Bauhinia orbiculata A.C.B. Santos & L.P. Queiroz, 2023

Dos Santos, Antonio C. B., De Queiroz, Luciano P., Da Silva, Maria A. P., Paula, Antonio P. O., Feitoza, Lidiane De L. & Carvalho, Reginaldo De, 2023, Bauhinia orbiculata (Cercidoideae, Leguminosae), a new species from Chapada Diamantina, Bahia, Brazil, Phytotaxa 584 (4), pp. 285-292 : 286-289

Bauhinia orbiculata A.C.B. Santos & L.P. Queiroz , sp. nov.

Type: — BRAZIL. Bahia: Morro do Chapéu, ca. 3.2 km do entroncamento com a BA-144 ( Morro do Chapéu / Utinga ) na estrada para o Morr„o (entrando a ca. 1 Km sul de Morro do Chapéu), 11º34’23”S 41º10’52”W, 07 May 2019 [fl., fr.], L.P. de Queiroz et al. 16580 (holotype HUEFS!, isotypes (to be distributed) CEPEC, HCDAL, K, PEUFR, P, RB) . Figures 1 , 2 .

Diagnosis: — Bauhinia orbiculata is similar to Bauhinia acuruana Moricand (1840: 77) due to the entire unifoliolate leaves, with rounded to obtuse apex and cordate base, as well as the indumentum of ferruginous trichomes intermixed with yellowish and globose glandular hairs on the lower leaflet surface, but differing by the leaves with (rarely 7) 9 primary veins (vs. 5 to 7 primary veins in B. acuruana ), with a deep green, glabrous, shiny, smooth upper surface, with inconspicuous primary, secondary and tertiary venation (vs. villous upper surface with heavily imprinted tertiary and quaternary veins giving the surface a rugose appearance), coriaceous, orbiculate to widely ovate leaf blade (vs. chartaceous and oblong leaf blade), linear and smooth floral buds (vs. clavate floral buds, 5-costate at the apex). Figure 3 .

Description: —Multi-stemmed unarmed shrubs, (0.8–) 1–3 m tall, with thin trunks, rarely treelets up to 3.5 m tall with trunk 5–6 cm diam.; distal internode 1.3–4.2(–6) cm long; indumentum densely pubescent with short, ferruginous, erect and soft trichomes intermixed with yellowish and globose glandular hairs on young branches, lower surface of the leaflet blade, inflorescence peduncle and rachis, outer surface of the hypanthium, sepals and ovary; branch extrafloral nectaries not seen (probably absent). Stipules 1–2 × 1 mm, ovate, puberulous, membranaceous and early caducous, present only in young distal leaves. Leaves unifoliolate; petiole 0.5–0.8(–1.2) cm long; pulvinus 2–3 mm long; pulvinulus 2–3(–5) mm long; leaflet blade entire, (3.5–)5–7 × (3.5–) 5–7 cm, coriaceous, orbiculate or widely ovate, base cordate or truncate, apex rounded or retuse, rarely obtuse or acute, primary veins (7–)9, upper surface deep green, glabrous, shiny, smooth, with primary, secondary and tertiary venation inconspicuous, lower surface brown with raised and strongly reticulate primary, secondary and tertiary venation defining small areola, densely pubescent with short and soft trichomes, ferruginous on the veins and whitish at the areola, intermixed with yellowish glandular and globose trichomes. Inflorescences in terminal pseudoracemes, (1.5–)3.7–12.6(–17.5) cm long; peduncle 1.0– 2.5 cm long; partial inflorescences 2-florous; bracts and bracteole 1–3 × 1 mm, alternate at the base of the pedicel; pedicel 4–8(–13) mm long. Floral buds 2.0–3.5(–4.7) cm long, linear, smooth. Flowers 3.0–4.5(5.4) cm long, zygomorphic; hypanthium 10–15(–18) mm long, cylindrical, internally glabrous and black; sepals 5, 20–25 × 3–4 mm, fleshy, internally glabrous, becoming twisted in open flowers; petals 5, 25–27 × 3–4 mm, white, linear, glabrous, venation reticulate, all petals becoming upright in the open flowers; stamens 10, filaments 17–21 mm long, joined at the base into a 1–2 mm long staminal column, internally pubescent, anthers 6–7 × 2 mm, dorsifixed, opening by longitudinal slits; gynoecium 35–45 mm long, stipe 15–17 mm long, ovary 7–11 × 2–3 mm, style 12–15 mm long, stigma ca. 1.5 mm diam, oblique. Fruit an elastically dehiscent legume, (5.5–)8–9 × 1–1.5 cm, linear, apex and base acute, stipe (1–) 2–3 cm long; valves woody, pubescent, becoming twisted at dehiscence. Seeds 7–8(–18) × 5–6 mm, compressed; testa dark brown, smooth, bony.

Distribution and habitat: — Bauhinia orbiculata is restricted to the northern part of the Chapada Diamantina mountain range, in the central area of the state of Bahia, northeastern Brazil. Most of the collections are from the municipality of Morro do Chapéu, where the species is common, with relatively dense populations ( Figure 4 ).

It grows in the seasonally dry shrubby vegetation locally known as ‘carrasco’, characterized by a dense shrubby layer with sparse trees on sandy and gravelly soil, sometimes in disturbed vegetation along roads. The new species occurs in association with other endemic species, e.g., Abarema diamantina , Indigofera morroensis , Mimosa mensicola Barneby (1985: 133) , Philcoxia tuberosa , Trigonia bahiensis Guimar „es, Miguel & Fontella (1979: 1) and Lapidia apicifolia Roque & Ferreira (2017: 6) .

Phenology: —Flowering and fruiting specimens were found throughout the year, with more records from March to June.

Conservation status: —The new species was assessed as endangered (EN) according to IUCN (2012) criteria B2a,b(i,ii,iii) as it has an AOO = 32 km ² and EOO = 5801.7 km ².

Etymology: —The epithet “orbiculata” refers to the almost circular leaflet shape.

Vernacular name: —Mororó (J. Castro et al. 02, HUEFS).

Figures

FIGURE 1. Bauhinia orbiculata—A: flowering branch; B: lower leaf surface; C: glandular and globose hairs; D: detail of the primary and secondary veins; E: flower in frontal view; F: floral buds; G: cylindrical hypanthium; H: detail of the petal; I: detail of the sepal; J: stamen; K: anther; L: detail of the minutely tomentose staminal column; M: stipitate gynoecium; N: oblique stigma; O: immature fruit and P: seeds. Drawing by R. Carvalho based on the holotype.

FIGURE 2. General aspect of the branch of Bauhinia orbiculata showing leaf disposition, floral buds, flower and immature fruit. Field photos:A.C.B. Santos & L.P. Queiroz.

FIGURE 3. Comparative characters illustrating the differences between Bauhinia orbiculata—A: linear floral buds; B: coriaceous, orbiculate leaf blade; C: 9 primary veins and Bauhinia acuruana—a: clavate floral buds; b: chartaceous and oblong leaf blade; c: 5 to 7 primary veins. Field photos:A.C.B. Santos & L.P. Queiroz.

FIGURE 4. Map of northeastern Brazil showing the state of Bahia (BA) and the distribution of Bauhinia orbiculata (black triangles).