Oxalis itatingae Fiaschi, 2025

Fiaschi, Pedro, Cabral, Fernando Santos, Caballero, Leonardo Ronald Gaspar & Lima, Duane Fernandes, 2025, Updating the taxonomy of polymorphic plant taxa: six Atlantic Forest species segregated from the widely circumscribed Oxalis polymorpha Mart. ex Zucc. (Oxalidales, Oxalidaceae), European Journal of Taxonomy 989, pp. 144-188 : 170-173

Oxalis itatingae Fiaschi sp. nov.

urn:lsid:ipni.org:names:77360849-1

Figs 11–12

Diagnosis

This new species is very similar to Oxalis tijucana , from which it can be distinguished by the leaflet blades abaxially with abundant, short appressed hairs along the midrib (vs glabrous or with occasional hairs along the midrib); terminal blades ≥ 2 × longer (vs up to 1.5 × longer) than the lateral ones, with 5–7 (vs 8–12) pairs of secondary veins, and inflorescences with the peduncle 9–50 mm long (vs 82–110 mm long).

Etymology

The name of this species refers to the ʻPadre Estadual da Pedra Brancaʼ (Pedra Branca State Park, an important protection area where this species is known to occur ( Fig. 12 ). In the tupi-guarani language, ʻitaʼ means ʻpedraʼ (the Portuguese word for rock) and ʻtingaʼ means ʻbrancaʼ (white, in Portuguese), thus the epithet ʻ itatingae ʼ.

Type material

BRAZIL – Rio de Janeiro • Rio de Janeiro, Prainha, “Área de Proteção Ambiental da Pedra Branca” [Pedra Branca Environmental Protected Area]; 23°02′16″ S, 43°30′25″ W; 23 Mar. 2015; P. Fiaschi et al. 4472; holotype: FLOR .

Other material examined

BRAZIL – Rio de Janeiro • Rio de Janeiro, “ Área de Proteção Ambiental Prainha, Trilha para o Cruzeiro do Sul ” [Prainha Environmental Protection Area, Trail to Cruzeiro do Sul]; 8 Apr. 2015; D.R. Gonzaga & C. Martins 516; RB • Rio de Janeiro, Camorim; 19 Dec. 1933; Excursão O. Sampaio Freire, Peckolt e Oswaldo Costa s.n.; R [ 70501 ] • Rio de Janeiro,; Camorim, Pedra da Rosilha, “acesso pela estrada da Boca do Mato - Vargem Pequena” [access via Boca do Mato - Vargem Pequena road]; 23 Jan. 2023; P. Feliz 372; RB • Rio de Janeiro,; Campo Grande, “Batalhão de Operações Especiais de Fuzileiros Navais (Batalhão Tonelero)” [Marine Special Operations Battalion (Tonelero Battalion)]; 22.8541 o S, 43.5859 o W; 25 Apr. 2017; A.L. Scudeler et al. 443; ESA, FLOR • Rio de Janeiro, Grumari; 2 Apr. 1984; V.F. Ferreira 3344; RB • Jacarepaguá, Vargem Grande, Mata de Lagôa ; 150–350 m a.s.l.; 21 Apr. 1980; T. Plowman 10108; RB • Rio de Janeiro, Parque Municipal Ecológico da Prainha, “subida para o mirante Cruzeiro do Sul” [ascent to the Cruzeiro do Sul viewpoint]; ca 320 m a.s.l.; 13 Nov. 2003; fl; J.M.A. Braga et al. 7256; K n.v., MBM, NY n.v., RB • Rio de Janeiro, Parque Municipal Ecológico da Prainha, “subida para o mirante Cruzeiro do Sul” [ascent to the Cruzeiro do Sul viewpoint]; 7 Mar. 2024; st; J.C. Vasques et al. 86; FLOR • Rio de Janeiro, Restinga do Recreio dos Bandeirantes, Morro da Prainha ; 4 Dec. 1978; G. Martinelli 5551; RB • Rio de Janeiro, Serra do Mendanha ; ca 450 m a.s.l.; 27 Feb. 1969; D. Sucre & P.I. Braga 6386; RB .

