Belongs within: Fucophycidae.
Desmarestia, acid kelp, is a genus of brown algae in which many species sequester sulphuric acid in intracellular vacuoles (Norris 2010).
Characters (Norris 2010): Sporophytic thalli macroscopic, erect, with a single cylindrical or compressed main axis that is ligulate
to broadly bladelike, usually pinnately or oppositely branched, occasionally simple and unbranched, attached below by discoid holdfast. If thallus branched, branches are cylindrical, compressed or flat, with opposite or alternate branchlets. Trichothallic growth occuring at apices of axis and branches. Main axial filament surrounded by thick medulla of large, colourless cells developed by downward growing hyphae. Cortical layer composed of small cells becoming progressively smaller toward thallus surface. Cells with lenticulate plastids and vacuoles (often containing sulfuric acid), lacking pyrenoids. Phaeophycean hairs absent. Unilocular sporangia isolated, scattered over surface cells, developing from transformation of cortical cells, or on stalk cells in small sori along with one- to two-celled paraphyses. Gametophytic thalli, where known, microscopic, irregularly branched filaments, endozooic or endophytic. Gametophytes monoecious or dioecious, dimorphic in cell size of filaments. Elongated oogonia developing on cells of filamentous thalli of larger diameter; each oogonium producing a single oocyte. Antheridia developing on cells of filamentous thalli of narrower diameter, usually borne in clusters, producing motile spermatozoids.
Desmarestia Lamouroux 1813 (nom. cons.)N10
|--+--D. ligulata (Lightfoot) Lamouroux 1813SRR14, N10 (see below for synonymy)
| | |--D. l. var. ligulataAH76
| | `--D. l. var. firma (Agardh) Agardh 1848 (see below for synonymy)AH76
| `--D. viridis (Müller) Lamouroux 1813SRR14, N10 [=Fucus viridis Müller 1782N10]
`--+--D. menziesiiSRR14
`--Himantothallus Skottsberg 1907 [incl. Phaeoglossum Skottsberg 1907, Phyllogigas Skottsberg 1907]SRR14
`--H. grandifoliusSRR14
Desmarestia incertae sedis:
D. aculeata [incl. D. dresnaii]G64
D. ancepsGW97
D. farcta Setchell & Gardner 1924S57
D. filamentosa Dawson 1944N10
D. intermedia Postels & Ruprecht 1840S57
D. kurilensis Yamada 1935N10
D. latifrons Kützing 1859AH76
D. latissima Setchell & Gardner in Pease 1920S57
D. mediaN10
|--D. m. var. mediaS57
`--D. m. var. tenuis Setchell & Gardner 1924S57
D. munda Setchell & Gardner 1924N10
|--D. m. ssp. mundaN10
`--D. m. ssp. mexicana (Dawson) Norris 2010 [=D. mexicana Dawson 1944]N10
D. pacifica Setchell & Gardner 1924N10
D. tabacoidesKS00
D. willii Reinsch. 1890L27
Desmarestia ligulata (Lightfoot) Lamouroux 1813SRR14, N10 [=Fucus ligulatus Lightfoot 1777N10; incl. F. herbaceus Turner 1808AH76, Desmarestia herbacea (Turner) Lamouroux 1813AH76, D. ligulata f. herbaceaS57, Sporochnus herbaceusBS-V28, D. jordanii Gardner 1940AH76, D. linearis Smith 1944AH76, D. pinnanerviaG64]
Desmarestia ligulata var. firma (Agardh) Agardh 1848 [=Sporochnus herbaceus var. firma Agardh 1824; incl. D. foliacea Pease 1920]AH76
*Type species of generic name indicated
References
[AH76] Abbott, I. A., & G. J. Hollenberg. 1976. Marine Algae of California. Stanford University Press.
[BS-V28] Bory de Saint-Vincent, J. B. 1828. Voyage Autour du Monde, Exécuté par Ordre du Roi, Sur la Corvette de Sa Majesté, La Coquille, pendant les années 1822, 1823, 1824 et 1825. Botanique. Cryptogamie. Arthus Bertrand: Paris.
[GW97] Gómez, I., G. Weykam, H. Klöser & C. Wiencke. 1997. Photosynthetic light requirements, metabolic carbon balance and zonation of sublittoral macroalgae from King George Island (Antarctica). Marine Ecology—Progress Series 148: 281–293.
[G64] Gray, J. E. 1864. Handbook of British Water-weeds or Algae. R. Hardwicke: London.
[KS00] Kawai, H., & H. Sasaki. 2000. Molecular phylogeny of the brown agal genera Akkesiphycus and Halosiphon (Laminariales), resulting in the circumscription of the new families Akkesiphycaceae and Halosiphonaceae. Phycologia 39: 416–428.
[L27] Laing, R. M. 1927. A reference list of New Zealand marine algae. Transactions and Proceedings of the New Zealand Institute 57: 126–185.
[N10] Norris, J. N. 2010. Marine algae of the northern Gulf of California: Chlorophyta and Phaeophyceae. Smithsonian Contributions to Botany 94: 1–276.
[S57] Scagel, R. F. 1957. An annotated list of the marine algae of British Columbia and northern Washington (including keys to genera). National Museum of Canada Bulletin 150: 1–289.
[SRR14] Silberfeld, T., F. Rousseau & B. de Reviers. 2014. An updated classification of brown algae (Ochrophyta, Phaeophyceae). Cryptogamie, Algologie 35 (2): 117–156.