Lavoisiera itambana 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

22. Lavoisiera itambana Martius & Schrank ex Candolle (1828: 104) . Type:— BRAZIL. Minas Gerais: “In summo cacumine Montis Itambé da villa, alt. supra mare 1.100 hexap., Provincieae Minas Geraes,” C. F. P. Martius s.n. (holotype: M-0165451-n.v, online image!, photos: CAS!, F!, UEC!: isotype: G-DC-n.v., online image!).

Erect, densely branched shrubs to 2 m tall. Branches and branchlets subquadrangular to obscurely subrounded, furrowed longitudinally on opposite faces, glabrous; internodes 3–7 mm long, with knobby thickenings that persist where a leaf has fallen away, nodes with short glandular trichomes. Leaves sessile to subsessile or tapering to a flattened petiole 1–1.5 × 1–2 mm, spreading to imbricate on the uppermost branchlets; blade 10–18 × (4–) 6–10 mm, chartaceous to subcoriaceous, oblong to ovate-oblong or elliptic-oblong, base subrounded to attenuate, apex rounded-obtuse, margin cartilaginous, inconspicuously crenate-glandular, glabrous, somewhat viscid, randomly and sparingly glandular-punctate on both surfaces, yellowish-green to dark green, 1(–3)-nerved, the marginal pair barely conspicuous but extending to the leaf apex. Flowers 6–8-merous, subsessile, pedicel ca. 1 mm long, solitary, terminal on primary and secondary branchlets but eventually becoming central with elongation of lateral shoots. Bracts 6–8, subsessile, flattened petioles 2 mm long, blade 0.7–1.4 × 0.4–0.8 mm, ovate, base attenuate to subrounded, apex obtuse, margin crenate, glandular-punctate, 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, yellowish-green. Calyx tube 0.5–1 mm long; calyx lobes (at anthesis) 1–1.2 × 1.2 mm, subtriangular to subrounded, apex obtuse to rounded, yellow-green, margins entire, glandular, sparsely glandular-punctate abaxially, glabrous adaxially or obscurely glandular-punctate, caducous in post-anthesis. Petals 15(–25) × 8(–11) mm (adherent basally and falling away together with stamens as a unit after anthesis), yellow, obovate-

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MARTINS & ALMEDA oblong, apex obliquely emarginate at the apex, base attenuate, margin entire, inconspicuously glandular-ciliolate, connate for a short distance at the base and falling together as a unit after anthesis. Stamens 12, 14, or 16, dimorphic: large (antesepalous) stamens 6–8, filaments 8–11 mm long, anther thecae 4–4.5 × 1.5 mm, yellow, oblong, rostrum ca. 0.5 mm long, brownish, pedoconnective 5–6 mm long, appendage 1.5–2 mm long, emarginate to obscurely bilobed, yellow; small (antepetalous) stamens 6–8, filaments 8–9 mm long, anther thecae 3.5–4 × 1.5 mm, yellow, oblong, rostrum ca. 0.5 mm long, white, connective 1.5–2 mm long, appendage 0.5–1 mm long, rounded. Ovary 6–8-locular, 2/3 inferior, style 8–9 mm long, slightly curved to straight, glabrous, stigma truncate. Fruiting hypanthium (including calyx lobes) 11 × 6 mm, broadly campanulate to 9–10 mm wide distally, calyx tardily caducous. Capsule (at maturity) 6–7 mm long, elliptic to globose, enveloped by the persistent hypanthium, dehiscing from the base to the apex. Seeds 0.78–1.03 × 0.43–0.50 mm, oblong to reniform, reddish-brown to orangish-brown, periclinal cell walls of the testa concave (foveolate), raphal zone about 66% the length of the seed. Chromosome number unknown.

Illustrations:— Figure 45 ; Martius (1831: t. 271).

LAVOISIERA ( MELASTOMATACEAE )

Phytotaxa 315 (1) © 2017 Magnolia Press • 119

Photographic images:— Figures 3I–K .

Phenology:—Flowering February through April, July and November; fruiting July and November.

Distribution and habitat:—Endemic to Minas Gerais where it is known only from the upper slopes of Pico do Itambé (Parque Estadual do Pico do Itambé) in campo rupestre and campo limpo commonly near rocks and boulders at 1400–1700 m elev. Figure 39 .

