(3105) Proposal to reject the name Polycarpon urbanianum (Caryophyllaceae)

(3105) Polycarpon urbanianum Muschl. in Bot. Jahrb. Syst. 45: 452. 25 Jul 1911 [Angiosp.: Caryophyll.], nom. utique rej. prop. Typus: non designatus. As part of the ongoing research on the taxonomy of Caryophyllaceae Juss. in South America (e.g., Iamonico & Montesinos-Tubée in Phytotaxa 327: 299–300. 2017; Iamonico in Darwiniana, n.s., 10: 116–133. 2022; Iamonico & Zanotti in Bonplandia 31: 89–95. 2022; Montesinos-Tubée & Iamonico in Plants (Basel) 12: 1064. 2023; Montesinos-Tubée & Teillier in Gayana Bot. 79: 124–139. 2022; Montesinos-Tubée & Kool in Phytotaxa 220: 77–82. 2015) and specifically the investigation of Polycarpon Loefl. (Iamonico & Montesinos-Tubée, in prep.) we came across a name, Polycarpon urbanianum Muschl., which has notable difficulties from the nomenclatural point of view and that requires, in our opinion, the present proposal for rejection. Muschler (in Bot. Jahrb. Syst. 45: 452–453. 1911) validly published Polycarpon urbanianum by providing a detailed description; a syntype (Art. 9.6 of the Shenzhen Code; Turland & al. in Regnum Veg. 159. 2018) was cited: "Peru: Cordillera blanca prope Huaraz, in formatione plantis caespitosis pulvinaribusque composita, 4300–4400 m a.s.l. (Weberbauer 2985. Specimina florigena fructiferaque 14. Maii 1903. - Herb. Berol.)." According to HUH-Index of Botanists, Weberbauer's herbarium and types are deposited at B, MOL, and USM. Collections at B were mostly destroyed during World War II, while no Weberbauer specimen useful for typification was traced at MOL (Aldo Ceroni, pers. comm.) and USM. Lacking surviving original material, a neotypification would be required to fix the application of the name according to Art. 9.8. However, neotypifying Muschler's name is a difficult issue. First, at altitudes of 4300–4400 m a.s.l. no Polycarpon taxon occurs in Peru, based on our investigation at the locus classicus (Cordillera blanca, Huaraz, central Peru) and adjacent territories. Second, after checking the original description by Muschler (l.c.) we verified that the morphology of P. urbanianum cannot be ascribed to any known member of Polycarpon. Polycarpon urbanianum is an annual species (Muschler, l.c.) and only five taxa in Polycarpon are annual, i.e., P. tetraphyllum subsp. depressum (Nutt.) Iamonico (in Novon 24: 159–164. 2015; based on P. depressum Nutt. in Torrey & Gray, Fl. N. Amer. 1: 174. 1838), P. tetraphyllum subsp. dunense (P. Fraga & Rosselló) Iamonico (in Willdenowia 45: 120–121. 2015; based on P. dunense P. Fraga & Rosselló, Fl. Montiber. 47: 30. 2011), P. tetraphyllum subsp. arabicum (Boiss.) Iamonico (in Atti Soc. Tosc. Sci. Nat. Pisa, Mem., Ser. B, 123: 5–8. 2016); based on P. arabicum Boiss., Diagn. Pl. Orient. 10: 13. 1849), P. tetraphyllum subsp. alsinifolium (Biv.) Ball (in J. Linn. Soc., Bot. 16: 370. 1877; based on Hagaea alsinifolia Biv., Stirp. Rar. Minus. Cognit. 3: 7. 1815), and P. tetraphyllum (L.) L. subsp. tetraphyllum (Syst. Nat., ed. 10: 881. 1759; based on Mollugo tetraphylla L., Sp. Pl.: 89. 1753) (the latter two subspecies can be also perennials). Since the height of the plant described by Muschler (l.c.) was 2–4 cm, we can exclude both P. tetraphyllum subsp. alsinifolium (5–20 cm) and subsp. tetraphyllum (8–35 cm) (see, e.g., Iamonico in Pignatti, Fl. Ital., ed. 2, 2: 146–147. 2017). Concerning the remaining three subspecies, note that P. tetraphyllum subsp. depressum has sepals 0.5–0.7 mm long and inflorescences lax (sepals are 1–2 mm long and inflorescence is dense in P. urbanianum), P. tetraphyllum subsp. dunense has sepals ovate, obtuse, and not keeled (lanceolate, acute, and keeled in P. urbanianum), P. tetraphyllum subsp. arabicum has leaves spatulate and seeds brown coloured (leaves are not spatulate and seeds are reddish in P. urbanianum); note, moreover, that these three subspecies are endemics to California, the western U.S.A. plus Baja California, and Mexico (subsp. depressum); the Balearic Islands and mainland Spain (subsp. dunense); and the Arabian Peninsula plus Egypt (subsp. arabicum). All things considered, Muschler's Polycarpon urbanianum does not apply to a species of Polycarpon. It should be noted that MacBride (in Publ. Field Mus. Nat. Hist., Bot. Ser. 13: 628. 