Borreria minensis E. L. Cabral, L. M. Miguel & E. B. Souza 2015, sp. nov.
Creators: name: Miguel, Laila M.
name: Souza, Elnatan B.
name: Cabral, Elsa L.
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Gentianales
Rubiaceae
Borreria
Borreria minensis

description: Borreria minensis E. L. Cabral, L. M. Miguel & E. B. Souza sp. nov.
Type:— BRAZIL. Minas Gerais: Serra do Ibitipoca, Pico do Pião, formação rupícola em arenito da série de Lavras, entre 1580–1600 m, 11 May 1970, D. Sucre 6677 (holotype RB!, isotypes CTES!, SI!). (Figs. 1, 3 A–C, 4 A–B).
Borreria minensis is very close to B. tenera Candolle (1830: 543), but differs from that species by its plants many branched from the base (vs. a main stem with few opposite branches), inflorescence with terminal and subterminal glomerules (vs. terminal and numerous axillary glomerules), and stipular sheath with bristles 2–4 mm long (vs. bristles 1–1.5 mm long).
Erect subshrubs, 6–40 cm tall; main stems 3–15, with numerous side branches, quadrangular, puberulous or with short hairs on the angles, internodes 3–30 mm long. Leaves opposite, with axillary brachyblasts, blades linear, 4– 18 × 0.5–1.5 mm, glabrous, margins revolute. Stipular sheath 1–1.2 mm long, pubescent to puberulous, edge truncate, with 5–7 bristles; bristles 2–4 mm long, glabrous. Glomerules terminal and subterminal, spherical or subspherical, 4–10 mm diam.; involucral bracts 4–10, linear to narrowly elliptic, 4.3–15.6 × 0.56–2.08 mm, of the same length or twice as long the glomerule. Flowers sessile; hypanthium 0.9–1.2 mm long, glabrescent to puberulous; calyx 4–lobed, lobes narrowly triangular, 1.6–1.8 mm long; corolla 4–lobed, infundibuliform, 2.5–2.8 mm long, white, externally glabrous with papillae at the apex of lobes, internally with a ring of moniliform hairs near the middle of the tube; stamens exerted, filaments 0.8–1 mm long, anthers 1–1.2 mm long; style 3–3.5 mm long, stigma slightly 2–lobed, 0.2 mm wide, nectariferous disc bipartite. Capsules subglobose, 2.5–2.9 × 1.8–2.2 mm, glabrescent to puberulous at the apex. Seeds ellipsoid, 1.2–1.5 × 0.6–0.8 mm, brown; ventral face with a longitudinal groove covered by the strophiole, raphides located around the strophiole, not showing up clearly on SEM images, hilum on ventral surface, just below the centre of the seed, resembling a small swelling; seed coat surface reticulate-foveate, exotesta cells hexagonal, isodiametrical, microsurface of exotesta cells microperforate, microperforations less than 1.5 μm and in the center of the cell.
Pollen morphology: —Pollen grains of B. minensis are spheroidal, 6–7 zonoporate, and 19–21 μm in diam., in polar view the outline is circular. The exine is 3 μm thick, the ectopore is 2–2.3 μm in diam., the operculum is present; the endoaperture is an indistinct endopore. The tectum is perforated and microspines are uniformly present (Fig. 4 A–B).
Phenology: —Flowering and fruiting from January to May.
Distribution and Habitat: — Borreria minensis is apparently endemic to Minas Gerais, where it is found in “campos rupestres” between 1100 and 1600 m elevation, in the Serra do Ibitipoca, Serra da Piedade, and Ouro Preto. This area comprises parts of the Mantiqueira Moutains and parts of the Espinhaço Range, including cangas of the Iron Quadrangle (Souza et al. 2012), which have one of the highest levels of endemism (Giulietti et al. 1997). (Fig. 5)
Representative specimens examined (paratypes): — BRAZIL. Minas Gerais: Caeté, Serra da Piedade, campo rupestre, 19º49’S, 43º40’W, 1670 m, 28 April 1985, L. Cunha et al. 5845 (BHCB, CTES); ídem, 19º54’S, 43º38’W, 1480−1650 m, 14 May 1990, M. Arbo et al. 4105 (CTES); Ouro Preto, Falcão, campo, 28 January 1942, Mendes Magalhães 1208 (BHCB, CTES).
Conservation status: —The species is known from four localities, representing three locations, all outside protected areas. The calculated extent of occurrence is 2,552.106 km 2. The estimated area of occupancy is 12 km 2 (cell size 2 km). Therefore, following the IUCN criteria (IUCN 2012), the species should be considered as endangered: EN, B1 a,b(iii) + B2a,b(ii).
Etymology: —The epithet ‘ minensis ’ refers to its distribution in the state of Minas Gerais.
Comments: —This species could be confused with B. rosmarinifolia E. L. Cabral & Bacigalupo, another endemic species from “campos rupestres” between 1100 and 1300 m elevation, in Minas Gerais. However B. rosmarinifolia can be differentiated due to its linear leaves and involucral bracts, which are rigid and oriented towards the apex.
description: Published as part of Miguel, Laila M., Souza, Elnatan B. & Cabral, Elsa L., 2015, Two new species of Borreria (Spermacoceae, Rubiaceae) from the states of Goiás and Minas Gerais, Brazil, pp. 149-157 in Phytotaxa 201 (2) on pages 150-153, DOI: 10.11646/phytotaxa.201.2.5, http://zenodo.org/record/13641405