Oxalis timida J.Vasques, 2024

Vasques, Jasmim C., Vago, Walgery A. & Fiaschi, Pedro, 2024, A new species of Oxalis sect. Holophyllum (Oxalidaceae) from the Brazilian state of Espírito Santo, discovered with the help of citizen science, Phytotaxa 663 (5), pp. 294-300 : 295-298

Oxalis timida J.Vasques , sp. nov. ( Figure 1 )

Type:— Brazil. Espírito Santo: São Roque do Canaã, Distrito de São Dalmácio , 170 m., 19°44’47.9”S 40°37’51.7”W, 15 November 2023, J. Vasques et al. 52 [holotype: FLOR; isotypes (to be distributed): MBML, RB, SPF, VIES] .

Diagnosis:— This new species differs from O. occulta Fiaschi & Bilk in Fiaschi et al. (2024b: 183) by the adaxial leaf blades with abundant, patent hairs (vs. glabrous), the peduncles shorter than the leaves, 34.5–77.0 × 5.5–10.0 mm (vs. longer than leaves, 72.7–111.7 × 1.3–3.5 mm), and the pedicel 3.0–5.0 mm long (vs. 6.8–8.8 mm long).

Description:— Herbs or subshrubs, 10–30 cm tall, unbranched. Stem (young) 1.2–2.2 mm diam., with moderate to abundant, antrorse or retrorse, curved, yellowish hairs. Leaves congested at stem apex, internodes 1–9 mm long; petioles 15.0–84.5 × 0.6–0.8 mm, longitudinally channeled adaxially, width homogeneous along the length, with abundant, patent hairs and short, curved hairs; petiolules 1.0– 1.8 mm long, with abundant, patent hairs. Leaf blades 44.0–71.0 × 42.0– 65.5 mm, very widely ovate, base truncate to subcordate, margin ciliate, apex acuminate; adaxial surface with abundant, patent hairs, abaxial surface with moderate, appressed hairs, more densely along the midrib. Venation: midrib impressed to slightly canaliculate adaxially, prominent abaxially; secondary veins 5–10 pairs. Inflorescences shorter than the leaves; peduncle 34.5–77.0 × 5.5–10.0 mm, flattened dorsiventrally, winged, distally wider than proximally, with moderate to abundant, appressed hairs, margin ciliate; dichasial branches inconspicuous, up to ca. 0.5 mm long; bracts ca. 0.5 mm long, lanceolate, pubescent; floral bracts 0.5–1.3 mm long, with abundant, patent long hairs. Flowers: pedicel 3.0–5.0 mm long, with abundant, appressed to ascending hairs and moderate to abundant, short glandular hairs; flower buds with very abundant, patent hairs in the exposed parts; sepals ca. 5.0 × 2.0 mm, ovate, apex acuminate, with moderate to abundant, patent hairs and short, glandular hairs; petals yellow, each with two orange spots in the throat, ca. 5.6 mm long, 8.2–8.8 mm diam.; mid-styled morph with the longer filaments ca. 4.2 mm long, distally pubescent; anthers ca. 0.8 × 0.5 mm; shorter filaments ca. 2.5 mm, glabrous, with a basal rounded nub; gynophore ca. 0.5 mm long; ovary ca. 1 mm long; styles ca. 1.5 mm long, sparsely pubescent. Capsules 4.0–5.2 × ca. 3.8 mm, very broadly ovoid, glabrous; locules one-seeded, seeds 2.0–2.2 × ca. 1.2 mm, foveolate.

Additional specimens examined:— BRAZIL. Espírito Santo: Aldeiamento dos Índios, Rio Pancas, margem direita, 8 July 1942, E.A. Bueno & Luiz Emygdio Mello Filho 224 (R).

Distribution and Ecology:— This species is only known from two localities in the west of Espírito Santo, growing in shady areas of semideciduous seasonal forests ( Figure 2 ).

Phenology:— Oxalis timida has been collected with flowers in July and November and with fruits in November.

