Pleroma curucutuense F.S.Mey. & R.Goldenb., 2023

Meyer, Fabrício Schmitz & Goldenberg, Renato, 2023, A new species of Pleroma (Melastomataceae) from high-altitude grasslands of the state of São Paulo, Brazil, Phytotaxa 616 (1), pp. 89-98 : 91-95

Pleroma curucutuense F.S.Mey. & R.Goldenb. sp. nov. ( Figures 1−2 ).

Type:― BRAZIL. State of São Paulo, Municipality of São Paulo, Parque Estadual da Serra do Mar—Núcleo Curucutu , -23.97929, - 46.73450, 14 February 2012, F.S. Meyer, M. Reginato, R. Goldenberg & R.J.F. Garcia 1107 (holotype: UPCB!; isotypes: RB!, SP!, UEC!) .

Diagnosis: — Pleroma curucutuense differs from Pleroma caissara Meyer (in Meyer & Goldenberg 2012: 9527) by the smaller leaves, 2.4–5.6 × 1.2–2 cm (vs. 2.4–8.5 × 1.2–3.4 cm in P. caissara ), the smaller hypanthium, 5.5–6 × 4.5–5.5 mm (vs. 6.7–8.8 × 5.2–7.7 mm) and smaller sepals, 3.3–4.5 × 2.3–3.3 mm (vs. 6.7–10.2 × 2.7–4.6 mm). In addition, P. curucutuense has antesepalous stamens with a smaller pedoconnective, 2.8–3.8 mm long (vs. 4–5 mm long), smaller anthers, 7.8–9.5 mm long (vs. 11.5–14.4 mm long), and smaller style, 13.5–18 mm long (vs. 19.7–23.4 mm long).

Description: —Shrubs with sympodial growth, moderately branched, 0.4–2 m tall. Younger branches moderately strigose, trichomes 0.4–0.9 mm long, eglandular, appressed, the base linear, not immersed, not forked; the older branches with the same indumentum as the younger branches, but sparser, frequently decorticating; nodes slender. Leaves opposite; petioles 4–8 mm long; blades 2.4–5.6 × 1.2–2 cm, chartaceous slightly discolorous, elliptical, base obtuse, apex acute to obtuse, margins entire, slightly crenulate at the apex, 3 acrodromous veins, basal, domatia absent, reticulation inconspicuous on the abaxial surface; adaxial surface flat, brown to dark green in dry specimens, green in fresh material, moderately strigose, trichomes 0.3–0.6 mm long, eglandular, appressed, the base linear, immersed, not forked, followed by a sequence of white dots, abaxial surface flat, yellowish-green or brown in dry specimens, palegreen in fresh material, moderately strigose on the actual surface, trichomes 0.1–0.5 mm long, eglandular, appressed, the base linear, not immersed, not forked, moderately strigose on the primary and secondary veins, trichomes 0.3–1 mm long, eglandular, appressed, the base linear, not immersed, not forked. Dichasial cymes 1.5–2.5 × 1.5–3 cm, terminal, 3–7(–9) flowers, axis quadrangular, with the same indumentum as the branches; bracts in pairs, the color similar to that of the leaves, late deciduous, leafy, petioles 1–3 mm long, blade 2–13 × 1–8 mm, elliptical, base obtuse, apex acute to obtuse, flat, indumentum the same as that on the leaves; bracteoles 2, cream, reddish or cream-reddish in fresh material, brown in dry specimens, early deciduous, 9–11.2 × 8–9.2 mm, cucullate, base obtuse, apex obtuse [and covering the apex of the flower bud], concave, adaxial surface glabrous, abaxial surface moderately strigose, with indumentum arranged along the entire abaxial surface, sparser near the margins and the apex, trichomes 0.3–0.9 mm long, eglandular, appressed, the base linear, not immersed, not forked. Flowers 5-merous, on pedicels 0.7–1.2 mm long; hypanthium, 5.5–6 × 4.5–5.5 mm, not costate, the epidermis green to reddish-green in fresh material, brown in dry specimens (adaxial surface), the apex not constricted, densely sericeous, trichomes 1.1–2.2 mm long, eglandular, appressed, the base slightly broadened, not immersed, not forked; sepals early deciduous, 3.3–4.5 × 2.3–3.3 mm, obovate, the epidermis green to reddish-green in fresh material, brown in dry specimens, margins ciliolate, apex obtuse, adaxial surface glabrous, abaxial surface with the same indumentum as the hypanthium, trichomes concentrated on the central portion of each sepal; petals 21.5–25 × 15.5–19 mm, obovate, apex retuse, emarginate or mucronate, purple with a white base (during anthesis) or purple with a red base (in senescent flowers), glabrous in both surfaces, margin ciliate, moderately pilose, trichomes 0.1–0.3 mm long, eglandular or glandular (often mixed), erect, the base linear, not immersed, not forked; stamens 10, strongly dimorphic, the antesepalous with the filaments white in the basal portion, and purple (during anthesis) to reddish (in senescent flowers) in its apical portion, 10.2–11 mm long, glabrous or sparsely pilose on its basal portion, trichomes 0.3–0.5 mm long, glandular, curved, the base linear to slightly broadened, pedoconnective light purple (during anthesis) to reddish (in senescent flowers), 2.8–3.8 mm, glabrous, ventral appendages bilobed, light purple (during anthesis) to purple (in senescent flowers), patent, apex obtuse, ca. 0.6 mm long, glabrous, thecae white in the basal portion, and purple in its apical portion (during anthesis) to whitish (in senescent flowers), 7.8–9.5 mm long, falcate, the antepetalous with filaments white (during anthesis) to reddish (in senescent flowers), 8–9.5 mm long, glabrous, pedoconnective white to light purple (during anthesis) to reddish (in senescent flowers), 1.1–1.5 mm long, glabrous, ventral appendages bilobed, white (during anthesis) to light purple (in senescent flowers), patent, apex obtuse, ca. 0.6 mm long, glabrous, thecae white (during anthesis) to whitish (in senescent flowers), 7.8–8.2 mm long, falcate; ovary ca. 5–6 × 4–4.5 mm, 5-locular, apex densely strigose, trichomes 0.2–0.6 mm long, eglandular, appressed, the base linear, not immersed, not forked; style whitish to light purple (during anthesis) to lilac (in senescent flowers), 13.5–18 mm long, apex curved, glabrous. Immature capsular fruits 6.2–7.5 × 7–8 mm, sepals early deciduous, epicarp undivided when mature, ecostate. Seeds not seen.

