Proposal to conserve the name Colurolejeunea tenuicornis (Colura tenuicornis) against Lejeunea ceratophora (Colura ceratophora) (Marchantiophyta: Lejeuneaceae)

(2969) Colurolejeunea tenuicornis A. Evans in Trans. Connecticut Acad. Arts Sci. 10: 455. Mar 1900 [Hepatics], nom. cons. prop. Lectotypus (hic designatus): Hawaii, Oahu, Kalihi ridge of Nuuanu, 11 Jun 1898, Cooke (YU barcode YU.216401; isolectotypus: G barcode G00115870). (=) Lejeunea ceratophora Nees in Gottsche & al., Syn. Hepat.: 405. 11–13 Dec 1845, nom. rej. prop. Lectotypus (hic designatus): “in cortice peruviano”, hb. Nees. (STR!; isolectotypus: G barcode G00283388). The liverwort Colura tenuicornis (A. Evans) Steph. (Sp. Hepat. 5: 942. 1916), based on Colurolejeunea tenuicornis A. Evans (in Trans. Connecticut Acad. Arts Sci. 10: 455. 1900), is a widespread and well-known pan-tropical taxon also known under several synonyms (see Jovet-Ast in Rev. Bryol. Lichénol. 22: 203–206. 1954). The name is used in many recent publications (e.g., Eggers, Trop. Bryol. 20: 109–115. 2001; He & Zhu in Cryptog. Bryol. 32: 107–112. 2011; Lavocat-Bernard & Schäfer-Verwimp in Cryptog. Bryol. 32: 233–272. 2011; Pócs in Chenia 11: 12. 2013; Schäfer-Verwimp & Van Melick in Cryptog. Bryol. 37: 305–348. 2016; Wigginton in Trop. Bryol. 9: 1–138. 2018; Gradstein in Mem. New York Bot. Gard. 121: 1–723. 2021; Lee & al. in PhytoKeys 199: 29–111. 2022). The C.M. Cooke gathering from Oahu was first indicated as type by Bonner (Index Hepat. 4: 882. 1963) but without identification of the herbarium in which the specimen was preserved. Zhu & So (in Nova Hedwigia Beih. 121: 233. 2001) referred to the specimen at YU as the “holotype”, but this was not an effective lectotypification under Art. 7.11 of the ICN (Turland & al. in Regnum Veg. 159. 2018), lacking the phrase “designated here”. Second-step lectotypification by this specimen is accomplished above. The specimen is to be seen at https://bryophyteportal.org/portal/collections/individual/index.php?occid=2493834). A second specimen, probably detached by Stephani from the type and thus an isolectotype, is in G (G barcode G00115870, to be seen at https://www.ville-ge.ch/musinfo/bd/cjb/chg/adetail.php?id=236382). Lejeunea ceratophora was described by Nees (in Gottsche & al., Syn. Hepat. 3: 405. 1845) from peruvian bark (“cortice peruviano”) (Cinchona officinalis L.), widely assumed to be from Peru, and later reported from a few places in Central America (Standley in Field Mus. Nat. Hist., Bot. Ser. 10: 62. 1931; Herzog in Rev. Bryol. Lichénol. 20: 175. 1952). Jovet-Ast (l.c.) placed it, as Colura ceratophora (Nees) Trevis. (in Mem. Reale Ist. Lombardo Sci., Ser. 3, Cl. Sci. Mat. 4(13): 402. 1877), in synonymy with C. tenuicornis with some doubts, but using the latter, younger name for the taxon, although noting that there was a priority problem. This has been followed since then without anyone proposing to use the older name with the exception of Menzel (in Willdenowia 14: 492. 1984). The type that we have designated, preserved in STR, consists of tiny twig bark pieces with a few shoots in poor condition. A duplicate in G (which we have only seen online at https://www.ville-ge.ch/musinfo/bd/cjb/chg/adetail.php?id=280153) contains a small piece of bark which seems to be in equally bad condition. Search in the online international bibliographic databases JSTOR (http://www.jstor.org), Web of Science (https://apps.webofknowledge.com/), and Google Scholar (http://scholar.google.com/), respectively (using the species names as search terms, accessed 6 Apr 2023), for use of the names in the literature gave the following numbers of hits: Colura ceratophora (1, 0, 1), Colura tenuicornis (29, 4, 174). Colura tenuicornis is the name that has been widely and persistently used for this taxon for almost 70 years. Usage has become well established. In order to maintain a stable nomenclature, we propose conserving Colurolejeunea tenuicornis, the basionym of Colura tenuicornis, against Lejeunea ceratophora, the basionym of Colura ceratophora. LS, https://orcid.org/0000-0002-9315-4978 AH, https://orcid.org/0000-0001-8390-319x TP, https://orcid.org/0000-0002-1359-1298 FB, https://orcid.org/0000-0002-1532-3609 We wish to thank John McNeill and John Wiersema for comments on the proposal and for making us aware of an isotype that we had overlooked.