(2977) Proposal to reject the name Robinia pyramidata ( Fabaceae )
2023; Wiley; Volume: 72; Issue: 4 Linguagem: Inglês
10.1002/tax.13011
ISSN1996-8175
Autores Tópico(s)Botanical Research and Chemistry
Resumo(2977) Robinia pyramidata Mill., Gard. Dict., ed. 8: Robinia No. 7. 16 Apr 1768 [Angiosp.; Legum.], nom. utique rej. prop. Typus: non designatus. Robinia pyramidata was described by Philip Miller in the eighth edition of The gardeners dictionary (Miller, Gard. Dict., ed. 8: Robinia No. 7. 1768), based on an account of a plant discovered by Charles Plumier in the West Indies at the end of the 17th century and on the specimens collected by William Houstoun in Mexico in the 1730s. We have recently established that these two elements belong to two very different legume taxa, described independently, and many years after Miller's work, as Poitea multiflora (Sw.) Urb. (Urban, Symb. Antill. 2: 291. 1900) and Erythrostemon yucatanensis (Greenm.) Gagnon & G.P. Lewis (Gagnon & al. in PhytoKeys 71: 126. 2016) var. yucatanensis. This taxonomic confusion not only makes the correct application of Miller's name ambiguous, but it also threatens the priority of the names of both taxa included by Miller in its circumscription. Plumier's material, cited by Miller in synonymy as “Pseudoacacia flore pyramidato coccineo Plum. Cat. 19” (Plumier, Nov. Pl. Amer.: 19. 1703), belongs to Poitea multiflora (Sw.) Urb., a small tree (up to 2.5 m tall) with pinnately compound leaves and bright red flowers in loose pyramidal racemes, endemic to Haiti and the Dominican Republic (Lavin in Syst. Bot. Monogr. 37: 1–87. 1993). A detailed drawing directly corresponding to Plumier's description is held at the library of the National Museum of Natural History in Paris, France (Plumier, “Botanicum Americanum …” MSS vol. 7 t. 142). Miller did not have access to this illustration, but its black and white copy reproduced by Johannes Burman (in Plumier, Pl. Amer.: t. 233, fig. 1. 1760) was available to him according to the sale catalogue of his library (Baker & Leigh, Cat. Libr. Philip Miller: 11. 1774). Both the original plate and its published copy, however, clearly show a plant with once-pinnate leaves, which is at odds with the bipinnate leaves reported by Miller for his own species. Houstoun's material, cited by Miller in the description of Robinia pyramidata, belongs to Erythrostemon yucatanensis (Greenm.) Gagnon & G.P. Lewis var. yucatanensis according to our studies. This medium-size tree (up to 20 m tall) with bipinnate leaves and pyramidal inflorescences of bright yellow flowers is native to southeastern Mexico and the northern parts of Belize and Guatemala (Lewis, Caesalpinia: Revis. Poincianella-Erythrostemon Group: 81. 1998). Miller's own specimen in the General Herbarium at BM (BM000952035) was collected by Houstoun in Campeche. A duplicate in the Sloane Herbarium (H.S. 317 fol. 73), also at BM, is identified by Miller as “Poinciana flore luteo, pinnis foliorum latissimis Houst.”. Erythrostemon yucatanensis, to which both specimens belong, is part of the Caesalpinia Group, a large pantropical clade of around 205 species of legumes in subfamily Caesalpinioideae, morphologically and genetically very different from the Robinieae tribe of subfamily Papilionoideae, where Poitea multiflora is correctly placed (Lavin & Sousa in Syst. Bot. Monogr. 45: 1–165. 1995; Gagnon & al., l.c.: 1–160). The only noticeable similarity between these two taxa is their pyramidal inflorescences, which possibly fooled Miller into thinking that they were conspecific. This confusion is also reflected in the somewhat idiosyncratic description of R. pyramidata, in which Miller combined the elements of Erythrostemon (a 30 feet [ca. 9 m] tall tree with bipinnate leaves and prominent lenticels) with the floral characters of Poitea (scarlet-red flowers in pyramidal inflorescences). Because of this taxonomic mix-up, we think it is best to propose Miller's name for outright rejection under Art. 56.1 (Turland & al. in Regnum Veg. 159. 