Lavoisiera tetragona Martius & Schrank ex Candolle (1828: 103)

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

40. Lavoisiera tetragona Martius & Schrank ex Candolle (1828: 103) . Type:— BRAZIL. Minas Gerais: “In summo cacumine montis Itambé da Villa et prope Tejuco, in districtum adamantium,” C. F. P. Martius s.n. (holotype: M, photos: CAS!, F!, NY!, UEC!; isotype: G-DC-00219853-n.v., online image!).

= Lavoisiera tetragona var. crenata Chamisso (1834: 370) ex Cogn. in Martius (1883: 162). syn. nov. Type:— BRAZIL. Minas Gerais: Serra do Santo Antônio (Itambé), F. Sellow s. n. (holotype: B, destroyed; isotypes: BR-518636!, K-584881!, K-584882!, M!, P-723518!, US-1050286!). Only the isotypes at P and US have the numbers 1165 and 1747 on the same label. These numbers, which were cited by Cogniaux in Flora Brasiliensis , are here interpreted to represent only one collection and not two different syntypes .

= Lavoisiera lycopodioides Gardner in Hooker (1843: t. 502). Type:— BRAZIL. Minas Gerais: in bare elevated rocky places, Serra do Frio ( Diamantina ), Province of Minas Geraes , G. Gardner 4577 (holotype: BM!; isotypes: BR!, E, F!, G-2!, K-2!, NY-2!, P!, SP, US!, W!).

Decumbent, dichotomously much-branched subshrubs 20–30 cm tall, essentially glabrous, perennating from a lignotuber. Branches and branchlets quadrangular, conspicuously furrowed on opposite faces, the branchlets at first leafy to the base, glabrous, defoliating and decorticating basally and then becoming rounded with age; internodes ca. 1.5 mm long, with knobby thickenings that persist where a leaf has fallen away, nodes with conspicuous leaf scars and short vinaceous glandular trichomes. Leaves sessile, semi-amplexicaul, erect and densely imbricate and concealing the internodes; blade 4–5 × 3–4 mm, thick, subcoriaceous and somewhat fleshy, ovate to oblong-ovate, widest at the middle, base subrounded, apex bluntly obtuse or broadly rounded-acute, margins subcallose with minute purple sessile glands, shallowly crenulate distally, sometimes entire basally, yellowish-green to dark green on both surfaces, keeled, 1-nerved, the vein thickened. Flowers 5-merous, solitary, terminal but overtopped by the elongation of lateral branches, sessile. Bracts frequently 2, blade 6 × 4 mm, ovate, base broadly attenuate, apex obtuse to subrounded, margins inconspicuously crenulate, subcoriaceous. Hypanthium (at anthesis) 3.5–4 × 4–5 mm, broadly campanulate, glabrous except for a few purple sessile glands at the base. Calyx tube 0.5–1 mm long; calyx lobes (at anthesis) 3–3.5 × 4–4.5 mm, subcoriaceous, triangular, acute to subrounded at the apex, margins subcrenulate and glandular, red-purple turning black when dry, glabrous on both

LAVOISIERA ( MELASTOMATACEAE )

Phytotaxa 315 (1) © 2017 Magnolia Press • 169 surfaces, persistent. Petals 15–20 × 7–9 mm, bright pink at anthesis with a greenish-white or yellow-white base, but white in bud, obovate, apex slightly emarginate, base attenuate, margin minutely glandular-ciliolate. Stamens 10, dimorphic: large (antesepalous) stamens 5, filaments 8–9 mm long, yellow, anther thecae 4 × 1 mm, oblong, yellow, vinaceous when dry, rostrum 0.6 mm long, pedoconnective 9–10 mm long, appendage 1.5 mm long,

170 • Phytotaxa 315 (1) © 2017 Magnolia Press

MARTINS & ALMEDA bilobed, yellow; small (antepetalous) stamens 5, filaments 6–7 mm long, anther thecae 4 × 1 mm, oblong, yellow, vinaceous when dry, rostrum ca. 0.5 mm long, pedoconnective 1.5–2 mm long, appendage 0.7 mm long, subrounded to obscurely bilobed. Ovary 5-locular, 1/2 inferior, style 8–9 mm long, glabrous, curved distally, stigma punctiform. Fruiting hypanthium (including calyx lobes) 8–10 × 6 mm, oblong-campanulate, greenvinaceous. Capsule (at maturity) 5–6 × 4 mm, coriaceous, enveloped by the persistent hypanthium and calyx lobes, dehiscing from the base to the apex. Seeds 1.23–1.75 × 0.83–0.97 mm, oblong to reniform, dark brown, periclinal cell walls of the testa concave (foveolate), raphal zone about 60% the length of the seed. Chromosome number unknown.

