Oxalis polymorpha Mart. ex Zucc., 1825

Fiaschi, Pedro, Cabral, Fernando Santos, Caballero, Leonardo Ronald Gaspar & Lima, Duane Fernandes, 2025, Updating the taxonomy of polymorphic plant taxa: six Atlantic Forest species segregated from the widely circumscribed Oxalis polymorpha Mart. ex Zucc. (Oxalidales, Oxalidaceae), European Journal of Taxonomy 989, pp. 144-188 : 151-156

Oxalis polymorpha Mart. ex Zucc.

Figs 1, 5

Oxalis polymorpha Mart. ex Zucc. ( Zuccarini 1825: 174) . – Oxalis polymorpha Mart. ex Zucc. var. staphyleoides Zucc. ( Zuccarini 1825: 175) . – Oxalis staphyleoides (Zucc.) Progel ( Progel 1877: 509) . – Type: BRAZIL – “Provinciae Bahiensis” [Bahia] • habitat in sylvis Catingas dictis ad flumen St. Francisci; s.d. [Oct. 1818]; C.F.P. von Martius s.n.; lectotype: M [M-0172333], designated by Lourteig (1994: 150).

Other material examined

BRAZIL – Bahia • Blanchet 5256; P [photo] • Almadina, Faz. Beija-Flor, Serra da Pancadinha ; 11 Aug. 1972; Pinheiro 1902; P [photo] • same data as for preceding; Pinheiro 1904; CEPEC, P [photo] • Almadina ; 18 Jul. 1978; Mori et al. 10261; CEPEC • Almadina, Faz. Beija-Flor, ca 3 km al Sul de Almadina ; 19 Jul. 1978; Mori et al. 10298; CEPEC, P [photo] • Ibicaraí, Itapé , lado sul; 3 Mar. 1971; Pinheiro 1035; P [photo] • same data as for preceding; Pinheiro 1041; P [photo] • Ibicaraí, Rod. BR-415, a 2 km W de Ibicaraí; 17 Mar. 1979; Mori et al. 11602; CEPEC, P [photo] • Ilhéus, Área do CEPEC; 2 Oct. 1979; Mori 12486; CEPEC, P [photo] • same data as for preceding; 14 Oct. 1981; Hage & Brito 1471; CEPEC, P [photo] • Itabuna ; 16 Dec. 1966; Emygdio et al. 2423; R • Mucuri, Fazenda Afonsópolis; 7 Aug. 1965; Lanna Sobrinho 1130 ; P [photo] • Mucuri , “próx. à ponte sobre o Rio Mucuri ” [close to bridge above Mucuri River ]; 15 Sep. 1978; Mori et al. 10535; CEPEC, P [photo] • Porto Seguro , junto à fonte; 30 May 1962; Duarte 6721; P [photo] • Porto Seguro ; 19 Oct. 1969; Jesus 477; CEPEC • Porto Seguro ; 28 Nov. 1970; Emygdio & Emmerich 3012; P [photo] • Porto Seguro ; 21 Mar. 1974; Harley 17217a; CEPEC, P [photo], RB • 9 Oct. 1969; Jesus 478; CEPEC • Porto Seguro, Km 16 de Porto Seguro-Eunápolis; 17 Jul. 1981; Brito & da Vinha 41; CEPEC • Porto Seguro ; 13 Oct. 2006; Amorim et al. 6447; CEPEC, HUEFS • Prado , “Parque Nacional do Descobrimento” [Descobrimento National Park]; 17°11′ S, 39°20′ W; 3 Nov. 2009; Matos et al. 1916; CEPEC • Santa Cruz Cabrália ; 21 Mar. 1978; Mori et al. 9767; CEPEC • Santa Cruz Cabrália ; 18 Oct. 1978; Mori et al. 10817; CEPEC, P [photo] • Santa Cruz Cabrália , “Estação Ecológica do Pau-Brasil” [Pau-Brasil Ecological Station]; 3 Nov. 1978; Euponino 350; P [photo] • Santa Cruz Cabrália , “Estação Ecológica do Pau-Brasil” [Pau-Brasil Ecological Station]; 4 Mar. 1983; Brito & da Vinha 184; CEPEC • Santa Cruz Cabrália ; 21 Nov. 1984; Santos 456; CEPEC .