2018), which will also preserve the current usage of the names for the two taxa included by Miller in its circumscription. Since its publication in 1768, Robinia pyramidata has attracted little attention in the taxonomic literature. Thomas Martyn, the editor of the ninth edition of The gardeners dictionary, renamed it as Caesalpinia pyramidata (Mill.) Martyn (in Miller, Gard. Dict., ed. 9: Caesalpinia No. 4. 1795–1807), but this escaped the attention of the compilers of Index Kewensis (Jackson, Index Kew. 1. 1893) and Martyn's new combination is currently not listed on its online derivative, IPNI (International Plant Names Index, http://www.ipni.org, accessed 20 Mar 2023), although R. pyramidata is included in both resources. James Britten and Edmund Baker (in J. Bot. 35: 227. 1897) briefly mentioned Miller's name under “Caesalpinia sp.” in their account of the Central American legumes collected by William Houstoun. Paul Standley (Fl. Yucatan: 284. 1930) tentatively synonymised it with Caesalpinia pulcherrima (L.) Sw. in his treatment of legumes for the Flora of Yucatan. POWO currently lists R. pyramidata under Cenostigma gaumeri (Greenm.) Gagnon & G.P. Lewis, but without any supportive data (Plants of the World Online, http://www.plantsoftheworldonline.org, accessed 27 Mar 2023). The limited and conflicting usage of Robinia pyramidata is in stark contrast to the frequent and taxonomically consistent citations of the names of the two taxa included by Miller in its circumscription. Poitea multiflora (Sw.) Urb., based on Clitoria multiflora Sw. (Prodr.: 106. 1788), is mentioned in no less than 10 publications spanning the current and the last century (e.g., Rydberg in Britton & al., N. Amer. Fl. 24: 242. 1924; Lavin & Sousa, l.c.: 79; Acevedo-Rodríguez & Strong in Smithsonian Contr. Bot. 98: 454. 2012). Erythrostemon yucatanensis (Greenm.) Gagnon & G.P. Lewis and its synonym Poincianella yucatanensis (Greenm.) Britton & Rose (in Britton & al., N. Amer. Fl. 23: 330. 1930), based on Caesalpinia yucatanensis Greenm. (in Publ. Field Columb. Mus., Bot. Ser. 2: 252. 1907), appear in twice as many books and scientific papers (e.g., Standley & Steyermark in Fieldiana, Bot. 24(5): 105. 1946; Durán & al. in Harvard Pap. Bot. 3: 288. 1998; Campos-Ríos & Cabrera in Polibotanica 22: 115. 2006; Villaseñor in Revista Mex. Biodivers. 87: 755. 2016; Banks & Lewis in Bot. J. Linn. Soc. 187: 62. 2018; Ortiz-López & al. in Molecules 27(17): 5494. 2020). If our proposal to reject Miller's name were not accepted, typifying Robinia pyramidata on Plumier's plate or on Houstoun's material could, in theory, fix its application to Poitea multiflora or Erythrostemon yucatanensis var. yucatanensis. This action, however, would also necessitate publishing a new combination for one of these two taxa, depending on which element was chosen as a type, because Miller's binomial is the source of the oldest epithet available for both of them (Art. 11.4). It would be very disruptive to taxonomy to change such well-established and consistently used plant names. Selecting one of Houstoun's specimens as a lectotype of R. pyramidata would also impact on the names of two other varieties currently recognised within E. yucatanensis, i.e., E. yucatanensis var. chiapensis (G.P. Lewis) Gagnon & G.P. Lewis (Gagnon & al., l.c.: 127) and E. yucatanensis var. hondurensis (G.P. Lewis) Gagnon & G.P. Lewis (Gagnon & al., l.c.: 127). Designating R. pyramidata Mill. as a nomen utique rejiciendum, as proposed by us here, would on the other hand easily eliminate the need for these nomenclatural changes and protect the use of both P. multiflora and E. yucatanensis. JW, https://orcid.org/0000-0002-2329-9186 GPL, https://orcid.org/0000-0003-2599-4577
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