Oxalis niederleinii R. Knuth (1919: 299)

Nuernberg-Silva, Anelise & Fiaschi, Pedro, 2021, Taxonomic revision and morphological delimitation of Oxalis sect. Ripariae (Oxalidaceae), Phytotaxa 529 (1), pp. 125-159 : 142-144

6. Oxalis niederleinii R. Knuth (1919: 299) . Type (lectotype designated by Lourteig 1983: 69):— ARGENTINA.

Misiones: Pirapitai, October 1892, G. Niederlein 243d ( S-R-9790 [fragm. From B] image of the lectotype available at https://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen.s-r-9790). (figs. 11–12).

= Oxalis refracta var. debilis Saint-Hilaire (1825: 119) . Type (lectotype designated by Lourteig 1983: 67, first-step; second-step designated here):— URUGUAY. Arroyo del Rosario, December 1816 –1821, A. Saint-Hilaire C²2326 (P02440263! image of the lectotype available at https://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen.p02440263, isolectotypes: MPU018620 [web]!, P02440264!, P02440265!).

= Oxalis refracta var. grandiflora Briquet (1899: 155) . Type (lectotype designated here:— BRAZIL. Rio Grande do Sul: Porto Alegre, endroits incultes et talus de l’Avenida Brazil, October 1897, E.M. Reineck & J. Czermak 32 ( G00414388 [photo]!).

= Oxalis refracta var. hirsuta Arechavaleta (1900: 236) . Type:—Not designated.

= Oxalis refracta var. erecta Arechavaleta (1900: 237) . Type:—Not designated.

Erect herb. Stem ca. 25 cm long; shorter hairs ca. 0.1 mm long, patent and descending and/or curved, occasional to moderate; longer hairs 0.5–1 mm long, patent, ascending and descending, moderate; glandular hairs ca. 1 mm long, occasional to moderate; internodes 0.3–2.7 cm long. Stipules ca. 2 × 2 mm, rectangular, connate to the petiole, hairs ca. 1 mm long; petioles 1–3.5 cm long; shorter hairs 0.1 mm long, patent and descending, sparse to moderate; longer hairs 0.5–1 mm long, patent, ascending to descending, sparse to moderate; pulvina ca. 0.3 mm long. Leaf blades 4–22 × 6–24.6 mm, membranous, depressed obovate to widely depressed obovate, concolours, the base cuneate, the apex cleft, sinus markedly U-shaped, generally symmetrical with respect to the central vein; hairs ca. 0.5 mm long, patent, occasional to sparse adaxially, ca. 0.5 mm long, appressed to ascending, sparse to moderate abaxially. Dichasia with 2–13 flowers, as long as the leaves; peduncle 3.5–12.5 cm long; shorter hairs 0.1 mm long, patent and descending, moderate, sometimes curved; longer hairs 0.5–1 mm long, patent, ascending and descending, moderate; glandular hairs ca. 0.5 mm, sparse to moderate; bracts 1–3 mm, lanceolate, hairs ca. 0.5 mm long; bracteoles 0.5–1.5 mm, lanceolate. Pedicels 0.5–12 mm long; sepals 3–4 × 1 mm, base rounded, apex acute; shorter hairs ca. 0.2 mm long, thin, patente or ascending, moderate; longer hairs 0.5–0.8 mm long, ascending, sparse; glandular hairs ca. 0.2 mm long, occasional to moderate; petals yellow, 11–15 mm long, spatulate, the apex crenate-denticulate, adaxially with glandular hairs; shorter stamens 2.5–3 mm long, glabrous; longer hairs 5–5.5 mm long, ascending; pistil 5.5–7 mm long, hairs ascending, abundant, stigmas papillose. Capsules 2–5(6–10) × 3–5 mm, depressed ovoid to ovoid, 5-lobed, hairs ca. 1 mm long, ascending, moderate. Seeds 1–3 per locule, 2.1–2.5 × 1.2–1.5 mm, elliptic, the base rounded, the apex acute.

Distribution and habitat: —This is the most common species of Oxalis sect. Ripariae , with a wide distribution in southern Brazil, including São Paulo state ( Fiaschi & Conceição 2005), Argentina ( López 2017), Paraguay, and Uruguay (fig. 12). It is apparently indifferent to specific soil conditions, and has been collected at forest edges, roadsides, and even sidewalk crevices in large towns.

