Oxalis paranaensis Lourteig.

Nuernberg-Silva, Anelise & Fiaschi, Pedro, 2021, Taxonomic revision and morphological delimitation of Oxalis sect. Ripariae (Oxalidaceae), Phytotaxa 529 (1), pp. 125-159 : 147-148

8. Oxalis paranaensis Lourteig. Type (lectotype designated by Lourteig 2000: 309, first-step; second-step designated here):— BRAZIL. Paraná: São José dos Pinhais, Rod. BR2 , Rio Pequeno , 31 September 1961, G. Hatschbach 8288 ( P02440281 ! image of the lectotype available at https://science.mnhn.fr/institution/mnhn/collection/p/item/p02440281; isolectotypes: CTES 0000701 [web]!, FUEL010383 [web]!, MBM0000972 [web]!, MO2476715 [web]!, MU149448 [web]!, P02440282 !, S-R-9795 [web]!, SPF00222700 [web]!, US00005305 [web]!, US 00288643 [web]!) (figs. 12, 14).

Scandent caespitose subshrub. Stem slender, up to ca. 180 cm tall; shorter hairs ca. 0.1 mm long, curved, ascending and patent, very abundant; longer hairs ca. 1 mm long, ascending and patent, abundant; glandular hairs ca. 1 mm long, occasional to moderate; internodes 0.2–3.5 cm long. Stipules 1.5–3 × 1.2 mm, semicircular, the apex connate to the petiole, petioles 1.7–3.8 cm long; hairs as in stem; pulvina ca. 0.1 mm long. Leaf blades 9.5–15.1 × 10–13.5 mm, coriaceous, widely depressed obovate to very widely obovate, discolorous, the base cuneate, the margin revolute, the apex retuse to rounded, sometimes mucronulate; shorter hairs ca. 0.1 mm long, ascending and curved, occasional to abundant adaxially, very abundant abaxially; longer hairs 1–2 mm long, ascending and patent, sparse adaxially, very abundant abaxially; glandular hairs ca. 1 mm long, occasional adaxially, occasional to sparse abaxially. Dichasia with 3 flowers, longer than the leaves; peduncle 5.6–8 cm long, hairs as in stem; glandular hairs moderate; bracts 2.6–4 × 0.5 mm, lanceolate; bracteoles 2 × 0.5 mm, lanceolate. Pedicels 5–11 mm long; sepals 6.5–10 × 2.5–3 mm, base rounded, apex acute; hairs up to ca. 1 mm long, simple and glandular, appressed and ascending, abundant; petals yellow, 13.8– 18.7 mm long, spatulate, the apex crenate-denticulate, adaxially with abundant glandular hairs; shorter stamens ca. 4 mm long, glabrous, longer ca. 6 mm long, with ascending hairs; mid-styled pistil ca. 5 mm long, hairs ascending, abundant, stigmas papillose. Capsules ca. 4 × 4 mm, very widely ovoid, 5-lobed, hairs ca. 2 mm long, patent, abundant. Seeds 1 per locule, ca. 2 × 1.5 mm (immature), widely elliptic to elliptic, the base rounded, the apex acute.

Distribution and habitat: —This species is endemic to the surroundings of Curitiba (Paraná state), where it was found in the municipalities of São José dos Pinhais and Piraquara, always associated to swamps along the Rio Pequeno lake.

Phenology: —Flowers and fruits have been collected from September to March.

Conservation status: — Oxalis paranaensis is restrict to swamps along a small river running to Iguaçu river. Even if the population is flourishing, it is very near to Pinus plantation. Indeed, any lake alteration could impact drastically the entire population. In general, Oxalis paranaensis habitat is threatened by silviculture expansion, urbanization, water regime alteration and polution. The species is currently listed as Critically Endangered (CR) ( MMA 2014).

Nomenclatural notes: — In the original publication, Lourteig (2000) indicated two specimens deposited at P as the “ holotype ” and “isotype” of Oxalis paranaensis . However , she did not distinguish among these two exsiccatae which one was the “ holotype ”. Based on Art. 9.17 of the ICN, we selected P02440281 as the second-step lectotype because it bears more material, with dissected flowers and fruits, and fits unambiguously the diagnostic morphological traits indicated in the protologue. Other duplicates from CTES, FUEL, MO, UM, SPF, and S are listed as isolectotypes .

Taxonomic notes: —This species can be easily recognized among the other species of Oxalis sect. Ripariae by the small leaflet blades (9.5–15.1 × 10–13.5 mm), very widely obovate to widely depressed obovate, base cuneate, apex retuse to rounded, sometimes mucronulate, discolorous, with the abaxial surface densely covered with whitish hairs. It is morphologically similar to Oxalis benjaminii , from which it differs by the cespitose habit with branches ca. 1 m long, leaning on other plants (vs. decumbent stem, branching from the base in O. benjaminii ), and 3-flowered (vs. 5-flowered) inflorescences.

Specimens examined: — BRAZIL. Paraná: São José dos Pinhais, Rio Pequeno, 11 January 2018, A . Nuernberg et al.1951 ( FLOR); 17 January 1969 G . Hatschbach & J . Fontella 20785 ( FURB02905 [web], HCF000004685 [web], MBM, P, W 1992-0016717 [web]); 18 October 1980, G . Hatschbach 43223 ( HUEFS0005050 [web], MBM); 4 March 1980, G . Hatschbach 42777 ( MBM, NY00470509 [web]); 28 December 1982, R . Kummrow 2145 ( MBM); Rodovia BR-277, próximo ao Rio Pequeno , 15 February 1995, J. M . Silva 1427 ( HCF000004687 [web], MBM, P, SJRP00009149 [web]); 07 November 1996, O. S . Ribas et al. 1599 ( ALCB036719 , SJRP00009150 ) [web]; 18 October 1998, O. S . Ribas 2739 ( MBM); 29 January 2002, O. S . Ribas et al. 4271 ( HUEFS067685 [web], MBM, SPF00153353 [web], W 2003-0000494 [web]); 27 March 2007, J. M . Silva & E . Barbosa 5647 ( FURB36677 [web], HCF000004686 [web], MBM); 22 September 2015, P . Fiaschi et al. 4477 ( FLOR); Piraquara, Santa Maria, 11 October 1969, G . Hatschbach 22423 ( ASU0033852 [web], MBM, P) .