1937), for his Flora of Peru, stated that Polycarpon urbanianum is "otherwise like P. englerianum", a species currently recognized as Drymaria engleriana (Muschl.) Baehni & J.F. MacBr. (l.c.: 621, based on Polycarpon englerianum Muschl., l.c.: 452) (see, e.g., POWO, accessed 2 May 2025). Based on our personal knowledge and analysis of Muschler's (l.c.) work, his description of Polycarpon urbanianum cannot be ascribed to Drymaria engleriana since several key morphological traits indicated by Muschler (l.c.) are inconsistent with the current concept of D. engleriana. Specifically, P. urbanianum is described as an annual species with a root system consisting of very thin, whitish-yellow roots, 5–6 cm long (vs. annual to biennal with short, 3–5 cm long, yellow roots); the stem is thicker in P. urbanianum, 0.5–1.0 mm in diameter at the base (vs. up to 0.5 mm diameter in D. engleriana); leaves are ovate-lanceolate, usually acute or very acute, with a long petiole and whitish squamiform pubescence in P. urbanianum (vs. oblanceolate or obovate-oblanceolate leaves, which are obtuse or acute, with shorter petioles and curly hairs); inflorescences are compound dichasia with shortened secondary branches and curled pedicelled flowers in P. urbanianum (vs. inflorescences lacking curls with mostly subsessile flowers); calyx lobes are small, i.e., outer lobes 1 mm, inner lobes almost 2 mm in P. urbanianum (vs. outer lobes 2 mm, inner lobes almost 3 mm); petals are 5 in P. urbanianum (vs. sometimes lacking). The morphological and chorological discrepancies discussed above make it impossible for a neotypification to fix, without doubt, the identity of Muschler's Polycarpon urbanianum. All things considered, we conclude that Muschler may have mixed up characters found in other taxa (of unknown Caryophyllaceae genera) and/or wrongly described P. urbanianum. In this regard, it should be noted that Muschler was subject to legal proceedings and ultimately dismissed from the Berlin Botanic Garden and Museum in 1913 for falsifying data and descriptions in some of his publications on African plants (see Schweinfurth in Verh. Bot. Vereins Prov. Brandenburg 56: 170–175. 1915; Engler in Bot. Jahrb. Syst. 53: 366–375. 1915). Nevertheless, Polycarpon urbanianum is accepted as a species endemic to Peru in POWO and World Flora Online; in other cases, Muschler's name is indicated as provisionally accepted with uncertain status (e.g., Hassler, World Plants. Synonymic Checklist and Distribution of the World Flora; all databases accessed 2 May 2025); finally, it is rarely cited in the literature (MacBride, l.c.; Cano & Sánchez in Revista Peruana Biol. 13(2): 251. 2006). The citation by Cano & Sánchez (l.c., "Herbarios peruanos: MOL (isotipo)") seems to be a mistake since, as stated above, Aldo Ceroni (herbarium MOL) confirmed the non-existence of this material. The inability to designate a proper lectotype or neotype for Polycarpon urbanianum, as well as the rare number of citations of this name in the literature, make it impossible to establish with certainty the identity of Muschler's name, which could create nomenclatural instability were it to be used as a synonym of some Polycarpon or Drymaria name over which it has priority (e.g., against Drymaria auriculipetala Mattf. [published in 1936], D. ladewii Rusby [published in 1934], or D. praecox Baehni & J.F. Macbr. [published in 1937]). These facts culminate here in the proposal to reject this name.