Updating the taxonomy of polymorphic plant taxa: six Atlantic Forest species segregated from the widely circumscribed Oxalis polymorpha Mart. ex Zucc. (Oxalidales, Oxalidaceae) Fiaschi, Pedro Cabral, Fernando Santos Caballero, Leonardo Ronald Gaspar Lima, Duane Fernandes European Journal of Taxonomy 2025 2025-05-05 989 144 188 Fiaschi Fiaschi & Cabral & Caballero & Lima 2025 [615,875,778,805] Magnoliopsida Oxalidaceae Oxalis Plantae Oxalidales 23 167 Tracheophyta species idimae sp. nov.  urn:lsid:ipni.org:names:77360848-1  Figs 5, 10    Diagnosis   Oxalis idimae sp. nov.differs from  O. decipiensby the glabrescent young stem (vs with abundant to very abundant, curved hairs), leaf blades abaxially glabrous (vs with abundant, appressed hairs), sometimes with occasional hairs on the margin (vs with abundant hairs), venation with the midrib impressed (vs canaliculate) adaxially, conspicuous secondary veins (vs slightly visible or inconspicuous), and areolation of good (vs moderate) development, inflorescences with (1–)2 single branches (vs with (1–)2(–3) usually bifid branches), flowers with white (vs yellow) flowers, and broadly ovoid (vs pyriform) capsules with the carpels lacking apical prolongations or prolonged to only ca 0.5 mmof their length (vs with the carpels prolonged for ca 2 mmof their length).    Etymology This new species honors the plant collector and amateur botanist Idimá Gonçalves Costa, who has recently discovered several new species of plants in the forest of northern Rio de Janeiro state, such as  Anthurium idimaeTheófilo & Nadruz ( Valadares & Coelho 2017),  Besleria aureaI.G.Costa & G.E.Ferreira ( Ferreira et al.2016),  Conchocarpus hendrixiiGroppo, I.G.Costa & Bruniera ( Groppo et al.2019),  Eugenia asemaI.G.Costa & M.C.Souza ( Sobral et al.2017), and  Hippeastrum idimaeDutilh & R.S.Oliveira ( Oliveira et al.2017).     Typematerial   BRAZIL–  Rio de Janeiro• Cardoso Moreira, localidade de Vinhático; 21°31′8.86″ S, 41°37′18.01″ W;  238 ma.s.l.;  6 Mar. 2017;  I.G. Costa879; holotype: FLOR[ FLOR 66532];  isotypes: HUEFS,  RB,  SPF.   Other material examined    BRAZIL–  Rio de Janeiro• Cardoso Moreira, “  3 kmapós ponte via BR 356 sentido Campos dos Goytacazes, entrada à direita” [ 3 kmafter bridge, on road BR 356 to Campos dos Goytacazes, entrance to the right]; 21°30′58″ S, 41°36′27″ W;  27 Jan. 2018; fl, fr;  E. Richettiet al. 70; FLOR•  Cardoso Moreira;  5 Mar. 2024;  J.C. Vasqueset al. 78; FLOR, RB, SPF•  Italva, “ localidade de Quimbira, em escarpa de afloramento rochoso no interior da mata” [locality of Quimbira, on a rocky outcrop escarpment inside the forest]; 21°27′23″ S, 41°35′47′′ W;  150 ma.s.l.;  11 Apr. 2014; fl;  I.G. Costa 400; RB, SPF•  Italva, Quimbira; 21°27′25″ S, 41°35′43.7″ W;  51 ma.s.l.;  18 Feb. 2017; fl;  T.S. Costaet al. 123; FLOR•  Italva;  5 Mar. 2024;  J.C. Vasqueset al. 81; FLOR, HUEFS, RB•  Italva, Pão de Ló; 21°27′29″ S, 41°36′25″ W;  13 Dec. 2015;  J. Rossini& I.G. Costa 835; R.    Description Unbranched or few-branched, erect subshrubs, 60–120 cmtall; young stem glabrescent, with occasional to sparse, curved to appressed hairs; older stem ochreous, terete, slightly striate longitudinally. Leavespinnate-trifoliolate, arranged along the stem, densely grouped at stem apex, sometimes forming multiple pseudo-whorls, the internodes 5–40 mmlong; the petioles 31–110 × 0.5–0.8 mm, slightly canaliculate adaxially, with occasional, appressed hairs, more densely in the proximal region, the base pulvinate, enlarged to ca 1.2 mmdiam.; the rachis 10–28 mmlong, similar to the petiole; petiolules ca 1 mmlong, with sparse, appressed hairs; leaflet blades adaxially glabrous, abaxially glabrous, the margin sometimes with occasional hairs in the proximal part; membranous, adaxially green, abaxially lighter green. Venation:midrib impressed adaxially, impressed to slightly raised abaxially; secondary veins 5–8 pairs, conspicuous, impressed on both surfaces, sometimes very slightly raised abaxially, angle of divergence inconsistent; intercostal tertiary veins irregular-reticulate, exterior tertiary course looped, quaternary veins fabric irregular-reticulate, areolation of good development, free ending veinlets unbranched or with one branch. Terminal blade54–110 × 24–48 mm, ovate to lanceolate, the apex acuminate, the base obtuse. Lateral leaflets opposite, the blades 31–73 × 15–33 mm, ovate to lanceolate, the apex acuminate, the base subsymmetrical to asymmetrical, rounded to almost truncate. Dichasial cymescauliflorous, shorter than the leaves; the peduncle 6–65 mmlong, slightly flattened laterally, with moderate, curved or appressed hairs; dichasial branches (1–)2, 0.5–8 mmlong, each with the flowers (or scars) densely grouped along the