Conservation status:—This local endemic of Pico do Itambé is known to us from just six collections. This a reflection of the little collecting that has been done on the Pico. The EOO is 12 km ² and the AOO is 12 km ². The only known population is afforded some protection because it occurs within the Parque Estadual do Pico do Itambé. Fires appear to be the only threat since livestock were removed once the park was established in early 1998. In view of its local geographic and elevational distribution we recommend a classification of Critically Endangered (CR): B1ab(iii).

Discussion:— Lavoisiera itambana is readily recognized by its consistently yellow petals, oblong to ovate-oblong or elliptic-oblong leaf blades that are crenate-glandular, glandular-punctate on both surfaces, and well-defined flattened petiole (when present). The calyx lobes are short (1–1.2 mm long), yellow-green in color without pigmented margins or markings, and subtriangular to subrounded with an obtuse to rounded apex. No other species of Lavoisiera has yellow flowers across its entire range. Lavoisiera nervulosa is commonly yellow-flowered in the Mucugê region of Bahia but the petals always appear to be flushed with red on the abaxial surface and in bud, and its leaf blades are oblong-lanceolate with an acute apex and laxly reticulate venation abaxially.

The only notable variation exhibited by L. itambana involves flower merosity (6–8-merous) and ovary locule number (6–8-locular).

Lavoisiera itambana is most closely allied to L. rundeliana which is also endemic to Pico do Itambé. Based on our field studies, the former always appears to be shrubby whereas the latter frequently becomes a small tree ( Figures 3J ; 5B ). In sterile condition, these two species can be difficult to tell apart because of their similar leaf morphology but the latter has glandular punctations only on the abaxial foliar surfaces whereas L. itambana has glandular punctations on both surfaces. Flowering or fruiting material of these two species are readily distinguished from one another. They exhibit overlap in floral merosity and ovary locule number. The latter, however, has deep pink petals with a white base (vs. uniformly yellow petals), its calyx tube is longer (1–2 mm vs. 0.5–1 mm), its calyx lobes are larger (5–6 × 3–4 mm vs. 1–1.2 × 1.2 mm), oblong to subspatulate in shape with a rounded apex and commonly pigmented with dark red or maroon distally or along most of their length ( Figures 3I, K ; 5A, C ).

Lavoisiera itambana and L. rundeliana have modally different but overlapping elevational distributions on Pico do Itambé. Lavoisiera itambana occurs at 1400–1700 meters whereas L. rundeliana occurs from 1540–2250 meters. On the upper slopes of the Pico at about 2000–2250 meters we encountered plants that appear to be hybrids or introgressants between these two species. Putative hybrids that we examined in the field in 2009 were growing mostly with L. rundeliana . All of the putative hybrid collections known to us were flowering and fruiting in February, March, April, September, and November. Thus flowering phenology is consistent with that of putative parents. The intermediates stand out by virtue of their petal color, calyx lobe shape and size, and the distribution of glandular punctations on the leaf blades. All of the putative intermediates that are in flower have pale yellow or lemon yellow petals with a distinct flush of pink or reddish on the adaxial margins. This color marking is especially evident in bud but persists on the abaxial surface of expanded petals. The calyx lobe morphology in some of the hybrids (Windisch & Gillany 184) is similar to that of L. rundeliana but intermediate in size between the putative parents (4 × 2.5 mm). In most of the putative hybrids leaf blade punctation is restricted to the abaxial surface like L. rundeliana but Furlan et al. CFCR 3041 has most (but not all) leaves that are punctate on both surfaces like L. itambana and calyx lobes resembling L. rundeliana in shape but smaller in size (4 × 2 mm). Almeda et al. 9695 has leaves that are punctate on both surfaces but its calyx lobes approach L. itambana in shape and are smaller than other intermediates but just slightly larger (2 × 2 mm) than typical L. itambana . All other individuals of the hybrid swarm that we studied fall within these extremes with calyx lobes ranging from 3–3.5 mm long and 2–2.5 mm wide and with leaves punctate on both surfaces, only on the abaxial surface, or punctate abaxially and with some scattered punctations adaxially on some but not all leaves. The earliest hybrid/introgressant collections known to us were gathered in 1972 and 1974 so it appears that they have persisted for several decades. This is not surprising for long-lived shrubby plants of campo rupestre habitats. Gene exchange that has resulted in the segregation and recombination of parental character differences has evidently been promoted by the narrowly overlapping elevational distributions, coincident flowering, and undoubtedly shared pollinators.

