Pleroma ceciliana P.J.F.Guim.& Oliveira da Silva, 2015

Guimarães, Paulo José Fernandes & Silva, Marcus Felippe Oliveira Da, 2015, A new species of Pleroma (Melastomataceae, Melastomeae) from southeastern Brazil, Phytotaxa 205 (1), pp. 51-58 : 52-57

Pleroma ceciliana P.J.F.Guim.& Oliveira da Silva sp. nov. (Figs. 1,2).

A species similar to Tibouchina divaricata Cogn. differing by its stamens dimorphic in size, pedoconnectives of both sets with ventral bituberculate appendages and with stipitate glands, and sigmoidal, weakly incurved style.

Type: ― BRAZIL. Rio de Janeiro: Campos dos Goytacazes. Distrito de Ibitioca, Fazenda Pedra Negra, sopé do morro de Itaoca (“ morro do Rato ”), elevation 40 m, 23 March 2001, fl., fr., J. M. A. Braga 6648 (holotype: RB!; isotypes: K!, NY!, R!, SP!) .

Shrubs 1.6–2 m, with branches sub-tetragonal, but not angled. The uppermost cauline internodes, petioles, pedicels and inflorescence branches moderately to densely covered with sericeous-strigose hairs and with some white dots over the stem surface, most visible in older stems; older cauline internodes glabrescent. Leaves opposite and isophyllous, flat; petioles 3–16 mm; blade 1.4–5.5 × 0.8–2.9 cm, lanceolate-ovate, base rounded and slightly truncate, apex acute, margin entire, ciliate, adaxial surface moderately to densely strigose or sericeous-strigose, hairs 0.5–1.25 mm long, adnate for 1/3 their length, base of the hairs with white dots, abaxial surface sericeous between the main ribs and sericeous-strigose on the nerves with hairs 1.75–4.5 mm long, 3+2-nerved, with the external pair diverging 1–2 mm from the base of the leaf, primary veins impressed adaxially and prominent abaxially. Inflorescence 1–3.5 cm long, terminal, dichasium to botryoid, with 3–12 flowers, pedicels ca. 1–2 mm; bracteoles 2.4–5 × 2–2.5 mm, enveloping young floral buds, concave, ovate, apex acute, margin ciliate, caducous after anthesis. Flowers 5-merous; hypanthium (at anthesis) 2.5–3 mm, campanulate, sericeous-strigose and with few stipitate glands; calyx lobes 2–3 mm long, lanceolate, apex acute, margins ciliate, moderately covered with stipitate glands and sericeous-strigose hairs, caducous in fruit; petals 10–12 × 4–5 mm, purple, obovate, apex truncate, margins covered with small glandular hairs; stamens 10, dimorphic in size, glandular hairs present at the lower half of the filaments, pedoconnective with ventral bituberculate appendages, with stipitate glands, thecae incurved, subullate with a terminal ventrally inclined pore. Antepetalous stamens: filaments 5–5.5 mm long; pedoconnective 1.5–2 mm long; thecae 4.5–5 mm long, erect; appendages 0.2–0.3 mm long. Antesepalous stamens: filaments 4–4.5 mm long; pedoconnective 0.8–1 mm long; thecae 4.5–5 mm long, incurved, geniculate; appendages ca. 0.1 mm long. Ovary base half adhered to hypanthium, apex with congested setose hairs; style 5–6 mm long, glabrous, sigmoidal, weakly incurved at apex. Capsule 3–5 mm; seeds cochleate.

Etymology:— This species is named in honor of the eminent botanist Dr. Cecília Gonçalves Costa, from the “Instituto de Pesquisas Jardim Botânico do Rio de Janeiro ”, Brazil. Dr. Cecília works with anatomical studies of several families of tropical plants, including Melastomataceae .

Distribuition and habitat:— Currently Pleroma ceciliana is found in the northern part of Rio de Janeiro state, Brazil, from lowland to submontane Atlantic coastal forest, at elevations between 20 to 600 m, and with an area of extent of occurrence (EOO) of 2,684km 2. This distribution is bordered to the north by the municipality of Campos dos Goytacazes, to the south by Silva Jardim, and to the west by the Sossego Mountains in Santa Maria Madalena and Colégio River in São Fidelis.

This species grows on rocky outcrops, in secondary forest and along roads, which may suggest a high tolerance to disturbed environments.

