Oxalis decipiens Progel, 1877

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 : 162-167

Oxalis decipiens Progel

Figs 5 , 8

Oxalis decipiens Progel ( Progel 1877: 507) . – Type: BRAZIL – “ Rio de Janeiro ” [Minas Gerais] • “[Vila] Casal, près dʼUba (Ubá), sur la ligne du chemin de fer de D. Pedro 2°, avec Mr.Albuquerque” [Village Casal, near Ubá, along the railway line of Dom Pedro 2°, with Mr. Albuquerque]; 26 Feb. 1875; A.F.M. Glaziou 7561; lectotype: C [C10016336], designated by Lourteig (1994: 150); isolectotypes: P [P02440302], S [S-R-8335].

Oxalis polymorpha var. cauliflora Zucc. ( Zuccarini 1825: 176) . – Type: BRAZIL – “ Rio de Janeiro ” [Espírito Santo] • zwichen Villa Nova [now Nova Almeida ] und Praya Molle; M. Neuwied s.n.; Apr. 1816 [presumably Dec. 1815, see Nomenclatural remarks]; lectotype: M [M-0121064, pro parte], designated by Lourteig (1994: 150) — only the left and central branches (see Fig. 9A ); isolectotype: FI [ FI005091 ] .

Other material examined

BRAZIL – Espírito Santo • Colatina, Fazenda São Gabriel ; 24 Mar. 1978; fl; A. Lourteig 3217; CEPEC, P [photo] • Colatina, Fazenda São Gabriel ; ca 120 m a.s.l.; 24 Mar. 1978; fl; A. Lourteig 3219; P [photo] • Colatina, Santa Rosa da Graça Aranha ; ca 120 m a.s.l.; 24 Mar. 1978; fl; A. Lourteig 3221; CEPEC, P [photo] • Governador Lindemberg, Pedra de Santa Luzia, prop. Firmino Sottele ; 19°16′54″ S, 40°27′43″ W; 350–600 m a.s.l.; 26 Apr. 2007; fl, fr; V. Demuner et al. 3890; MBML, SPF • Governador Lindemberg, Morelo, propr. Fernando Nicolli ; 19°08′55″ S, 40°27′28″ W; 13 Nov. 2006; V. Demuner et al. 3043; SPF • Linhares, Reserva Florestal de Linhares – Cia. Vale do Rio Doce , MME, talhão 89; 12 May 2000; fl; P. Fiaschi et al. 240; FLOR, SPF • Linhares , “Reserva Florestal da Companhia Vale do Rio Doce ( CVRD), área experimental do MME” [Vale do Rio Doce Company Forest Reserve, experimental area of the MME], RFL 89; 19°07′57″ S, 40°04′58″ W; 75 m a.s.l.; 1 Feb. 2002; fl; P. Fiaschi et al. 964; FLOR, RB, SPF • Linhares ,; “Reserva da Vale, nas proximidades do escritório” [Vale Reserve, near the office]; 19 Jan. 2011; fl; P. Fiaschi et al. 3469; FLOR, SPF • Linhares , “Reserva Natural Vale, proximidades do escritório” [Vale Natural Reserve, near the office]; 19°00′03″ S, 40°41′16″ W; 5 Feb. 2016; fl; P. Fiaschi & J.L. Costa Lima 4656; FLOR • Linhares, Reserva Natural Vale, Estrada Aceiro ; 3 Apr. 1993; fl; G.L. Farias 605; CVRD, FLOR, SPF • Linhares, Reserva Natural Vale, Estrada Municipal do MME, RFL-089/86; 4 Mar. 2008; fl, fr; D.A. Folli 5877; CVRD, FLOR, SPF • Linhares, Reserva Natural Vale, Estrada Peroba Amarela ; 12 Mar. 1987; fl; D.A. Folli 629; CVRD, FLOR, SPF • Linhares, Reserva Natural Vale do Rio Doce (particular); 30 m a.s.l.; 26 Sep. 1978; fl; A.M. Carvalho et al. 83; FLOR, RB • Linhares, Reserva Florestal Vale do Rio Doce ; 14 Oct. 1992; fl, fr; G. Hatschbach et al. 58067; MBM • Linhares, Reserva Natural da Vale, Trilha do Flamengo ; 19°09′47.8″ S, 39°58′58″ W; ca 50 m a.s.l.; 12 May 2012; fl; J.A. Lombardi