Tibouchina falcifolia F.S.Mey. & R.Goldenb., 2023

Meyer, Fabrício Schmitz, Diniz, Danielle De Oliveira, Ziemmer, Juliana Klostermann & Goldenberg, Renato, 2023, Two new species of Tibouchina (Melastomataceae) from the Brazilian Cerrado, Phytotaxa 599 (1), pp. 51-64 : 53-58

Tibouchina falcifolia F.S.Mey. & R.Goldenb. , sp. nov. ( Figures 1–2 , 3A , 4 )

Type:— BRAZIL, Goiás, Alto Paraíso de Goiás, Trilha para a Cachoeira na Pedra da Baleia , Arredores do Parque Nacional da Chapada dos Veadeiros, -14.071511°, -47.391086° 21 March 2012, fr., F.S. Meyer 1193 (holotype: UPCB0029934!; isotypes: MBM!, UEC114238 !) .

Diagnosis:— Tibouchina falcifolia differs from Tibouchina aegopogon ( Naudin 1850: 153) Cogniaux (1885: 383) var. angustifolia Cogniaux (1885: 384) by its decorticant older branches (vs. non decorticant older branches in T. aegopogon var. angustifolia ), slightly discolorous leaves (vs. strongly discolorous), with the abaxial surface moderately strigose, covered with trichomes (vs. covered with flattened and proximally attached scales; sensu Wurdack 1986; Figure 3B ).

Description:—Shrub 0.6–1 m tall; younger and older branches subcylindrical to cylindrical; younger branches and inflorescence axes moderately to densely covered with whitish scales 1–3 mm long, oblanceolate or lanceolate, appressed, ciliate at the margins in its median portion (cilia up to 0.1 mm long), the apex eciliate; the same scales on the nodes, somewhat longer, 3–6 mm long, older branches decorticant. Leaves with petioles 3–9.1 mm, densely covered with whitish scales 2.1–4.5 mm long, lanceolate, appressed, ciliate at the margins in its median portion, (cilia up to 0.1 mm long), the apex eciliate; blade 4.8–16 × 0.9–1.9 cm, lanceolate to linear, conduplicate, curved downwards, and sickle-shaped in lateral view, apex acute, base obtuse, acrodromous veins 3, all united at the base, adaxial surface lacking scales, but moderately strigose, whitish trichomes 0.8–2.1 mm long, unbranched, appressed, eglandular, the base slender to swollen, immersed in the leaf tissue, not forked to 1–3 forked, abaxial surface moderately covered with whitish scales 1–2.7 mm long, crescent-shaped, appressed, ciliate along the entire margin (cilia up to 0.4 mm long), the apex eciliate, the scales on the primary and secondary veins whitish, 1.5–3.2 mm long, lanceolate or crescent-shaped, appressed, ciliate at the margin in its median portion (cilia up to 0.3 mm long), the apex eciliate, the same scales on the leaf margins,, somewhat longer, 2.4–4.4 mm long. Inflorescences in short cymes or thyrsoids, 4.8–9.4 × 4.4–5.5 cm, with 5–19 lax flowers; bracts 2, foliaceous, petiole 3.6–4.2 mm long, blade 5–12.6 × 0.8–1.1 cm, lanceolate, conduplicate, pendulous, apex acute, base obtuse, late deciduous, acrodromous veins 3, all united at the base, the same scales and trichomes as on the leaves on both surfaces and margins; bracteoles 2, sessile, blade 6.6–7.5 × 1.3–1.6 mm, lanceolate, apex acute, base obtuse, slightly concave, early to late deciduous, adaxial surface glabrous, abaxial surface moderately covered with whitish scales 2–3 mm long (the longer ones on its central portion), lanceolate, appressed, ciliate at the margin in its basal and median portion (cilia up to 0.1 mm long),), the apex eciliate. Flowers 5–merous, pedicels 2.1–3 mm long; hypanthium 7–9.5 × 4.7–6.1 mm, campanulate, abaxial surface densely covered with whitish scales 2.1–4.2 mm long, lanceolate, appressed, ciliate along the entire margin and at the apex (cilia up to 0.1 mm long); between the sepals sparsely covered with the same scales as the abaxial surface of the hypanthium, somewhat longer, 3.8–5 mm long; sepals 8.7–10 × 3.2–3.9 mm, narrowly triangular, apex attenuate, adaxial surface glabrous, abaxial surface covered with the same scales as the abaxial surface of the hypanthium, somewhat shorter, 2–3.6 mm long (larger scales concentrated on its central portion), margin moderately covered with the same scales as the abaxial surface of the sepals, somewhat shorter, 0.7–1.8 mm long; petals purple, 18.2–19 × 9–11.6 mm, obovate, apex cuspidate, margin moderately glandular-pilose, whitish trichomes 0.3–0.6 mm long, unbranched, erect, glandular, the base slender, not immersed in the leaf tissue; stamens 10, slightly dimorphic in size, the antesepalous with filaments 10.5–11.1 mm long, glabrous to sparsely villose on its middle portion, whitish trichomes ca. 0.5 mm long, unbranched, twisted, eglandular, the base slender, not immersed in the leaf tissue, pedoconnective 3.8–4.1 mm prolonged below the thecae, glabrous, ventral appendages bilobed, apex obtuse, ca. 0.5 mm long, moderately villose, whitish trichomes 0.9–2 mm long, unbranched, twisted, eglandular, the base slender, not immersed in the leaf tissue, thecae 12.3–12.8 × ca. 1.3 mm, falcate, apex attenuate, the antepetalous with filaments 9–9.7 mm long, with trichomes similar to the antesepalous, pedoconnective 1.6–2 mm prolonged below the thecae, glabrous, ventral appendages bilobed, apex obtuse, ca. 0.4 mm long, with trichomes similar to the antesepalous, thecae 8.1–8.5 × ca. 1 mm, falcate, apex attenuate; ovary superior, 5-locular, ca. 8.7 × 4.1 mm, apex densely sericeous, whitish trichomes 2.5–3.4 mm long, unbranched, appressed, eglandular, the base slender, style ca. 16.5 mm, filiform, apex curved, glabrous or sparsely villose, whitish trichomes 1–1.5 mm long, unbranched, twisted, eglandular, the base slender, stigma truncate. Velatidia with persistent sepals, 14.5–16 × 7–7.5 mm, seeds 931–937 × ca. 576 μm.

