Fucus crenatus S. Gmelin, 1768: 184, pl. XXIV: fig. 1 (syntype localities: Cornwall, England; Kamchatka, Siberia).
Fucus sinuosus Goodenough & Woodward, 1797: 102, 111, nom. illeg.
Delesseria sinuosa Lamouroux, 1813: 124, nom. illeg.— Biswas, 1945: 529, pl. II: fig. 7.—S. Dixit, 1968: 22.
Phycodrys crenata (S. Gmelin) P. Silva.
Note: Biswas's record from Pakistan is based on a specimen (in CAL) collected by Murray at Karachi, bearing the manuscript name Delesseria subdichotoma J. Agardh. Judged from the description and photograph, this specimen is not representative of Phycodrys.For many years the well-known North Atlantic species to which Biswas referred the Karachi specimen was called P. sinuosa (Goodenough & Woodward) Kützing. Goodenough & Woodward, having concluded (erroneously as it turned out) that Fucus rubens Linnaeus (1753: 1162; type locality: "Oceano'') applied to the alga that came to be known as Phyllophora, gave the name Fucus sinuosus to the alga to which they thought contemporary authors (Hudson, 1762: 475; Lightfoot, 1777: 943; Hudson, 1778: 573; Withering, 1792: 235) were misapplying the Linnaean name. They listed Fucus crenatus S. Gmelin as a synonym, but chose to pass over this name in favor of a new name, remarking that Gmelin's figure represents this species "in a more advanced state, but very indifferently''. Fucus sinuosus is thus superfluous and hence illegitimate, as are all combinations that attempt to use F. sinuosus as a basionym.
As part of an effort to place the nomenclature of British seaweeds on a firm basis with regard to priority, Batters (1902: 76) decided that not only did F. crenatus (erroneously cited as F. crenulatus) have priority over F. sinuosus, but that F. rubens Hudson (1762: 475) was a still earlier epithet-bringing name. Accordingly, he made the alleged combination Phycodrys rubens (Hudson) Batters. In fact, "F. rubens Hudson'' is a circumscription, not a name, inasmuch as Hudson cited F. rubens Linnaeus. The Linnaean name had long been referred to Phyllophora, as P. rubens (Linnaeus) Greville (1830: lvi, 135), on the basis of specimens in Linnaeus's herbarium (LINN). Batters (op.cit.: 65) thought that it was "more than probable'' that Linnaeus had proposed the binomial F. rubens to replace the polynomial Fucus caule tereti ramoso, frondibus oblongis undulatis sinuatis of Royen (1740: 514) in the absence of original material, and that he subsequently placed specimens in his herbarium that he thought were representative of Royen's alga. Implying that the Linnaean name could not be used until the identity of the Royen alga was known, Batters adopted a later epithet-bringing name for the alga then known as Phyllophora rubens, making the combination Phyllophora epiphylla (O.F. Müller) Batters (Fucus epiphyllus O.F. Müller, 1777: 5, pl. 708; type locality: Drøbak, Norway). Batters made no attempt to locate authentic material of Royen's alga. Dixon (1964: 56) did so, however, and found that it was representative of Phycodrys rather than Phyllophora, thus showing that Goodenough & Woodward erred. Dixon assumed that Phycodrys rubens (Linnaeus) Batters was the correct name for this species, but that binomial must not be considered a combination of Fucus rubens Linnaeus but rather a superfluous name for F. crenatus S. Gmelin, the earliest available epithet-bringing name. The correct name for the alga incorrectly called Phyllophora rubens (Linnaeus) Greville or P. epiphylla (O.F. Müller) Batters is P. crispa (Hudson) Dixon (1964: 63) (Fucus crispus Hudson, 1762: 472; type locality: England).