(3051) Proposal to conserve the name Thymus marschallianus (Lamiaceae) with a conserved type

(3051) Thymus marschallianus Willd., Sp. Pl. 3: 141. 1800 Angiosp.: Lab., nom. cons. prop. Typus: Ukraine, Khmelnytskyi Region, Vinkivtsi District, Maidan-Oleksandrivskyi village, north-eastern outskirts, a roadside, among grasses, 48°59′08.2″N, 27°11′43.1″E, 309 m, 29 Jul 2013, Nachychko VN 778 (LWS on two sheets barcodes 120095 and 120096; isotypi: KW No. 116767, LWKS barcode LWKS0033201), typ. cons. prop. Thymus marschallianus Willd. (Sp. Pl. 3: 141. 1800) was in broad use as an accepted name until the 1970s (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 Komarov, Fl. URSS 21: 511. 1954; Pawłowski, Fl. Polsk. 11: 173. 1967), but is treated nowadays mostly as a synonym of T. pannonicus All. (Auct. Syn. Meth. Stirp. Hort. Regii Taur.: 6. 1773). The latter concept has been confirmed by modern molecular and taxonomic studies (e.g., Sostaric Nachychko Plants of the World Online, http://www.plantsoftheworldonline.org; World Plants: Synonymic Checklist and Distribution of the World Flora. Version 19.3, http://www.worldplants.de; all accessed 22 Jun 2024). At the same time, botanists from some Eastern European and Asian countries still traditionally treat T. marschallianus as a recognized species (e.g., Lazkov Sennikov Pînzaru in J. Bot. (Chisinau) 14: 40. 2022) and the name appears over 2200 times in scientific literature since 1970 (Google Scholar, accessed 30 Jun 2024). It was shown that the extant original material of Thymus marschallianus belongs to other taxa, which contradicts the traditional application of this name (Nachychko Nachychko Wilson, l.c.). Therefore, following the above recommendation, we propose to conserve the name Thymus marschallianus with a conserved type under Art. 14.9 of the Shenzhen Code (Turland Pawłowski, l.c.). The specimen shows parts of the same hermaphrodite plant, displaying different types of shoots, i.e., generative shoots of the first (spring) generation in the fruiting stage, generative shoots of the second (summer) generation in the flowering stage, and innovation shoots. The various combinations of these shoots under different environment conditions and growth stages, together with gynodioecy and hybridization phenomena, contribute to a broad polymorphism within this plant group (e.g., Schmidt in Vent, 100 Jahre Arboretum (1879–1979): 174. 1980; Berko in Ukrain. Bot. J. 45: 30. 1988; Gogina, Izmenčivost i formoobrazovanie v rode Timjan The variability and morphogenesis in the genus Thyme. 1990). Thus, the chosen specimen effectively demonstrates the habit of such a plant. It also generally corresponds to the original diagnosis and description of Willdenow (l.c.). Specifically, the average length of orthotropic generative shoots in the present plant is 14.7 cm, and their stems are regularly pubescent all around in the upper part ("Caules semipedales, …, teretes superne pubescentes" = Stems are half a foot long, …, smooth pubescent above). The leaves are opposite, subsessile, linear-lanceolate, glabrous on both sides and ciliate at the base, with an average size of 17.2 × 2.9 mm, but exhibit significant variability in size within the present plant ("Folia opposita lineas 8 longa, sesqui lineas lata, brevissime petiolata, lineari-lanceolata, …, utraque pagina glabra, …, margine basin versus ciliata" = Leaves are opposite, 8 lines long i.e., 18 mm, given that 1 line is 2.25 mm; Stearn, Bot. Latin, ed. 3: 113. 1983, 1.5 lines i.e., 3.4 mm wide, very short-petiolate, linear-lanceolate, …, glabrous on both sides, …, ciliate along the margin at the base). The inflorescence is verticillate, spicate, and often branched ("Flores verticillati, verticillis ad apicem caulis congestis et in spicam confertis" = Flowers verticillate, verticillasters are connivent at the apex of the stem and congregated into a spike). The calyx is sparsely pilose and shorter than the corolla ("Calyces hirti striati. Corollae calyce longiores" = Calyces are villous-striate. The corolla is longer than the calyx). The proposed conservation will resolve the nomenclatural conflict between Thymus marschallianus and T. callieri and allow some botanists to continue to use the name T. marschallianus in the traditional sense, preserving nomenclatural stability. At the same time, the proposed conserved type, which demonstrates the T. pannonicus plant, will help establish the use of the latter name, which is currently accepted for this taxon. This work has been realized in the frames of the project "Digitization of natural history collections damaged as a result of hostilities and related factors: development of protocols and implementation on the basis of the State Museum of Natural History of the National Academy of Sciences of Ukraine" (No. 2022.01/0013), financed by the National Research Foundation of Ukraine in the grant program "Science for the Recovery of Ukraine in the War and Post-War Periods".