Paratypes:— BRAZIL. Goiás, Municipality of Alto Paraíso de Goiás, Arredores do Parque Nacional da Chapada dos Veadeiros , 20 March 2012, F.S. Meyer 1173 ( UEC114696 !) ; ibidem, F.S. Meyer 1174 ( UEC114695 !) ; ibidem, F.S. Meyer 1175 ( UEC114694 !) ; ibidem, F.S. Meyer 1176 ( UEC114693 !) ; ibidem, F.S. Meyer 1177 ( UEC114692 !) ; ibidem, F.S. Meyer 1178 ( UEC114691 !) ; ibidem, F.S. Meyer 1179 ( UEC114690 !) ; ibidem, F.S. Meyer 1180 ( UEC114687 !) ; ibidem, F.S. Meyer 1181 ( UEC114686 !) ; Parque Nacional da Chapada dos Veadeiros, Morro da Baleia , 27 November 2014, M. Verdi et al. 7373 ( RB00996221 !) ; Parque Nacional da Chapada dos Veadeiros, à 6 km da placa de entrada Bona Spero , próximo à cauda da Baleia, 11 December 2015, D.O. Diniz et al. 724 ( UFG 67556 !) .

Distribution and habitat:—The collections of Tibouchina falcifolia come from Cerrado and associated grasslands (“Campos Rupestres”), on well-drained soils. The species was collected only in the municipality of Alto Paraíso de Goiás, state of Goiás, in the Parque Nacional da Chapada dos Veadeiros (PNCV), and in the Área de Proteç„o Ambiental de Pouso Alto (APAPA; Figure 5 ).