Typification remarks

Zuccarini (1825) described O. polymorpha based on a material collected by von Martius while the Bavarian naturalist was traveling in the São Francisco River, presumably in the surrounding of Malhada or Carinhanha, in the state of Bahia, in October of 1818. This specimen was mounted in M (Fig. 1) and faithfully represented in the tab. III of Zuccarini (1825).

While describing O. polymorpha, Zuccarini (1825) proposed several varieties (a to f; Table 1), which, in his opinion, represented a morphological range of several other interconnected forms (“ polymorphae hujus specie varietates, plurimis allis formis inter se conuexae ”). The first of these varieties (“var. a) staphyleoides ”) was characterized as presenting “leaflets always subrhombic, acuminate, pubescent, and peduncles with simple or bifid divisions” (i.e., the dichasial branches). As interpreted by Lourteig (1994), this variety and the name that it received at species level, O. staphyleoides (Zucc.) Progel , were typified by the same specimen used to typify the species, i.e., the sample gathered by von Martius in the state of Bahia.

Another specimen also collected by Martius in a nearby location, but presumably on the other side of the São Francisco River, in the state of Minas Gerais, and housed at G (G00383166) (Fig. 4), was listed by Lourteig (1994) as an isotype of O. polymorpha . Despite the overall similarity of these two specimens (Figs 1, 4), we prefer not to treat this material as belonging to the same gathering, not only because it was collected on the other side of the river São Francisco, but also because it differs from the type by the more congested leaves in the stem distal end, the less pronounced indumentum on the distal end of stem, and the less pronounced leaf venation on the abaxial side of the leaflet blades (Fig. 4).

Fig. 4 (on next page). A. Specimen (G00383166) that was listed by Lourteig (1994) as an isotype of Oxalis polymorpha Mart. ex Zucc. , but not accepted as type collection here (see Fig. 1 and discussion in “Typification remarks”). B. Detail of the inflorescence dichasial branches. Modified from a high-resolution image provided by the Conservatoire et Jardin botaniques de Genève.

General remarks

Other than the type, which was likely collected in semideciduous forests along the São Francisco River, we are not convinced that other specimens can be unambiguously assigned to O. polymorpha ; however, to help in the application of this name, we list above several specimens collected in the southern Bahia coastal rainforests ( Fig. 5 ) that could also belong to this taxon in the narrower circumscription adopted here.

Oxalis polymorpha includes plants with the young stem with abundant to very abundant, curved or patent hairs, leaves either congested and almost forming one or more pseudo-whorls or more or less equally distributed along the stem, leaflet blades with moderate to abundant, appressed hairs, glabrescent in the adaxial surface, more densely arranged abaxially, apex usually acute to acuminate, lateral leaflets with a slightly to strongly asymmetric base, inflorescences with the dichasial branches usually elongated, having the flowers distally congested or, less commonly, distributed along the branches, pedicels lacking glandular hairs, corollas ranging from white to slightly pinkish (or even yellow, following the label from Martius s.n., M-0172333), and capsules with short apical prolongations, up to ca 0.5 mm long (see Table 3 for a comparison with species segregated here).

Fiaschi (2014) adopted a very wide circumscription for O. polymorpha , as noted from the leaf morphological variation that was illustrated in his fig. 7G–H. Based on the updated circumscription presented here, the first four specimens of this illustration belong to O. decipiens, Amorim 5549 (CEPEC) belong to a yet undescribed taxon, and the remaining specimens belong to O. polymorpha s. str. According to this same author, O. polymorpha is very similar to O. puberula Nees & Mart. , and hardly distinguishable by the acute to acuminate (vs usually obtuse to rounded) leaflet apex. Moreover, despite O. polymorpha appears to differ consistently from O. neuwiedii by the pedicels lacking glandular hairs ( Lourteig 1994; Fiaschi 2014), the distinction between these two species is sometimes confusing, and should be investigated with a more comprehensive sampling using morphometric and molecular data.

To adopt the narrower circumscription of O. polymorpha presented here, several taxa formerly placed as synonymous, treated at infraspecific level, or representing new species whose specimens were previously listed under this taxon are described below.

Figures

Fig. 5. Geographic distribution map of Oxalis polymorpha Mart. ex Zucc. (the single record in the Caatinga domain represents the type) and some of the segregated species recognized here, all of which are endemic to the Brazilian Atlantic Forest domain.