(2810) Thymus marschallianus Willd., Sp. Pl. 3: 141. 1800 [Angiosp.: Lab.], nom. utique rej. prop. Lectotypus (vide Schmidt in Feddes Repert. 83: 666. 1973): “Thymus marschallianus, e Tauria, M. Bieberstein, W. det.” (HAL barcode HAL0014427; isolectotypus: B barcode B -W 11029 -01 0). The name Thymus marschallianus Willd. (Sp. Pl. 3: 141. 1800) was proposed by Willdenow, who used the specific epithet for a newly described species to honour Marschall von Bieberstein, on whose material from the Crimean Peninsula (Ukraine) the species description was based. Until the 1970s, this name was often used as an accepted name (e.g., Marschall von Bieberstein, Fl. Taur.-Caucas. 2: 59. 1808; Besser, Enum. Pl.: 24. 1822; Borbás in Math. Term. Közlem. 24: 98. 1890; Ronniger in Repert. Spec. Nov. Regni Veg. Beih. 30(2): 349. 1930; Klokov in Schischkin, Fl. URSS 21: 511. 1954; Pawłowski, Fl. Polsk. 11: 173. 1967), but was also sometimes treated as a synonym (e.g., Bentham, Labiat. Gen. Spec.: 345. 1834) or as a basionym of nomenclatural combinations for different taxa (e.g., Ledebour, Fl. Ross. 3: 346. 1849; Velenovský in Beih. Bot. Centralbl. 19(2): 278. 1906; Lyka in Hegi, Ill. Fl. Mitt.-Eur. 5: 2312. 1927). Jalas (in Bot. J. Linn. Soc. 64: 259. 1971), when elaborating his taxonomic concept of the genus Thymus L. for Flora Europaea, proposed the inclusion of T. marschallianus into T. pannonicus All. (Auct. Syn. Meth. Stirp. Hort. Regii Taur.: 6. 1773) as a variant with glabrous leaves (the hairy-leaved plants being assigned to T. pannonicus s.str.), preserving the earlier name T. pannonicus for this species. This viewpoint appears well supported by modern molecular studies based on AFLP-markers (Sostaric & al. in Flora 207: 654–661. 2012), showing a lack of distinction between T. pannonicus s.str. and T. marschallianus at the genetic level. Schmidt (in Feddes Repert. 83: 666. 1973) examined Willdenow's original material of T. marschallianus and found two duplicates that he regarded to be parts of a single plant collected by Marschall von Bieberstein in the Crimea. These specimens are stored in Willdenow's own collection (B barcode B -W 11029 -01 0, https://herbarium.bgbm.org/object/BW11029010) and in the herbarium of the Martin-Luther-Universität in Halle (HAL barcode HAL0014427, https://herbarium.univie.ac.at/database/detail.php?ID=168331). However, as Schmidt stated, these specimens do not belong to T. marschallianus in its conventional treatment (see below) but represent a different species with the accepted name T. callieri Borbás ex Velen. (in Sitzungsber. Königl. Böhm. Ges. Wiss. Prag., Math.-Naturwiss. Cl. 28: 16. 1904). In addition, a specimen from Willdenow's herbarium labelled “An Thym. Zygis, Nicolaef (Pallas)” (B barcode B -W 11029 -05 0, https://herbarium.bgbm.org/object/BW11029050), collected by Pallas, apparently in 1794 (see, Pallas, Reise Südl. Statthaltersch. Russ. Reich. 2: 509–514. 1801), can also be associated with the T. marschallianus protologue, where Willdenow (l.c.) cited “Thymus Zygis” sensu Pallas (in Nova Acta Acad. Sci. Imp. Petrop. Hist. Acad. 10: 313. 1797, non L.). However, this specimen also does not belong to T. marschallianus, having been identified by Braun (in Oesterr. Bot. Z. 42: 336–337. 1892) and Vasjukov (in Novosti Sist. Vyssh. Rast. 45: 117. 2014) as a species with the accepted name T. pallasianus Heinr. Braun (l.c.: 337). Based on our examination of this specimen's digital image, we conclude that it actually belongs to an allied species T. borysthenicus Klokov & Des.-Shost. (in J. Agric. Bot., Charkov 1(3): 134. 