Paratypes: — BRAZIL. S ã o Paulo, Municipality of S ã o Paulo, Parque Estadual da Serra do Mar, Núcleo Curucutu , 23°59’28”S 46°44’36”W, 28 March 1996, G.M.P. Ferreira et al. 71 (PMSP image online!, UEC!) ; ibidem, 23°59’16”S, 46°44’1”W, 13 February 1997, R.J.F. Garcia et al. 1034 ( PMSP image online!), ibidem, 14 May 1997, N.S. Chukr et al. 567 ( PMSP image online!), ibidem, 22 August 1997, P. Affonso et al. 92 ( PMSP image online!), ibidem, 23º59’S, 46º44’W, 11 April 2001, F.T. Farah et al. 2127 ( ESA!), ibidem, F.T. Farah et al. 2131 ( ESA!), ibidem, -23.97988, - 46.73509, 14 February 2012, F.S. Meyer et al. 1108 ( MBM!, RB!, UPCB!), ibidem, -23.98846, -46.73916, 14 February 2012, F.S. Meyer et al. 1109 ( MBM!, RB!, UPCB!); Reserva Estadual do Curucutu , 23°59’28”S 46°44’36”W, 16 August 1995, S.A.P. Godoy et al 768 ( SP!, UEC!).”

Distribuition and habitat:— Pleroma curucutuense occurs in the state of S ã o Paulo, only at the Parque Estadual da Serra do Mar, in the Núcleo Curucutu, which is located inside the municipality of S ã o Paulo, and only about 70 km to the south of the city of S ã o Paulo ( Garcia 2003, Garcia & Pirani 2005a, Silva & Affonso 2005). The vegetation is mostly represented by Atlantic Forest on the slopes, but with high-altitude grasslands on higher ground (“Refúgio Vegetacional Altomontano”, according to the classification by IBGE 2012; see Figure 3 ), where P. curucutuense has been found. Apart from P. curucutuense , other six species in the same genus can be found nearby (see identification key, below).

Phenology:—Flowering between February to April, and fruiting starting in April. There is only one sample with flowers collected in August, but that is probably not the most intense flowering period. We did not find samples with mature fruits.

Conservation status:—The species is currently known from a very small population, with restricted distribution. Its extent of occurrence (EOO) is 530 km 2 and its area of occupancy (AOO) is about 4.0 km 2, but this can be underestimated. Pleroma curucutuense has been only collected in high-altitude grasslands close to the headquarters of the Núcleo Curucutu, but the same vegetation extends further east and south on the highest ridges of this portion of the Serra do Mar ( Figure 3 ). It is very likely that P. curucutuense may be also distributed in these places, and for this reason, we consider that the species should be preliminarily considered within the Data Deficient Category (IUCN 2022).

Etymology:—The epithet “ curucutuense ” refers to the Núcleo Curucutu, a subunit of the Parque Estadual da Serra do Mar and the only place of occurrence for the species until now. The toponym “Curucutu” is of onomatopoeia origin, in reference to the hoot of an owl ( CEO 2002, Garcia & Pirani 2005b).

Affinities:— Pleroma curucutuense is morphologically close to P. caissara due to the elliptical leaves with conspicuous petioles (3–15 mm long in P. caissara and 4–8 mm long in P. curucutuense ), strigose blades on both surfaces, moderately strigose branches, inflorescences in short cymes, with 3–7(–9) flowers, and cucullate bracteoles. Both species also share the 5-merous flowers, sericeous hypanthium, and purple petals with a white base at anthesis, becoming reddish during senescence. Pleroma curucutuense differs from P. caissara by the characters pointed out in the diagnosis, and by the shrubby habit, 0.4–2 m tall plants (vs. arboreal habit, 2–7 m tall in P. caissara ), leaves with only 3 veins (vs. 5 veins), and smaller petals 21.5–25 × 15.5–19 mm (vs. 35.5–45 × 29.5–36 mm in P. caissara ). One of the samples of the new species (Godoy et al. 768) had been indicated as a paratype of P. caissara ( Meyer & Goldenberg 2014) , which can be explained by the great similarity between the two species. These species also occur in different habitats: P. curucutuense occurs above 750 m in high-altitude grasslands, while P. caissara occurs between 10–400 m elevation, in Restinga and Lowland and Submontane Atlantic Forest.

