(241) Proposal to amend Article H.11.1 by additionally allowing a combination of the name of a hybridogenous genus and a nothospecific epithet for naming a nothospecies of which the postulated or known parent species belong to different genera

Under the present wording of Art. H.11.1 of the International Code of Nomenclature for algae, fungi, and plants (Turland & al. in Regnum Veg. 159. 2018), “The name of a nothospecies of which the postulated or known parent species belong to different genera is a combination of a nothogeneric name with a nothospecific epithet.” No other option for naming such bigeneric or multigeneric hybrids is mentioned in the Code, and therefore we think that Art. H.11.1 is restrictive rather than instructive, regardless of the initial intent of the authors of this nomenclatural provision. While considering some problems of taxonomy and nomenclature of Sorbus L. s.l. (see, e.g., Mosyakin & al. in Taxon 71: 480–481. 2022), we noticed that, according to Art. H.11.1 as it stands now, the nothospecies name Majovskya ×ambigua (Decne.) Sennikov & Kurtto (in Memoranda Soc. Fauna Fl. Fenn. 93: 63. 2017) is incorrect because it is not “a combination of a nothogeneric name with a nothospecific epithet”. The same is true for several other names of intergeneric hybrids placed by Sennikov and Kurtto in hybridogenous genera (see below). This conclusion is further supported by Art. H.11 Ex. 1, which states that the name Heuchera ×tiarelloides Lemoine & É. Lemoine (the basionym of ×Heucherella tiarelloides (Lemoine & É. Lemoine) H.R. Wehrh., the intergeneric hybrid that probably “originated from the cross between a garden hybrid of Heuchera L. and Tiarella cordifolia L.”) is incorrect. We interpret the term “incorrect” used here as meaning “not correctly applicable to a particular taxon under a particular taxonomic concept”. Non-compliance with Art. H.11 does not make a name illegitimate or not validly published. Since Majovskya ×ambigua was considered by Sennikov & Kurtto (l.c.) to be a non-stabilized intergeneric hybrid (but not a hybridogenous species!) between Chamaemespilus alpina (Mill.) K.R. Robertson & J.B. Phipps (Sorbus chamaemespilus (L.) Crantz) and Aria edulis (Willd.) M. Roem. (Sorbus aria (L.) Crantz), its correct name under that taxonomic treatment should be a combination of a nothogeneric name, in this case ×Chamaearia Mezhenskyj (Netradytsiini Plodovi Kul'tury: 27. 2012 = Chamaemespilus Medik. × Aria (Pers.) Host) and the epithet “ambigua”: ×Chamaearia ambigua (Decne.) Mosyakin & McNeill, comb. nov. ≡ Aria ambigua Decne. in Nouv. Arch. Mus. Hist. Nat. 10: 165. 1874. As it stands now, Art. H.11.1 requires the double generic nomenclature, with different nothogeneric and generic names for nothospecies and hybridogenous species, respectively, that resulted from the same intergeneric crosses. For example, those entities that originated from crosses between taxa of Chamaemespilus and Aria that are considered to be hybridogenous species should be placed in Majovskya Sennikov & Kurtto (l.c.: 63; a hybridogenous genus), while entities of the same origin considered to be nothospecies (hybrids) should be placed in ×Chamaearia (a nothogenus). By analogy, the hybrid Normeyera ×hostii (J. Jacq. ex Host) Sennikov & Kurtto (l.c.: 65), which “is not considered a constant taxon” (Sennikov & Kurtto, l.c.), under that taxonomic concept should be correctly placed not in the hybridogenous genus Normeyera Sennikov & Kurtto (l.c.: 64) but in the nothogenus ×Chamariosorbus Mezhenskyj (l.c.: 29; Aria × Chamaemespilus × Sorbus) and be called ×Chamariosorbus hostii (J. Jacq. ex Host) Mezhenskyj (l.c.: 29). Our further nomenclatural comments on intergeneric hybrids in Sorbus s.l. will be published separately (in preparation). Considering this and some other similar cases, we propose the following amendment to Art. H.11.1. We also think that adding a new Example based on the case of Majovskya ×ambigua would be useful for illustrating the proposed amendment. “H.11.1. The name of a nothospecies of which the postulated or known parent species belong to different genera is either a combination of a nothogeneric name with a nothospecific epithet or a combination of a name of a hybridogenous genus 1 with a nothospecific epithet.” [footnote] “1 For the purposes of this Code, a hybridogenous genus is a genus that is derived from and has evolved from an intergeneric hybridization event or events and that contains one or more hybridogenous species, i.e. evolutionarily stabilized species that, although of hybrid origin, are regularly treated similarly to other species of non-hybrid origin; however, a hybridogenous genus may also contain hybrids (including intergeneric ones).” “Ex. 1bis. Majovskya ×ambigua (Decne.) Sennikov & Kurtto (in Memoranda Soc. Fauna Fl. Fenn. 93: 63. 2017) is considered to have originated from the cross between Chamaemespilus alpina (Mill.) K. R. Robertson & J. B. Phipps and Aria edulis (Willd.) M. Roem. Sennikov & Kurtto (l.c.) treated it as a non-stabilized intergeneric hybrid (for which, however, the correct name is ×Chamaearia ambigua (Decne.) Mosyakin & McNeill in Taxon 72: 442-443. 2023) but placed it in a hybridogenous genus. Despite that, their combination is considered correct and acceptable under certain taxonomic treatments, e.g. if all crosses between Chamaemespilus Medik. × Aria (Pers.) Host are treated as belonging to a hybridogenous genus but not a nothogenus.” If our proposed amendment is adopted, the definitions of a hybridogenous genus and a hybridogenous species should be added to the Glossary. We are grateful to Nicholas J. Turland (Botanischer Garten und Botanisches Museum Berlin, Freie Universität Berlin, Germany) and John H. Wiersema (Smithsonian Institution, Washington, D.C., U.S.A.) for their useful comments and editing.