Pleroma littorale F.S.Mey. & R.Goldenb.

Meyer, Fabrício Schmitz, Arantes, Fabíula Moreno & Goldenberg, Renato, 2024, Two new species and a new combination in Pleroma (Melastomataceae) from the Brazilian Atlantic Forest, Phytotaxa 638 (3), pp. 209-226 : 210-215

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

Type:― BRAZIL. Paraná: Guaratuba, Estrada da Limeira , 25°49’0”S, 48°46’0.9”W, 8 August 2022, (fl.), F. S. Meyer & A. L. G. Frantz 2741 (holotype: UPCB!; isotypes: RB!, UEC!) .

Diagnosis: — Pleroma littorale differs from Pleroma urvilleanum ( De Candolle 1828: 130) Guimarães & Michelangeli (in Guimarães et al. 2019: 991) by the cucullate bracteoles, with its apex obtuse and covering the flower bud (vs. ovate, with its apex acute and not covering the flower bud in Pleroma urvilleanum ), and sepals with an obtuse apex (vs. attenuate).

Description: —Shrubs with sympodial growth, moderately to strongly branched, 1–4 m tall. Younger branches quadrangular, not winged, moderately strigose, trichomes 0.4–1.3 mm long, unbranched, eglandular, appressed, the base linear, not immersed, not forked; the older branches quadrangular, not winged, strigose as the younger branches, but more sparsely so, frequently decorticating; nodes slender. Leaves opposite; petioles 2.3–7.4 mm long; blades 3.2–8.1 × 1.4–2.9 cm, chartaceous, slightly discolorous, ovate, base obtuse, apex acute, margins entire, slightly crenulate, 5(–7) acrodromous veins, the first and second lateral pairs confluent near the leaf base, and the submarginal pair tenuous, domatia absent, reticulation conspicuous on the abaxial surface; adaxial surface flat, dark green in dry specimens, green in fresh specimens, with moderately to densely short-sericeous trichomes 0.5–1.2 mm long on the surface and 0.9–1.7 mm long on the main vein near the base, unbranched, eglandular, appressed, the base linear, immersed, not forked, followed by a sequence of white dots, abaxial surface flat, light-green to pale-green in fresh and dry specimens, moderately short-sericeous on the surface, secondary and tertiary veins, trichomes 0.7–1.9 mm long, unbranched, eglandular, appressed, the base linear, not immersed, not forked, moderately short-sericeous to strigose on the primary veins, trichomes 0.8–2.2 mm long, unbranched, eglandular, appressed, the base linear, not immersed, not forked. Compound dichasium 6.7–11.5 × 3.7–9.7 cm, terminal, with 7–19 flowers, axis quadrangular, not winged, with the same indumentum as the branches; bracts in pairs, the color similar to the leaves, late deciduous, leafy, petioles 1.2–4 mm long, blades 2.2–4.5 × 0.6–1.5 cm, ovate, base obtuse, apex acute, flat, indumentum the same as on the leaves; bracteoles 2, cream to whitish in fresh material and in dry specimens, early deciduous, 11–14 × 9.5–11.5 mm, cucullate, base obtuse, apex obtuse and covering the apex of the flower bud, concave, adaxial surface glabrous, abaxial surface moderately strigose, with larger indumentum on the central portion, trichomes 1–1.8 mm long, and smaller near the margins, trichomes 0.1–0.4 mm long, unbranched, eglandular, appressed, the base linear, not immersed, not forked. Flowers 5-merous, about 4–5 cm diam., on pedicels 3–4.4 mm long; hypanthium 7.8–9 × 5.3–6.2 mm, not costate, green in fresh material, brown in dry specimens (adaxial surface), the apex not constricted, densely sericeous, trichomes 1.5–3 mm long, unbranched, eglandular, appressed, the base linear, not immersed, not forked; sepals early deciduous, 7.1–8.6 × 3.8–5 mm, obovate, flat or revolute in fresh material, green to reddish-green in fresh material, brown in dry specimens, margins ciliate, apex obtuse, adaxial surface glabrous, abaxial surface with the same indumentum as the hypanthium, with longer trichomes concentrated on the central portion of each sepal; petals 3.3–3.8 × 2.7–3.1 cm obovate, apex obtuse to 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 ca. 0.2 mm long, unbranched, eglandular or glandular (often mixed), erect, the base linear, not immersed, not forked; stamens 10, dimorphic, the antesepalous with the filaments white in (during anthesis) to lilac (in senescent flowers), 13.5–15.5 mm long, narrow at the base, moderately pilose in its lower 4/5, or along its entire length, trichomes 0.2–0.8 mm long, unbranched, glandular, erect to curved, the base linear, pedoconnective light purple (during anthesis) to purple (in senescent flowers), 2–2.5 mm prolonged below the thecae, glabrous, ventral appendages bilobed, white (during anthesis and in senescent flowers), patent, apex obtuse, 0.4–0.6 mm long, glabrous, thecae light-purple (during anthesis) to purple (in senescent flowers), 12–15 × 0.9–1.1 mm, falcate, narrow, the antepetalous with filaments white (during anthesis) to lilac (in senescent flowers), 8.8–10 mm long, narrow at the base, moderately pilose in its middle portion, trichomes 0.2–0.5 mm long, unbranched, glandular, erect to curved, the base linear, pedoconnective white (during anthesis) to light-purple (in senescent flowers), 0.5–0.8 mm long, prolonged below the thecae, glabrous, ventral appendages bilobed, white (during anthesis and in senescent flowers), patent, apex obtuse, 0.3–0.5 mm long, glabrous, thecae white (during anthesis) to light-purple (in senescent flowers), 9.4–11.7 mm × 1 mm, falcate, narrow; ovary 7.1– 9.2 × 4.4–5.2 mm, 5-locular, apex densely sericeous, trichomes 0.6–1.5 mm long, unbranched, eglandular, appressed, the base linear, not immersed, not forked; style whitish (during anthesis) to light purple (in senescent flowers), 26.8– 34.3 mm long, apex curved, moderately setose in its lower 3/5, trichomes 0.5–1.8 mm long, unbranched, eglandular, erect to curved, the base linear. Capsular fruits 10.3–11.8 × 8.6–10 mm, cupuliform, sepals lacking, epicarp undivided when mature, ecostate. Seeds 0.5–0.7 × 0.2–0.3 mm, cochleate.

