Lavoisiera mellobarretoi Markgraf (1940: 220–221)

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

24. Lavoisiera mellobarretoi Markgraf (1940: 220–221) . Type:— BRAZIL. Minas Gerais: “Gebirge ostlich von Montes Claros, Serra Geral nordlich von Grão Mogol, 1000 m u.d. M., Sandboden am Bachrand im lichten, sonst trockenen Berg-Buschwald,” fr. 12 November 1938, F. Markgraf, H. L. Mello Barreto und A. C. Brade, n. 3454 und 3441 (holotype: RB!; isotypes: BHCB-2!, BHCB ex BHMH!, SPF). Both numbers following the collector names are given on the labels of the holotype and the isotype at BHCB. The isotypes at BHCB have only the number 3454 on the label. Evidently more than one of the collectors probably assigned their collecting number to this collection. It is clear that all of the specimens are part of the same gathering.

LAVOISIERA ( MELASTOMATACEAE )

Phytotaxa 315 (1) © 2017 Magnolia Press • 125 Erect shrubs 0.5–2.5 m tall, dichotomously or trichotomously branching from the base. Branches and branchlets quadrangular and sulcate to subrounded, furrowed longitudinally on opposite faces, glabrous, corky, defoliating and decorticating with age at the base; internodes 5–17 mm long, the distal ones commonly flushed red when fresh, with knobby thickenings that persist where a leaf has fallen away, nodes with conspicuous leaf scars and beset with vinaceous, short, glandular trichomes. Leaves congested on the branchlets distally, normally reduced in size distally but becoming wider toward the inflorescence, the upper ones frequently punctate, sessile, semi-amplexicaul, spreading to subimbricate on the uppermost branchlets; blade 35–80 × (7–) 10–30 mm, coriaceous, oblong to elliptic, base rounded to subauriculate, apex obtuse to broadly acute, occasionally shortly mucronulate, margin typically entire or rarely sparsely and inconspicuously serrulate, conspicuously callose-thickened, glabrous on both surfaces but sometimes sparsely beset with long trichomes on the adaxial surface or only at the base, essentially flat, pale green to yellowish-green, sometimes flushed with pink along margins and midvein, 3–7- nerved but normally only the midvein conspicuous on abaxial surface. Flowers 5-merous, aggregated in a congested, mostly 8-flowered compound dichasium simulating a glomerulate head, terminal but becoming central or pseudolateral with the elongation of lateral shoots. Bracts several, gradually reduced in size, imbricate, subcoriaceous, subsessile, petiole 1.5 mm long, flattened, blade 15–35 × 10–20 mm, orbicular or ovate, rounded to subcordate at the base, obtuse at the apex, margins entire and frequently glandular-ciliate, frequently glabrous and punctate on both surfaces, occasionally with a few glandular trichomes on abaxial surface; bracteoles 10–15 × 6–8 mm, ovate, membranaceous, glandular-ciliate. Hypanthium (at anthesis) ca. 10 × 4 mm, subcylindric to suburceolate, granulose, constricted distally above the ovary but below the torus into a neck, glabrous basally and distally, at the middle beset with a band of sparse or dense eglandular or glandular trichomes 5 mm long, rarely glabrous throughout. Calyx tube 2–3 mm long; calyx lobes (at anthesis) 5–6 × 2–3 mm, membranaceous, persistent, triangular, apex acute, margin entire or sparsely and inconspicuously serrulate-ciliate, essentially glabrous on both surfaces with a few spreading gland-tipped trichomes at the abaxial base of calyx lobe sinuses. Petals 20–25 × 10–12 mm, pink to lavender with a yellow base, obovate, apex truncate to shallowly emarginate, base attenuate to unguiculate, margin entire and shortly glandular-ciliolate. Stamens 10, dimorphic: large (antesepalous) stamens 5, filaments 8–10 mm long, anther thecae 4–5 × 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 mm long, anther thecae 4 × 1 mm, oblong, yellow becoming brownish following pollination, rostrum 0.5 mm long, pedoconnective 1–1.5 mm long, appendage 0.6 mm long, inconspicuous, yellow. Ovary 5-locular, 4/5 inferior, style ca. 10 mm long, glabrous, stigma truncate. Fruiting hypanthium (including calyx lobes) 12–13 × 8 mm, strongly constricted above the ovary. Capsule (at maturity) ca. 10 mm long, enveloped by the persistent hypanthium and calyx lobes, maroon, dehiscing from the base to the apex, the vascular strands occasionally persisting after capsule walls have fallen away. Seeds 0.82–1.19 × 0.33–0.42 mm, oblong, dark grayish-brown, periclinal cell walls of the testa faintly convex and low domed (colliculate), raphal zone about 75% the length of the seed. Chromosome number unknown.

Illustration:— Figure 47 .

Phenology:—Flowering from February through August; fruiting in February, June, September and probably in intervening months.

Distribution and habitat:—Endemic to Minas Gerais where it appears to be restricted to the Grão Mogol region of the Cadeia do Espinhaço. It grows in campo rupestre, sandy and rocky cerrado, and creek margins at 750–1100 m elev. Figure 22 .

Conservation status:— In addition to the type, this species is known from 10 other collections, all of which were gathered in the municipio of Grão Mogol within Parque Estadual de Grão Mogol in northeastern Minas Gerais. The EOO is 16 km ² and the AOO is 16 km ². Like other campo rupestre and cerrado environments in the region, fire is the major threat to this habitat. We recommend a classification of Endangered ( EN): B1 ab(iii) .

