Lavoisiera rundeliana 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

34. Lavoisiera rundeliana Almeda & A. B. Martins , sp. nov.

Densely branched shrubs 1.5 m to small trees 2.5 m tall. Branches corky, glabrous. Leaves subsessile, subcoriaceous, spreading to imbricate, flat, glabrous, glandular-punctate on abaxial surface, margins shallowly crenulate-glandular, 3-nerved. Flowers 7–9(–10)-merous, solitary. Hypanthium broadly campanulate, moderately glandular-punctate, slightly viscid, reddish. Petals deep pink with a white patch at the base. Ovary 6-locular, 2/3 inferior.

Type:— BRAZIL. Minas Gerais: Mpio. Santo Antônio do Itambé. Parque Estadual do Pico do Itambé , trail from the Fazenda at 1367 m to the summit of the Pico at 2038 m, -18.39868, -43.34816, 2 March 2009, F . Almeda 9667, A. B . Martins , P. W . Fritsch , J. L. M . Aranha , C . Bush & R . Belinello (holotype: UEC!; isotypes: BHCB!, CAS!, K!, NY!, RB!) .

Erect shrubs 1.5 m to small trees 2.5 m tall with densely and openly branched upright habit. Bark fissured on main trunk. Branches and branchlets rounded or obscurely subrounded, furrowed longitudinally on opposite faces, corky, frequently leafy to the base or defoliating with age; internodes 2–4 mm long, with knobby thickenings that persist where a leaf has fallen away, nodes with conspicuous leaf scars, mostly glabrous or with yellowish inconspicuous caducous glandular trichomes. Leaves subsessile, spreading to imbricate on the uppermost branchlets, tapering to a flattened petiole 1–2 mm long; blade 10–14 × 6–8 mm, coriaceous to subcoriaceous, oblong to ovate-oblong or elliptic-oblong, base slightly rounded or attenuate, apex rounded-obtuse, margins shallowly crenulate-glandular, glabrous, somewhat viscid, glandular-punctate on abaxial surface only, dark green, flat, 3-nerved, the lateral pair frequently inconspicuous and not extending to the leaf apex. Flowers 7–9(–10)- merous, solitary, terminal on primary and secondary branchlets but often becoming central with elongation of lateral shoots, subsessile, pedicel 1 mm long, subtended by 6–8 subsessile bracts, petioles flattened ca. 0.8 mm long. Bracts 1–1.2 × 0.4–0.6 mm, ovate, base attenuate to subrounded, apex obtuse, otherwise similar to the principal leaves. Hypanthium (at anthesis) 3.5–4.3 mm, broadly campanulate, 4–4.5 mm wide distally, moderately glandular-punctate, slightly viscid, reddish. Calyx tube 1–2 mm long; calyx lobes (at anthesis) 5–6 × 3–4 mm, oblong to subspatulate, apex obtuse to broadly rounded, flushed with red-maroon at least distally, margins subcrenulate, sparsely glandular-punctate abaxially, glabrous adaxially, caducous in post-anthesis. Petals 18–22 × 9(–13) mm, deep pink with a white patch at the base, obovate-oblong to subspatulate, apex deeply emarginate, base attenuate, margin entire and shortly glandular-ciliolate. Stamens 14, 16, (20), dimorphic: large (antesepalous) stamens 7–8(–10), filaments 10 mm long, anther thecae 4–5 × 1.5 mm, yellow, oblong, rostrum ca. 0.5 mm long, pedoconnective thickened, 5–6 mm long, appendage 1.5–2 mm long, obscurely lobed, yellow; small (antepetalous) stamens 7–8(–10), filaments 8–9 mm long, anther thecae 3.5–4 × 1.5 mm, yellow, oblong, rostrum 0.5 mm long, pedoconnective 1.5–2 mm long, appendage 0.5–1 mm long, rounded, yellow. Ovary 6-locular, 2/3 inferior, style 8–9 mm long, straight, glabrous, stigma punctiform. Fruiting hypanthium (including calyx lobes) 11 × 6 mm, broadly campanulate to 9–10 mm wide at the apex. Capsule (at maturity) 6–7 mm long, globose, enveloped by the persistent hypanthium, dehiscing from the base to the apex. Seeds 0.95–1.31 × 0.47–0.52 mm, oblong to reniform, pale creamy brown, periclinal cell walls of the testa concave (foveolate), the raphal zone about 20% the length of the seed. Chromosome number unknown.

Illustration:— Figure 57 .

Photographic images:— Figures 5A–C ; 13A, B .

