Mitracarpus diversifolius E.B. Souza & E.L. Cabral, Rodriguésia

Florentin, Mariela Nuñez, Salas, Roberto M., Souza, Elnatan Bezerra De & Cabral, Elsa L., 2017, A complete description of Mitracarpus diversifolius (Rubiaceae) reveals new characters for the genus, Phytotaxa 314 (1), pp. 96-102 : 97-99

Mitracarpus diversifolius E.B. Souza & E.L. Cabral, Rodriguésia 61(2): 328. 2010.

Type:— BRAZIL. BAHIA: Boa Nova, Fazenda Cotermaia, entrance 1.2 km E of Boa Nova on road to Dario Meira , 14º22.419’S, 40º11.305’W, 810 m, 18 May 2001 (fl.), W. W. Thomas & S. Sant’Ana 12485 (holotype CEPEC!; isotypes MO!, NY!, SP!) Fig. 1

Creeping herb, rooting at nodes. Stems 15–50 cm long, tetragonal, winged at angles, densely pubescent along margins. Stipular sheath 3–5 mm long, glabrous, with 6–7 fimbriae, 2–5 mm long, pubescent. Leaves opposite, without axillary brachyblasts, pseudopetiolate, anisophyllous at each node, with large and small leaves alternating along the branches, the large ones lanceolate, 2.5–4 × 1.2–2.6 cm, the small ones ovate, 1.2–2.1 cm acute at apex, cuneate or slightly oblique at the base, chartaceous, scabrous at margins, adaxial surface scabrous, abaxial surface glabrous; 2–4 secondary veins on each side of midrib. Inflorescences with 2–15 fascicles per branch; fascicles pseudoaxillary, pauciflorous, 3–7 mm diam., subtended by 2 leaf-like, anisophyllous bracts. Flowers sessile. Hypanthium obconic, glabrous. Calyx 4–lobed, one pair of lobes longer than the other, the two longer ones lanceolate, 2.2–2.5 mm long, acuminate, ciliate; the two smaller ones narrowly triangular, 1–1.2 mm long, acuminate, ciliate. Corolla hypocrateriform, 4–5 mm long; tube 3–4 mm long, glabrous externally, with a ring of moniliform trichomes in the lower third of the corolla throat; lobes ovate, 1 mm long, glabrous on both surfaces or papillate at the apex on both surfaces. Stamens subsessile, inserted at corolla throat; anthers oblong, 0.8–1 × 0.2–0.4 mm, partially included. Style filiform, 4–5 mm long; stigmatic branches ca. 1 mm long. Capsules globose or oblong-ellipsoid, 0.9–1.1 × 0.9–1.2 mm, glabrous; corolla tube and a portion of corolla lobes persistent. Seeds oblong-obovate, 0.3–0.7 × 0.7–0.9 mm, brown or dark brown, dorsal surface without depressions, exotesta reticulate-foveate, with polygonal cells, anticlinal walls thickened, periclinal walls concave, ventral surface with a longitudinal medial groove, narrowly oblong, without the projections of the ventral groove, covered by the strophiole.

Distribution and ecology: — Mitracarpus diversifolius is only known from two collections from two localities in Bahia state, in the municipalities of Boa Nova and Ilhéus. Unlike most Mitracarpus species, which are heliophilous, this species inhabits humid areas and forest interiors.

Conservation status: —We calculate the AOO for Mitracarpus diversifolius as 50 km 2 (cell width 5 km), based on the three collections that represent two subpopulations, both in Bahia state; because there are only two localities, EOO cannot be calculated. IUCN (2014) guidelines consider this AOO to indicated an Endangered (EN) status, under the B2 ab (ii, iii) criteria: number of subpopulations less than 5, and continuing decline in the area, extent and quality of habitat, due to deforestation and land use for agriculture. The type collection was gathered in a transitional area between semideciduous and humid forest, at Boa Nova municipality. The last two collections were made in areas of Cocoa cultivation [ Theobroma cacao Linnaeus (1753: 782) ], at the CEPEC institute, which since many years have agricultural practices as the extraction of herbaceous weeds and application of herbicides. Originally, this area was a humid forest; hence the actual vegetation is strongly modified. The collections date from 1981 and 1986 and until now no new registers are known at the CEPEC herbarium. To arrive to a better conclusion on its conservation assessment, new studies at population level and intensive herbaria consultation covering all Mitracarpus species and related genera are needed.

Examined material: — BRAZIL. Bahia: Mun. Ilhéus, Área do CEPEC (Centro de Pesquisas do Cacau), km 22 da Rodovia Ilhéus / Itabuna ( BR 415 ), região de Mata Higrófila Sul Baiana, Quadra A, entre o Setor de Treinamento e a residência do diretor do CEPEC, 50 m, 28 January 1986, J. H. Hage & H. S. Brito 1826 ( CEPEC, NY) ; same locality, 27 August 1981 T. S. Santos 3651 ( CEPEC) .

Figures

FIGURE 1. Mitracarpus diversifolius. A, Branch, showing anisophyllous leaves; B, Stipular sheath; C, Flower; D, Open corolla; E, Fruit, with persistent corolla; F, Seed, dorsal side; G, Seed, ventral side.All from J.H. Hage & H.S. Brito 1826. Drawn by Laura Simón.