Miconia macuxi Meirelles, Caddah & R.Goldenb., 2015

Meirelles, Julia, Caddah, Mayara Krasinski & Goldenberg, Renato, 2015, Miconia macuxi (Miconieae, Melastomataceae): a new species from the Amazonian white sand vegetation, Phytotaxa 220 (1), pp. 54-60 : 56-57

Miconia macuxi Meirelles, Caddah & R.Goldenb. , sp. nov.

Distinguished by the following set of features: strongly discolorous leaves with dense stellate trichomes on their abaxial surfaces, secund inflorescences, calyx persistent in fruit, petal margins with glandular-stipitate trichomes, and white stamens, the antepetalous with the connective with two ventral lobes and a dorsal tooth.

Type:— BRAZIL. Roraima: Caracaraí, Parque Nacional do Viruá , Estrada entre a entrada do parque e a sede. 21 October 2011 (fl., fr.), M. K.Caddah & J.Meirelles 900 (holotype: INPA!; isotypes: NY!, UPCB!, UEC!, UFRR!). Figures 1–3 .

Shrubs up to 1.5 (–3) m high; young branches, petioles, abaxial surface of the leaves, panicles, outer surface of the hypanthium and outer surface of the calyx lobes densely covered by ferrugineous, stellate to shortly dendritic trichomes, with the axes usually darker than the arms mostly in the trichomes on the leaves, panicles and hypanthium. Young branches flattened, with tenuous interpetiolar ridges. Leaves opposite, strongly discolorous; petioles 1–2.3 cm long, sulcate; blades 8–14 × 3–5 cm, elliptic-lanceolate, apex acute to shortly acuminate, base round to cordate, margin entire, sometimes slightly revolute and undulate, chartaceous, longitudinal nerves 3, with an additional marginal pair, basal, adaxial surface with sparse, caducous stellate trichomes in young leaves, then glabrous in mature ones, abaxial surface with a dense ferrugineous indument consisting of trichomes as described above. Panicles 3.5–5.5 × 2–4 cm, with short, bifid, secund branches; bracts and bracteoles up to 3.3 mm long, triangular to lanceolate, persistent. Flowers 5(–6)-merous. Hypanthium 2.1–2.4 mm long, campanulate, inner surface glabrous; torus with sparse glandular trichomes. Calyx persistent in fruit, inner surface glabrous; tube 0.5 mm long, inner lobes 0.7 mm long, triangular, outer teeth not or up to 0.3 mm exceeding the inner lobes, subulate. Petals 2.8–4.1× 2.1–2.8 mm, white, elliptic to shortly obovate, apex emarginate and symmetric, margins with glandular-stipitate trichomes, both surfaces minutely papillose. Stamens white, dimorphic; filaments 3.1–3.7 mm long (antesepalous, larger whorl) or 2.3–2.7 mm (antepetalous, smaller whorl), glabrous; connectives not prolonged below the thecae, but skirt-like (larger whorl) or with two ventral lobes and a dorsal tooth (smaller whorl); anthers 1.7–2.3 mm long (larger whorl) or 1.6–2.1 mm long (smaller whorl), oblong with a single, small, terminal to ventrally (larger whorl) or dorsally (smaller whorl) displaced pore ca. 0.15 mm wide. Ovary ca. 1.5 mm long, half adherent to the hypanthium, 3-locular, apex sparsely furfuraceous; style 5.7–6.7 mm long, slightly curved, punctiform, with scattered glandular-stipitate trichomes on its basal half. Fruits baccate, 3.4–3.6 mm diam., purple with reddish persistent calyx lobes; seeds ca. 0.7–1 mm long, pyramidal, testa smooth, cells with anticlinal walls undulate.

Distribution and ecology: — Miconia macuxi is known from Amazonian white sand vegetation in Brazil and Venezuela. In Brazil, it is found in two National Parks in the state of Roraima (Viruá and Serra da Mocidade), as well as three localities in the state of Amazonas (Canutama, Careiro da Várzea and Nova Prainha), one of them in a State Park (Canutama). In Venezuela, it was found in the states of Amazonas and Atabapo.

Conservation status: —The lack of information doesn’t allow us to formally estimate or infer possible threats to this species, as proposed in the IUCN Red List guidelines ( IUCN Standards and Petitions Subcommittee 2014). The extent of occurrence of Miconia macuxi , calculated by the Geospatial Conservation Assessment Tool (http://geocat. kew.org), is 315,000 km 2. However, we suspect that this extent of occurrence will drastically reduce in the next 100 years, since some localities in Venezuela and in Brazil are outside natural reserves and are threatened by habitat loss. Therefore, we are able to assign the species as Endangered under the IUCN criterion [EN A3c] ( IUCN Standards and Petitions Subcommittee 2014).

Etymology: —The word “Macuxi ” was originally the name of the native people that lived where is now the city of Boa Vista, in Roraima. Nowadays its meaning has been broadened and it refers to people and things that come from the state of Roraima, from where most specimens of this species have been collected.

