Lavoisiera gentianoides Martius & Schrank ex Candolle (1828: 104)

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

16. Lavoisiera gentianoides Martius & Schrank ex Candolle (1828: 104) . Type :— BRAZIL. Minas Gerais: “Habitat in campis frigidiusculis Montis Itambé, altitudine 1000 hexaped. supra mare, Provinciae Minarum Generalium,” C. F . P. Martius 1375 (holotype: M, photos: CAS!, F!, NY!, UEC!; isotypes: G-DC-n.v, online image!, M) .

Moderately to little-branched erect shrubs 1–2 m tall. Branches and branchlets quadrangular to subrounded, glabrous, furrowed longitudinally on opposite faces, leafy only at the ends of branchlets; internodes 4–15(–20) mm

LAVOISIERA ( MELASTOMATACEAE )

Phytotaxa 315 (1) © 2017 Magnolia Press • 91 long, corky, with knobby thickenings that persist where a leaf has fallen away, the distal ones commonly flushed with crimson when fresh, nodes with conspicuous semi-circular horizontal scars and vinaceous glandular trichomes. Leaves gradually reduced in size upward along the branches, the basal ones sessile, semi-amplexicaul, commonly spreading perpendicular to the stems to somewhat reflexed; blade 45–100 × 10–25 mm, subcoriaceous to membranaceous, elliptic-lanceolate to oblong-lanceolate, base subrounded, apex acute, margin cartilaginous, frequently flushed with crimson, entire or rarely serrulate, adaxial surface glabrous or sparsely fine-setulose with trichomes 1 mm long, abaxial surface glabrous and inconspicuously but distinctly punctate, flat or cuculliform, glossy green to yellowish-green, faintly 5-nerved, only the central vein conspicuous, the marginal pairs frequently inconspicuous. Flowers 5-merous, essentially sessile, aggregated in a terminal (but becoming pseudolateral with elongation of lateral shoots), congested mostly 6–10-flowered dichasium simulating a glomerulate head. Bracts subtending the flowers several, semi-amplexicaul, gradually reduced in size upward, 13–20 × 12–18 mm, subsessile or with a petiole 1.5 mm long, cordiform to ovate-cordate, rounded to subcordate at the base, acute at the apex, margins entire, subcoriaceous to membranaceous, sparsely glandular-puberulous on both surfaces, translucent; bracteoles 14 × 7 mm, subsessile, oblong or elliptic-oblong, membranaceous, glandular-puberulous. Hypanthium (at anthesis) 11–13 × 4 mm, narrowly campanulate to cylindric-tubulose, constricted distally above the ovary, glabrous basally and apically, otherwise beset distally at and just below the constriction or for the entire upper half of the hypanthium with spreading eglandular or glandular trichomes 1.5 mm long, rarely glabrous throughout, green. Calyx tube 1–1.5 mm long; calyx lobes (at anthesis) 8–10 × 4 mm, membranaceous, triangular, acute at the gland-tipped apex, margin entire, sparsely to moderately covered with glandular trichomes on both surfaces, tardily caducous in post-anthesis, green. Petals 20 × 12 mm, white, yellowish-green with conspicuous translucent venation, obovate, apex asymmetrically apiculate with a terminal glandular trichome, sometimes red apically in bud, base attenuate, margin entire, eciliate. Stamens 10, dimorphic: large (antesepalous) stamens 5, filaments 9–10 mm long, anther thecae 4.5–5 × 1–1.5 mm, oblong, yellow, rostrum 0.5 mm long, pedoconnective 5 mm long, appendage 1.5–2 mm long, emarginate to bilobed, yellow; small (antepetalous) stamens 5, filaments 0.7–0.8 mm long, anther thecae 4–5 × 1–1.5 mm, oblong, yellow, rostrum 0.5 mm long, pedoconnective 1–1.5 mm long, appendage 0.7 mm long, rounded to shortly and inconspicuously lobed, yellow. Ovary 5-locular, 4/5 inferior, style ca. 10 mm long, straight to curved at the apex, glabrous, stigma punctiform. Fruiting hypanthium (excluding calyx lobes) 10–12 × 7–9 mm long, ovoid-oblong, constricted above the ovary. Capsule (at maturity) oblong, 10–12 mm long, enveloped by the persistent hypanthium, dehiscing from the base to the apex, vascular strands occasionally persisting long after capsule walls have fallen away. Seeds 0.72–0.96 × 0.40–0.52 mm, reniform to oblong, dark brown, periclinal cell walls of the testa convex and low domed (colliculate) but evidently becoming faintly concave (foveolate), raphal zone about 50% the length of the seed. Chromosome number unknown.

Illustrations:— Figure 37 ; Martius (1831: t. 267).

Photographic images:— Figures 2I ; 8A, B .

Phenology:—Flowering from March through August and November; fruiting March through May, August and November.

Distribution and habitat:—Largely restricted to the Chapada Diamantina in Bahia with a few older collections (including the type) known from Minas Gerais (Pico do Itambé and vicinity) in campo rupestre, stream banks and flood plains at 900–1600 m elev. Figure 33 .

Conservation status:— Extant populations of this species are known only from the Chapada Diamantina (Bahia) . The type was collected on Pico do Itambé in 1827 and a couple of other old collections were made in Minas Gerais but no recent collections have been made outside of Bahia. None of the Bahian populations occurs in a protected area. The EOO is 1,254 km ² and the AOO is 40 km ². We recommend a classification of Endangered ( EN): B1 ab(iii) .