Phenology: —Flowers and fruits have been collected throughout the year.

Conservation status: —Due to its wide extent of occurrence and habitat generalism, Oxalis niederleinii should be regarded as of least concern (LC) according with IUCN (2017) categories and criteria.

Nomenclatural notes: — Saint-Hilaire (1825) proposed to distinguish “ Oxalis refracta var. α” (i.e., O. refracta var. refracta ) and O. refracta var. debilis . Because the epithet “debilis” was occupied by Oxalis debilis R. Knuth, Knuth (1919) decided to propose the replacement name Oxalis niederleinii R.Knuth for recognizing this taxon at the species level ( Lourteig 1983, 2000).

Typification of Oxalis refracta var. debilis : — Saint-Hilaire (1825) described Oxalis refracta var. debilis with a brief diagnosis and adding “[inveni in] Decembre in sylvulis humidis umbrosisque ad ripas rivuli dicti Arroio del Rosario, provincial Cisplatina”. Lourteig (1983) cited two samples from P (Saint-Hilaire C 2 2326) as the “ holotype and isotype” (actually a lectotypification), but she did not discriminate these two samples. Among three Saint-Hilaire C 2 2326 specimens traced at P, we chose P02440263 as the second-step lectotype because it bears a complete specimen, with roots and flowers, and fits unequivocally the original description.

Typification of Oxalis refracta var. grandiflora : —In the original description of Oxalis refracta var. grandiflora, Briquet (1899: 155) cited “ E.M. Reineck & J. Czermak 32 ”, which was also cited by Knuth (1930), but without indicating the herbarium of deposit. There are two specimens collected by these authors at G: E.M. Reineck & J. Czermak 32 (field no.) (G00414388; 1/2, plus fragment; 2/2) and E.M. Reineck & J. Czermak 59 (G00414387), the latter of which was incorrectly cited as the type by Lourteig (1983). The material chosen here as lectotype follows the protologue and was annotated by Briquet.

Taxonomic notes: — Oxalis niederleinii can be easily distinguished from other species of Oxalis sect. Ripariae but may be similar to O. corniculata L. (O. sect. Corniculatae ), from which it can be distinguished by the presence (vs. absence) of glandular hairs, and depressed ovoid to ovoid (vs. narrowly ellipsoid) capsules with 1–3 seeds 2–2.5 × 1–1.4 mm per locule (vs. ca. 12 seeds 1.2–1.5 × 0.9–1 mm per locule).

Oxalis niederleinii has several synonyms due to its wide morphological variability. Populations from different localities do not display unique morphological atributes that allow recognition of infraspecific taxa, and the variation appears to be more related to environmental variation throughout its latitudinal distribution. The wide morphological variation of Oxalis niederleinii is specially observed in hairs density (from glabrescent to moderate), type (simple or glandular), and size (0.1–1 mm long), and leaflet size (4–22 × 6–24.6 mm) and shape (from depressed obovate to widely depressed obovate).