Comments: — Miconia macuxi and related species belong to Miconia sect. Miconia subsect. Seriatiflorae, sensu Cogniaux (1891) . These plants can be recognized by the apical inflorescences with secund branches, and anthers that are linear to oblong, uniporate, with connectives bearing basal-ventral projections. Among the species in this subsection, M. macuxi seems to be closely related to a group of four species (Meirelles et al. in prep.): M. argyrophylla Candolle (1828: 181) , M. fallax Candolle (1828: 181) , M. pterocaulon Triana (1871: 114) , and M. stenostachya . They have strongly discolorous leaves, glandular-ciliate petals, antepetalous stamens with anther connective appendages that are small and bilobate (not “skirt-like”), and blue-black ripe fruits, but all of them differ from M. macuxi due to the abaxial leaf surfaces covered with dense amorphous trichomes (arachnoid indument vs. stellate to shortly dendritic trichomes in M. macuxi ). Miconia fallax and M. stenostachya are shrubs occurring in savannah or open vegetation, and also differ from M. macuxi due to their yellow anthers (vs. persistently white), with connectives turning into red in older flowers. M. argyrophylla also differ from M. macuxi due to the deciduous calyx lobes (vs. persistent) while M. pterocaulon also differ from it due to the strongly winged young branches (vs. flattened). Both species are treelets or trees usually occuring in the understorey of “terra firme” (never flooded) forest.

Miconia macuxi also resembles M. albicans ( Swartz 1788: 70) Steudel (1841: 139) , another species from the same subsection that has discolorous leaves and white stamens. Nevertheless, Miconia albicans has amorphous trichomes on the abaxial leaf surface, eciliate petals, all stamens with skirt-like basal appendages and jade-green mature fruits.

Paratypes:— BRAZIL. Amazonas: Canutama, Parque Estadual do Matupiri, 5 o 00’45”S, 61 o 16’15”W, 30 October 2010, Prata et al. 864 ( INPA), 31 October 2010, Prata et al. 915 ( INPA) ; Careiro da Várzea , 19 July 2007, Silva 141 ( INPA) ; Nova Prainha, Projeto Radam Brasil , SB-20- ZC, Ponto 02, 24 July 1976 (fr), Mota & Monteiro s.n. ( INPA 60730 ) . Roraima: Caracaraí, Parque Nacional da Serra da Mocidade, 1º16’56”N, 61º44’33”W, 23 March 2012 (fr), Forzza et al. 6882 ( MIRR, RB) ; Caracaraí, P. N. da Serra da Mocidade, Rio Capivara , 1º05’56”N, 61º55’38”W, 7 December 2013 (bud), Schütz-Rodrigues et al. 2358 ( MIRR, UFRR, UPCB) ; Caracaraí, P. N. da Serra da Mocidade, Rio Capivara , December 2013 (bud), Schütz-Rodrigues et al. 2359 ( MIRR, UFRR) ; Caracaraí, P. N. da Serra da Mocidade, Rio Capivara , 7 December 2013 (bud), Schütz-Rodrigues et al. 2364 ( MIRR, UFRR) ; Caracaraí, P. N. da Serra da Mocidade, Igarapé Água branca (“ Preto ”), 7 December 2013 (bud), Schütz-Rodrigues et al. 2397 ( UFRR) ; Caracaraí, P. N. da Serra da Mocidade, Rio Capivara , 1º12’13”N, 61º56’23”W 8 December 2013 (fl), Schütz-Rodrigues et al. 2408 ( UFRR) ; Caracaraí, P. N. da Serra da Mocidade, Rio Água Boa do Univini , 1º23’04”N, 60º39’23”W, 10 December 2013 (fl), Schütz-Rodrigues et al. 2459 ( MIRR, UFRR, UPCB) ; Caracaraí, P. N. da Serra da Mocidade, Rio Água Boa do Univini , 1º23’04”N, 60º39’23”W, 10 December 2013 (fl), Schütz-Rodrigues et al. 2489 ( MIRR, UFRR, UPCB) ; Caracaraí, Parque Nacional do Viruá, Campinarana , Estirão do Jurema , 1º02’18”N, 61º14’29”W, 30 July 2011 (bud, fl), Zartman et al. 8506 ( INPA, NY, UPCB) ; Caracaraí, P. N. do Viruá, “Depois da segunda bueira”, 25 January 2011 (fr), Cangani et al. 132 ( INPA, UFRR) ; Caracaraí, P. N. do Viruá, BR-174, 19 October 2011 (bud, fl), Meirelles et al. 761 ( INPA, UPCB) ; Caracaraí, P. N. do Viruá, 21 October 2011 (fl, fr), Goldenberg et al. 1594 ( INPA, UPCB) . VENEZUELA. Amazonas: La Esmeralda, 2 November 1928, Tate 322 ( NY, P, US), 14 November 1950, Maguire 29432 ( NY). Atabapo: Cerro Huachamacari, 5 March 1980, Huber 4998 ( NY, US), 24 February 1985, Liesner 17918 ( US) .

Figures

FIGURE 1. Miconia macuxi (from the isotype at UPCB). A. Branch with leaves, flowers and fruits. B. Abaxial surface of the leaf. C. Branch with fruits. D. Flower bud. E. Petal. F. Flower. G. Longitudinal section of the hypanthium and ovary, in detail, outer tooth of the calyx. H. Antepetalous stamen. I. Antesepalous stamen.

FIGURE 2. Live plants of Miconia macuxi. A. Flowering branch. B. Detail of the inflorescence. C. Infructescence. D. Flower. E. Leaf, abaxial surface. F. Immature fruits. (A: Mayara Caddah [from Caddah & Meirelles 900]; B, D. Gustavo Shimizu [Caddah & Meirelles 900]; C, E, F: Renato Goldenberg [Goldenberg et al. 1594].

FIGURE 3. SEM Images of trichomes and seeds of Miconia macuxi (from Caddah & Meirelles 900). A–B. Indument on the abaxial surface of the leaf; C. Seed, lateral view. D. Detail of the seed surface.