Pleroma cleistoflora (Ule) P.J.F. Guim., Oliveira da Silva & Michelangeli, 2014

Silva, Marcus Felippe Oliveira Da, Guimarães, Paulo José Fernandes & Michelangeli, Fabián A., 2014, Nomenclatural and taxonomic novelties in the tribe Melastomeae (Melastomataceae), Phytotaxa 186 (4), pp. 222-228 : 225-226

Pleroma cleistoflora (Ule) P.J.F. Guim., Oliveira da Silva & Michelangeli , comb. nov. ( Figs. 1 , 2 )

Basionym: Purpurella cleistoflora Ule (1895: 418–419) . Type:— BRAZIL. Rio de Janeiro: “Serra do Itatiaia ” (in the label), “habitat in campis ad Serram Itatiaiae, in altitudine 2100–2400 metrum” (in the protologue), E.H.G. Ule 3349 (Holotype B†, photo F!, Lectotype HBG [522987], here designated, Isolectotypes: HBG [522988, 522989?]) .

Homotypic synonyms:— Purpurella cleistopetala Ule (1896: 169) nom. superfl. et illeg.; Itatiaia cleistopetala (Ule) Ule (1908: 235) nom. illeg.

Subshrubs, prostrate; branches sub-tetragonal, not angled, covered with pilose and appressed-strigose hairs, as the stem, petioles and pedicels. Leaves opposite, flat; petioles 1–2 mm long; blade 3–6 × 2–5 mm, oval, oval to elliptic, base rounded to truncate, apex acute to acuminate, margin ciliate, adaxial surface glabrous or sparsely pilose, abaxial surface glabrous to pilose, 3-nerved, veins confluent at the base. Inflorescence reduced to one terminal flower; pedicels ca. 0.5 mm long; bracteoles 2, 4–5 × 0.8–1.2 mm, flat, lanceolate, apex acute, margin ciliate, caducous after anthesis; Flowers 4-merous, hypanthium 2.5–3 mm long, campanulate, moderately covered with strigose hairs and sparsely covered with basal glandular trichomes; calyx lobes lanceolate, apex acute, caducous in fruit; corolla globose; petals 8–10 × 5–6 mm, white, obovate; stamens 8, isomorphic, filaments 2.5–3 mm long, white, glabrous, connective not prolonged, ventral appendage bicalcarate, 1–1.5 mm long, thecae 1–1.5 mm long, purple, linear, apex truncate. Ovary basal half adhered to hypanthium; style 5–6 mm long, glabrous. Capsule 4–5 mm long; seeds cochleate.

Features: Pleroma cleistoflora is a prostrate subshrub with many adventitious roots, that can be recognized by its 4-merous, closed flowers at anthesis, and stamens with ventral bicalcarate appendages equal in size to the thecae. The other representatives of Pleroma usually have ventral appendages that are smaller than the thecae.

Habitat and distribution:― Pleroma cleistoflora is endemic to southeastern Brazil. It occurs on moist soils and shaded places in a few localities on the highlands of Itatiaia National Park, between 2,200 –2,430 m elevation, in an area of approximately 10 km 2 ( Pinheiro 2013), along the border between Rio de Janeiro and Minas Gerais States ( Baumgratz 2014). As a result of its restricted area of occurrence, it is probably endangered; however, a paper including considerations on its geographic distribution patterns and conservation strategies is in preparation (Felipe Pinheiro, pers. comm.)

Phenology:― This species has been collected with flowers and fruits from November to May. Although a single experiment has verified the presence of nectar in flowers ( Pinheiro 2013), no other study was conducted to confirm the occurrence of cleistogamy, seed dispersal or vegetative propagation.

Additional specimens examined:― BRAZIL. Rio de Janeiro: Resende, Parque Nacional do Itatiaia: Planalto , ao longo da trilha entre o abrigo Rebouças e o Pico das Agulhas Negras, 2430 m, 7 May 2009, J.F. Baumgratz et. al. 1141 ( RB) . Idem, trilha para Pedra Furada , às margens da trilha, 11 February 1990, L. Sylvestre 299 ( RB) . Idem, abrigo Rebouças , 30 December 1966, H. E. Strang 826 ( MBM, NY) . Idem, entre abrigo Masena e Macieira , 14 January 1961, H. E. Strang 246 ( NY) . Idem , 28 November 1952, F. Markgraf & A.C. Brade 21275 ( RB) . Idem , 28 November 1952, C. Raben 21275 ( NY) . Idem, Planalto , 21 February 1948, A.C. Brade 18900 ( RB) . Idem, Planalto, Pedra Assentada , 8 February 1945, A.C. Brade 17415 ( RB) . Idem , ribeirão das flores, 22 November 1938, F. Markgraf 3718 ( RB) . Idem , ribeirão das flores, 26 February 1936, A.C. Brade 15149 ( RB) . Idem , 2,300 m, 28 December 1934, Pilger & Brade s.n. (RB 29929). Idem , 2,000 –2,300 m, 5 January 1929 L. B. Smith 1689 ( NY, US). Idem , 2,000 –2,300 m, 11 December 1928, L. B. Smith 1481 ( NY, US). Idem , estrada de Registro para o Planalto, s.d., S.V. de Andrade 612 ( RB) .

Figures

FIGURE 1. Pleroma cleistoflora.A. habitat in the Itatiaia highlands. B. Subprostrate habit. C. Closed buds with white petals and leaves. D. Opened flower (manually). Photos by M.O. Pellegrini.

FIGURE 2. Pleroma cleistoflora. A. Habit, B. adaxial leaf surface. C. abaxial leaf surface. D. Opened flower (manually). E. Stamens, front and lateral views. F. Ovary crowded with setose hairs, style and stigma.