Lavoisiera setosa A. B. Martins & Almeda, 2017

Martins, Angela B. & Almeda, Frank, 2017, A Monograph of the Brazilian endemic genus Lavoisiera (Melastomataceae: Microlicieae), Phytotaxa 315 (1), pp. 448-450 : 448-450

38. Lavoisiera setosa A. B. Martins & Almeda , sp. nov.

Subshrubs 70 cm tall. Branches sparsely to moderately covered with hirsute-glandular trichomes mixed with sessile to subsessile reddish glands. Leaves sessile, subcoriaceous, retrorsely spreading, flat but sometimes slightly revolute, margins subcallose, subserrulate, and glandular-ciliate, apex acute with a pungent trichome, abaxial surface sparsely glandular-hirsute with inconspicuous reticulation, 5–7(–9)-nerved. Flowers 6-merous, solitary. Hypanthium campanulate with a few spreading gland-tipped trichomes. Petals reportedly lilac. Ovary 6-locular, 1/2 inferior.

Type :— BRAZIL. Goiás: “Mpio. Niquelândia. Macedo. Cerrado no curva de mina, solo laterítico, elev. 1095 m, 14°21’36”S, 48°24’13”W,” 22 November 1997, F. C. A . Oliveira 1000, M. L . Fonseca , M. L. M . Azevedo & A. J. V . Santos (holotype: UEC!; isotypes: CAS!, HEPH, SP) .

Erect, dichotomously branched or cespitose subshrubs 70 cm tall. Branches and branchlets quadrangular or quadrisulcate to obscurely subrounded toward the base, sparsely to moderately covered with spreading gland-tipped trichomes ca. 1 mm long mixed with scattered sessile to subsessile reddish glands 0.2 mm long, like the hypanthium and calyx lobes, defoliating and decorticating basally with age; internodes (2–) 3–5 mm long, furrowed longitudinally on opposite faces, with knobby thickenings that persists where a leaf has fallen away, nodes with conspicuous leaf scars and inconspicuous glandular trichomes. Leaves sessile, semi-amplexicaul, spreading but recurved apically, laxly imbricate toward the branchlet tips; blade 5–7 × 5–6 mm, chartaceous to subcoriaceous, ovate to ovate-oblong, base rounded or sometimes shortly subauriculate, apex acute with a pungent trichome, margins obscurely and narrowly subcallose and subserrulate-ciliate, the cilia ca. 1 mm long, frequently gland-tipped especially on the uppermost leaves, adaxial surface grayish-green, glabrous, abaxially pale green to yellowish-green, sparsely beset with ± spreading gland-tipped trichomes, basically flat but sometimes slightly revolute, 5–7(–9)-nerved, with reticulate inconspicuous venules evident only on abaxial surface. Flowers 6- merous, solitary, terminal, but becoming central because of elongation of lateral shoots, sessile, subtended by several bracts or upper leaves gradually changing from the base to the apex, becoming a little wider toward the

164 • Phytotaxa 315 (1) © 2017 Magnolia Press

MARTINS & ALMEDA LAVOISIERA ( MELASTOMATACEAE )

Phytotaxa 315 (1) © 2017 Magnolia Press • 165 base of the flowers. Bracts 6–7 × 6–7 mm, suborbicular, base rounded, apex acute, glandular-apiculate, margins glandular-ciliate, subsessile, pedicel flattened ca. 1.5 mm long. Hypanthium (at anthesis) 5–6 mm long, campanulate, 6–7 mm wide distally, with scattered glandular trichomes 1 mm long and a mixture of minute trichomes, or almost glabrous. Calyx tube inconspicuous to 0.5 mm long; calyx lobes (at anthesis) 4–5 × 2–3 mm, triangular, membranaceous, beset with spreading gland-tipped trichomes abaxially, glabrous adaxially, margins glandular-ciliate, caducous. Petals 20 × 15 mm, reportedly lilac, obovate, apex subrounded to truncate, base attenuate, margins entire, eciliate or shortly and sparsely glandular-ciliate. Stamens 12, dimorphic: large (antesepalous) stamens 6, filaments 8–9 mm long, anther thecae 4–4.5 × 1.5 mm, linear-oblong, yellow flushed with red, rostrum ca. 0.7 mm long, yellow, pedoconnective 7–8 mm, appendage 1.5–2 mm long, obscurely lobed to spatulate, yellow; small (antepetalous) stamens 6, filaments 6–7 mm long, anther thecae 3–4 × 1.5 mm, yellow, linear-oblong, rostrum 0.6 mm long, yellow, pedoconnective 6–7 mm long, appendage 1–1.5 mm subrounded, yellow. Ovary 6-locular, 1/2 inferior, globose, style 9–10 mm long, slightly curved distally, glabrous, stigma truncate. Fruiting hypanthium, capsule, dehiscence, and seeds not seen. Chromosome number unknown.

Illustration:— Figure 61 .

Phenology:—Flowering in November; fruiting time unknown.

Distribution and habitat:—Known only from the type locality where it is rare in cerrado at 1095 m elevation ( Figure 33 ). The Macedo region of Goiás is well known for its extensive ultramafic outcrops so it is highly likely that this species is a serpentine endemic like Microlicia macedoi [(L. B. Sm. & Wurdack) in Smith 1955: 200] and Pterolepis haplostemona ( Almeda & Martins 2015: 234) .

Conservation status:—The geographic coordinates for the type and only known collection of this species are nearly identical to those for the type of Pterolepis haplostemona ( Almeda & Martins 2015: 234) . Lavoisiera setosa appears to be restricted to the nickel mine site of Companhia Niquel de Tocantins (CNT). Because we had a single geographic coordinate we were unable to calculate the EOO and AOO for this species using GeoCAT but we feel confident in assigning it a classification of Critically Endangered (CR): B1ab(iii) because the opencast operations of the CNT mine have substantially modified the original plant cover of the area.

Discussion:— Lavoisiera setosa is distinguished by its consistently 6-merous flowers and 6-locular ovaries, spreading leaf blades with glandular-ciliate margins and a pungent somewhat recurved apical trichome, and upper cauline internodes and hypanthia with scattered gland-tipped trichomes. It is similar to two other rare and little-collected species that grow on non-serpentine soils in Goiás and the Distrito Federal, L. arachnoidea and L. quinquenervis . The former differs from both L. setosa and L. quinquenervis in having upper internodes, abaxial surfaces of uppermost leaves, hypanthia, and both calyx lobe surfaces that are covered with an arachnoid-pulverulent indumentum. Lavoisiera quinquenervis differs most notably from L. setosa in having uppermost cauline internodes that are glabrous to inconspicuously and sparsely beset with minute glandular trichomes. It also has hypanthia that are glabrous or caducously glandular-puberulous distally and longer (7–9 mm) calyx lobes that are essentially glabrous or minutely and caducously glandular-puberulous abaxially.

Etymology:—The specific epithet is derived from the Latin word setosus, meaning bristly or beset with stiff hairs, alluding to the prominent pungent trichome that terminates each leaf blade.

Figures

FIGURE 33. Distributions of Lavoisiera cordata, L. gentianoides, L. grandiflora, L. pohliana, and L. setosa.

FIGURE 61. Lavoisiera setosa. A. Habit. B. Abaxial leaf surface. C. Adaxial leaf surface. D. Flower. E. Hypanthium and calyx lobes. F. Abaxial calyx lobe surface with enlargement of margin detail (right). G. Petal with enlarged detail of apex (above) and lateral margin (left). H. Ventral view of antesepalous stamen. I. Ventral view of antepetalous stamen. (Based on: A–I, Oliveira et al. 1000, CAS, UEC.)