Phenology:—Flowering and fruiting in February, May, and November.

Distribution and habitat:—Endemic to Minas Gerais where it is restricted to campo rupestre on the upper slopes of Pico do Itambé (Parque Estadual do Pico do Itambé) at 1540–2250 m elev. Figure 22 .

Conservation status:—This species is known from half a dozen collections, all of which come from a population of less than fifty individuals at the type locality. The EOO is 8 km ² and AOO is 8 km ². The entire population of this species occurs within Parque Estadual do Pico do Itambé so it is afforded some protection. In view of its limited range, small population size, and threat of habitat destruction by fires we assign a classification of Critically Endangered (CR): B2ab(iii).

Discussion:— Lavoisiera rundeliana is readily recognized by its shallowly crenulate-glandular leaves that are glandular-punctate abaxially but devoid of an indumentum adaxially, 7–9(–10)-merous flowers, 6-locular ovary, petals that are obovate-oblong to subspatulate, deeply emarginate at the apex, and pink-magenta in color with a white patch at the adaxial base. The petals also appear to fall away individually and not as a unit after anthesis. It also has distinctive calyx lobes (at anthesis) 5–6 mm long that are flushed with red-maroon distally and broadly rounded to obtuse at the apex and glandular-punctate abaxially.

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MARTINS & ALMEDA LAVOISIERA ( MELASTOMATACEAE )

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Vegetatively, L. rundeliana may be confused with L. itambana , another Pico do Itambé endemic that has similar-sized leaves with crenulate-glandular margins. The latter has leaf blades that are glandular-punctate on both surfaces, 6–8-merous flowers, a 6–8-locular ovary, and petals that are uniformly lemon yellow, obliquely emarginate at the apex, adherent for about 0.25 mm at the base and falling away with stamens as a unit following anthesis. The calyx lobes of L. itambana also differ in being only 1–1.2 mm long, uniformly yellow-green, and subtriangular to subrounded. Lavoisiera rigida is the only other species with which L. rundeliana might be confused because of its similar petal color and foliar size and shape. In L. rigida , however, the leaves have uniformly entire margins that are minutely glandular, and they are somewhat viscid adaxially and sparingly glandular-punctate on both surfaces. The flowers of L. rigida are modally 8-merous (rarely 6–7-merous), the ovary is 8-locular, and the calyx lobes which are persistent (vs. caducous) in post-anthesis are triangular-acute to cuspidate and sometimes terminate in a glandular trichome.

Mello Barreto also recognized what we are calling L. rundeliana as an undescribed species. He placed the name “ Lavoisiera crenulata sp. nov. ” on the label of the single collection that was evidently known to him (Mendes Magalhães 1652B) but he never formally published this name.

For a discussion of what we interpret to be natural hybridization between L. rundeliana and L. itambana , see the latter.

Etymology:—The specific epithet honors James A. Rundel (b.1945–), retired California attorney, avid naturalist, and plant enthusiast who has provided crucial support for some of our Brazilian field expeditions and the preparation of the diagnostic illustrations for all of the species in this monograph through the M. Stanley Rundel Charitable Trust.

Additional specimens examined:— MINAS GERAIS: Pico do Itambé. Trail to the summit upslope from Santo Antônio do Itambé at 1544 m, 18˚23’58.5”S, 43˚19’25.5”W, Almeda et al. 9028 (CAS!, UEC!); Serra do Espinhaço. Summit of the Pico do Itambé, Anderson et al. 35768 (MO!, NY!, UB!, US!); Mpio. Santo Antônio do Itambé, a 18 km da cidade, alto do Pico do Itambé, Kameyama et al. CFCR 11255 (SPF!, US!); Mpio. Serro, alto do Pico do Itambé, Mendes Magalhães 1652B (UB!).

Figures

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 13. 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. rundeliana (Kameyama et al. 11255). C–D. L. senae (Anderson et al. 36197). E–F. L. subulata (Figuereido & Kubitski 83-22). Scale bars: A & C=250 µm; B=60 µm; D=30 µm; E=200 µm; F=50 µm.

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

FIGURE 57. Lavoisiera rundeliana. A. Habit. B. Abaxial leaf surface with enlargement of surface detail (right). C. Flower. D. Hypanthium, calyx lobes and style. E. Ovary cross-section. F. Petal with enlargement of margin detail (lower right). G. Ventralviewof antesepalous stamen. H. Ventral view of antepetalous stamen. I. Seed. (Based on: A–I, Almeda et al. 9667, CAS, UEC.)