Mimosa pseudoracemosa T.P. Mendes, Marc. F. Simon & M.J. Silva, 2021

Mendes, Thainara Policarpo, Simon, Marcelo Fragomeni, Perez, Ana Paula Fortuna & Silva, Marcos José Da, 2021, Novelties in Mimosa sect. Mimosa ser. Mimosa subser. Polycephalae: a new species, new status, and new synonyms, Phytotaxa 505 (2), pp. 121-138 : 131-136

3. Mimosa pseudoracemosa T.P. Mendes, Marc. F. Simon & M.J. Silva , sp. nov. ( Figs. 4 , 5 ).

Subshrub, up to 1.6 m tall, with up to five stems arising from a woody base; stipules oval-lanceolate; leaves emerging mainly from the plant base; petioles up to 19.5 cm long; pinnae with 9–12 pairs of leaflets; paraphyllidia subulate; leaflets narrow-elliptic or ovallanceolate, with entire, corneous and yellowish margins; synflorescence pseudoracemose; bracteoles lanceolate; ovary pubescent; 2–4-articulated subcoriaceous craspedium.

Type: — BRAZIL. Goiás: Alto Paraíso de Goiás, Parque Nacional Chapada dos Veadeiros, porteira a 25 km do entroncamento de Alto Paraíso em direção a São Jorge, 4 km N em estrada de chão, 14°06’26’’S, 47°43’40’’W, 1190 m, 26 May 2017, fl., fr., M . F . Simon et al. 3061 (holotype: CEN!. isotypes: BOTU!, UFG!) .

Subshrubs, 1.3–1.6 m tall, erect. Stems with one to five tillers arising from a lignified subterranean system similar to a xylopodium; branches striated, light brown when young, and dark brown when older, unarmed, both strigosescaberulous covered with setiform trichomes with bulbous bases and papillose external surface, yellowish, including the external surfaces of the stipules, petiole, rachilla, leaflet margins, axes of inflorescence, peduncle, articles, and replum of the fruits. Stipules 0.8–1.2 × 0.2–0.3 cm, oval-lanceolate, glabrous on the adaxial surface, brown, 2-nerved, persistent. Leaves basal, emerging from short woody stems, usually subterranean or from the aerial stem, ascending, with 1 pair of pinna; internodes 0.9–2.3 cm long; petioles 2.8–19.5 cm long, angulate, canaliculate above, not striated; pulvinus 1.9–2 mm long, not dilated; interpinnal projection 2–5 × 0.4 mm, lanceolate, apex acute, persistent; pinnae with 9–12 pairs of leaflets, decreasing from the base to the apex of the rachilla; petiolules 0.6–1.9 mm long; rachilla 8.3–17.7 cm long, cylindrical, keeled on the upper side, striated; rachilla projection 1–2 mm long; paraphyllidia 0.5–1 × 0.1 mm, subulate, apex obtuse, persistent; leaflets 1.7–4.6 × 0.4–1.8 cm, narrow-elliptic or oval-lanceolate, margins entire, corneous, yellowish, apex obtuse, non-mucronulate, base subcordate or obtuse, concolorous, dark green on adaxial face, green-opaque on abaxial face, glabrous on both surfaces; venation palmate, with 3–6 pairs of main veins from the base, yellowish, prominent on both surfaces; interfoliolar segment 0.9–2.3 mm long. Synflorescences 1–1.5 m long, terminal on defoliated branches, lax with glomerules pareated on a main axis with a pseudoracemose structure; peduncle 4.5–8.2 cm long. Glomerules 1.9–2.7 cm in diameter at anthesis, including filaments, solitary. Bracteoles 2 × 2.9 mm, lanceolate, apex acute, margins entire, brown, ciliate close to the apex, persistent. Flowers tetramerous, isostemonous, 7.8–12 mm long; calyx 1.6–3.2 mm long, campanulate, paleaceous, tube 0.5–1 mm long, glabrous, lobes 1.1–2.2 mm long, fimbriate; corolla 3.8–4.4 mm long, tube 3–3.2 mm long, funnelform, glabrous, lobes 0.8–1.2 mm long, cymbiform, dorsally keeled, papillose and puberulent; stamens 1.1–1.6 cm long; monadelphous, between 2–3 mm long, enveloping the ovary, free portion of the filaments 0.9–1.3 cm long, with 0.5–0.9 mm exserted from the corolla, glabrous; anthers 0.3 mm long, not mucronulate at the apex; ovary 0.8 - 1.1 mm long, pubescent; style 1–3 cm long, puberulent. Craspedium 2–3.2 × 0.8–0.9 cm, subcoriaceous, flattened, 2–4-articulated, narrow-oblong, rounded base, obtuse and apex non-aristate, brown; articles 0.7–1.2 × 0.8–1 cm, squarish, non-stipitate; replum 1 mm. Seeds not seen.

Additional specimens examined: — BRAZIL. Goiás: Alto Paraíso de Goiás, 14°09’30’’S 47°50’10’’W, 870 m, 14 December 2010, fl., M. F . Simon et al. 1114 ( CEN); ib., Parque Nacional da Chapada dos veadeiros, ca. 3 km da bifurcação da estrada que leva às sete quedas do Rio Preto , ca. 4 km ao norte da GO 239 , 14°6’2’’S, 47°44’24’’W, 1106 m, 15 February 2015, fl., R. C . Sodré et al. 1673 ( UFG); ib., Parque Nacional Chapada dos Veadeiros, ca. 3.6 km N da GO-239, ponto 3500 do módulo RAPELD - UnB, 6 May 2016, fl., fr., M . Mendoza et al. 5205 ( CEN, UB). Cavalcante. Parque Nacional da Chapada dos Veadeiros, ca. 2.5 km da bifurcação da estrada que leva às sete quedas do Rio Preto , ca. 4 km ao norte da GO 239 , 14°6’8.1’’S 47°44’21.6’’W, 1106 m, 15 February 2015, M. J . Silva 6447 ( UFG) .

