Oxalis riparia Norlind (1926: 18)

Nuernberg-Silva, Anelise & Fiaschi, Pedro, 2021, Taxonomic revision and morphological delimitation of Oxalis sect. Ripariae (Oxalidaceae), Phytotaxa 529 (1), pp. 125-159 : 151-153

10. Oxalis riparia Norlind (1926: 18)

≡ Oxalis villosa Progel (1877: 495) , nom. illeg. non O. villosa Bieberstein (1808: 355) , nec O. villosa Don (1831: 762) ≡ Acetosella villosa (Progel) Kuntze (1891: 91) . Type:—Illustration CIV [104], Fig. II in Progel (1877) (lectotype designated here). Epitype (designated here):— BRAZIL: Minas Gerais, opp. Caldas, s.d., G.A. Lindberg 297a ( BR526860 [web]! image available at https://plants.jstor.org/stable/viewer/10.5555/al.ap. specimen.br0000005268603?loggedin=true, isoepitype: SR-9808 [web]!) (figs. 16, 17).

= Oxalis irreperta Lourteig (1983: 47) , syn. nov. Type:— BRAZIL. Paraná, Cerro Azul, Río Ribeira, 14 ago 1966, J.C. Lindeman & J.H. de Haas 2314 (U0005430 [web]! image available at https://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen.u0005430, isotypes: CTES0000699 [web]!, MBM fide Lourteig, P02286675!).

Stoloniferous herb. Stem slender 0.30–1 m long; hairs 0.5–1 (2) mm long, appressed, ascending or descending, rarely very occasional, normally moderate to abundant, very abundant in younger parts; internodes (0.5) 1.1–12.7 cm long, nodes slightly radicant. Stipules absent, or stipules inconspicuous 3–4.5 × 1–1.5 mm, elongated, narrow, apex semicircular, glabrous, petiole 2.5–9.5 (18) cm long; shorter hairs 0.5–1 mm long, ascending, patent and descending, abundant, rarely occasional; longer hairs 1.5–2 mm long, patent, very abundant in younger parts, or absent in some specimens; pulvina ca. 1 (1.5) mm long; hairs 0.5–1 mm, appressed, ascending or patent, moderate to abundant. Leaf blades 0.8–3.6 × 1–3.1 (4.1) cm, widely depressed obovate to widely obovate, chartaceous or membranous, slightly discolorous, the base cuneate to obtuse, the apex emarginate to obcordate, occasionally mucronulate, or rarely cleft, hairs ca. 0.5 mm long, appressed, sparse to moderate, rarely occasional adaxially; hairs ca. 0.5 mm long, appressed, sparse to abundant, rarely occasional abaxially. Dichasia with 3–7 flowers, longer than the leaves, peduncle 1.7–9 (11) cm long, glabrous or shorter hairs ca. 0.2 mm, appressed, ascending or descending, very occasional or most commonly moderate to abundant; longer hairs 0.5–1 mm, ascending, patent and descending, moderate to abundant, or rarely hairs ca. 0.2 mm, appressed, occasional, or absent; bracts 2–6 × 0,3– 1 mm, lanceolate, hairs (0.2) 1 mm long, appressed, moderate to abundant, rarely occasional; bracteoles 1,5–2 × 0.2–0.5 mm, lanceolate. Pedicels 5–24 mm long; sepals 4–7 × 1–2 mm, base rounded, apex acute, hairs (0.2) 1 mm long, ascending, sparse; petals yellow, 9–18 mm long, spatulate, the apex crenate-denticulate, adaxially with very occasional glandular hairs; shorter stamens ca. 3–5 mm long, glabrous, longer 4.5–7 mm long, with hairs ascending; pistil 7–10 mm long, hairs ascending, abundant, stigmas papillose. Capsules 5–7 × 2–3 mm, ovoid, 5-lobed, hairs ca. 1 mm long, ascending, sparse. Seeds 1–3 per locule, ca. 2.1 × 1.1 mm, elliptic, the base rounded, the apex acute.

Distribution and habitat: —This species was previously reported from the states of Minas Gerais, São Paulo, and Paraná ( Lourteig 1983, 2000), and here the known distribution is expanded to Santa Catarina and Rio Grande do Sul states (fig. 17), due in part to the inclusion of Oxalis irreperta as its nomenclatural synonym (see below). Oxalis riparia usually grows at riverbanks and riparian forest edges.

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

Conservation status: — Oxalis riparia has an extent of occurrence (EOO) of about 133,244 km ², with an area of occupation (AOO) of ca. 60 km ². There are only few recent collections of this species in the last ten years, but it is presumably protected at some protected areas, so we suggest it should be categorized as near threatened (NT).