Illustrations:— Figure 63 ; Gardner (1843: t. 502, as L. lycopodioides ).

Photographic image:— Figure 5J .

Phenology:—Flowering collections have been made in June, August, and September; the only fruiting collection was made in May.

Distribution and habitat:—Endemic to Minas Gerais where it is known only from the municípios of Serro and Santo Antônio do Itambé (Pico do Itambé) on the Cadeia do Espinhaço in campo rupestre and sandy areas at about 1300–1400 m elev. Figure 20 .

Conservation status:—We know of only nine collections of this apparently rare and local species. Except for the one collection we made during one of our field expeditions, we have no geographical coordinates. It appears however, that none of the known populations occurs within a protected area. Because we lack the information needed to make an extinction risk assessment based on its distribution and population status we consider it Data Deficient (DD).

Discussion:—This species is a decumbent, essentially glabrous shrub that perennates from a lignotuber. Its leaf blades are somewhat fleshy when fresh, 1-nerved, prominently keeled on the abaxial surface, erect, imbricate and concealing the internodes on leafy branches. The floral buds are white with an apical flush of pink but the five petals expand to a deep pink color with a distinctive undulate band of yellowish-white or greenish-white at the adaxial base ( Figure 5J ). The entire androecium and style are yellow and the ovary is 5-locular.

Vegetatively, Lavoisiera humilis is reminiscent of L. tetragona . It also has a distinctive decumbent habit, imbricate glabrous leaves, and an androecium and style that are uniformly yellow. Its petals are also pink but they are paler with a diffusely white or yellowish base unlike the well-differentiated color band on the petals of L. tetragona ( Figures 3E ; 5J ). Lavoisiera humilis is a much more delicate and sparingly-branched plant with juvenile leaves on short basal branches that differ in shape and width from the mature upper cauline leaves, consistently rounded calyx lobe apices, shorter petals (10–12 mm), (5–)6-merous flowers and a uniformly 4-locular ovary.

The taxa that we include here in synonymy differ in no consistent and taxonomically significant way from what we consider typical L. tetragona .

Additional specimens examined:— MINAS GERAIS: Mpio. Serro, estrada para o Distrito de Milho Verde , ca. 6 km da cidade de Serro, 18°38'S, 43°22'W, Almeda et al. 7808 ( CAS!, MO!, NY!, UEC!); exact locality not specified, Gardner 4582 B (S!); from Conceição along road to Diamantina, Maguire et al. 49112 ( MICH!, NY!, RB!, UB!, US!); Mpio. Serro, Lapa dos Tropeiros, entre Capivari e o Pico do Itambé, Mendes Magalhães 1646 ( BHCB ex BHMH!) . MINAS GERAIS?: Sellow s.n. ( W!) .

Figures

FIGURE 3. Images of Lavoisiera species. A. L. grandiflora (unvouchered image). B−C. L. grandiflora (Almeda et al. 9459). D. L. harleyi (unvouchered image). E−F. L. humilis (Almeda et al. 8497). G. L. imbricata (Almeda et al. 8497). H. L. imbricata (Almeda et al. 9032). I−K. L. itambana (Almeda et al. 9663). L. L. macrocarpa (Almeda et al. 8545). Image credits: A. Pinterest at www.pictopin.com; B, C, E−L. Frank Almeda; D. Fernando B. Matos.

FIGURE 5. Images of Lavoisiera species. A−C. L. rundeliana (Almeda et al. 9667). D, F. L. sampaioana (unvouchered images). E. L. sampaioana (Almeda et al. 9198). G−H. L. senae (Almeda et al. 9186). I. L. subulata (Almeda et al. 8571). J. L. tetragona (Almeda et al. 7808). K−L. L. vestita (Aranha et al. 164). Image credits: A−C, E, G−J. Frank Almeda; D, F. Ernesto Lemes; K, L. Gustavo Shimizu.

FIGURE 20. Distributions of Lavoisiera angustifolia, L. belinelloi, L. bradeana, L. punctata, L. sampaioana, L. scaberula, and L. tetragona.

FIGURE 63. Lavoisiera tetragona. A. Habit. B. Abaxial leaf surface. C. Abaxial bract surface. D. Flower. E. Hypanthium and calyx lobes with lobe margin detail (upper right) and enlarged detail of adaxial intercalycine sinus. F. Ovary cross-section. G. Petal with lateral margin detail (lower left). H. Ventral view of antesepalous stamen. I. Ventral view of antepetalous stamen. J. Seed. (Based on: A–J, Almeda et al. 7808, CAS, UEC.)