(2957) Dryopteris affinis (Lowe) Fraser-Jenk. in Fern Gaz. 12: 56. Aug 1979 (Nephrodium affine Lowe in Trans. Cambridge Philos. Soc. 6: 525. 1838), nom. cons. prop. Typus: Portugal, Madeira, Ribeiro Frio, by the Levada to the right, 1 Nov 1828, Lowe (K [on 3 sheets] barcodes K000351173, K000351174 & K000351175). (H) Dryopteris affinis Kinahan in Phytologist 5: 197. 1856, nom. rej. prop. Lectotypus (vide Fraser-Jenkins & Corley in Brit. Fern Gaz. 10: 222–223. 21 Mar 1973): Azerbaidjan, Karabakh: Helenendorf [= Khanlar], 1836, Hohenacker (LE barcode LE01053081). The name Dryopteris affinis (Lowe) Fraser-Jenk. has been almost universally used since 1979 in Floras and other taxonomic and horticultural works throughout the range of the species in Europe, Macaronesia, NW Africa, Turkey, the Caucasus and N Iran. It has been used in a strict sense, as a diploid species, or in an aggregate sense, as the name for the whole cytologically complex apomictic aggregate, in both cases containing subspecies within it of various different cytotypes, diploid, triploid or tetraploid. Many important works from three continents, including every country in Europe, utilize the name D. affinis (Lowe) Fraser-Jenk. Approximately 300 works accepting it are known to us, as opposed to 3 works utilising D. affinis Kinahan (attributed to “(Newman) Kinahan”), one of which is now in the process of amendment. A geographical selection of works accepting D. affinis (Lowe) Fraser-Jenk. includes Heywood (in Tutin & al., Fl. Eur., ed. 2, 1: 1–33. 1993), Castroviejo & al. (Fl. Iber. 1: 128–144. 1986), Hutchinson & Thomas (Welsh Ferns: 121–143. 1996), Stace (New Fl. Brit. Isles, ed. 4: 35–39. 2019), Jonsell & Karlsson (Fl. Nordica 1: 74–84. 2000), Prelli & Boudrie (Fougères Pl. Alliées Eur.: 361–370. 2021), Euro+Med PlantBase (http://ww2.bgbm.org/EuroplusMed/), Güner & Ekim (Resimli Türkiye Florası 2: 239–263. 2019) and many other local, taxonomic, chemical, horticultural and systematic publications. The name Nephrodium affine Lowe (in Trans. Cambridge Philos. Soc. 6: 525. 1838), on which D. affinis (Lowe) Fraser-Jenk. is based, was lectotypified by Fraser-Jenkins (in Willdenowia 10: 108. 1980). But in 2022, IPNI (International Plant Names Index, http://www.ipni.org) discovered and brought to notice an earlier validation of Dryopteris affinis by Kinahan (in Phytologist 5: 197. 1856), based on Dryopteris filix-mas var. affinis of Newman (Hist. Brit. Ferns, ed. 3: 187. 1854), a synonym of D. caucasica (A. Braun) Fraser-Jenk. & Corley (in Brit. Fern Gaz. 10: 222. 1972). Newman (l.c.) based his varietal name on Aspidium affine Fisch. & C.A. Mey. (in Bull. Soc. Imp. Naturalistes Moscou 11: 240. 1838), non Blume (1828). Another species name based on A. affine and cited by Newman was Polystichum affine Ledeb. (Fl. Ross. 4: 515. 1853), but this is also illegitimate as A. caucasicum A. Braun (in Flora 24: 707. 1841) had already been published as a replacement name for A. affine Fisch. & C.A. Mey. and Ledebour should have adopted Braun's epithet. In consequence, Newman's D. filix-mas var. affinis lacks a basionym and so cannot be treated as a new combination, and is, therefore, illegitimate as Newman cited in synonymy Lastrea filix-mas var. incisa T. Moore (in Phytologist 3: 137. 1848), the epithet of which he should have adopted. Consequently, Kinahan's species name is also not a new combination but must be attributed to him alone. As Kinahan based his name entirely on Newman's account, it is to be typified by the type of Newman's varietal name. Although this is superfluous and illegitimate, it is not automatically typified by the type of Moore's varietal name, because, in citing A. affine Fisch. & C.A. Mey. as an intended basionym, Newman indicated a different type, that of Fischer & Meyer's name (Art. 7.5 & Ex. 6). Dryopteris affinis Kinahan was previously unknown, appearing in a note on ferns in a small valley in Ireland, was not listed in any other works and was made inadvertently following Newman's account where the heading was given as Dryopteris affinis, but the text gave it as Dryopteris filix-mas var. affinis and Newman explained that it was a variety of D. filix-mas. Neither Newman nor Kinahan realised that the name applied to the separate species, D. caucasica, not present in Britain, Ireland, or all of W and C Europe, and they had misapplied this D. filix-mas var. affinis and D. affinis to D. filix-mas. Kinahan simply gave the name as “D. affinis Newman”, without other nomenclatural information. This earlier D. affinis Kinahan, although also illegitimate, being necessarily typified by the type of D. caucasica, the legitimate replacement name for Aspidium affine Fisch. & C.A. Mey., pre-occupies the name and thus renders D. affinis (Lowe) Fraser-Jenk. an illegitimate later homonym. The disruption and instability caused by the earlier name would be very extensive and would also involve the aggregate having to be referred to by the name, Dryopteris borreri (Newman) Kinahan, of a different cytotype from D. affinis sensu stricto, and the diploid species being changed to D. pseudomas (Woll.) Holub & Pouzar, with many new combinations being required for subsidiary subspecies and varieties, whether treated as a single complex species aggregate, or as in a strict sense as a separate diploid species. Any use of D. affinis ultimately based on Aspidium affine Fisch. & C.A. Mey. would therefore create great disruption in what is already known to be a complex group. Accordingly it is proposed here to conserve the name Dryopteris affinis (Lowe) Fraser-Jenk. against D. affinis Kinahan to maintain nomenclatural stability for the species concerned. CRFJ, https://orcid.org/0000-0003-4490-8523 FJR, https://orcid.org/0000-0003-4459-6769 LE, https://orcid.org/0000-0003-3947-787X ACP, https://orcid.org/0000-0001-6021-9360 We are especially grateful to Prof. J. McNeill and Dr J. Wiersema for their thorough elucidation of the complex nomenclature of Kinahan's Dryopteris affinis and for editorial corrections.