Pleroma costatocalyx F.S.Mey., L.Kollmann & R.Goldenb., 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 : 198-201

1. Pleroma costatocalyx F.S.Mey., L.Kollmann & R.Goldenb. sp. nov. ( Figures 1–2 )

Diagnosis:— Pleroma costatocalyx differs from Tibouchina decemcostata Cogniaux (1885: 331) by the moderately strigose to setulose branches, with eglandular trichomes (vs. densely sericeous to villose branches, with glandular trichomes), smaller and narrower leaves (3.5–5.6 × 1.9–3 cm vs. 5.5–6.4 × 3.6–4.7 cm in T. decemcostata ), with only 5 nerves (vs. 5–7 nerves in T. decemcostata ), and also concolorous, with trichomes that do not cover the entire abaxial surface (vs. discolorous, with trichomes covering the entire abaxial surface in T. decemcostata ).

Type:— BRAZIL. Espírito Santo: Mantenópolis (cultivated at Santa Teresa, at the property of Ludovic Kollmann), May 2015, (fl.), L. Kollmann & A. P. Fontana 12977 (holotype: MBML!; Isotypes: P!, RB!, NY!) .

Shrub 0.8–2 m tall. Branches terete, not winged, moderately strigose to setulose, trichomes 0.6–2.1 mm long, non glandular, appressed or curved, narrow to slightly enlarged at the base. Leaves opposite; petioles 3.6–11.8 mm long; blades 3.5–5.6 × 1.9–3 cm, elliptic or ovate-elliptic, concolorous, base obtuse to slightly cordate, apex acute or apiculate, chartaceous, 5 acrodromous nerves, the marginals confluent (meeting the secondaries at the leaf base before joining the midrib), main and transversal nerves prominent, reticulation prominent on the abaxial surface, adaxial surface moderately to densely sericeous, trichomes 0.8–2.1 mm long, non glandular, appressed or curved, slightly bullate, immersed and with a several-forked base, abaxial surface moderately setose on the primary veins, trichomes 1.5–3 mm long, non glandular, curved, slightly enlarged at the base, and also densely villose on the surface and on the secondary, tertiary and quaternary veins, trichomes 0.4–0.8 mm long, non glandular, coiled, narrow at the base. Thyrsoid 7.5–13 × 6–12.5 cm, axis rounded to subterete, with the same indumentum as the branches; bracts caducous, leafy, petioles 1.9–2.4 mm, blade 12.1–18.2 × 6.8–8.7 mm, elliptic, indumentum the same as on the leaves; bracteoles early caducous, 3–5.6 × 1.3–3 mm, ovate to elliptic, apex acute, margins entire, ciliate, abaxial surface moderately strigose to sericeous, adaxial glabrous. Flowers (4–)5-merous, on pedicels 2–2.4 mm long; hypanthium 6.7–7.3 × 3–3.9 mm, oblong, longitudinally costate, moderately setose, the trichomes 0.3–0.9 mm long, glandular, curved, narrow to slightly enlarged at the base; sepals 1.7–1.9 × 1.8–2 mm, triangular, margins ciliolate, apex acute, with the same trichomes as the hypanthium; petals purple with a white base, 17.6–20.2 × 14.2–17.2 mm, obovate, apex obtuse; stamens 8–10, slightly dimorphic, antesepalous with filaments white, 5.6–6.1 mm long, moderately setulose on the base, trichomes 0.1–0.4 mm long, glandular, erect to curved, narrow at the base, connective white, 1.4–1.7 mm, prolonged below the thecae, glabrous, ventral appendages 2, ca. 0.1 mm long, glabrous, thecae purple, 5.7–6.1 mm long, antepetalous stamens with filaments white, 4–4.9 mm long, moderately setulose on the base, trichomes 0.1–0.4 mm long, glandular, erect to curved, narrow at the base, connective white, 0.4–0.6 mm, prolonged below the thecae, sparsely setulose, trichomes 0.1–0.3 mm long, glandular, erect, narrow at the base, ventral appendages 2, ca. 0.1 mm long, glabrous, thecae white or light purple on its ventral portion, 3.1–4.3 mm long; ovary 4.1–4.4 × 3.4–3.7 mm, 5-locular, apex densely sericeous, trichomes 0.5–0.8 mm, non glandular, appressed, narrow at the base, style white, 5–5.4 mm long, apex curved, moderately setulose on the lower two-thirds, trichomes 0.3–0.6 mm, non glandular, erect, narrow at the base. Capsules 8.7–9.5 × 5.7–6.7 mm, conspicuously costate, lacerated when mature.

Paratypes:— BRAZIL. Espírito Santo: Mantenópolis , 26 September 2012, (fl., fr.) L. Kollmann & A. P. Fontana 12512 ( MBML!, UPCB!); (cultivated at Santa Teresa, at the property of Ludovic Kollmann) , 13 April 2016, (fl., fr.), F. S. Meyer & L. Kollmann 2213 ( MBM!, UPCB!, NY!) .

Distribuition and habitat:— Pleroma costatocalyx occurs in Espírito Santo, between 800–900 m, on vegetation associated to rocky outcrops intermingled with montane seasonal forest (“Floresta Estacional Semidecidual Altomontana” according to the official Brazilian classification - Veloso et al. 1991). It probably occurs also in the state of Minas Gerais, since it was collected very close to the border between the two states ( Figure 3 ).

Phenology:—It flowers in April and May under cultivation, and in September in its natural habitat.

Conservation status:—This species may be considered as “Critically Endangered”, according to IUCN (2012), despite the fact that Mantenópolis and surrounding areas are still poorly collected, and there is not information enough to make a reliable risk assessment. An additional risk factor is that the plants were all collected outside protected areas, which are virtually absent in the region.

Etymology:—The epithet costatocalyx is related to the longitudinally costate hypanthium.

Affinities:— Pleroma costatocalyx is similar to T.decemcostata ,from the state of Minas Gerais, in the municipalities of Catas Altas and Santa Bárbara. Both have longitudinally costate hypanthia, the antepetalous stamens with eglandular connective and appendages, and also lacerated fruits. It differs from T. decemcostata by the characters pointed on the diagnosis, and also by the prominent reticulation on the abaxial surface of the leaves (vs. inconspicous reticulation in T. decemcostata ), and smaller sepals (1.7–1.9 mm long vs. 3–4 mm in T. decemcostata ). Pleroma costatocalyx is also similar to Tibouchina heteromalla (D. Don 1822b: t. 644) Cogniaux (1885: 336), whose type [Riedel s.n. (K329034!)] is from an unknown locality, but probably from Minas Gerais. Both have flowers with purple petals with a white base, and the antesepalous stamens with glandular connective and appendages. Pleroma costatocalyx differs from T. heteromalla by the concolorous leaves (vs. discolorous in T. heteromalla ), longitudinally costate hypanthia (vs. smooth, ecostate in T. heteromalla ), and moderately setulose style (vs. glabrous in T. heteromalla ).

Figures

FIGURE 1. Images of the holotype of Pleroma costatocalyx. 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. Flower. G. Stamens. H. Gynoecium. I. Fruit. (all from Kollmann & Fontana 12977 at MBML).

FIGURE 2. Living plant photos of Pleroma costatocalyx. A. Habit. B. Leaf (abaxial surface). C. Leaf (adaxial surface). D. Part of the inflorescence. E. Dichasium with one central older bud, showing the longitudinally costate hypanthium. F. Detail of the stamens. (All photos by R. Goldenberg).

FIGURE 3. Distribution maps of P. costatocalyx, P. kollmanniana and P. subsessilis.