Distribution and habitat: — Species probably restricted to the Chapada dos Veadeiros National Park, in northern Goiás State, Brazil, in the municipality of Alto Paraíso de Goiás ( Fig. 7C ). It grows in rocky savannas (“cerrado rupestre”) ( Fig. 7A ), on sandy soils or on rock outcrops, between 870 –1,190 m a.s.l.

Phenology: —Collected with flowers and fruits between December and May, and with fruits in May

Etimology: —The specific epithet “ pseudoracemosa ” alludes to the aspect of the new species’ synflorescence, where the glomerules are paired in a pseudoracemose structure.

Preliminary conservation status: — Mimosa pseudoracemosa is currently known from only two localities and presented an Extent of Occurrence estimated at 17 km 2. Nonetheless, the species was found in the Chapada dos Veadeiros National Park, a permanent protection area protected by law, where it grows in areas unsuitable for cultivation or housing construction, and is therefore classified as Least Concern [LC].

Characterization and morphological affinities:— Mimosa pseudoracemosa is a subshrub up to 1.6 m tall, with leaves basal with a pair of pinnae, flowers with paleaceous calyxes, fimbriate lobes and stamens monadelphous surrounding the ovary basally, which allows its positioning in Mimosa sect. Mimosa ser. Mimosa subser. Polycephalae , as circumscribed by Barneby (1991). Among the species of the latter, the new species is quite similar to, and can be morphologically confused with, M. flavocaesia by their subshrubby habit, with leaves emerging from an subterranean stem, leaflets glabrous with a corneous, yellow, and ciliate margin, covered by simple bulbous-base trichomes, filaments puberulent, paraphyllidia subulate, and corolla with papillose lobes, and by their partially sympatric distributions ( Figs. 6D , 7D ) and preferred environments (typical rocky savannas, Fig. 6B ). However, M. pseudoracemosa differs from M. flavocaesia by its height between 1–1.6 m tall (vs. up to 0.3 m), stipules oval-lanceolate and 2-nerved (vs. lanceolate and 1-nerved), interpinnal projection 0.2–0.5 mm long (vs. 8–10 mm long), leaves 23.5–36 cm long (vs. 14.5–22.6 cm long), emerging only from a subterranean stem (vs. may emerge from a subterranean or aerial stem), narrow-elliptic, oval, or oval-lanceolate (vs. oval-oblong), 1.7–4.3 × 0.4–1.8 cm (vs. 1.1–2.8 × 0.8–1.5 cm), prominent veins on both surfaces (vs. prominent veins on the abaxial face), petioles 2.8–19.5 cm long (vs. 1–8.7 cm long), paraphyllidia conspicuous (vs. vestigial), glomerules in anthesis including filaments 1.9–2.7 cm long (vs. 4.7–6.5 cm long), bracteoles lanceolate (vs. spatulate), corolla papillose and puberulent (vs. puberulent), and ovary pubescent (vs. papillose).

Mimosa pseudoracemosa also resembles M. pseudoradula and M. detonsa by their subshrubby habit with basal leaves, stems> 60 cm long, and pinnae with 6–12 pairs of leaflets. However, Mimosa pseudoracemosa differ from these two species by having stipules oval-lanceolate and 2-nerved (vs. lanceolate and 1-nerved in the others), leaflets narrow-elliptic, oval elliptic, or oval-lanceolate, with prominent venation on both sides (vs. semi-oval or semi-cordate, and prominent veins only on the abaxial face in the others), bracteoles lanceolate (vs linear-oblanceolate in M. detonsa and spatulate in M. pseudoradula ). Besides the previously mentioned characters, other quantitative features help in the differentiation of the taxa, as presented in table 3.

Considering the taxonomic adjustments proposed in this work, the morphological similarities between the taxa, and the fact that they are often mistakenly identified in herbaria, we provide a key to the identification of M. pseudoracemosa , M. pseudoradula , and related taxa.

Figures

FIGURE 4. Mimosa pseudoracemosa. A. Habit (arrow). B. Leaves. C. Glomerule. D. Fruits.

FIGURE 5. Mimosa pseudoracemosa. A. Habit. B. Stipule. C. Leaf. D. Interpinnal projection. E. Paraphyllidia. F. and G. Leaflets with different shapes. H. Detail of leaflets margins. I. Detail of the synflorescence. J. Bracteoles. K. Flower. L. Androecium. M. Detail of the filament. N. Anthers. O. Gynoecium. P. Detail of the ovary.

FIGURE 6. Phytophysiognomies of the sites of occurrence and map of the geographical distribution of the studied species. A. “Campo sujo” (M. detonsa, Cristalina-GO). B. “Cerrado típico” (M. detonsa and M. flavocaesia, Brasília-DF and Alto Paraíso de Goiás-GO, respectively). Geographic distribution, C. M. detonsa. D. M. flavocaesia. GO=Goiás State, DF= Federal District.

FIGURE 7. Phytophysiognomies of the sites of occurrence and map of the geographical distribution of the studied species. A. “Cerrado rupestre”. (M. pseudoracemosa, Chapada dos Veadeiros National Park – GO). B. “Cerrado ralo” (M. pseudoradula, Brasília-DF). Geographical distribution, C. M. pseudoracemosa. D. M. pseudoradula. GO=Goiás State, DF= Federal District.