Discussion:— Lavoisiera gentianoides is a sparingly branched shrub with glossy leaves that are somewhat reflexed or more or less perpendicular to the stem ( Figures 2I ; 37A ). Other diagnostic characters include its leaf blades that are glandular-punctate abaxially, inflorescence consisting of a congested cluster of sessile flowers, spreading gland-tipped trichomes on bracts, bracteoles, hypanthia and calyx lobes, 5-merous flowers, white petals, and 5-locular ovary.

Among the consistently white-flowered species of Lavoisiera only L. alba has 5-merous flowers and a 5- locular ovary. Lavoisiera alba , which is mostly centered in Minas Gerais, differs in its overall glabrosity, quadrangular upper branchlets that are prominently angled and carinate to narrowly winged, bluish-green or pale

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MARTINS & ALMEDA green glaucous leaves that lack glandular punctations on both surfaces, and persistent calyx lobes. For a comparison with L. grandiflora , which has modally 6-merous flowers, a 6-locular ovary, and some white-flowered populations, see the discussion under that species.

Additional specimens examined:— BAHIA: Mpio. Rio de Contas , estrada para Mato Grosso , ca. 15 km da cidade de Rio de Contas , 13°28'S, 41°51'W, Almeda et al. 8314 ( CAS!, UEC!); Mpio. Rio de Contas , estrada para Campo do Queiróz , próximo ao rio Brumadinho, 13°31'S, 41°53'W, Almeda et al. 8318 ( CAS!, MO!, UEC!); Mpio. Rio de Contas, Pico das Almas; ao longo da estrada e ca. 2–3 km da Fazenda Morro Redondo, em direção à cidade, Atkins et al . CFCR 14770 ( ESA!, SPF!); Mpio. Abaíra, Caminho Boa Vista para Bicota, França et al. 1293

LAVOISIERA ( MELASTOMATACEAE )

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(CAS!); Mpio. Abaíra, Distrito de Catolés , caminho Barra-Ouro Fino, Campo da Pedra Grande, 13°14'S, 41°55'W, Ganev 227 ( CAS!, HUEFS!) ; Mpio. Abaíra, Tanque do Boi , 13°16'S, 41°54'W, Ganev 617 ( HUEFS!) ; Mpio. Rio de Contas , Encosta da Serra dos Frios, Agua Limpa , 13°52'S, 42°19'W, Ganev 2111 ( HUEFS!) ; Mpio. Abaíra, Agua Limpa, Morro do Cuscuzeiro , 13°18'S, 41°53'W, Ganev 3166 ( HUEFS!) ; Mpio. Rio de Contas , Serra Marsalina (Serra da antena de TV) , 13°35'S, 41°49'W, Harley et al. PCD 4484 ( ALCB!) ; Mpio. Rio de Contas , ca. 15 km WNW from Vila do Rio de Contas along road to the Pico das Almas, 13°33'S, 41°53'W, Harley et al. 19821 ( CEPEC!, K!, US!) ; Mpio. Rio de Contas , about 2 km N of the town of Vila do Rio de Contas in flood plain of the Rio Brumado, 13°34'S, 41°50'W, Harley et al. 19837 ( CEPEC!, NY!, UEC!, US!) ; Mpio. Rio de Contas , arredores de Rio de Contas, Hatschbach 46499 ( C!, CAS!, CEPEC!, MBM!, NY!, US!) ; Piatã-Abaíra, estrada para Catolés, Koch et al. 707 ( UEC!) ; Serra Marsalina, Luetzelburg 69 (M!); Mpio. Rio de Contas , Pico das Almas, a 18 km ao SNW de Rio de Contas, 13°33'S, 41°57'W, Mori et al. 12491 ( CEPEC!, US!) ; Mpio. Abaíra, Distrito de Catolés. Estrada para Serrinha e Bicota, Queiroz et al. 5052 ( CAS!) ; Mpio. Abaíra / Piatã, Malhada da Areia , Stannard et al. H51911 ( CAS!) . MINAS GERAIS: ad Agua Boa, Pohl s.n. (BM!); “Ad aquas inter Rio Jequitinhonha et Agua boa,” Pohl 1288 ( K!, NY!, W!) .

Figures

FIGURE 2. Images of Lavoisiera species. A. L. cordata (Almeda et al. 7798). B−C. L. cordata (Almeda et al. 9696). D. L. crassifolia (Almeda et al. 8442). E. L. crassifolia (Almeda et al. 7807). F. L. crassifolia (Almeda et al. 9051). G−H. L. firmula (Almeda et al. 9197). I. L. gentianoides (Almeda et al. 8314). J. L. glandulifera (Almeda et al. 9700). K. L. glandulifera (Almeda et al. 9199). L. L. glandulifera (unvouchered image). Image credits: A−K. Frank Almeda; L. Livia Echternacht.

FIGURE 8. SEM images of seeds for representative Lavoisiera species showing lateral symmetrical plane (left) and detail of testa cells and cell wall microrelief (right). A–B. L. gentianoides (Mori et al. 12491). C–D. L. glandulifera (Glaziou 14758). E–F. L. grandiflora (Macedo 3578). Scale bars: A=300 µm, B=30 µm; C & E=430 µm; D=43 µm, F=150 µm.

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

FIGURE 37. Lavoisiera gentianoides. A. Habit. B. Adaxial leaf surface with enlarged detail of of abaxial surface (upper right). C. Abaxial bract surface. D. Abaxial bracteole surface. E. Flower. F. Hypanthium and calyx lobes. G. Ovary cross-section. H. Petal. I. Ventral view of antesepalous stamen. J. Ventral view of antepetalous stamen. K. Seed. (Based on: A–K, Almeda et al. 8318, CAS, UEC.)