et al. 9643; CVRD [photo] • Linhares, Reserva Natural Vale do Rio Doce, Estrada da bomba dʼágua; 21 Apr. 1983; A.L. Peixoto & H.C. de Lima 1778; RB, SPF • Linhares, Reserva Natural da Vale, Estrada Guaribu Amarelo ; 24.26936° S, 49.26981° W; 14 Apr. 2011; J.C. Lopes et al. 161; ESA, SPF • Linhares, Ponta de Ouro , “margens da Rodovia ES-358” [margins of Highway ES-358]; 19°12′29.9″ S, 40°10′01.7″ W; 80 m a.s.l.; 16 Nov. 2012; fl; A.M. Assis & J. Freitas 3350; MBML • Rio Bananal , “Estrada pavimentada para Novo Brasil” [Paved road to Novo Brasil]; 19°09′05.9″ S, 40°20′51.6″ W; 26 Jan. 2009; C.P. Bruniera et al. 145; SPF • Sooretama, Reserva Biológica de Sooretama, estrada Cupido ; 19°03′42″ S, 40°08′18″ W; 30 m a.s.l.; 20 Feb. 2021; fl; C.A.P. Toledo & H. Medeiros 578; FLOR, RB • Sooretama, Reserva Natural da Vale ( RNV); 19°09′03.4″ S, 40°04′15.1″ W; 59 m a.s.l.; 3 Feb. 2013; fl, fr; M.G. Caxambu et al. 4564; HCF [photo] • Sooretama, Reserva Natural da Companhia Vale do Rio Doce , MME; 19°08′03.2″ S, 40°05′02.2″ W; 74 m a.s.l.; 30 Apr. 2008; M.M.M. Lopes et al. 1592; SPF • Sooretama , “Reserva Biológica de Sooretama, entrada da picada em frente ao antigo posto de vigia” [Sooretama Biological Reserve, track entrance in front of old watch post]; 24 Aug. 2012; fl, fr; T.B. Flores & G.O. Romão 1119; MBML [photo], RB • Sooretama, Sooretama, Parque do Zooretama ; 26 May 1965; fl; A.J. Andrade & M. Emmerich 1981; P • Sooretama , “Sooretama, do lado Norte da sede da Reserva de Sooretama” [Sooretama, on the north side of the Sooretama Reserve headquarters]; 11 Jul. 1969; D. Sucre 5449; RB • Serra , “a 1–3 km de Nova Almeida , em direção a Santa Cruz” [1–3 km from Nova Almeida , going to Santa Cruz]; 19 Jul. 1973; D. Araujo & A.L. Peixoto 309; RB, SPF . – Minas Gerais • Coronel Pacheco, Fazenda da Companhia ; 2 Jun. 1945; fl; E.P. Heringer 1921; SP, SPF • Coronel Pacheco, Fazenda da Liberdade ; 20 Feb. 1942; E.P. Heringer 946; SPF • Marliéria , “ 2 km após a entrada do Parque Estadual do Rio Doce, em direção à ponte Queimada e aos experimentos da Teresa Spósito ( GEF)” [2 km beyond the Rio Doce State Park entrance, in direction to Queimada bridge and Teresa Spósitoʼs experiments]; 19°42′12″ S, 43°30′52″ W; 29 Nov. 2000; fl; A.A. Santos et al. 866; CEN, FLOR • Marliéria, Pq. Estadual do Rio Doce, Mumbaça ; 26 Mar. 2006; J. Ordones et al. s.n.; SPF 176576 • Marliéria, Parque Rio Doce, Trilha da Campolina ; 19°41′55″ S, 42°30′23″ W; 24 Jan. 2018; fl; E. Richetti et al. 64; FLOR • Marliéria, Parque Florestal do Rio Doce ; 15 Feb. 1973; L.E. Mello-Filho et al. 3755; R . – Rio de Janeiro • Cantagalo ; s.d.; Peckolt s.n.; BR • Barra Mansa, ARIE Floresta da Cicuta ; 22°32′54″ S, 44°05′18″ W; 2 Mar. 2024; J.C. Vasques et al. 57; FLOR, HUEFS, RB, SPF • Volta Redonda, Floresta da Cicuta ; 12 Oct. 1985; J.P.P. Carauta et al. 5095; RB ; • Volta Redonda ; 21 Feb. 1987; R.B. Pineschi 40; RB • Volta Redonda ; 21 Feb. 1987; R.B. Pineschi 41; RB ; • Volta Redonda ; 2 Jan. 1992; M.R. Ascenção et al. 18; RB .