entire length or with the proximal part elongated, and the scars far from the terminal flower; bracts 0.7–1.5 mmlong, lanceolate to linear, abaxially with moderate to abundant, appressed hairs; bracteoles ca 0.5 mmlong, triangular-ovate, with moderate, appressed hairs. Flower buds4–4.5 × ca 1.5 mm, lanceolate, acuminate. Pedicel 3–6 mmlong, articulated at base, leaving a persistent foot up to ca 0.5 mmlong; with moderate to abundant, appressed hairs. Sepalsgreenish, ca 6 × 1.7–1.8 mm, lanceolate, the exposed part with sparse to moderate, appressed hairs, the apex acuminate. Corollawhite, ca 10 mmdiam., petals ca 10 mmlong, each with two orange maculae above the throat; short-styled morph: filaments connate for ca 0.5 mmof their length; shorter filaments ca 3.5 mmlong, glabrous, each with a basal knob, longer filaments ca 5 mmlong, non-appendiculate, hispidule; pistil: ovary ca 0.7 mmlong; styles ca 0.7 mmlong, proximally hispidule; stigmas oblate; gynophore ca 0.5 mmlong; long-styled morph: filaments connate for ca 0.5 mmof their length; shorter filaments ca 1.2 mmlong, glabrous, each with a basal knob, longer filaments ca 3.5 mmlong, non-appendiculate, hispidule in the distal ⅓; pistil: ovary ca 0.8 mmlong; styles ca 3 mmlong, erect, hispidule along the entire length; stigmas oblate; gynophore ca 0.3 mmlong. Capsulesca 4.5 × 4.5 mm, broadly ovoid, glabrous, slightly shorter than the calyx lobes, the apex not prolonged or prolonged to ca 0.5 mmlong; locules one-seeded, internally glabrous; seeds ca 2 × 1.2 mm, semi-obloid, with a honeycombed-foveolate surface.    Preliminary conservation status assessment This species is only known from a few seasonally dry forest fragments in the northern part of Rio de Janeiro state, which has historically suffered from a steady conversion of forests in cultivated areas for agricultural activities or pastures for cattle farming. The species is not known from any protected area, and the only fragments where it occurs are privately-owned; thus, it may be suffering from both extent and quality loss. With an EOO of only 8.6 km ², it is suggested that this species should be considered as Critically Endangered following the IUCN criteria CR B1ab(iii) ( IUCN 2012).    Remarks  Costa et al.(2019)had access to one specimenof  O. idimae sp. nov.( I.G. Costa 400, RB), but they decided to treat it under  O. polymorphasubsp. polymorpha, which was distinguished from  O. polymorphasubsp. tijucanaby the leaves spacely distributed along the stem (vs grouped in a pseudo-whorl at stem apex).   Oxalis idimae sp. nov.can be distinguished from all other species that are here segregated from  O. polymorphaby the following combination of character states: glabrescent young stem, glabrous leaf blades (the margin sometimes with occasional hairs), inflorescences mostly cauliflorous, with white flowers, and capsules with the carpels without apical prolongation or prolonged to only ca 0.5 mmlong. Moreover, it can be distinguished from  O. decipiens, which also sometimes bears cauliflorous inflorescences, by several additional features (see Table 3).    Distribution and ecology This species is presumably endemic to the northern part of Rio de Janeiro state, where it is known only from seasonally dry forests. 5163202366 2017-03-06 FLOR I. G. Costa Brazil 238 -21.519127 localidade de Vinhatico 1 -41.621666 Cardoso Moreira 23 167 FLOR 66532 1 Rio de Janeiro holotype 5163202314 [1073,1284,1617,1643] 2017-03-06 HUEFS I. G. Costa Brazil 238 -21.519127 localidade de Vinhatico 1 -41.621666 Cardoso Moreira 23 167 1 Rio de Janeiro isotype 5163202407 [1291,1338,1617,1643] 2017-03-06 RB I. G. Costa Brazil 238 -21.519127 localidade de Vinhatico 1 -41.621666 Cardoso Moreira 23 167 1 Rio de Janeiro isotype 5163202379 [1345,1395,1617,1643] 2017-03-06 SPF I. G. Costa Brazil 238 -21.519127 localidade de Vinhatico 1 -41.621666 Cardoso Moreira 23 167 FLOR 66532 1 Rio de Janeiro isotype 5163202301 2018-01-27 FLOR E. Richetti Brazil -21.516111 3 km apos ponte via BR 356 sentido Campos dos Goytacazes, entrada a direita 21 -41.6075 Cardoso Moreira 23 167 1 Rio de Janeiro 5163202386 2024-03-05 FLOR, RB, SPF J. C. Vasques Brazil Cardoso Moreira Cardoso Moreira 23 167 1 Rio de Janeiro 5163202371 2014-04-11 RB, SPF I. G. Costa Brazil 150 -21.45639 localidade de Quimbira, em escarpa de afloramento rochoso no interior da mata 21 -41.596386 Italva 23 167 1 Rio de Janeiro 5163202356 2017-02-18 FLOR T. S. Costa Brazil 51 -21.456945 Quimbira 15 -41.59547 Italva 23 167 1 Rio de Janeiro 5163202323 2024-03-05 FLOR, HUEFS, RB J. C. Vasques Brazil Italva Italva 23 167 1 Rio de Janeiro 5163202378 2015-12-13 R J. Rossini & I. G. Costa Brazil -21.458055 Pao de Lo 21 -41.60694 Italva 23 167 1 Rio de Janeiro