Description

Unbranched or few-branched, erect subshrubs, 10–35 cm tall, with an elongated horizontal stem up to ca 30 cm long spreading under the leaf litter; young stem covered by scars of the fallen leaves and inflorescences; glabrescent, with sparse to moderate, short, curved or appressed hairs; older stem brownish, terete, smooth. Leaves pinnate-trifoliolate, densely grouped at stem apex, appearing arranged in a terminal pseudo-whorl, the internodes indistinct (<0.5 mm long), sometimes up to ca 8 mm long; the petioles 14–68 × ca 0.5 mm, canaliculate adaxially or only slightly flattened, adaxially with abundant, curved hairs, abaxially with occasional to sparse hairs, the base pulvinate, enlarged to ca 1 mm diam., articulated at 0.5–2 mm long; the rachis 6–21 mm long, similar to the petiole; petiolules ca 0.5 mm long, with hairs slightly larger and thicker than the petiole ones; leaflet blades adaxially glabrous, with hairs restricted to the ciliate margin; abaxially with abundant, short appressed hairs along the midrib; membranous to chartaceous, abaxially lighter colored than adaxially. Venation: midrib impressed to slightly canaliculate adaxially, impressed to slightly raised in the proximal part abaxially; secondary veins 5–7 pairs, inconspicuous, impressed on both surfaces, angle of divergence increasing towards the apex; tertiary and quaternary veins inconspicuous (not described). Terminal blade 45–108 × 17–46 mm, lanceolate to almost narrowly trullate, the base cuneate to obtuse, the margin plane, ciliate, the apex acuminate. Lateral leaflets opposite, the blades 17–54 × 12–29 mm, ovate to widely ovate, the base asymmetrical to strongly asymmetrical, the proximal side> 1.5 wider than the distal one, rounded to almost truncate, the apex acuminate to obtuse. Dichasial cymes axillary, shorter than the leaves; the peduncle 9–50 mm long, slightly flattened, with sparse to moderate (abundant), curved or appressed hairs; dichasial branches 2, 1–7 mm long, each with the flowers (or scars) densely grouped along the entire length, sometimes recurving the branches; bracts ca 0.5 mm long, triangular, abaxially with abundant, appressed hairs; bracteoles ca 0.5 mm long, triangular, with abundant, appressed hairs. Flower buds ca 6.5 × 2.8 mm, ovate to lanceolate, acuminate. Pedicel 5–7 mm long, articulated at base, leaving a persistent foot up to ca 0.5 mm long; with abundant, short, patent to slightly retrorse hairs, sometimes distally mixed with antrorse, longer hairs. Sepals light green, ca 7 × 1.7–2 mm, narrowly elliptic or lanceolate, symmetric to slightly asymmetric, the apex acute to rounded, sometimes mucronate, the exposed part with moderate, appressed hairs. Corolla dark yellow, ca 16 mm diam., petals ca 15 mm long, each with two orange maculae above the throat; short-styled morph: filaments connate for ca 1 mm of their length; shorter filaments ca 2.5 mm long, glabrous; longer filaments ca 4.5 mm long, non-appendiculate, distally hispidule; pistil: ovary ca 1 mm long; styles ca 3.5 mm long, erect, hispidule for the entire length; stigmas oblate; gynopohore ca 1 mm long; long-styled morph: filaments connate for ca 1.2 mm of their length; shorter filaments ca 2.5 mm long, glabrous, longer filaments ca 4 mm long, non-appendiculate, distally hispidule; pistil: ovary ca 1.2 mm long; styles ca 2.8 mm long, erect, hispidule for the entire length; stigmas oblate; gynophore ca 1 mm long; carpels uniovulate. Capsules ca 4 × 5.5 mm, obloid, glabrous, shorter than the calyx lobes, the apex prolonged for ca 1 mm of its length; locules one-seeded, internally glabrous; seeds ca 3 × 1.7 mm, semi-obloid, with a honeycombed-foveolate surface.

Preliminary conservation status assessment

Oxalis itatingae sp. nov. is restricted to preserved forests in the western part of Rio de Janeiro municipality ( Fig. 12 ), the second largest Brazilian city, which suffers from a continuous historic decline of habitat quality and extent. It is known to occur in some protected areas, such as Parque Municipal Ecológico da Prainha, but this protection may not be enough to safeguard it from further declines, as this region is still subjected to illegal squatting for real estate development. With an EOO of 190 km 2 and an AOO of 24 km 2, this species should be conservatively treated as Endangered following the IUCN criteria EN B2ab(iii) ( IUCN 2012).

Remarks

Specimens belonging to this new species have been previously treated as O. polymorpha subsp. tijucana by Fiaschi (2014), Costa et al. (2019), and Richetti et al. (2023). However, during fieldwork in the municipality of Rio de Janeiro, we were able to locate one population of this latter taxon, which is here elevated to species level (as O. tijucana (Lourteig) Fiaschi ). The main differences between O. itatingae sp. nov. and O. tijucana are presented in the diagnosis above (see also Table 3 ).

Distribution and ecology

This species is restricted to rainforests in the surroundings of Rio de Janeiro city, especially in Camorim, Campo Grande, and Jacarepaguá neighborhoods ( Fig. 12 ), where it is only found in shady environments of preserved forests.

Figures

Fig. 11. Oxalis itatingae Fiaschi sp. nov. A. Habit. B. Leaf adaxial surface. C. Leaf abaxial surface (one lateral leaflet removed). D. Detail of leaflet ciliate margin. E. Habit (under cultivation).F. Detail of leaflet blades insertion, adaxial surface. G. Detail of leaflet blades insertion, abaxial surface H. Inflorescence with flower buds. I. Inflorescence with closing flower and young buds. J. Detail of hairs on the pedicel. K. Mature fruit, lateral view. L. Fruit after seeds ejected, lateral view. M. Seed, lateral view. Photos: A: Pablo Feliz; B-L: Pedro Fiaschi; M: Gabriela Rhoden. A based on P. Feliz 372, RB; B–C, E, H–M based on P. Fiaschi et al. 4472, holotype, FLOR; D, F–G based on J.C. Vasques et al. 86, FLOR.

Fig. 12. Geographic distribution of Oxalis itatingae Fiaschi sp. nov. and O. tijucana (Lourteig) Fiaschi comb. et stat. nov. Inset shows southeastern Brazilian states.