Specimens examined: — ARGENTINA. Buenos Aires: Isla Martín García, camino a la casa de Bombas , 12 November 1994, J. A . Hurrell 2100 ( MBM, RB00271098 [web], SI); Isla Martín García, camino de Los Alamos, 9 December 1993, J. A . Hurrell 1560 ( SI) ; Corrientes: Curuzú Cuatiá, Estancia Araguá , 2 November 1979, T. M . Pedersen 12519 ( CTES, ICN, MBM); Capital, 7 September 1983, A . Schinini 23855 ( CTES, RB00271124 [web]); Santo Tomé, Ayo. Chimiray , 23 September 1974, A . Krapovickas 26133 ( CTES); Monte Caseros, Orillas del Timboi , Estancia La Potota , 17 October 1949, E. G . Nicora 4947 ( SI); Paso de los Libres, Laguna Mansa, 21 September 1973, A . Schinini 7230 ( CTES, RB, RB00271124 [web]) ; Entre Ríos: Diamante, 15 May , A . Burkart et al. 25341 ( SI); Misiones: Apóstoles, Alrededores del pueblo, 4 September 1985, M. E . Múlgura 373 ( SI); Candelaria; Bonpland , s.d. P . Jorgensen 32335 ( CTES, RB00271128 [web]); Eldorado, 9 July 1972, A . Schinini 4875 ( CTES); Guaraní, Parque Provincial Moconá, 27°09’S, 53°54’W, 26 February 1995, F. O . Zuloaga 5019 ( CTES); Iguazú, Parque Nacional Iguazu, Ruta 101, Ayo.Yacui , 8 August 1995, R. O . Vanni 3400 ( CTES); Oberá, 10 August , S. M . Pire 405 ( CTES, SI); San Pedro, Ruta Provincial 16, hacia Parque Provincial Esmeralda, 26°40’07’’S 53°57’40’’W, 28 November 2004, F. O . Zuloaga 8244 ( SI) ; Tucumán: Chicligasta, Quebrada de las Pavas , puesto Sta. Rosa , 24 March 1953, A. G . Schulz 8409 ( SI) . BRAZIL. Paraná: Araucária , 25°37’42.8’’S, 49°27’21.5’’W, 1 October 2016, A . Nuernberg et al. 1810 ( FLOR) ; Bocaiúva do Sul, Barra Grande , G . Hatschbach 4070 ( MBM, P); Colombo, Rio Palmital , 1 January 1973, G . Hatschbach 32808 ( CTES, MBM027680 [web], MO2574919 [web], MO1061577 [web]); Foz do Iguaçu, Parque Nacional do Iguaçu , 07 May 1949, A. P . Duarte & E . Pereira 1634 ( FLOR, RB); Guarapuava, 27 September 2009, O. S . Ribas et al. 8318 ( MBM); Ivaí, Rio Palmital , G . Hatschbach 22367 ( MBM, P) ; Laranjeiras do Sul, Estrada Campo Novo - Pinhal Ralo , J. C . Lindeman et al. 2950 ( MBM, NY00470506 [web], UB); Ponta Grossa, 02 November 1928, F. C . Hoehne s.n. ( NY01096316 [web], P, SP23335 , SPF00140633 [web]) ; Rio Branco do Sul, Rod. PR-092, 10 January 1985, G . Hatschbach 48830 ( FLOR, FUEL, MBM, RB); Roncador, Aterrado Alto, G . Hatschbach 32904 ( MBM, P) ; Rio Grande do Sul: Agudo, Morro Agudo , 27 September 1985, D. B . Falkenberg 3333 ( FLOR, MBM); Bento Gonçalves, 29 September 1986, F . Vieira s.n. ( FLOR21073 ) ; Caçapava do Sul, Parque Nacional do Iguassú , 03 October 1961, E . Pereira 6634 ( RB00652613 [web], UB); São Francisco de Assis , October 2016, A . Nuernberg et al. 1837 ( FLOR) ; São Pedro do Sul, 29°30’S, 54°08’W, 28 October 2016, A . Nuernberg et al. 1828 ( FLOR) ; Santa Catarina: Araranguá , Morro dos Conventos, G . Hatschbach et al. 57867 ( MBM, P); Ipira, Rio do Peixe , 16 September 1994, G . Hatschbach et al. 61075 ( FLOR, MBM, P); Itapiranga, Linha Coqueiro, 01 January 1964, R . Reitz & R. M . Klein 16821 ( CRI006040 [web], CRI006041 [web], FLOR, P); Mondaí, 28 August 1964, R. M . Klein 5622 ( CRI006039 [web], FLOR); Nova Teutônia, 27 September 1943, P . Plaumann 133 ( RB); São Joaquim, próximo da ponte do rio invernadinha na estrada que liga São Joaquim a São José dos Ausentes, 28°26’26.44’’S, 49°53’18.55’’W, 4 November 2016, A . Nuernberg et al. 1850 ( FLOR); São Miguel d’Oeste, Canela Gaúcha , 01 September 1964, R. M . Klein 5744 ( CRI006043 [web], FLOR, P); Urubici, 27°59’S, 49°38’W, 4 November 2016, A . Nuernberg et al. 1857 ( FLOR) . PARAGUAY. Alto Paraná: Tatiyupi , sitios bajos e humedos, 8 July 1987, R . Degen 241 ( CTES) ; Itapúa. Bella vista, 7 October 1993, A . Krapovickas & C. L . Cristóbal 44489 ( CTES) . URUGUAY. Florida: Timote, Santa Clara , 10 October 1943, R . Gallinal et al. PE 5309 ( MO 04782008 [web]) ; Montevideo: Montevideo, F. Sellow s.n. (M-0172320 [web]) .