Pleroma subsessilis F.S.Mey. & L.Kollmann, 2016

Meyer, Fabrício Schmitz, Goldenberg, Renato & Kollmann, Ludovic J. C., 2016, Three new species of Pleroma (Melastomataceae) from Inselbergs of Espírito Santo, Brazil, Phytotaxa 282 (3), pp. 197-210 : 205-206

3. Pleroma subsessilis F.S.Mey. & L.Kollmann sp. nov. ( Figures 6–7 )

Diagnosis:— Pleroma subsessilis differs from Pleroma kollmanniana by the smaller leaves (5.2–11.5 × 2.2–5.3 cm vs. 15.5–20.5 × 8.8–12 cm in P. kollmanniana ), and the connective appendages of the antepetalous stamens without glandular trichomes (vs. sparsely setulose, with trichomes 0.1–0.3 mm long in P. kollmanniana ).

Type:— BRAZIL. Espírito Santo: Afonso Cláudio, Alto Três Pontões ( Pico da Antena de Rádio Amador ), 16 August 1990, (fl., fr.), H. Q. Boudet Fernandes et al. 2999 (holotype: MBML!; Isotypes: RB!, UPCB!) .

Shrub 0.7–3 m tall. Branches terete, angled to winged, sparselly to moderately strigose, trichomes 0.3–1.3 mm long, non glandular, appressed, narrow at the base. Leaves opposite; petioles 0.6–1 mm long; blades 5.2–11.5 × 2.2–5.3 cm, ovate or ovate-elliptic, concolorous, base slightly cordate, apex acute, chartaceous, nerves 7, acrodromous, the marginals confluent (meeting the secondaries at the leaf base before joining the midrib), main nerves very prominent, transversals and reticulation prominent on the abaxial face, adaxial face densely scabrous, trichomes 0.5–1.2 mm long, non glandular, appressed, enlarged at the base, abaxial face moderately setulose to setose on the primary and secondary veins, trichomes 0.6–1.4 mm long, covered with black spots (each one ca. 0.02 mm), non glandular, curved, slightly enlarged at the base, the actual surface, tertiary and quaternary veins densely villose, trichomes 0.2–0.4 mm long, non glandular, coiled to curved, narrow to slightly enlarged at the base. Thyrsoid 29–36 × 28–36 cm, axis rounded to subterete, with the same indumentum as the branches; bracts caducous, leafy, petioles 0.7–1 mm, blade 5–6.5 × 1.8–2.4 mm, elliptic, indumentum the same as on the leaves; bracteoles early caducous, 5.9–8 × 1.7–2.4 mm, narrowtriangular, apex subulate, margins entire, ciliate, abaxial surface densely strigose, adaxial glabrous. Flowers 5-merous, on pedicels 0.9–1.1 mm long; hypanthium 5.3–5.6 × 3–3.3 mm, obovate, smooth (not costate), densely sericeous to strigose, the trichomes 0.4–0.7 mm long, non glandular, dendritic with short arms, appressed, narrow to slightly enlarged at the base; sepals 3.8–4.1 × 1.6–1.8 mm, triangular, margins ciliolate, apex acute or subulate, with the same trichomes as the hypanthium, but these restricted to the central portion of each sepal; petals purple with a white base, 15–15.7 × 12.1–13.3 mm, obovate, apex emarginate or asymmetric; stamens 10, slightly dimorphic, antesepalous with filaments white or light purple, 5.9–6.5 mm long, sparsely to moderately setulose at the base, trichomes 0.1–0.4 mm long, glandular, erect, narrow at the base, connective white or light purple, 0.7–0.9 mm, prolonged below the thecae, sparsely setulose, trichomes 0.1–0.3 mm long, glandular, erect, narrow at the base, ventral appendages 2, ca. 0.2 mm long, with the same indumentum as the connective, thecae white or light purple, 4.4–4.8 mm long, antepetalous stamens with filaments white or light purple, 4.3–4.7 mm long, sparsely to moderately setulose at the base, trichomes 0.1–0.3 mm long, glandular, erect, narrow at the base, connective white, ca. 0.3 mm, prolonged below the thecae, glabrous, ventral appendages 2, ca. 0.1 mm long, glabrous, thecae white, 3.9–4.3 mm long; ovary 4.5–4.9 × 2.7–3.1 mm, 5-locular, apex densely setulose, trichomes 0.3–0.6 mm, non glandular, erect, narrow at the base, style white or light purple, apex curved, 4.7–5 mm long, moderately setulose on the lower two-thirds, trichomes 0.2–0.6 mm, non glandular, curved, narrow at the base. Capsules 7.2–8.3 × 4.1–4.5mm, slightly costate, non lacerated when mature.