Description

Unbranched, erect subshrubs, 15–60 cm tall; young stem with abundant to very abundant, curved hairs, more densely so at the distal end; older stem beige-cinereous to brownish, terete, slightly striate longitudinally. Leaves pinnate-trifoliolate, distributed along the stem, mostly grouped at stem apex, but not forming a pseudo-whorl, the internodes 3–22 mm long; the petioles 36–65 × 0.7–1.2 mm, canaliculate adaxially, with moderate to abundant, patent to curved hairs, curved along the channel, the base pulvinate, enlarged to ca 2 mm diam.; the rachis 8–20 mm long, similar to the petiole, sometimes slightly thinner, slightly enlarged distally; petiolules ca 1 mm long, with abundant, appressed to curved hairs; leaflet blades adaxially glabrous, ciliate along the margin, abaxially with abundant, appressed hairs; chartaceous, adaxially dark green, sometimes with a lighter shaded band along the midrib, abaxially lighter green, sometimes vinaceous. Venation: midrib canaliculate adaxially, raised abaxially; secondary veins 7–12 pairs, slightly visible or inconspicuous, impressed adaxially, slightly raised abaxially; intercostal tertiary veins sometimes visible, irregular-reticulate, exterior tertiary course looped, quaternary veins fabric irregular-reticulate, areolation moderately developed, inconspicuous, free ending veinlets not seen. Terminal blade 46–122 × 20–43 mm, ovate to lanceolate, the apex acuminate to slightly caudate, the base cuneate to obtuse. Lateral leaflets opposite, the blades 33–85 × 13–32 mm, ovate to lanceolate, the apex acuminate to slightly caudate, the base subsymmetrical to asymmetrical, obtuse to rounded. Dichasial cymes axillary and cauliflorous, except in young plants, which may lack cauliflorous inflorescences, shorter than the leaves; the peduncle 10–75 mm long, slightly flattened, with abundant, curved hairs; dichasial branches (1–)2(–3), usually bifid at the very base, and thus appearing as 4(–6), 1–7 mm long, each with the flowers (or scars) densely grouped along the entire length; bracts ca 1 mm long, triangular, abaxially with moderate to abundant, appressed hairs; bracteoles 0.5–0.7 mm long, triangular, with moderate to abundant, appressed hairs. Flower buds 4–4.5 × 1.4–2 mm, ovate-acuminate. Pedicel 1.5–3.5 mm long, articulated at base, leaving a persistent foot up to ca 0.5 mm long, with abundant, short, appressed or curved hairs. Sepals greenish, 5–5.5 × 1–2.2 mm, oblong to lanceolate, the exposed part with abundant, curved hairs, the apex acuminate to obtuse. Corolla yellow, ca 9 mm diam., petals 8.5–9.5 mm long, each with two orange maculae above the throat; short-styled morph: filaments connate for ca 0.5 mm of their length; shorter filaments ca 3 mm long, glabrous, each with a basal knob, longer filaments ca 4.5 mm long, non-appendiculate, hispidule; pistil: ovary ca 0.8 mm long; styles ca 1 mm long, recurved, with a few setae; stigmas oblate; gynophore inconspicuous, up to ca 0.5 mm long; long-styled morph: filaments connate for 0.5–0.7 mm of their length; shorter filaments ca 1.2 mm long, glabrous, each with a basal knob, longer filaments 2.8–3.8 mm long, non-appendiculate or very slightly appendiculate at ca 1.5 mm long, hispidule or almost glabrous; pistil: ovary ca 0.8 mm long; styles ca 4 mm long, erect, hispidule for the entire length; stigmas oblate; gynophore 0.3–0.5 mm long. Capsules ca 5.5 × 5.5 mm, pyriform, glabrous, slightly longer than the calyx lobes, the apex prolonged for ca 2 mm of its length; locules one-seeded, internally glabrous; seeds ca 2.5 × 1.2 mm, ovoid, with a honeycombed-foveolate surface.

