Lavoisiera daviesiana Almeda & A. B. Martins, 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

14. Lavoisiera daviesiana Almeda & A. B. Martins , sp. nov.

Dichotomously branched shrubs 2 m tall. Branches sparsely to densely covered with glandular trichomes, the glands clustered, sessile to short-stalked. Leaves sessile, chartaceous to subcoriaceous, spreading to laxly imbricate, margins subcallose, entire to dentate or denticulate (sometimes bluntly so), shortly glandular-ciliate, apex frequently recurved, both surfaces with sessile glandular trichomes, abaxial surface conspicuously reticulate, 5–7-nerved. Flowers 6-merous, solitary. Calyx lobe margins glandular-ciliate with long stiff bristly trichomes 0.5–0.7 mm long. Petals white. Ovary 5-locular, 2/3 inferior.

Type :— BRAZIL. Minas Gerais: “Mpio. Juramento, Rod. Montes Claros a Itacambira, Serra do Catuni,” 17 March 1997, G . Hatschbach 66392, M . Hatschbach & E . Barbosa (holotype: MBM!) .

Dichotomously branched shrubs 2 m tall. Branches and branchlets rounded to subrounded, furrowed longitudinally on opposite faces, defoliating basally with age; internodes 2–4 mm long with knobby thickenings that persist where a leaf has fallen away, sparsely to densely glandular, the glands sessile and clustered to short-stalked, yellowish turning brown; nodes with short, vinaceous, glandular trichomes. Leaves sessile, semi-amplexicaul, spreading, laxly imbrícate and mostly congested toward the ends of branchlets; blade 8–12 × 5–6 mm, chartaceous to subcoriaceous, ovate, base rounded to subrounded, apex obtuse to somewhat rounded and frequently recurved apically, margins subcallose, entire to variously denticulate and revolute, shortly glandular-ciliolate, adaxial surface with scattered sessile glandular trichomes that are frequently clustered and sometimes caducous, yellowish-green turning brown, abaxial surface pale green or yellowish-green, conspicuously reticulate, sparsely to moderately covered with sessile, clustered glandular trichomes, the glands to 0.1 mm long, yellow-orange turning brown, 5–7-nerved at the base. Flowers 6-merous, solitary, terminal at ends of branches but becoming central with elongation of lateral shoots, sessile or subsessile. Bracts subtending the flowers 6–8, the flattened petiole ca. 1 mm long, ovate, base rounded to attenuate, apex rounded, margin subcallose, slightly erose, glandular-ciliate or eglandular-ciliate, membranaceous, 10–11 × 5 mm, sparsely glandular-granulose on both surfaces, 7–9-nerved. Hypanthium (at anthesis) 6 × 4–5 mm, ca. 6–7 mm wide distally, campanulate, moderately beset with minute short-stalked glandular trichomes; calyx tube ca. 1 mm long; calyx lobes (at anthesis) 7–9 × 4–5 mm, oblong to spatulate, membranaceous, rounded at the apex, margins glandular-ciliate with long stiff bristly eglandular trichomes 0.5–0.7 mm long, somewhat erose, mixed with sessile glands sparsely to densely glandular-puberulous and granulose on both surfaces, the glands sessile, probably caducous in post-anthesis. Petals 17–20 × 12 mm, white, obovate-oblong, apex surbrounded or asymmetrically truncate, base attenuate, margins very shortly and inconspicuously glandular-ciliolate. Stamens 12, dimorphic: large (antesepalous) stamens 6, filaments 7–8 mm long, anther thecae 5–5.5 × 0.1 mm, linear-oblong to oblong, yellow, rostrum 0.5 mm long, pedoconnective ca. 10 mm long, appendage 1.5–2 mm long, bilobed, yellow; small (antepetalous) stamens 6, filaments 6–7 mm long, anther thecae 4.5–5 × 0.8 mm, linear-oblong, yellow, rostrum 0.5 mm long, pedoconnective 2–3 mm long, appendage 1 mm long, rounded, yellow. Ovary 5-locular, 2/3 inferior. Style 10–12 mm long, curved apically, glabrous, stigma subtruncate to punctiform. Fruiting hypanthium, capsule, dehiscence, and seeds not seen. Chromosome number unknown.