Pleroma curucutuense is also morphologically related to Pleroma andersregnellii Guimar ã es & Michelangeli (in Guimar ã es et al. 2019: 974) due to the inflorescences in short cymes, with 3–7(–9) flowers, and cucullate bracteoles. Both also share the 5-merous flowers, sericeous hypanthium, and purple petals. Pleroma curucutuense differs from P. andersregnellii by the smaller elliptical leaves, 2.4–5.6 × 1.2–2 cm (vs. larger ovate leaves, 8–11 × 3–4 cm in P. andersregnellii ), with only 3 veins (vs. 5 veins), smaller petioles 4–8 mm (vs. 10–15 mm long), and smaller petals 21.5–25 × 15.5–19 mm (vs. 30–35 × 25–30 mm; see Cogniaux 1885). In addition to the indicated morphological characters, these species occur in different vegetation types; P. curucutuense is exclusive to high-altitude grasslands in the state of S ã o Paulo, and P. andersregnellii occurs in Cerrado in the state of Minas Gerais, being known from a single collection from Serra de Caldas ( Cogniaux 1885).

Pleroma curucutuense also seems to be related to P. trichopodum due to the elliptical leaves with conspicuous petioles (4–14 mm long in P. trichopodum ), flowers gathered in inflorescences, the 5-merous flowers, and the purple petals, with a white base in young flowers and becoming reddish in mature flowers ( Meyer et al. 2010). Pleroma curucutuense differs from P. trichopodum by the smaller habit, i.e., the first is a small shrub and the second is a shrub or treelet, larger cucullate bracteoles, 9–11.2 × 8–9.2 mm (vs. smaller ovate to orbicular bracteoles, 3.9–7.2 × 3.2–6 mm in P. trichopodum ), and its densely sericeous hypanthium (vs. moderately setulose). Whereas Pleroma curucutuense is exclusive to high-altitude grasslands in S ã o Paulo, P. trichopodum occurs in Restinga, Lowland and Submontane Atlantic Forest in the states of Espírito Santo, Minas Gerais, Rio de Janeiro, S ã o Paulo, Paraná, Santa Catarina, and Rio Grande do Sul (Guimar ã es 2023). Pleroma trichopodum was also collected in high-altitude grasslands of the Núcleo Curucutu, and occurs in sympatry with P. curucutuense , but its occurrence at higher altitudes was unknown until now.

Finally, P. curucutuense shares some morphological features with P. sellowianum —the elliptical leaves with conspicuous petioles (3–15 mm long in P. sellowianum ), the blades with 3 veins, and strigose on both surfaces, the 5-merous flowers, and the sericeous hypanthium. Pleroma curucutuense differs from P. sellowianum by the flowers gathered in inflorescences (vs. solitary in P. sellowianum ), floral buds surrounded by 2 bracteoles (vs. 6 bracteoles), and purple petals with a whitish base at anthesis (vs. white petals at anthesis, turning lilac during senescence). Although both species occur in sympatry, so far P. curucutuense is only known from the high-altitude grasslands at the Parque Estadual da Serra do Mar, Núcleo Curucutu, while P. sellowianum occurs in Araucaria Forest and high-altitude grasslands in Minas Gerais, Rio de Janeiro, S ã o Paulo, Paraná, Santa Catarina, and Rio Grande do Sul (Guimar ã es 2023).

Figures

FIGURE 1. Photos of living specimes of Pleroma curucutuense. A. Habit. B. Flowering branch. C.Apex of the flowering branch showing the inflorescence, the flower buds free or enclosed by the bracteoles, and a mature flower. D. Flower in anthesis (lateral view). E. Highaltitude grasslands of the Parque Estadual da Serra do Mar, Núcleo Curucutu [Photos A–B and D by Renato Goldenberg, Photos C and E by Fabrício Schmitz Meyer].

FIGURE 2. Illustration made with photos from herbarium specimens of Pleroma curucutuense, based on the holotype and isotypes. A. Branch; the white arrow indicating the base of the inflorescence. B1–B2. Leaves (abaxial surface), variation in size. C. Detail of the indumentum on the adaxial surface of the leaf. D. Detail of the indumentum on the abaxial surface of the leaf. E. Bracteoles covering the floral bud. F. Detail of the indumentum on the abaxial surface of the hypanthium. G. Petal (adaxial surface). H. Antesepalous stamen. I. Glandular trichomes on the base of the filament of the antesepalous stamen. J. Antepetalous stamen. K. Gynoecium.

FIGURE 3. Distribution map of Pleroma curucutuense.