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MARTINS & ALMEDA

We have collected specimens of one other variant on Pico do Itambé (Almeda et al. 9689) that appear to be intermediate between L. itambana and L. imbricata , another sympatric congener at that locality. This specimen has 6-merous flowers with yellow petals that are flushed with pink. Its leaf blades have the setose marginal trichomes of L. imbricata but they are shorter (0.5 mm long vs. 1–2 mm in L. imbricata at that locality) and the abaxial leaf surfaces are glandular-punctate like L. itambana but the adaxial surfaces are glabrous as they are in L. imbricata . The abaxial foliar surfaces also have a few scattered appressed setose trichomes on the distal portions of the median vein like L. imbricata . The calyx lobes are oblong, ciliate, apically rounded with a terminal rigid trichome (0.25 mm long vs. 1–1.5 mm in L. imbricata ). The marginal gland-tipped trichomes on the calyx lobes are 0.5 mm long (vs. 0.5–0.75 mm in L. imbricata on Pico do Itambé).

Other species of Lavoisiera that grow on the upper slopes of Pico do Itambé include L. pulcherrima , L. sampaioana , and L. vestita but we found no other combinations of interspecific hybridization during our field work on the Pico. The type of L. gentianoides was reportedly collected on Pico do Itambé as were some old collections of L. tetragona . No recent collections of the latter two species are known from the Pico but few botanists have visited the area which is still in need of additional botanical exploration.

Additional specimens examined:— MINAS GERAIS: Pico do Itambé , trail to the summit from Santo Antônio do Itambé. 18˚24’5.9” S, 43˚19’3” W, Almeda et al. 9029 ( BHCB!, CAS!, NY!, UEC!) ; Mpio. Santo Antônio do Itambé. Parque Estadual do Pico do Itambé along trail from the Fazenda at 1367 m to the summit of the Pico at 2038 m, -18.39868, -43.34816, Almeda et al. 9663 ( BHCB!, CAS!, NY!, RB!, UEC!) ; Mpio. Santo Antônio do Itambé , eastern slopes of the Pico do Itambé , Anderson et al. 35853 ( CAS!, NY!, US!); Mpio. Santo Antônio do Itambé, Pico do Itambé, 18°24'S, 43°19'W , V. C. Souza et al. 21110 ( CAS!, MBM!, SPF!) ; Mpio. Santo Antônio do Itambé , a 18 km da cidade, alto do Pico do Itambé, Zappi et al . CFCR 11267 ( CAS!, SPF!, UEC!, US!) .

Putative hybrids between Lavoisiera itambana and L. rundeliana :— 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°S, - 43.34816°W, Almeda et al. 9680 (CAS!, UEC!); Ibid., Almeda et al. 9690 (CAS!); Ibid., Almeda et al. 9691 (CAS!, RB!, UEC!); Ibid., Almeda et al. 9692 (CAS!, UEC!); Ibid., Almeda et al. 9693 (CAS!, UEC!); Ibid., Almeda et al. 9694 (BHCB!, CAS!, RB!, UEC!): Ibid., Almeda et al. 9695 (CAS!, UEC!); Mpio. Santo Antônio do Itambé, Summit of the Pico do Itambé, Anderson et al. 35771 (NY!, US!); Mpio. Santo Antônio do Itambé, Subida ao Pico do Itambé, 18°24'S, 43°21'W, Furlan et al. CFCR 3041 (CAS!, SPF!, US!); Mpio. Santo Antônio do Itambé, Alto do Pico do Itambé, Mendes Magalhães 1644 (F!, NY!, RB!); Mpio. Santo Antônio do Itambé, Pico do Itambé, Serra do Gavião, Windisch & Ghillany 184 ( US!).

Putative hybrid between Lavoisiera itambana and L. imbricata :— 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, Almeda et al. 9689 (CAS!, UEC!).

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 39. Distributions of Lavoisiera glandulifera, L. itambana, L. macrocarpa, and L. mucorifera.

FIGURE 45. Lavoisiera itambana. A. Habit with detail of abaxial leaf apex (right). B. Adaxial bract surface. C. Flower. D. Hypanthium and calyx lobes with enlargement of adaxial sinus (above). E. Ovary cross-section. F. Petal. G. Ventral view of antesepalous stamen. H. Ventral view of antepetalous stamen. I. Seed. (Based on: A–I, Zappi et al. CFCR 11267, UEC.)