Illustration:— Figure 35 .

LAVOISIERA ( MELASTOMATACEAE )

Phytotaxa 315 (1) © 2017 Magnolia Press • 87 88 • Phytotaxa 315 (1) © 2017 Magnolia Press

MARTINS & ALMEDA

Phenology:—Flowering and fruiting in March.

Distribution and habitat:—Known from Serra do Catuni and Serra do Bota, Minas Gerais, in campo rupestre at 914–1170 m elev. Figure 22 .

Conservation status:—Our attempts to relocate this population at the type locality were unsuccessful. We suspect it may be restricted to Serra do Catuni and Serra do Bota but we have inadequate data to make an informed assessment of its abundance and distribution since it is known only from the holotype and two other fertile collections. Future research may show that threatened status is justified but until more information is available we regard the status of this species as Data Deficient (DD).

Discussion:— Lavoisiera daviesiana , an apparently local and uncommon species, has openly dichotomous branching, ovate leaf blades that are commonly entire with revolute margins, an indumentum of scattered, sessile, solitary or clustered glands on both foliar surfaces, calyx lobes with stiff evenly-spaced eglandular trichomes along the margins, 6-merous flowers with white petals, and a 5-locular ovary.

The holotype of Lavoisiera daviesiana exhibits some variation in the nature of foliar margins. Most of the principal leaves are entire and revolute but some leaves are irregularly dentate to denticulate ( Figure 35B ). There appears to be no pattern to the occurrence of this leaf margin variation on any of the distally leafy branches.

Lavoisiera daviesiana is clearly related to L. pohliana , a species that now appears to be restricted to a small area in Goiás state. The latter also has white petals, (5–)6-merous flowers, and a (5–)6-locular ovary. It also has the minute sessile yellowish-orange glandular trichomes on hypanthia but they occur only on the abaxial leaf surfaces (vs. both surfaces). The leaf apex of L. pohliana is acute to obtuse-acuminate [vs. obtuse to somewhat rounded ( Figure 51A )], the bracts subtending the flowers are not differentiated from the principal leaves and lack a petiole, and the calyx lobe margins are devoid of the stiff evenly-spaced eglandular spreading trichomes 0.5–0.7 mm long ( Figure 51D ).

Etymology:—The epithet of this species honors the late Paul L. Davies, Jr. (1930–2014), long-time trustee and chairman of the board at the California Academy of Sciences, in recognition of his exemplary leadership, vision, and support of its research and educational programs over many years.

Additional specimens examined:— MINAS GERAIS: Itacambira, Serra do Bota, Caminho para a Cachoeira do Onça , estrada de terra, campo rupestre, 17º 00' 7.9''S, 43º33'8.3''W, elev. 914 m, 3 March 2017, fr., R . Pacifico 356 ( CAS!, HUEM, SPF). Ibid., 16º 59' 59.1''S, 43º32'33.8''W, elev. 920 m, 3 March 2017, fl. & fr., R . Pacifico 358 ( CAS!, HUEM, SPF) .

Figures

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

FIGURE 35. Lavoisiera daviesiana. A. Habit. B. Abaxial leaf surface with detail of revolute margin (left). C. Abaxial bract surface. D. Hypanthium and calyx lobes at anthesis (petals removed) with enlarged surface detail (lower right). E. Stamens (ventral view), antesepalous (left) and antepatalous (right). F. Flower. (A–F, Hatschbach et al. 66393, MBM.)

FIGURE 51. Lavoisiera pohliana. A. Habit. B. Abaxial bract surface. C. Flower. D. Hypanthium and calyx lobes with enlargement of calyx lobe margin (upper right) and hypanthial surface (lower right). E. Ovary cross-section. F. Petal with enlargement of margin detail (lower right). G. Ventral view of antesepalous stamen. H. Ventral view of antepetalous stamen. I. Seed. (Based on: A–B, Koschnitzke & Matsumoto 35624, UEC; C–H, Irwin et al.13296, UEC; I, Romero et al. 5509, UEC.)