Preliminary conservation status assessment

Despite its widespread distribution ( Fig. 5 ), O. decipiens occurs in a very fragmented area of lowland to submontane Atlantic forests in the states of Rio de Janeiro, Espírito Santo and Minas Gerais. The main threats to this species are the historical forest conversion into agricultural land for cattle grazing and eucalyptus reforestation for cellulose production. The region where this species occurs suffered from both extent and quality loss, but it is protected in large lowland Atlantic Forest remnants, such as the Rio Doce State Park, in Minas Gerais state, and the Reserva Natural Vale and Sooretama National Park, both in the state of Espírito Santo. Oxalis decipiens has an EOO of 81 772 km 2 and an AOO of 60 km 2, which could be expanded if additional populations are found. For these reasons we recommend that O. decipiens should be considered as Least Concern (LC) following IUCN (2012).

Nomenclatural remarks

Oxalis decipiens was described by Progel (1877) based on two syntypes: Glaziou 7561, from the surroundings of Ubá (Minas Gerais state) and Peckolt s.n. ( BR529076 (bc) (photo)!), from Cantagalo (Rio de Janeiro state). Lourteig (1994) chose the specimen Glaziou 7561 at C as the lectotype, as it bears an identification label handwritten by A. Progel.

Two specimens collected by Prince Max. Neuwied during his journey to Brazil from 1815 and 1817 are available at M and labeled as types of O. polymorpha var. cauliflora . The first (M-0121064) was collected “zw[ischen] Villa N[ova] u[nd] Praya Molle”, between localities that, according to Moraes (2009) were visited between 20 th and 21 st December 1815, and which correspond to the current town of Nova Almeida and Praia Mole, at Espírito Santo state. This specimen was inadvertently chosen as the lectotype of Oxalis polymorpha var. cauliflora by Lourteig (1994), but it is a ʻmixtum compositumʼ, where the central leaf-bearing branches and the left stem with a few cauliflorous inflorescences correspond to this taxon ( Fig. 9A ), while the two pieces of stem on the right side likely belong to what we are describing here as O. idimae sp. nov. ( Fig. 9B ). The second specimen (M-053323, Fig. 9C ) appears to belong to the same gathering of these two pieces of stem that were mounted on the right side in M-0121064. In support of this interpretation, the petioles, and peduncles from Fig. 9B are clearly thinner than those of Fig. 9A , and the single leaf blade of Fig. 9B dried greenish as those of Fig. 9C , contrasting to the brownish color of the leaves from Fig. 9A . Moreover, while the branches in Fig. 9A bear inflorescences with bifid dichasial branches, which are commonly observed in O. decipiens ( Fig. 5I ), those from Fig. 9C are not bifid, resembling what is observed in O. idimae (see Fig. 10F ). The locality where M-053323 was collected is unknown, but it was very likely gathered during the part of Neuwiedʼs expedition when he visited the northern part of Rio de Janeiro state, between September and November of 1815 ( Moraes 2009), the region where O. idimae is presumably endemic ( Fig. 5 ).

