(2959–2960) Proposals to conserve the name Abelmoschus against Laguna, and Pavonia, nom. cons., against the additional names Malvaviscus and Malachra (Malvaceae)

Abstract

The taxonomy of Malvaceae tribe Hibisceae is notoriously complex and optimal generic boundaries have been much debated (see Pfeil & Crisp in Austral. Syst. Bot. 18: 49. 2005). Phylogenetic analyses with novel genetic data enables a new generic classification to be proposed (Hanes, M.M., Blanchard Jr, O.J., Valencia-D., J.E., McLay, T.G.B., Abbott, J.R., McDaniel, S., Barrett, R.L., Mathews, S. & Neubig, K.M., submitted). Assessment of available names at generic rank in preparation for a new classification has revealed three issues of priority that each require decisions on possible conservation of generic names. (2959) Abelmoschus Medik., Malvenfam.: 45. 1787 (ante 9 Mai) [Malv.], nom. cons. prop. Typus: A. moschatus Medik. (=) Laguna Cav., Diss. 2, [App.]: [V]. Jan–Apr 1786, nom. rej. prop. Typus: L. aculeata Cav., Diss. 3: 173. Feb 1787. Abelmoschus is a well-recognised and agronomically important genus as the source of the fruit of okra, eaten as a vegetable around the world (Lamont in HortTechnol. 9: 179. 1999). The genus Laguna Cav. has usually been treated as a synonym of Hibiscus L.; however, its type and only original species, L. aculeata Cav., is unquestionably a synonym of Abelmoschus ficulneus (L.) Wight & Arn. (okra). This name is based on a single specimen collected near Pondicheri, India, by Couzier and apparently seen by Cavanilles at P (Diss. 3: 173, t. LXXI, fig. 1. 1786). This collection has not been traced; however, the material was illustrated in the protologue in sufficient detail that it can be confidently matched to A. ficulneus by the circa six, narrow epicalyx segments and the shortly beaked, ovoid-oblong capsules with stiff hairs. The figure could serve as lectotype if the original specimen cannot be located and a copy of the protologue and illustration are mounted together on a single sheet at MA (MA 654889). Laguna was included under Hibiscus at a time when Abelmoschus was also included in Hibiscus and appears to have been subsequently overlooked as the earliest name when recognised as distinct from Hibiscus. A decision is therefore required if Abelmoschus is to be maintained, regardless of any taxonomic changes proposed in Hibisceae. Since its description by Cavanilles (Diss. 2, [App.]: [V]. 1786), Laguna has had little acceptance as a genus (e.g., Sprengel, Bot. Gart. Halle: 52. 1800; Willdenow, Sp. Pl. 3: 733. 1800; Gaudichaud, Voy. Uranie, Bot.: 476. 1830; Don, Gen. Hist. 1: 505. 1831), and not at all since Richard, Tent. Fl. Abyss. 1: 71. 1847. IPNI (www.ipni.org; accessed 6 Mar 2023) lists 12 names under Laguna, most of which apply to Hibiscus species, so a new type species could be selected. However, even if this course of action were taken, the name would remain a synonym of Hibiscus under our proposed circumscription, so this is not considered advantageous. In contrast, while sometimes included within Hibiscus (e.g., Don, l.c.: 479; Hochreutiner in Annuaire Conserv. Jard. Bot. Genève 4: 49. 1900), Abelmoschus has been in more or less continuous usage and is currently widely accepted (Fryxell in Syst. Bot. Monogr. 25: 20–24. 1988; Fryxell, Fl. Ecuador 44: 7–8. 1992; Paul, Fl. India 3: 300–310. 1993; Thulin, Fl. Somalia 2: 54–56. 1999; Tang & al. in Wu & Raven, Fl. China 12: 283–286. 2007; Verdcourt & Mwachala, Fl. Trop. E. Africa, Malv.: 75–79. 2009). Six to fifteen species are recognised by most recent authorities, with a number of entities variously recognised as species or subspecies, though a modern global revision is lacking. Web of Science (www.webofscience.com; accessed 22 Mar 2023) returned no references to Laguna as a genus, and 1605 for Abelmoschus. Accordingly we propose to conserve Abelmoschus Medik. (1787) against Laguna Cav. (1786) to maintain the traditional acceptance of Abelmoschus. If this proposal is not accepted, then 6–15 new combinations would be needed in Laguna, which is a relatively small numerical change, but considering the global importance of okra (A. esculentus (L.) Moench, A. manihot (L.) Medik., A. moschatus Medik.) and the horticultural popularity of other Abelmoschus species, such a change would be highly disruptive. Laguna has long been placed in synonymy of Hibiscus, and therefore has minimal recognition as a generic name. (2960) Pavonia Cav., Diss. 2, [App.]: [V]. Jan–Apr 1786 [Malv.], nom. cons. Typus: P. paniculata Cav., Diss. 3: 135. Feb 1787. (=) Malvaviscus Fabr., Enum.: 155. 