in the cells of plants raised in culture from tetraspores. Starch gel electrophoresis of ten enzymes from selected Atlantic and Pacific Palmariaceae led Lindstrom and South (1989) to suggest that Atlantic D. ramentacea is more closely related to the Pacific species Palmaria mollis (Setchell et Gardner) van der Meer et C. Bird and to other Pacific Palmaria species than it is to the Atlantic species P. palmata. The authors question whether the Pacific species of Palmaria might be best placed in Devaleraea or that D. ramentacea and the Pacific species of Palmaria should be referred to the genus Halosaccion. This is clearly a taxonomic impasse as the electrophoretic results do not accord with acceptable morphological criteria. These authors conclude (despite some molecular clock contradictions) that the Palmariaceae represents a family of boreal species that can only have become circumboreal with the opening of the Bering Strait 3-3.5 million years ago. As the genus Palmaria is bipolar in its distribution - as perhaps is Devaleraea: some Antarctic entities require further examination - another possibility is that the group was not always cold-water in its affinities or that migration to the Atlantic may have taken place by a route other than the polar one. Species of Devaleraea are so far known only from the very cold waters of the northern hemisphere: D. ramentacea is the only species known from the North Atlantic and reaches its southern limit on the Faeroe Islands in the east (Irvine, 1982) and Massachusetts in the west (South and Tittley, 1988); it also occurs in Alaska (Lindstrom 1987). According to Bird and McLachlan (1992) the species is incapable of thriving at water temperatures above 15%C. Munda (1976, 1977) describes the effects of local conditions on D. ramentacea populations in Iceland. Munda (1977), Rueness and Tananger (1984) and Novaczek et al. (1990) all examined the effect of temperature on growth of this species in culture. The latter authors found that Atlantic plants could survive temperatures of 18-20%C and grew extraordinarily well at -2 and 0%C, even under high irradiance and long daylengths; one Canadian isolate even had a temperature optimum of 0%C. Additionally, plants could survive short periods of freezing at -5 and -20%C. Like Palmaria palmata this is a very variable species with simple, almost saccate plants being found in sheltered water and more highly branched plants occurring in more wave-exposed situations. D. arctica (A.D. Zinova) Guiry occurs in the subarctic and is poorly known; D. yendoi (I.K. Lee) Guiry is known from Japan, the Kurile Islands (Lee 1978) and Pacific Russia (Klochkova and Selivanova 1989). D. compressa (Ruprecht) O.N. Selivanova and N.G. Klochkova and D. microspora (Ruprecht) O.N. Selivanova and N.G. Klochkova are known from Pacific Russia (Klochkova and Selivanova 1989).

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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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G.M. Guiry in Guiry, M.D. & Guiry, G.M. 01 September 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 15 June 2024

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