Conservation:— Pleroma ceciliana was recorded from one conservation unit, the Desengano State Park, in Santa Maria Madalena, and close to another, the Poço das Antas Biological Reserve, in Silva Jardim. However, other specimens were collected in disturbed environments near areas with sugar cane cultivation, and the holotype is from Itaoca Hill, an area threatened by granite extraction. The estimated area of occupancy (AOO) of this species is 24 km 2, based on the IUCN default cell width of 2 km, and may be considered as endangered [EN B1ab(iii)].

Comments:— Pleroma ceciliana can be recognized by the association of leaf and stamen characteristics. The leaf blades have the base rounded and slightly truncate and 3+2 nerves with the marginal pair 1–2 mm suprabasal. In addition, the stamens are dimorphic in size with pedoconnective appendages covered with stipitate glands.

The leaf blades vary in size and indument. Specimens from Santa Maria Madalena and Silva Jardim have leaves up to 5.5 cm long with sericeous-strigose hairs on the adaxial leaf surface, while the specimens from Campos dos Goytacazes have leaves up to 3cm long and strigose hairs on the adaxial leaf surface. This variation on leaf morphology may be due to differences in exposure to sunlight ( Boeger et al. 2008, Boeger et al. 2009, Pil et al. 2011, Somavilla & Graciano-Ribeiro 2011), once one of the specimens was collected in a moist and shaded environment along the roadside in Silva Jardim and the other one was collected in a dry rocky outcrop at Campos dos Goytacazes.

This species is similar to Tibouchina divaricata Cogniaux (1883 –85: 397) due to the stipitate glands on the connective appendages and its general appearance. Tibouchina divaricata is endemic to Minas Gerais State, Brazil, and known from only two specimens, the holotype collected by Saint-Hilaire at Araçuaí municipality and another collected in 1982 by G. Hatschbach at Medina, both from the Jequitinhonha valley. They differ from each other mainly by the dimorphic stamens of Tibouchina divaricata , in which the antepetalous ones have glabrous appendages and the antesepalous ones have appendages covered with stipitate glands. The leaves are sessile in T. divaricata , while Pleroma ceciliana has leaves with petioles 3–16 mm long.

Pleroma ceciliana is also similar to Tibouchina corymbosa (Raddi) Cogniaux (1883 –85: 363), endemic to Rio de Janeiro state; both have leaf blades with the base rounded and slightly truncate with the marginal pair suprabasal and similar trichomes on the abaxial and adaxial surfaces. However, Tibouchina corymbosa has larger leaves 4.5–9 cm long, and isomorphic stamens with glabrous appendages.

This new species inhabits similar environments to that of Tibouchina gaudichaudiana (A.P. de Candolle) Baillon (1881:7) , which occurs in the states of Espírito Santo and Rio de Janeiro, and Tibouchina trichopoda (A.P. de Candolle) Baillon (1877:75) , recorded from Espírito Santo to Santa Catarina. They also share similar shrubby habits about 2 meters tall and stamen filaments covered with stipitate glandular hairs, but the presence of these hairs on connective appendages occurs only in Pleroma ceciliana . In table 1 the characteristics of P. ceciliana are compared with the features of Tibouchina divaricata , T. corymbosa , T. gaudichaudiana and T. trichopoda . The latter four species will be further transferred to Pleroma (Guimarães & Michelangeli unpublished data).

Paratypes:— BRAZIL. Rio de Janeiro: São Fidelis, 21° 46’ 48’’S, 41° 51’ 00’’W, 8 July 2014 (fl., fr.) T. M. Scarponi , L. S. Nascimento, R. A. Ammon & D. Hottz 53 ( RB) ; São Sebastião do Alto, “fragmento de floresta estacional semidecídua fortemente alterado, sobre solo argiloso e terreno muito declivoso +/- 40°”, elevation 470 m, 21° 57’ 36”S, 42° 07’ 12”W, 12 December 2013 (fl.) L. B. Pimentel , A. S. C. Junqueira, M. Ramos & R. Giovanetti-Alvaes, s.n. ( RB) ; Silva Jardim , BR 101 , elevation 20 m, 22°35’ 11’’S, 42° 23’6’’W, 29 December 2004 (fl.) P. J. F. Guimarães & N. N. R. Campos 369 ( RB) ; Santa Maria Madalena, sub-bosque de mata secundária da Serra do Sossego, 28 April 1995 (fl., fr.) L. C. Giordano , S. V. A. Pessoa, Y. Brito & L. Goldfarb 1946 ( RB, R, US, NY) ; Santa Maria Madalena, Represa, 21 March 1989 (fl., fr.) L. C. Giordano , R. Marquete , N. Marquete & M. C. Valente 603 ( RB, R, US, NY) .