1759, nom. rej. prop. Typus: M. arboreus Cav., Diss. 3: 131. Feb 1787 (Hibiscus malvaviscus L.). (=) Lass Adans., Fam. Pl. 2: 400, 568. Jul–Aug 1763, nom. rej. Typus: Hibiscus spinifex L. (=) Malachra L., Syst. Nat., ed. 12: 450, 458; Mant. Pl.: 13. 15–31. Oct 1767, nom. rej. prop. Typus (vide Hutchinson, Gen. Fl. Pl. 2: 565. 1967): M. radiata L. (=) Malache B. Vogel in Trew, Pl. Select.: 50. 1772, nom. rej. Typus: M. scabra B. Vogel Pavonia is a well-known genus with its centre of diversity in the Americas, but, as traditionally defined, it is a pantropical genus of 291 species (Fryxell in Fl. Neotrop. Monogr. 76: 1–284. 1999; Govaerts & al. in Sci. Data 8: 215. 2021). Phylogenetic analyses with new molecular data place the type of Pavonia, P. paniculata Cav., in a clade of 15 species sister to a large number of New World Pavonia species (c. 220 monographed by Fryxell, l.c. 1999), but also including the currently accepted genera Malvaviscus Fabr. (Enum.: 155. 1759) (5–11 species; Turner & Mendenhall in Ann. Missouri Bot. Gard. 80: 439. 1993), Malachra L. (Mant. Pl.: 13. 1767) (8 or 9 species; Cervantes-Ceballos & al. in Plants 11: 2808. 2022) and Peltaea (C. Presl) Standl. (in Contr. U.S. Natl. Herb. 18: 113. 1916), nom. cons. (19–21 species; Krapovickas & Cristóbal in Kurtziana 2: 135. 1965; Fernandes-Júnior & Esteves in Phytotaxa 255: 75. 2016). Peltaea is conserved against Peltostegia Turcz. (in Bull. Soc. Imp. Naturalistes Moscou 31(1): 223. 1858). Most of the Old World taxa currently in Pavonia (47 species) belong elsewhere in the Hibisceae, so in order to create monophyletic genera within Hibisceae based on molecular data, Pavonia as we envisage it will be essentially restricted to the Americas, including just a small number of pantropical species. Web of Science (www.webofscience.com; accessed 22 Mar 2023) returned 161 references to Pavonia, 51 to Malvaviscus and 15 for Malachra. The three genera have all been recognised in relatively recent studies (e.g., Bayer & Kubitzki in Kubitzki, Fam. Gen. Vasc. Pl. 5: 288–289. 2003; Fryxell in Syst. Bot. Monogr. 25: 262–270, 288–298, 309–342. 1988; Fryxell, l.c. 1999: 5; Dorr in Smithsonian Contr. Bot. 98: 496–529. 2012). While we do not currently promote the idea, one option is to break up Pavonia further, to maintain one, or all, of the currently recognised genera Malvaviscus, Malachra and Peltaea. Under this option, Pavonia would need to be broken into at least three additional genera to maintain Malvaviscus, an additional genus to maintain Peltaea, and a fifth to maintain Malachra. With Pavonia in the Americas broken up into six separate lineages, the type lineage would likely contain just 15 species. Another option is to conserve Pavonia with a new type; however, this would still require a similar break-up of the genus, which may be no less disruptive, and the largest clade which could bear the name Pavonia would contain less than 50 species. Of the 41 species currently recognised in Malvaviscus, Malachra and Peltaea, 14 already have combinations in Pavonia, so if this proposal is accepted, just 27 new combinations or names would be required to combine the genera. The least disruptive nomenclatural solution for the re-circumscription of Pavonia is to include the smaller genera Malachra, Malvaviscus and Peltaea in a novel concept of Pavonia. However, the first two of these names pre-date the publication of Pavonia, so conservation is necessary before this can be achieved. It is possible that some might suggest splitting up Pavonia further in future, and this is one of the reasons we prefer to conserve Pavonia (rather than rejecting the other names) so it does not prevent someone taking such action. The Pavonia clade contains only a few species of minor or moderate horticultural importance (Fryxell, l.c. 1999: 9–10; e.g., P. hastata, Yue & Ruter in HortScience 56: 732, 2021; Malachra capitata, Cervantes-Ceballos & al., l.c.; Malvaviscus arboreus, Turner & Mendenhall, l.c.) and we consider nomenclatural stability to be the primary consideration in proposing conservation of Pavonia. The name Pavonia has already been conserved against Lass Adans. (Fam. Pl. 2: 400, 568. 1763) and Malache B. Vogel (in Trew, Pl. Select.: 50. 1772). If this proposal is successful, 27 new combinations will be required in Pavonia. If this proposal is not successful, c. 260 new combinations will be required in Malvaviscus, or New World Pavonia will need to be further divided, with up to 210 new combinations required. Conserving Pavonia will not prevent the segregation of genera if that is preferred by future authors. RLB, https://orcid.org/0000-0003-0360-8321 MMH, https://orcid.org/0000-0002-7702-3898 TGBM, https://orcid.org/0000-0001-6405-8007