Mimosa confusa J. Gelma, L.P. Queiroz & Van den Berg, 2023

Do Nascimento, Janaína Gelma A., Rocha, Lamarck, Dutra, Valquíria F., De Queiroz, Luciano P. & Berg, Cássio Van Den, 2023, Four new species of Mimosa sect. Batocaulon ser. Cordistipulae (Leguminosae) from Bahia, Brazil, Phytotaxa 599 (5), pp. 265-279 : 269

2. Mimosa confusa J. Gelma, L.P. Queiroz & Van den Berg , sp. nov. Figs. 2A–H , 5 .

Type:— BRAZIL, Bahia: Mun. Morro do Chapéu, Lages , 10 March 2003 (fl., fr.), L.P. Queiroz et al. 7733 (holotype: HUEFS [barcode 000001174]!; isotype HUEFS [barcode 000001237]!) .

Affinis M. cordistipula Bentham (1842: 411) sed rachibus 15–25(–30) mm longis (nec 5–10 mm longis), stipulis 2.8–4 mm longis (nec 4–6 mm longis), foliis 4–7-pinnatis (nec 2–4(–5)-pinnatis, capitulis 55–70 mm diametro (nec 15–25 mm diametro) differt.

Subshrubs 0.3–1 m tall, rarely erect; branches cylindrical, rarely angulate, velutinous, lanuginose, rarely glabrous, with filiform trichomes, 0.9–1.2 mm long, and capitate-filiform glandular trichomes, 0.4–1 mm long. Internodes 20 –50 mm long. Stipules 2.8–4 × 0.8–1 mm, lanceolate, base truncate, apex acuminate, aristate, margin ciliate, 3-veined. Petiole 1–3(–4) mm long, rachis 15–25(–30) mm long, spinescent, aculeolate, first interpinnal segment 1–2 mm long, remaining segments 1–4 mm long; pinnae 4–7 pairs, median pinna 5–12(–15) mm long, increasing in size towards the apex of the leaf; leaflets 8–18 pairs per pinna (in median pinna), membranaceous, 2–4 × 0.8–1.8 mm, oblong, apex obtuse, base rounded, both surfaces sericeous, margin ciliate, 1-veined. Capitula 55–70 mm diam., 80–100-flowered; peduncle 22–45 mm long; bracts 1.4–1.8 × 0.1–0.2 mm, membranaceous, linear or spatulate. Flowers sessile or shortly pedicellate, pedicel ca. 0.2 mm long; calyx white or whitish-pink, 0.4–0.8 mm long, campanulate, lobes with apex truncate; corolla white, glabrous, subtubular, membranaceous, tube 1.2–2 mm long, lobes 0.8–1 mm long; stamens 6, pink, filaments connate ca. 0.3 mm long at the base, three longer 6–11 mm long, three shorter 5–6 mm long, anthers 0.5–0.7 mm long, globose, yellow; ovary 0.8–1.3 mm long, densely pilose, stipitate, stipe 0.3–0.4 mm long, 8–10- ovulate, style 6–8 mm long. Craspedium 30–50(–70) × ca. 5 mm, subsessile, linear, margin undulate, puberulous, with filiform and glandular capitate-filiform trichomes, 4–9-articulate, apical and basal articles triangular, median article quadrangular, 3–4 × ca. 4 mm. Seeds 2–2.3 × 3–3.5 mm, external surface smooth.

Distribution, habitat and phenology:— Mimosa confusa occurs in the Morro do Chapéu municipality, northern Chapada Diamantina range, Bahia, Brazil ( Figure 5 ). It was collected in “cerrado sensu stricto ”, campos rupestres and transitional areas of Caatinga vegetation, at 850–1,000 m of elevation, with flowers and fruits from December to July.