1927), clearly identified by the recurved leaf margin. Other specimens from Willdenow's collection (B) are either unlabelled or have a different provenance, and thus they cannot be unambiguously associated with the protologue. Only one of these specimens (B barcode B -W 11029 -02 0, https://herbarium.bgbm.org/object/BW11029020) matches the current treatment of T. marschallianus. However, the latter specimen lacks any label information and has been referred to by Schmidt & Knapp (in Wiss. Z. Martin-Luther-Univ. Halle-Wittenberg, Math.-Naturwiss. Reihe 26: 86. 1977) as “Herb. Stephanianum”, suggesting a different provenance of this specimen. According to Art. 9.12 of the Shenzhen Code (Turland & al. in Regnum Veg. 159. 2018), for lectotype designation the two aforementioned duplicates from HAL and B, comprising the only syntype and isosyntype cited in the protologue (see below), take precedence over any remaining original material. The HAL specimen (barcode HAL0014427), which was effectively designated by Schmidt (l.c. 1973) as a lectotype of T. marschallianus, provides a clear indication that the latter name sensu Willdenow (l.c.) pertains to a completely different species (i.e., T. callieri) from that to which the name has generally been applied. Recently, Vasjukov (l.c.: 117) sought to designate the above-mentioned unlabelled specimen B barcode B -W 11029 -02 0 as a lectotype of T. marschallianus, apparently being unaware of Schmidt & Knapp's (l.c.) discussion of Willdenow's original material and the published lectotypification by Schmidt (l.c. 1973). Vasjukov regarded the well-labelled specimen from HAL, which had been annotated “lectotype” in 1971 by Schmidt, as inappropriate for lectotypification because it “does not conform either with the description or current treatment of T. marschallianus (it actually belongs to T. callieri) [VON & YVS – translated from Russian]”. As follows from Art. 9.19, the lectotypification by Vasjukov has no standing for several reasons: (1) the lectotype already designated by Schmidt (l.c. 1973) has priority, and (2) Schmidt's lectotype cannot be superseded, not being in serious conflict with the protologue (in fact, it both corresponds to the superficial description and diagnosis and indicates the respective provenance) (see Art. 9.19(с)). Moreover, this specimen (HAL barcode HAL0014427) cannot be in serious conflict with the protologue because it is a part of the protologue (Art. 9.19 Note 7), as Willdenow (l.c.), in stating “Hanc plantarum in Tauria detexit L. B. Marschall ab Biberstein… [These plants were detected by L. B. Marschall ab Biberstein in Taurida…]”, referenced both the collector and the locality of this syntype gathering (Art. 40 Note 2), which survives in his herbarium. Most likely, Willdenow (l.c.) described T. marschallianus mainly from material belonging to T. callieri, a species of more common occurrence than the former in the Crimea, where T. marschallianus as currently treated is found only sporadically. Most occurrences are of synanthropic origin (Klokov, l.c.), giving it less chance of having been encountered and collected by Marschall von Bieberstein. Therefore, since supersession of the existing lectotype of T. marschallianus under Art. 9.19 is impossible, the conventional application of this name could only be preserved by conserving it with a new type under Art. 14.9. Menitsky (in Bot. Zhurn. (Moscow & Leningrad) 58: 992–993. 