Etymology: —The name Oxalis timida (from Latin “timidus”, meaning “shy” and “fearful”), refers to the interesting fact that this species keeps the immature flowers and fruits hidden beneath the winged peduncles (see Fig. 1g, h, k ).

Preliminary conservation assessment: —Critically Endangered: CR B2ab(iii). This new species is only known from two localities, one from a collection from more than 80 years ago (in 1942) and the other from the population discovered by the authors in 2022. The area of occupancy (AOO) of O. timida is estimated at 8 km ², and the main threat to the known populations is the fragmentation of the habitat by deforestation for agriculture and grazing lands.

Notes: — Oxalis timida can be distinguished from all remaining species of Oxalis sect. Holophyllum by the leaf blades up to ca. 1.6× longer than wide, adaxially with very abundant patent hairs, winged peduncles that are shorter than the leaves, and distally wider than proximally, and the flowers with yellow corolla. Moreover, the flower buds and immature capsules are kept hidden underneath the peduncles and are shown one by one when mature.

Oxalis timida shares with O. itamarajuensis Fiaschi & Bilk in Fiaschi et al. (2024b: 176) the distally wider than proximally winged peduncles, but it can be distinguished from this species by the yellow (vs. white) corolla lobes, leaf blades very widely ovate (vs. ovate to lanceolate, sometimes elliptic) and the peduncles 34.5–77 × 5.5–10 mm (vs. (20)41–129 × 0.8–3.5 mm). Moreover, while O. timida is found only in the state of Espírito Santo’s seasonally dry forests, O. itamarajuensis is restricted to southern Bahia moist forests.

Oxalis timida is also similar to O. occulta , sharing with this species the ovate leaf blades with the base truncate to subcordate, and the distally wider than proximally winged peduncles. However, it differs from O. occulta by the adaxial leaf blades with abundant patent hairs (vs. glabrous), by the peduncles 34.5–77 × 5.5–10 mm, shorter than the leaves (vs. 72.7–111.7 × 1.3–3.5 mm, longer than the leaves), and the pedicel 3–5 mm long (vs. 6.8–8.8 mm long). Moreover, while O. timida is found only in the state of Espírito Santo, O. occulta is also restricted to southern Bahia.

Lourteig (1994) treated the collection of O. timida from 1942 as O. alata Martius ex Zuccarini (1825: 155) , a widespread taxon that was synonymized under O. mandioccana Raddi (1820: 400) by Fiaschi et al. (2024b). This latter taxon differs from O. timida by the petioles laterally flattened or winged (vs. not winged), leaves adaxially glabrous (vs. with abundant patent hairs), and the flowers with white petals (vs. yellow petals). Both O. occulta and O. itamarajuensis were treated as varieties under O. alata by Lourteig (1994) and were recently recognized as two new species by Fiaschi et al. (2024b). Oxalis occulta can be distinguished from O. mandioccana by the leaf blades with a truncate to rounded (vs. obtuse to rounded) base, inflorescences with peduncle> 70 mm long (vs. ≤ 60 mm long), and flowers with yellow (vs. white) petals. Oxalis itamarajuensis differs from O. mandioccana by the peduncles usually longer (vs. shorter) than the petiole of the adjacent leaf and by pedicels with short, appressed hairs, intermixed with short, glandular hairs (vs. with diminute, patent hairs).

Figures

FIGURE 1. Oxalis timida J.Vasques. A. Habit showing inflorescence (arrowhead). B. Leaf pubescence detail. C. Leaf abaxial surface. D. Leaf base detail, abaxial surface. E. Leaf adaxial surface. F. Leaf base detail, adaxial surface. G. Peduncle with flower buds. H. Abaxial surface of the peduncle with flower buds and an open flower. I. Adaxial surface of the peduncle with an open flower. J. Flower, frontal view. K. Infructescence with a mature fruit. L. Mature fruits, lateral view. Scale bars: a, b, c, e, h, i = 10 mm; d, f, g, k, l = 5 mm; j = 3 mm. Photos by P. Fiaschi.

FIGURE 2. Geographic distribution map of Oxalis timida J.Vasques.