Paratypes: — BRAZIL. Paraná: Guaraqueçaba, Morro do Quitumbê ou do Costão , 25°17’S, 48°20’W, 14 April 1995 (fl.), S.F. Athayde & D.J.S. Carrião 287 ( FUEL!, HUEM!, UPCB!) ; ibidem, Rio Guaraqueçaba , 11 June 1993 (fl.), R.X. Lima 16 ( EFC!, MBM!, UPCB!) ; Guaratuba, Estrada da Limeira , 25°49’0”S, 48°46’0.9”W, 8 August 2022, (fl.), F.S. Meyer & A.L.G. Frantz 2740 ( MBM!, UPCB!) ; ibidem, (fl.), F.S. Meyer & A.L.G. Frantz 2742 ( RB!, UPCB!) ; Morretes, América de Cima , propriedade às margens da Ferrovia Curitiba-Paranguá , 25°28’37.7”S, 48°52’31.2”, 23 July 2022 (fl., fr.), F.S. Meyer & M.L. Brotto 2737 ( MBM!, RB!, UPCB!) ; ibidem, Zona rural de Morretes , capoeira nas margens do entrocamento entre a Rua Bocaiúva do Sul e a PR-408 , -25.51787, -48.80356, 2 June 2023, (fl.), F.S. Meyer & M.L. Brotto 2763 ( MBM!, RB! UPCB!) ; ibidem, -25.51804, -48.80368, 2 June 2023, (fl.), F.S. Meyer & M.L. Brotto 2764 ( MBM!, RB!, UPCB!) ; ibidem, -25.51770, -48.80362, 2 June 2023, (fl.), F.S. Meyer & M.L. Brotto 2765 ( MBM!, RB!, UPCB!) ; Paranaguá, EIA Porto Guará—Laguna , 25°31’28”S, 48°33’58”W, 26 March 2019 (fl.), M.E. Engels & T.A. Meyer 6778 ( HCF, MBM!, UPCB!) ; ibidem, Parque Estadual do Palmito , 26 March 2003 (fl.), A.C. Cervi & A.L.V. Vieira 8385 ( HUCP digital image!, UPCB!). Santa Catarina: Joinville, beira de estrada, 26°18’16”S, 48°50’44”W, 2004 (fl.), C.F. Wendel s.n. ( ESA 119515 !) ; São Francisco do Sul, Ilha Araújo do Meio , 10 December 2007 (fl.), J. Meirelles 149 ( JOI, UPCB!) ; ibidem, Ilha dos Barcos , 29 September 2008 (fl., fr.), J. Meirelles 207 ( JOI, UPCB!). São Paulo: Cananéia, Parque Estadual da Ilha do Cardoso , Morro do Sambaqui-Mirim , 21 September 1982, (fl.), S.A.C. Chiea 204 ( ESA!, SP, UB) ; Cubatão, 4 September 1991 (fl.), S.A.C. Chiea 697 ( SP!) ; Iguape, Subaúma , beira da estrada Subaúma-Iguape , 24°48’54.3”S, 47°44’32.4”W, 7 September 1994, (fl.), C.D. Sanchez et al. 22 ( SPF!) ; Santos, Área da Santa Casa de Misericórdia de Santos , Rua da Servidão da SABESP , 23 March 2007 (fl.), R.J.F. Garcia 2794 ( UPCB!) ; ibidem, margem da rodovia Anchieta , s.d. (fl.), M. Kuhlmann 4448 ( SP!, US) ; Undetermined municipality, Pedro Taques , Rodovia Cubatão-Mongaguá , March 1964 (fl.), J. Mattos 11821 ( SP!) ; ibidem, J. Mattos 11830 ( SP!) .