1973) did not accept either the lectotypification of T. marschallianus by Schmidt (l.c. 1973) or that of T. pannonicus by Jalas (l.c.), but he de facto proposed to preserve the later name T. marschallianus sensu Willdenow (l.c.) for T. pannonicus sensu Jalas (l.c.). Menitsky argued that “for the purpose of nomenclature stabilization, it is recommended to preserve the long-established and widely used names for species with broad distributions [VON & YVS – translated from Russian]”. Although in the present context this viewpoint appears questionable both in terms of nomenclature (including the arguments presented above) and taxonomy, it has been firmly established in countries of the former U.S.S.R., where the name T. marschallianus is still commonly accepted. Therefore, two principal applications of the name T. marschallianus are currently in use. Globally, following Jalas (l.c.) and Schmidt (l.c. 1973), the name T. marschallianus auct. non Willd. is considered as a taxonomic synonym of T. pannonicus All. or its derived combination T. pulegioides L. subsp. pannonicus (All.) Kerguélen, as in various contemporary European floras, identification keys, and checklists (e.g., Čáp & Šípošová in Bertová & Goliašová, Fl. Slovenska 5(1): 343. 1993; Tasenkevich, Fl. Carpathians: 308. 1998; Štěpánek & Tomšovic in Slavík, Květena České Republ. 6: 664. 2000; Oprea, Lista Crit. Pl. Vasc. Romania: 307. 2005; Ciocârlan, Fl. Il. României: 667. 2009; Schmidt in Jäger, Exkursionsfl. Deutschland, ed. 21: 686. 2017), as well as in global databases (Global Biodiversity Information Facility, https://gbif.org; Plants of the World Online, http://www.plantsoftheworldonline.org; World Flora Online, http://www.worldfloraonline.org; all accessed 1 Feb 2021). An alternative usage, adopted in some East European and Asian countries (especially those from the former U.S.S.R.), treats T. marschallianus sensu Menitsky (l.c.), non Willd., as a currently accepted name (e.g., Li & Hedge in Wu & Raven, Fl. China 17: 236. 1994; Czerepanov, Vasc. Pl. Russia Adjac. States: 303. 1995; Sautkina in Parfenov, Opred. Vysš. Rast. Belarusi [Key High. Pl. Belarus]: 271. 1999; Mosyakin & Fedoronchuk, Vasc. Pl. Ukraine: 243. 1999; Mirek & al., Flower. Pl. Pteridoph. Poland: 177. 2002; Knyasev in Bot. Zhurn. (Moscow & Leningrad) 100: 136. 2015). However, with its current typification, the name T. marschallianus has to be accepted for a species to which the later name T. callieri is currently applied (e.g., Ciocârlan, l.c: 666; Assyov & Petrova, Consp. Bulg. Vasc. Fl., ed. 4: 414. 2012; Vasjukov, l.c: 114; Knyasev, l.c.: 138; Global Biodiversity Information Facility, l.c.; World Flora Online, l.c.). Considering the above nomenclatural and regional confusion in applying the name T. marschallianus, three possible resolutions can be proposed: (1) conserve this name with a conserved type to preserve its traditional application, (2) use this name (with the existing lectotype) in lieu of T. callieri, and (3) reject the name outright. Conservation is not an ideal solution in view of current taxonomic treatments in which the name T. marschallianus auct. non Willd. is either a synonym or incorrectly accepted. On the other hand, scenario (2) would destabilize nomenclature by replacing the widely used but later name T. callieri, leading to further confusion and potential undesirable nomenclatural changes in the future. Rejection of the name (scenario 3) is deemed most suitable in this situation because it will not cause substantial nomenclatural changes (due to mostly synonymic treatment of the name) and will eliminate the nomenclatural conflict between T. marschallianus and T. callieri. In the cases of inappropriate acceptance of T. marschallianus, its rejection will help correct the long-standing mistake and establish the use of T. pannonicus. Hence, we propose the outright rejection of the name T. marschallianus under Art. 56. VON, https://orcid.org/0000-0001-6756-2823 YVS, https://orcid.org/0000-0003-0391-3502 The authors are grateful to Alexander Sennikov for his comments on the nomenclatural issues. Special thanks to John Wiersema and John McNeill for their valuable comments and suggestions on the manuscript. This work was supported by the SYNTHESYS+ Project http://www.synthesys.info/ (grant number CZ-TAF-1288) for VON.