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The 1986 neotypification of Mesophyllum lichenoides (J. Ellis) Me. Lemoine, type species of Mesophyllum (Hapalidiaceae, Corallinales, Rhodophyta), has to be superseded because the International Code of Botanical Nomenclature rules governing the selection of types have changed, and the new rules are retroactive. In accordance with the present rules, an illustration in the original account of the species is designated here as lectotype, and the superseded neotype is designated here as epitype. Relevant historical information and nomenclatural details associated with these changes are presented.
KEY WORDS: Corallinales, Hapalidiaceae, Mesophyllum, Nomenclature, Typification update
The coralline red algal genus Mesophyllum Me. Lemoine, 1928, p. 251 (Hapalidiaceae, Corallinales, Rhodophyta; see Harvey el al. 2003 for classification details) was established for 16 species. In the context of Preamble 7 and Art. 13.3 of the current ICBN (International Code of Botanical Nomenclature; see McNeill et al. 2006), six are considered fossil and 10 are nonfossil. Lemoine (1928) did not designate a type species, but subsequently Ishijima (1942, p. 174) lectotypified the genus with the nonfossil species M. lichenoides (J. Ellis) Me. Lemoine. Ellis (1768, p. 407, p1. 17, figs 9-11) originally described this species as Corallium lichenoides and treated it as a coral animal rather than an alga. Nevertheless, under the current ICBN, the name is treated as validly published in 1768 (Art. 45.4), even though the botanical nature of coralline red algae was not determined convincingly until many years later (Philippi 1837; Kützing 1841; Decaisne 1842a, b, c).
Ellis (1768) did not designate a type specimen for Corallium lichenoides, and his collections have not been rediscovered since they were sold in 1791 (Hutchins 1791; Dixon 1960). Consequently, Woelkerling & Irvine (1986b, p. 382, figs 1D, 3, 4) designated a neotype (BM, Algal Box Collection 1658, barcode 000568779BM) consisting of an individual with multiporate tetrasporangial conceptacles collected at Hannafore Point, West Looe, Cornwall, UK. This neotype designation was in accord with the ICBN rules governing the selection of types in force at the time (Voss et al. 1983). Duplicates of the neotype illustrated in Woelkerling & Irvine (1986b, fig. 1) also are housed in BM Algal Box Collection 1658.
This neotypification, however, has to be superseded because the ICBN rules governing the selection of types have changed, and the new...