Distribuition and habitat:— Pleroma littorale occurs in restinga (“vegetação com influência marinha”) and in secondary vegetation in lowland atlantic rainforest (“floresta ombrófila densa de terras baixas”), and submontane atlantic rainforest (“floresta ombrófila densa submontana” according to the classification by IBGE 2012), in the states of Santa Catarina, Paraná, and São Paulo ( Figure 3 ).

Phenology:—Collected with flowers between March and September, and in December. Collected with fruits in July and in September.

Conservation status:—The species is known from 21 specimens, distributed from the municipality of Joinville, state of Santa Catarina (southern limit), to the municipality of Santos, state of São Paulo (northern limit; Figure 3 ). Its Extent of Occurrence (EOO) is 15,976.231 km 2 and its Area of Occupancy (AOO) is 64.000 Km 2. These values would support a Vulnerable [V: B1a] conservation status according to IUCN (2022). There is a large gap in its northernmost distribution, especially between the municipalities of Iguape and Santos (both in the state of São Paulo). Despite this, in these places, there are habitats similar to those where the species occurs, and consequently, these gaps may represent poorly sampled sites. The species appears to be undemanding in terms of habitat quality; the first author's collections (Meyer & Frantz 2740, 2741, 2742 and Meyer & Brotto 2737, 2763, 2764 and 2765) are from open sites, with regenerating vegetation. Nevertheless, the species occurs in six conservation units, four of which are “Sustainable Use Units”, which means “with a few restrictions” (either “environmental protection areas” or “areas with special touristic interest”), and two in state parks that are full protection units. In the state of Paraná, the species was registered in the “Área de Proteção Ambiental de Guaraqueçaba”, “Área de Proteção Ambiental de Guaratuba”, “Área Especial de Interesse Turístico do Marumbi”, and “Parque Estadual do Palmito”. In the state of São Paulo, the species was registered in the “Área de Proteção Ambiental de Cananéia-Iguape-Peruíbe”, and “Parque Estadual da Ilha do Cardoso”. The populations in Santa Catarina have not been found inside protected areas (see Figure 3 ).

Etymology:—The epithet “ littorale ” refers to its occurrence in coastal areas.

Notes:— Pleroma littorale is morphologically similar to P. urvilleanum due to its shrubby habit, leaves with distinct petioles (3.6–12.2 mm long in P. urvilleanum , and 2.3–7.4 mm long in P. littorale ), ovate blades with 5(–7) acrodromous veins and sericeous adaxial and abaxial surfaces. They also share the flower buds surrounded by two bracteoles, 5-merous flowers, sericeous hypanthium, purple petals, filaments and style covered by glandular trichomes, and the habitat in “restingas” and lowland and submontane atlantic rainforest in the state of Santa Catarina (with P. urvilleanum extending a little further south, and reaching the state of Rio Grande do Sul). Pleroma littorale differs from P. urvilleanum by the characteristics explained in the diagnosis, and also by the usually smaller leaves, 3.2–8.1 × 1.4– 2.9 cm (vs. 5.5–10.7 × 2.2–5.1 cm in P. urvilleanum ), with shorter trichomes, 0.5–1.2 mm long on the abaxial surface of the blade (vs. 0.6–2 mm long), the base obtuse (vs. slightly cordate), and shorter antesepalous pedoconnectives, 2–2.5 mm long (vs. 5–8 mm long). One specimen of P. littorale (Athayde 287) was incorrectly identified as P. urvilleanum in a taxonomic study for the genus in the state of Paraná ( Meyer et al. 2010).