Typification of Oxalis riparia : —According to Lourteig (1983), the “type” of O. villosa Progel (“ In Brasilia meridionali: Sello ”, B), i.e., the specimen belonging to the original material, was destroyed in 1943 during World War II. When Norlind (1926) proposed O. riparia as a replacement name for O. villosa Progel , he did not indicate any type. The neotypification later carried out by Lourteig (1983: 46) was not legitimate, due to the existence of the original illustration of flower details by Progel (1877: Tab. CIV, Fig. II). This illustration is therefore selected as the lectotype. However, as it does not allow an unambiguous identification of the taxon, an epitype is also indicated, in accordance with Art. 9.9 of the ICN.

Taxonomic notes: — Oxalis irreperta is here treated as a synonym of O. riparia . According to Lourteig (1983) these two species could be distinguished by the inconspicuous stipules in Oxalis irreperta (vs. absent in O. riparia ), and a sparser indumentum in O. irreperta when compared with O. riparia . However, the type of Oxalis irreperta does not bear stipules, and only differs by the indumentum density from other samples of O. riparia from the same locality (Cerro Azul, Paraná). Stipules were observed in R. Reitz & R.M. Klein 13588, whose leaves have longer petioles and glabrescent leaves with the apex cleft, while another sample with similar leaves (A. Butzke et al. s.n.) do not bear stipules, suggesting that the features used by Lourteig (1983) to distinguish the two species might not justify their recognition.

Oxalis riparia can be distinguished from other species of O. sect. Ripariae by the combination of rhizomatose herbaceous habit and leaflets incised at apex, while the remaining species either lack an incised apex ( O. bifrons , O. hepatica , and O. sarmentosa ) or have a decumbent shrubby ( O. eriocarpa and O. refracta ) or stoloniferous herbaceous ( O. niederleinii ) habit.

Specimens examined: — BRAZIL. Minas Gerais: Caldas , August 1854, G. A . Lindberg 297 ( S-R-9808 [web]); 12 October 1855, I . Regnell 42 ( P); Campinas, próxima a estrada para Carmo de Minas , R . Mello-Silva et al. 82 ( SPF00067645 [web]); Delfim Moreira , 21 April 1939, M . Kuhlmann & Gehrt s.n. ( SP, CEN, SPF00140648 )[web]; 18 October 1950, M . Kuhlmann & A . Gehrt ( SP40242 [web]); Lagoa Santa , 28 August 1964, J. E. B . Warming 1020 ( NY00470564 [web]!); Lambari , 1935, P. P . Horta s.n. ( RB00271012 [web]); March 1942, H . Delforge s.n. ( RB); Ouro Fino, 11 May 1927, F. C . Hoehne s.n. ( SP19576 , SPF00163085 [web]); Poços de Caldas , 20 January 1980, A . Krapovickas & C. L . Cristóbal 35402 ( CTES); Santa Rita do Sapucaí, Serra da Bela Vista , 6 July 1996, O. S . Ribas 1424 ( MBM); São Thomé das Letras, Baipendi , 14 July 1950, A. C . Brade & Cepparieio s.n. ( RB) ; Paraná: Adrianópolis, Parque Estadual das Lauráceas , trilha da caverna, 24°51’12.7’’S, 48°43’08.6’’W, 14 September 2017, E . D. Lozano 3832 ( FLOR, MBM); Cerro Azul, Shaded sandbank of rio Ribeiro at foot of forested steep S-slope, ca. 10 km W of Cerro Azul, 14 August 1966, J. C . Lindeman 2314 ( P); Estrela, 22 July 1970, G . Hatschbach 24514 ( MBM, MO1061595 [web], NY00470563 [web], P, SP); G . Hatschbach 24519 ( SP); barra do Lageado Grande, 31 August 1978, G . Hatschbach 41571 ( MBM, MO1061593 [web], P, SP) ; Rio Grande do Sul: Erechim, estrada de Aratiba , 20 October 1995, A . Butzke et al. s.n. ( NY3321126 [web]) ; Santa Catarina: Santa Catarina: Canoinhas , 26 October 1962, R . Reitz & R. M . Klein 13588 ( CRI006026 [web]!, FLOR, P); Itajaí, rio do Testo (Pomerode), 12 February 1905, F . Muller 417 ( K001198510 [web]!) ; São Paulo: Águas de Prata, Reserva Estadual de Águas de Prata , 21°52’S, 47°20’W, 21 March 1994, A. B . Martins 31415 ( SP, SPF00098475 [web]!); Amparo, Monte Alegre , estação experimental, April 1943, M . Kuhlmann 472 ( SP, SPF00140649 [web]!); Joanópolis, Estrada para Campos de Jordão , 13 October 1979, P. G . Windisch 2518 ( P) ; São Paulo, Serra da Bocaina, caminho de Alambari , 1 January 1932, B . Lutz 736 ( P) .