Taxonomic remarks

Oxalis decipiens can be distinguished from O. polymorpha by the usually cauliflorous (vs only axillary) inflorescences with bifid dichasial branches (appearing 4(–6) branched) (vs with single, unbranched dichasial branches), and by the pyriform capsules with the carpels apically prolonged for ca 2 mm long (vs carpels prolonged up to ca 0.5 mm long).

Distribution and ecology

This species mostly occurs in the Rio Doce valley rainforests in the northern part of the state of Espírito Santo and in the eastern part of Minas Gerais, especially in the large forest fragment protected in the Parque Estadual do Rio Doce. In addition to these areas, there are a few records in the surroundings of Vitória (Espírito Santo state) and in highland areas along the state of Rio de Janeiro, in the municipalities of Barra Mansa, Volta Redonda and Cantagalo, but no additional samples from this latter area are known to date.

Figures

Fig. 5. Geographic distribution map of Oxalis polymorpha Mart. ex Zucc. (the single record in the Caatinga domain represents the type) and some of the segregated species recognized here, all of which are endemic to the Brazilian Atlantic Forest domain.

Fig. 8. Oxalis decipiens Progel. A–B. Habit (note cauliflorous and axillary inflorescences in B). C. Detail of young stem. D. Terminal leaflet, abaxial view. E. Lateral leaflet, abaxial view. F. Detail of leaflet blades insertion, abaxial surface. G–H. Detail of young inflorescences with flower buds. I. Older inflorescence with bifid dichasial branches. J. Inflorescence detail with flower and young buds. K. Flower, frontal view. L–M. Fruits, lateral view (note carpels prolonged for ca 2 mm of their length). N. Seed, lateral view (the central dark spot is likely due to incomplete SEM coating). Photos: A–M: Pedro Fiaschi; N: Gabriela Rhoden; A, C, G, N based on E. Richetti et al. 64, FLOR; B, L based on P. Fiaschi & J.L. Costa Lima 4656, FLOR; D–F, H–K, M based on J.C. Vasques et al. 57, FLOR, HUEFS, RB, SPF.

Fig. 9. A. Lectotype of Oxalis polymorpha var. cauliflora Zucc. (M-0121064, three pieces on the left), showing inflorescences with bifid dichasial branches (white arrowheads). Blue asterisks indicate the ends of the same broken branch. B. Pieces from a different gathering that do not belong to the type, but to the plant represented in C (M-0153323), which is here described as O. idimae Fiaschi sp. nov. Red asterisks indicate the ends of the same cut branch. Modified from high-resolution images provided by the Botanische Staatssammlung München.

Fig. 10. Oxalis idimae Fiaschi sp. nov. A. Habit. B. Leaf, adaxial surface. C. Terminal leaflet detail, adaxial surface. D. Lateral leaflet, adaxial surface. E. Detail of leaflet blades insertion, adaxial surface. F. Stem with cauliflorous inflorescences bearing flowers and buds. G. Detail of young inflorescence with buds. H. Older inflorescence detail, showing densely grouped flowers (scars) along the entire length. I. Developing fruit in lateral view. J. Flower, frontal view. K. Young inflorescence with buds, flower (lateral view) and fruits. L. Fruit, lateral view. M. Seed, lateral view. Photos: A–L: Pedro Fiaschi; M: Gabriela Rhoden. A, J based on J.C. Vasques et al. 81, FLOR, HUEFS, RB; B–G based on J.C. Vasques et al. 78, FLOR, RB, SPF; H–I, K–L based on T.S. Costa et al. 123, FLOR; M based on E. Richetti et al. 70, FLOR.