Pleroma littorale is also morphologically related to Pleroma clavatum ( Persoon 1805: 476) Guimarães & Michelangeli (in Guimarães et al. 2019: 974)—they resemble each other in their shrubby habit, and ovate leaf blades with sericeous adaxial and abaxial surfaces. They also share the flower buds enclosed by two bracteoles, 5-merous flowers, sericeous hypanthium, purple petals, filaments and style covered by glandular trichomes, and the habitat in “restinga” and lowland and submontane atlantic rainforest in the states of Santa Catarina, Paraná and São Paulo (with P. clavatum extending a little further north, and reaching the state of Rio de Janeiro; see Guimarães 2024). Pleroma littorale differs from P. clavatum by the conspicuous petioles, with 2.3–7.4 mm long (vs. inconspicuous or very short, ca. 1 mm long in P. clavatum ; see Meyer et al. 2010), leaf blades with an acute apex (vs. obtuse), obtuse base (vs. strongly cordate), and flowers with the antesepalous stamens with longer pedoconectives, 2–2.5 mm long (vs. 1.3–1.7 mm long).

Finally, P. littorale shares some morphological features with P. caissara Meyer (in Meyer & Goldenberg 2014: 2)—the strigose branches, leaves with conspicuous petioles (3–15 mm long in P. caissara ), the flower buds enclosed by two bracteoles, 5-merous flowers, sericeous hypanthium, and the filaments of the antesepalous stamens and style covered by glandular trichomes. Both species also share habitats in “restinga” and lowland and submontane atlantic forest in the states of Santa Catarina, Paraná, and São Paulo (see Meyer & Goldenberg 2014). Pleroma littorale differs from P. caissara by the shrubby habit (vs. arboreal in P. caissara ), ovate leaves (vs. elliptic), with the adaxial surface moderately to densely short-sericeous (vs. moderately strigose), and smaller petals 3.3–3.8 × 2.7–3.1 cm (vs. 3.5– 4.5 × 2.9–3.6 cm in P. caissara ; see Meyer & Goldenberg 2014).

Figures

FIGURE 1. Photos of living specimens of Pleroma littorale. A. Flowering branch. B. Leaf, adaxial surface. C. Leaf, abaxial surface. D. Flower in anthesis (lateral view). E. Partial inflorescence, with one flower bud enclosed by bracteoles (left) and the other in initial anthesis (right). F. Partial inflorescence with mature flower (in dorsal view), with the red arrow indicating the revolute sepals, also an immature fruit, and a flower bud G. Flower without petals, evidencing the androecium and gynoecium, and the revolute sepals. [All Photos by Fabrício Schmitz Meyer].

FIGURE 2. Plate with photos from herbarium specimens of Pleroma littorale, based on the holotype and paratypes. A. Branch. B. Leaf (abaxial surface). 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. Floral bud, with a black arrow indicating the obtuse apex of the sepal. G. Detail of the hypanthium and calyx, with revolute sepals (black arrow). H. Antesepalous stamen. I. Antepetalous stamen. J. Detail of the indumentum on the antesepalous filament. K. Detail of the indumentum on the antepetalous filament. L. Gynoecium. M. Mature fruit. [A-L: Meyer & Frantz 2741; M: Meyer & Brotto 2737].

FIGURE 3. Distribution map of Pleroma littorale.Abbreviations of the states:SC:Santa Catarina; PR:Paraná; SP:São Paulo.Conservation Units: 1. Área de Proteção Ambiental de Guaratuba; 2. Área Especial de Interesse Turístico do Marumbi; 3. Parque Estadual do Palmito; 4. Área de Proteção Ambiental de Guaraqueçaba; 5. Área de Proteção Ambiental de Cananéia-Iguape-Peruíbe; 6. Parque Estadual da Ilha do Cardoso.