Paratypes:— BRAZIL. Espírito Santo: Afonso Cláudio, Três Pontões, 12 October 2005, (fl.), C. Esgario et al. 5 ( MBML!). Brejetuba , Monte Feio , 27 July 2009, (fl.), A. P. Fontana & L. Menini-Neto 6052 ( MBML!). Itarana , São Sebastião , 5 September 2012, (fl., fr.), L. Kollmann & A. P. Fontana 12475 ( MBML!). Santa Teresa , cultivated at “Museu de Biologia Mello Leitão” (without information about the original material), 25 June 2001, (fl., fr.), L. Kollmann 4011 ( MBML!) ; 16 April 2016, (fl., fr.), F. S. Meyer& L. Kollmann 2220 ( MBM!, MBML!, UPCB!) .

Distribuition and habitat:— Pleroma subsessilis occurs only in Espírito Santo,between 900– 1.200m, in vegetation associated to rocky outcrops intermingled with montane rain forest (“Floresta Ombrófila Densa Altomontana”) and montane seasonal forest (“Floresta Estacional Semidecidual Altomontana” following the official Brazilian classification - Veloso et al. 1991). The plants were found on rock shallow crevices or bromeliad clusters on thin, organic soil, and among other shrubs and herbs. The inselbergs where these plants have been found (“Monte Feio”, “São Sebastião” and “Três Pontões”, respectively in the municipalities of Brejetuba, Itarana and Afonso Cláudio) do not belong to any conservation unit.

Phenology:—Collected with flowers and fruits from April to October.

Conservation status:—This species can be considered as “Endangered”, according to IUCN’s category B1biv (2012). The Area of Occupancy is about 12.000 km 2, and the Extent of Occurence 194.431 km 2. The vegetation in some places where these plants occur has been grazed by cattle or replaced with agriculture and reforestation. These plants apparently do not occur inside protected areas.

Etymology:—The epithet subsessilis is related to the leaves with very short petioles.

Affinities:— Pleroma subsessilis is similar to Pleroma kollmanniana , especially due to the almost sessile leaves, flowers with purple petals with white bases, and the antesepalous stamens with the connective covered with glandular trichomes. It differs from P. kollmanniana by the characters pointed at the diagnosis, and also by the scabrous leaves, rough to the touch in P. subsessilis (vs. sericeous, smooth leaves in P. kollmanniana ). It is also similar to Tibouchina radula Markgraf (1927: 49) , due to their rough leaves and antesepalous stamens with the connective covered with glandular trichomes. Pleroma subsessilis differs from T. radula by the leaves with shorter petioles (0.6–1 mm long in P. subsessilis vs. 10–20 mm long in T. radula ), and 7 nerves (vs. 5 nerves in T. radula ). These characters and measurements from T. radula were taken from the type [Markgraf 13348 (M!), from Leopoldina, Espírito Santo] and a few selected specimens [Boone 66 (MBML, UPCB), Kollmann et al. 2340 (MBML, UPCB), Kollmann et al. 7435 (MBML, UPCB), Michelangeli et al. 1597 (MBML, NY, UPCB)]. There are several herbarium specimens determined as T. radula that actually belong to a third, undescribed species (such as the ones cited by Meirelles & Goldenberg 2012), and therefore were not used in this comparison.

Figures

FIGURE 6. Images of the holotype (A–C and I) and floral parts of the one paratype (D–H) of Pleroma subsessilis. A. Branch. B. Detail of the leaf indumentum (adaxial surface). C. Detail of the leaf indumentum (abaxial surface). D. Bracteole (abaxial surface). E. Petal (abaxial surface). F. Part of the inflorescence, with a central older flower bud. G. Stamens. H. Gynoecium. I. Fruit. (A–C and I: Fernandes et al. 2999 at MBML; D–H: Meyer 2220 at UPCB).

FIGURE 7. Living plant photos of Pleroma subsessilis. A. Habit. B. Leaves. C. Leaf (abaxial surface). D. Part of the inflorescence. E. Flower. F. Detail of the stamens. (A by L. Kollmann; B–F by F.S. Meyer).