Oxalis lourteigiana Nuernberg-Silva & Fiaschi, 2021

Nuernberg-Silva, Anelise & Fiaschi, Pedro, 2021, Taxonomic revision and morphological delimitation of Oxalis sect. Ripariae (Oxalidaceae), Phytotaxa 529 (1), pp. 125-159 : 140-142

5. Oxalis lourteigiana Nuernberg-Silva & Fiaschi , sp. nov. Type:— BRAZIL. Paraná: Tibagi, Rodovia do Café , Rio Capivari , 11 February 1976, G. Hatschbach 38064 (holotype MBM48288!; isotypes P05551682 !, UEC045689 ) (figs. 6, 10).

Diagnosis: —This new species is similar to Oxalis serpens , from which it can be distinguished by the 1–3-flowered (vs. uniflorous) inflorescences, the glandular hairs (lacking in O. serpens ), emarginate (vs. retuse) leaflet apex and by the immersed inconspicuous secondary veins (vs. usually two conspicuous secondary veins abaxially in O. serpens ). Oxalis lourteigiana is also similar to O. bifrons , but it differs by the leaflets 0.8–1.4 cm long (vs. up to ca. 4 cm long), with an emarginate (vs. obtuse to rounded, sometimes retuse) apex, and immersed inconspicuous secondary veins (vs. secondary veins abaxially conspicuous in O. bifrons ).

Stoloniferous herb. Stem slender, up to ca. 45 cm long; shorter hairs 0.2–0.5 mm long, ascending, patent, descending, sometimes curved, moderate; longer hairs ca. 1 mm long, patent, occasional; glandular hairs ca. 0.5 mm long, patent, moderate; internodes 0.8–3.5 cm long, nodes radicant. Stipules 1.5–2 × 1–1.5 mm, semicircular, connate to the petiole; petioles 1–6 cm long; pulvina ca. 1 mm long. Leaf blades 0.8–1.4 × 0.85–1.32 cm, coriaceous, widely depressed obovate, discolorous, the base cuneate, the apex emarginate; shorter hairs ca. 0.5 mm long, appressed, occasional adaxially, sparse to moderate abaxially; longer hairs ca. 1 mm long, appressed, moderate adaxially, occasional abaxially; glandular hairs 0.5–1 mm long, appressed to ascending, sparse adaxially, moderate abaxially; margin with hairs 0.5–1 mm long, ascending, moderate. Dichasia with 3 flowers, shorter than the leaves; peduncle 0.5–2.7 cm long; shorter hairs ca. 0.2 mm long, ascending, descending, patent or curved, moderate to abundant; longer hairs 0.5–0.8 mm long, patent, sparse; glandular hairs ca. 0.5 mm long, patent, sparse to moderate; bracts ca. 1 × 0.2 mm, lanceolate; bracteoles ca. 0.5 × 0.2 mm, lanceolate. Pedicels 3–12 mm long; sepals 2.5–3.2 × 0.6–1 mm, base rounded, apex acute; shorter hairs ca. 0.2 mm long, appressed, moderate; longer hairs 0.5–1 mm long, appressed to ascending, moderate; glandular hairs ca. 0.5 mm long, appressed to patent, sparse to moderate; petals yellow, 7–8 mm long, spatulate, the apex crenate-denticulate, adaxially with sparse glandular hairs; shorter stamens ca. 3 mm long, glabrous, longer ca. 6 mm long, hairs appressed, moderate to abundant; mid-styled pistil ca. 3.5 mm long, hairs appressed, abundant, stigmas papillose. Capsules ca. 2 × 3 mm, depressed ovoid, 5-lobed, hairs ca. 0.5 mm long, appressed to patent, moderate, glandular hairs 0.5–1 mm long, patent, moderate. Seeds 1 per locule (immature), 2–2.5 × 2–2.5 mm, circular, the base rounded, the apex acute.

Distribution and habitat: —This species is known only from the type collection, presumably collected from gallery forests along the Capivari river at Tibagi, Paraná state.

Phenology: —Flowers and fruits were collected in February.

Etymology: —This species honors Alicia Lourteig (1913–2003), an Argentinian botanist whose life was partially dedicated to the study of Oxalis .

Conservation status: —The locality where this species was collected is immersed in a plantation matrix with small fragments of native forest along the Capivari river or in isolated patches among crop fields. It has not been recorded at protected areas and its habitat is severely fragmented and of poor conservation quality, with an AOO of just about 4 km ². We recommend to categorize this species as Critically Endangered following IUCN (2017) categories and criteria [CR B2a,b(iii)].