Discussion:— Lavoisiera mellobarretoi is distinguished by its oblong to elliptic leaves that are essentially glabrous without punctations, coriaceous, and prevailingly entire, with a conspicuous callose-thickened margin. It consistently has a 5-locular ovary and sessile 5-merous flowers born in congested terminal dichasia nested among the principal leaves and leafy bracts and hypanthia that are constricted into a well-developed neck distally above the ovary and below the torus. The hypanthia are commonly glabrous basally and distally at the constricted neck but otherwise with a wide central band of spreading smooth trichomes (these sometimes gland-tipped) that are 5 mm long ( Figure 47F ); the calyx lobes are ciliate and persistent; and the bracteoles are glandular-ciliate.

126 • Phytotaxa 315 (1) © 2017 Magnolia Press

MARTINS & ALMEDA LAVOISIERA ( MELASTOMATACEAE )

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Vegetatively, L. mellobarretoi resembles both L. belinelloi and L. punctata . The former, an endemic of Serra do Cabral, differs by its solitary 8-merous flowers and 8-locular ovary, glabrous but somewhat granulose hypanthia, and calyx lobes that lack elongate gland-tipped or eglandular smooth trichomes. Lavoisiera punctata differs in having 6–8-merous flowers, 6–8-locular ovaries, leaf blades that are sparsely but conspicuously glandular-punctate abaxially, hypanthia that are glabrous or slightly granulose and conspicuously fluted ( Figures 4I ; 54C, D ), and calyx lobes that are glabrous throughout.

Additional specimens examined:— MINAS GERAIS: Mpio. Grão Mogol, Parque Estadual, trilha da Serra do Barão , Aona & Belinello 707 ( CAS!) ; Mpio. Grão Mogol , Córrego Escurona, próximo à estrada, 16°35'S, 42°57'W, Bidá et al . CFCR 11938 ( SPF!, US!); Mpio. Grão Mogol, estrada Grão Mogol-Cristália, Cordeiro et al . CFCR 961 ( SPF!, US!); Mpio. Grão Mogol, prox. da ponte sobre o rio das Mortes, Giulietti et al . CFCR 3545 ( CAS!, SPF!, UEC!, US!); Mpio. Grão Mogol , Rio Itacambiruçu , Hatschbach 41334 ( ASU, BR!, ESA!, FLOR, HUEFS!, IPA, MBM, MO, NY!, SP!, UPCB, US!); Mpio. Grão Mogol, Trilha dos Garimpeiros, Hatschbach & Nicolack 54273 ( C!, MBM!, US!); Mpio. Grão Mogol, 15 km west of Grão Mogol , Irwin et al. 23541 ( F!, K!, LE!, MO!, NY!, US!); Mpio. Grão Mogol, Morro do Jambeiro, 16°36'S, 42°57'W, Meireles et al. 1123 ( CAS!, UEC) ; Mpio. Grão Mogol , contrafortes a leste da trilha da tropa que vai da cidade até Periperi , à esquerda do Ribeirão do Inferno, Mello-Silva et al. 1436 ( CAS!, HUEM, SP!, SPF, US!); Grão Mogol, vale do Riacho Ribeirão, Pirani & Mello-Silva CFCR 10764 ( SPF!, UEC!, US!): Mpio. Grão Mogol, estreito do Riacho Ribeirão, 16°33'S, 42°54'W, Zappi et al . CFCR 13117 ( SPF, UEC!) .

Figures

FIGURE 4. Images of Lavoisiera species. A−C. L. macrocarpa (Almeda et al. 9173). D. L. mucorifera (Almeda et al. 9607). E. L. pulchella (Almeda et al. 9830). F−G. L. pulcherrima (Almeda et al. 9666). H−I. L. punctata (Almeda 9709). J. L. rigida (Almeda et al. 9089). K. L. rigida (Almeda et al. 9604). L. L. rigida (Almeda et al. 9635). Image credits: A−L. Frank Almeda.

FIGURE 22. Distributions of Lavoisiera arachnoidea, L. confertiflora, L. daviesiana, L. harleyi, L. mellobarretoi, L. nervulosa, and L. rundeliana.

FIGURE 47. Lavoisiera mellobarretoi. A. Habit. B. Abaxial leaf surface. C. Abaxial flower bract surface. D. Abaxial bud bract surface. E. Flower. F. Hypanthium and calyx lobes. G. Ovary cross-section. H. Ventral view of antesepalous stamen. I. Ventralviewof antepetalous stamen. J. Seed. K. Petal, with enlargement of margin detail (right). (Based on: B–H, I, Pirani & Mello-Silva CFCR 10764, SPF; A, J, Cordeiro et al. CFCR 961, SPF.)

FIGURE 54. Lavoisiera punctata. A. Habit. B. Abaxial leaf surface with enlarged surface detail (upper left). C. Hypanthium, calyx lobes, and style with enlarged detail of calyx lobe base and intercalycine sinus (above). D. Ovary cross-section. E. Petal with enlarged detail of margin (right). F. Ventral view of antesepalous stamen (left), lateral view of antesepalous stamen (right). G. Ventral view of antepetalous stamen (left), lateral view of antepetalous stamen (right). H. Disintegrating mature hypanthium and enclosed capsule. I. Seed. (Based on: A, B, H, I, Semir 28670, UEC; C–G, Almeda et al. 9709, CAS, UEC.)