Palmaria Stackhouse, 1802, nom. rejic.

Lectotype species: Ceramium palmatum (Linnaeus) Stackhouse

Currently accepted name for the type species: Palmaria palmata (Linnaeus) F.Weber & D.Mohr

Original publication and holotype designation: Stackhouse, J. (1802 '1801'). Nereis britannica; continens species omnes fucorum in insulis britannicis crescentium: descriptione latine et anglico, necnon iconibus ad vivum depictis... Fasc. 3. pp. xxv-xl, 71-112, 1-4, 1-3, pls XIII-XVII, A-G. Bathoniae [Bath] & Londini [London]: S. Hazard; J. White.

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Description: Thallus with erect stipitate fronds arising from a basal disc, blades flattened, becoming cartilaginous with age, simple, dichotomously or palmately divided, frequently with marginal, palmately divided proliferations; construction multiaxial, cortex of 2-5 layers of small pigmented cells increasing in number rather than size as the thallus matures to form a meristoderm, medulla compact with 2-5 layers of large, rounded, loosely coherent, almost colourless cells with strings of bead-like chloroplasts.

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 large, in extensive, 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 modified, pigmented, sterile filaments, regenerating repeatedly from a basal generative stalk cell. Spores regularly cruciately or decussately arranged.

Information contributed by: M.D. Guiry. The most recent alteration to this page was made on 2022-04-06 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: Saunders, G.W., Jackson, C. & Salomaki, E.D. (2017 '2018'). Phylogenetic analyses of transcriptome data resolve familial assignments for genera of the red-algal Acrochaetiales-Palmariales complex (Nemaliophycidae). Molecular Phylogenetics and Evolution 119: 151-159, 2 fig., 3 tables.

Comments: Because of the apparent absence of plants bearing carposporophytes in the wild, the life history of species of Palmaria remained a tantalizing mystery until van der Meer and Chen (1979), van der Meer and Todd (1980) and van der Meer (1981) discovered that very young plants form female reproductive structures as early as 4 days after tetraspores have been inoculated into culture.As the spermatangial plants take much longer to mature (6-9 months), fertilization is not possible between sibling plants. Thus, in the wild, female plants may only be fertilized by the spermatia from a previous season?s plants, representing perhaps an effective mechanism for increasing heterozygosity in a population. As tetrasporangia and spermatangia are formed mainly in autumn and winter in P. palmata in the NE Atlantic, it is likely that reproduction is under temperature and perhaps daylength control. For many years, Palmaria palmata was included in the genus Rhodymenia (Rhodymeniales, Rhodymeniaceae, q.v.) mainly because of a superficial resemblance to species of that genus. On the basis of morphological features, notably the presence of generative stalk cells in the tetrasporangia, Guiry (1974a) proposed its removal, together with several other genera, to a new family, the Palmariaceae. Subsequently, this family formed the basis of a new order, the Palmariales (Guiry and D. Irvine in Guiry, 1978). Pueschel and Cole (1982) later provided fundamental evidence from pit-plug ultrastructure to support recognition of the Palmariales. The discovery (van der Meer, 1981) of a sessile carpogonium which, on fertilization, develops directly to form the tetrasporophyte, further strengthened the ordinal status of the Palmariales. The Palmariales shows some morphological features in common with a number of supposedly primitive red algal orders (Palmariales, Acrochaetiales, Nemaliales, and Batrachospermales), and a close relationship between these taxa is supported by sequence homologies in the small sub-unit of the ribosomal DNA of included species (Harper and Saunders, 1998 and included citations). Palmaria is bipolar in its distribution: P. decipiens (Reinsch) R.W. Ricker and P. georgica (Reinsch) R.W. Ricker, both formerly referred to Leptosarca, occur in the Antarctic and Subantarctic, P. palmata in the north-eastern and north-western Atlantic; P. hecatensis Hawkes, P. callophylloides Hawkes et Scagel and P. mollis (Setchell et Gardener) van der Meer et C. J. Bird in the north-eastern Pacific, and P. marginicrassa I.K. Lee, P. stenogona (Perestenko) Perestenko and P. moniliformis (Blindova and A.D. Zinova) Perestenko in the north-western Pacific. However, it is likely that further studies of the genus in the northern Pacific will reveal additional species. It is unlikely that true P. palmata occurs in the north-western Pacific and further comparative studies, particularly of supposed Japanese populations, are required. A haploid number of 18-23 chromosomes and a diploid number of 38-48 have been reported for Atlantic P. palmata by van der Meer (1976); Cole (1990) gives details of earlier reports. Yabu (1976) suggested that n = 21 and 26 counts obtained in Japanese populations of P. palmata were indicative of separate races; however, it is possible that the counts are of separate species. Van der Meer and Bird (1985) found counts of n = 21 and 2n = 42 in P. mollis from the Pacific although Sparling (1961) had earlier reported ca. 14 chromosomes in male plants. Halosacciocolax (q.v.) is a parasitic genus of Palmaria and Devaleraea (q.v.) found infrequently in the North Atlantic and North Pacific (Guiry 1974, 1975).

An oomycete fungus has been found on P. palmata forma mollis (Pueschel and van der Meer, 1985), now Palmaria mollis, q.v.

Palmaria palmata is an food item of ancient usage in the North Atlantic. The earliest record of its collection for food appears to be in a poem written in Irish that has been variously attributed (Newton 1951) to St Columba (St Columcille; A.D. 521-597), but which is more likely 12th century.In the Icelandic Sagas, it is recorded that Egil Skalla-Grimsson (A.D. 910-990) was tricked into eating it to create a thirst for milk whilst he was attempting to starve himself to death (Indergaard and Minsass, 1991).This species is variously known as dulse, dillisk, duilleasg or duillisg (Irish Gaelic), the narrower forms being called creannach (Irish Gaelic), soll (Icelandic), sou-söll, søl, blôm (Norwegian), goémon à vaches (French), and darusu (Japanese).Although early European herbals of the 18th century ascribed various medicinal properties to dulse (antidote to worm infestations, increasing one?s attractiveness to the opposite sex), none of these have been scientifically established.Dulse is, however, a good source of vitamins and minerals, particularly when compared to the more usual higher-plant vegetables (Morgan et al., 1980; Indergaard and Minsass, 1991), and is still eaten in Scotland, Ireland, Iceland, Brittany and Norway, although, in many of these areas, its use is only occasional.In the fruit shops and markets of Galway, on the west coast of Ireland, dried dulse collected locally is frequently sold loose; a wave-exposed form found on intertidal mussel beds is preferred to the more usual form which is regarded as being "tough" in consistency.When the Scottish seamen from the British naval exploratory vessels Erebus and Terror landed on the Malvinas Islands (Falkland Islands) off the coast of Argentina in the 1840s, they immediately recognized the local Palmaria (probably Palmaria georgica) as dulse (Cotton 1915), a fine example of natural taxonomy.

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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. 06 April 2022. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 16 July 2024

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