(3121) Proposal to conserve the name <i>Odontopteris schlotheimii</i> against <i>Osmunda nummularia</i> (Fossil <i>Medullosales</i>)

(3121) Odontopteris schlotheimii Brongn., Prodr. Hist. Vég. Foss.: 60. Dec 1828, nom. cons. prop. Typus: Germany, Thuringia, Manebach, Formation (Asselian Stage) (Mus. Naturkunde, Berlin No. 1987/333): [illustrated in] Schlotheim, Beschr. Kräuter-Abdr.: t. 3, fig. 5a. 1804, typ. cons. prop. (≡) Osmunda nummularia Sternb., Vers. Fl. Vorwelt 1(2): 33. Jan–Aug 1821 (‘numularia’) (lectotyp. des.: Kvaček & Straková, Cat. Fossil Pl. Descr. Sternberg: 110. 1997), nom. rej. prop. The name Odontopteris schlotheimii Brongn. (Prodr. Hist. Vég. Foss.: 60. 1828) is currently used for a fossil-species of medullosalean foliage adpressions that occurs in the uppermost Carboniferous and lower Permian fossil floras of Euramerica. The earliest published examples were from the Asselian Manebach Flora in Thuringia (Schlotheim, Beschr. Kräuter-Abdr.: t. 3, fig. 5, 6. 1804). The illustrations of these specimens were initially not provided with a species name but were subsequently associated with “Filicites osmundaeformis” Schloth. (Petrefactenkunde: 412. 1820). However, although the latter work included a diagnosis, this species name is invalid because Schlotheim's publication pre-dates the starting point for plant fossil nomenclature (ICN Art. 13.1(f), Turland & al. in Regnum Veg. 162. 2025). On Schlotheim's death in 1832, his publisher's son Friedrich Gottlieb Becker issued a volume reprinting some of Schlotheim's plates with accompanying explanatory text (Anon., Merkw. Verstein.: 6. 1832). Although there was no accompanying description, one of the entries makes direct reference to “Filicites osmundaeformis”, thereby referencing Schlotheim's 1820 description, and quotes the Schlotheim 1804 figures (t. 3, fig. 5, 6). Since this postdates the starting point for palaeobotanical nomenclature and the genus Filicites Schloth. ex Brongn. (Mém. Mus. Hist. Nat. 8: 209. 1822) had now been validly published, this effectively validated F. osmundiformis Schloth. (‘osmundaeformis’, Art. 60.10), although with two prior names (discussed below) listed in its synonymy the name was nonetheless superfluous and illegitimate (Art. 52). However, in the meantime, Adolphe Brongniart had included Schlotheim's specimens as original material for Odontopteris schlotheimii Brongn. (l.c. 1828). Although Brongniart did not directly provide a diagnosis, he unambiguously referred to Schlotheim's 1820 diagnosis and 1804 illustrations, thereby validating the name. Between 1828 and 1879 there were another 33 published records of O. schlotheimii (Jongmans & Dijkstra in Foss. Cat., Pars Pl. 48: 1194. 1961) but then in 1879 Charles René Zeiller concluded that F. osmundiformis was in fact validly published in 1820 and so resurrected that epithet, proposing a new combination Odontopteris osmundiformis (Schloth.) Zeiller (Explic. Carté Géol. France 4(2[Vég. Foss. Terr. Houiller]): 63. 1879, ‘osmundaeformis’) to replace O. schlotheimii. Over the next 80 years there were 45 published records of O. “osmundaeformis” (Jongmans & Dijkstra, l.c. 48: 1963. 1961, 68: 3965. 1968) and even after Schlotheim's 1820 work was ruled to be invalid in 1959 the species name continued to be used (e.g., Dijkstra & Van Amerom in Foss. Cat., Pars Pl. 90: 440. 1983). Eventually, however, the consequences for O. osmundiformis of Schlotheim's 1820 work being ruled as invalid became inescapable (Barthel, Veröff. Naturhist. Mus. Schleusingen 21: 33–72. 2006) and the name O. schlotheimii was reinstated. This species is now mostly referred to as O. schlotheimii and a search using Google Scholar (on 16 Jul 2025) found that since the year 2000, 69 published works mentioned the name with either the “schlotheimii” or “schlotheimi” spelling, whereas only 36 have used “osmundaeformis”. But this overlooks the fact that another species name predated Odontopteris schlotheimii, viz. Osmunda nummularia Sternb. (Vers. Fl. Vorwelt 1(2): 33. Jan–Aug 1821, ‘numularia’), later transferred to Neuropteris nummularia by Sternberg (Vers. Fl. Vorwelt 1(4, Tent.): xvii. Sep 1825), correcting the orthography. Sternberg (l.c. 1821) gave a clear diagnosis and made direct reference to Schlotheim (l.c. 1820), thereby fulfilling the requirements for valid publication. However, he (Sternberg, Vers. Fl. Vorwelt 2(6): 79. Apr 1833) later concluded that the species more correctly belonged to the genus Odontopteris and so adopted the Brongniart name (O. schlotheimii). Not only did Sternberg's names have priority, but N. nummularia (as “Nevropteris nummularia, Sternb.”) was cited by Brongniart (l.c. 1828) in the synonymy of O. schlotheimii, making the latter name superfluous, illegitimate, and homotypic to the former name (Art. 7.5). Following nomenclatural rules the correct name of the species involved would be a combination of the assigned genus name and the epithet of the earliest legitimate and available species name (Art. 11.4); in this case it would be a combination of Odontopteris and the species epithet nummularia, but there have been no records of usage of either Osmunda “numularia” or Neuropteris nummularia since their protologues. Since the combination “Odontopteris nummularia” has never been validly published this new combination would need to be proposed, but it is difficult to see what benefit would be gained in making such a change. Given that Odontopteris schlotheimii is now such a widely used name for a distinctive fossil-species of medullosalean fronds, the best way of ensuring nomenclatural stability would be to conserve it over any other homotypic species name, including Osmunda nummularia, thereby restoring its legitimacy. The original specimens figured by Schlotheim (l.c. 1804: t. 3, fig. 5, 6) would be the original material for both Odontopteris schlotheimii and Osmunda nummularia, the two names being homotypic. The specimen (Museum für Naturkunde Berlin, No. 1987/333) represented in Schlotheim's (l.c. 1804) fig. 5a was designated as lectotype of Osmunda nummularia by Kvaček & Straková (Cat. Fossil Pl. Descr. Sternberg: 110. 1997) and therefore also became the type of Odontopteris schlotheimii (Art. 7 Note 4). However, if the name O. schlotheimii is conserved and so made legitimate, this automatic typification under Art. 7.5 is removed, and another type designation is required. Selecting the same specimen designated by Kvaček & Straková (l.c.) for Osmunda nummularia as lectotype for O. schlotheimii will preserve the current usage of the latter name, so it makes sense to retain this typification with the conservation of O. schlotheimii. Because such a lectotypification could not become effective until conservation is approved, it would seem to be counterintuitive to designate it in accordance with Art. 7.11 when this proposal is published, so it is here offered as a “typ. cons. prop.”