Phenology:—Collected with flowers and fruits from November to March.

Conservation status:—According to IUCN’s criterion B1, Tibouchina falcifolia should be considered as Endangered (IUCN 2022). The species is known from few populations, and its distribution is restricted. Its Extent of Occurrence (EO) is 434,621 km 2, and its Area of Occupancy (AO) is about 16,000 km 2. Tibouchina falcifolia has been collected only 12 times, all between 2012 and 2015. The APAPA is a protected area with only a few restrictions; it is a buffer zone surrounding part of PNCV, and therefore highly prone to environmental degradation, especially through fire. The PNCV is a more restrictive protected area but, even so, it also has been frequently and severely impacted by fire ( Matos et al. 2020).

Etymology:—The epithet “ falcifolia ” is related to the shape of the leaves, which are lanceolate to linear, conduplicate, pendulous, and sickle-shaped in lateral view ( Figure 1B ).

Notes:—Among species of Tibouchina , only T. aegopogon var. angustifolia also has lanceolate or linear leaves, these also conduplicate, and curved downwards. Besides the differences mentioned in the diagnosis, Tibouchina falcifolia also differs from T. aegopogon var. angustifolia by the longer pedicels, 2.1–3 mm long (vs. 1.5–2 mm long in T. aegopogon var. angustifolia ), longer scales covering the hypanthium, 2.1–4.2 mm long (vs. 0.9–1.1 mm long) and longer calyx lobes, 8.7–10 mm long (vs. 3.2–4.3 mm long). In the younger branches of T. falcifolia , the internodes are short, giving the appearance that the leaves are whorled. The coordinates typed in the isotype’s label differ from those in the holotype due to a typing error.

Figures

FIGURE 1. Plate with photos from the paratype and holotype of Tibouchina falcifolia. A. Branch. B. Leaf. C. Detail of the indumentum on the adaxial surface of the leaves. D. Detail of the scales on the abaxial surface of the leaves. E. Bracteole, abaxial surface. F. Floral bud. G. Detail of the scales on the abaxial surface of the hypanthium. H. Antepetalous stamen. I. Antesepalous stamen. J. Gynoecium. K. Mature fruit with persistent sepals. (A – J from Verdi et al. 7373 at RB; K from Meyer 1193 at UPCB).

FIGURE 2. Photos of Tibouchina falcifolia in the field. A. Habit. B. Flowering branches. C. Detail of androecium and gynoecium. D. Mature fruits. E. One of the places where the species occurs, near Morro da Baleia, Chapada dos Veadeiros. (A, D, and E by F.S.Meyer; B – C by D.O. Diniz).

FIGURE 3. Indumentum on the adaxial surface of the leaves of Tibouchina falcifolia (A) and Tibouchina aegopogon var. angustifolia (B). (A from Meyer 1193 at UPCB; B from Labiak et al. 5879 at UPCB).

FIGURE 4. Scanning Electron Microscopy of vegetative and reproductive parts of T.falcifolia.A. Scales on young branches.B. Trichomes on the adaxial surface of the leaves. C. Detail of the trichome on the adaxial surface of the leaves. D. Scales on the abaxial surface of the leaves. E. Detail of the scale on the abaxial surface of the leaves. F. Scales on the abaxial surface of the hypanthium. G. Seed. H. Detail of surface of the seed. (A from Diniz et al. 724 at UFG; B–F from Verdi et al. 7373 at RB; G–H from Meyer 1193 at UPCB).

FIGURE 5. Distribution map of Tibouchina falcifolia (orange triangles) and Tibouchina longisquamata (yellow triangles).Abbreviations: DF: Distrito Federal; GO: Goiás; TO: Tocantins; MA: Maranh„o; PI: Piauí; BA: Bahia; MG: Minas Gerais.