Conservation:— We propose this species to be endangered (EN, criteria B2ab(iii)+D) because Mimosa confusa has been observed only in a single locality in the region of Morro do Chapéu State Park, at the margins of the BA-052 road, with an AOO of 8,000 km 2. Despite being collected in a protected area, the Morro do Chapéu State Park still suffers severe impacts of human action, such as livestock, opening of roads and settlements, in addition to fires (Lob„o & Vale 2009).

Etymology:— The epithet ‘confusa’ refers to the morphological similarity of the new species with Mimosa cordistipula , leading to misidentification under this taxa by several authors in herbarium collections.

Notes:— Morphological studies with multivariate analysis showed that M. confusa represents a new species ( Nascimento 2007). This species is vegetatively similar to M. cordistipula by presenting spinescent projections at the tip of leaf rachides and pinnae, and by pinnae increasing in size toward the apex of the leaf. Mimosa confusa can be recognized by the larger internodes and leaf rachis (20–50 mm and 15–25(–30) mm long, respectively), larger number of pinnae, 4–7 pairs, and capitula with 55–70 mm diam. and 80–100 flowers, whereas in M. cordistipula the internodes are shorter (10–15 mm long), the rachis of the leaves is 5–10 mm long, the pinnae are 2–4(–5) pairs, and the capitula are smaller, 15–25 mm diam. with 40–60 flowers ( Table 2).

Mimosa confusa seems to be the result of a local differentiation of M. cordistipula to a particular habitat in the municipality of Morro do Chapéu. While M. cordistipula is a relatively widespread species across the Chapada Diamantina mountain range, where it occurs in different caatinga vegetation habitats, M. confusa is found only in dystrophic quartz sands among sandstone rocks. In the same locality, some new taxa were recently described, such as Philcoxia tuberosa Carvalho & Queiroz (2014: 151) , Micranthocereus polyanthus subsp. alvinii Machado & Hofacker (2004: 127) and Pavonia queirozii Krapovickas (2012: 63) .

Paratypes:— BRAZIL. Bahia: Morro do Chapéu, 22 km W de Morro do Chapéu, 20 February 1971 (fl., fr.), Irwin et al. 32650 ( MBM, NY, R, UB, US); ibd., 14 January 1977 (fl.), G. Hatschbach 39588 ( CEPEC, MBM, NY, US); ibd., ca. 3, 5 km SE de Morro do Chapéu, ao longo da BA 052 (estrada do feij„o), 25 July 1993 (fl., fr.), L.P. Queiroz & N.S. Nascimento 3428 ( HUEFS, K); ibd., ca. 20 km W de Morro do Chapéu, na estrada para Irecê, 11°29’53”S, 41°19’58”W, 21 April 2001 (fl., fr.), E. Melo 3401 ( HUEFS, UB); ibd., Lages, na estrada para Irecê ca. de 20 km a O de Morro do Chapéu, 5 January 2005 (fl., fr.), J.G.A. Nascimento & M.C. Machado 202 ( FLOR, HUEFS); ibd., 5 January 2005 (fl., fr.), J.G.A. Nascimento & M.C. Machado 203 ( HUEFS); ibd., caminho para as Dunas, 11°29’30”S, 41°19’08”W, 8 March 2003 (fl., fr.), L.P. Queiroz et al. 7645 ( HUEFS); ibd., ca. 20 km para Morro do Chapéu , na estrada Jo „o Dourado-Morro do Chapéu , 12 April 2001 (fl., fr.), M.J.S. Lemos et al. 157 ( HUEFS).

Figures

FIGURE 2. Mimosa confusa. A. flowering branch. B. portion of the branch showing stipule. C. detail of the branch indument, showing simple trichomes. D. pinnae in adaxial surface. E–F. leaflets showing adaxial (E) and abaxial (F) surfaces. G. flower. H. craspedium (Drawing from Queiroz 7733, holotype—HUEFS, by Carla Lima).

FIGURE 5. Distribution map of new species of Mimosa ser. Cordistipulae from Bahia.