Miconia renatogoldenbergii Meirelles & Bacci, 2017

Meirelles, Julia & Bacci, Lucas F., 2017, Miconia renatogoldenbergii (Miconieae, Melastomataceae), a new species from savanna enclaves in southern Amazonia, Brazil, Phytotaxa 298 (2), pp. 187-193 : 188-191

Miconia renatogoldenbergii Meirelles & Bacci , sp. nov.

Diagnosis: Miconia renatogoldenbergii is similar to Miconia punctata [ Desrousseaux (1797: 50)] David Don (1823: 316); however, the first has a mucronate leaf apex, a thyrse with short secund-scorpioid branches, and subulate anthers with a rounded apex, an apical pore and cordate connective appendages ( Figs 1–3 ).

Type: BRAZIL, Pará: Cachoeira da Luz do Rio Curuá, 8˚45’S, 54˚ 57’W, 2 Jun 1983, Silva 190 (Holotype: MG! Isotypes: MO, NY!) Figs 1–3 .

Shrub to tree, 2.5–4 m tall, young branches flattened, older ones rounded; branches, inflorescences, petioles, abaxial surface of leaves and outer surface of hypanthia densely covered with lepidote-stellate rusty trichomes. Leaves opposite; petioles 1–2 cm long, sulcate; blades 8.4–19.5 × 4.4–10 cm, elliptic to obovate, apex acute to acuminate, and mucronate (ca. 1–3 mm long), base rounded to attenuate, margin entire, chartaceous, 3 nerved plus a faint marginal pair (3+2), basal or short suprabasal (ca. 5 mm above the base), main and transverse nerves prominent on abaxial surface, discolorous, adaxial surface glabrous. Thyrse 17.7–23 × 2–3 cm, terminal, with 4–8 whorls of paracladia (inflorescence branches, sensu Weberling, 1988), the whorls composed of 2–4 paracladia subunits per node, that bifurcate in two scorpioid branches (helicoidal cymes), where are the 5–9 flowers; bracteoles 0.6–0.8 mm long, long triangular, caducous. Flowers 5-merous. Hypanthium 2.8–3 mm long, campanulate; inner surface glabrous, torus glabrous. Calyx persistent in fruit, tube 0.5–0.7 mm long, sepals ca. 1 mm long, truncate, fused with an external diminute teeth, inconspicuous, but the only free part of calyx. Petals 1.8–2 × 1.5 mm, white, obovate, apex rounded, margin glabrous, both surfaces papillose. Stamens 10, dimorphic in size and appendage morphology, all completely white, the antesepalous stamens with filaments 3.7–4 mm long, glabrous, connectives prolonged below the thecae, with skirt-like and cordate appendages, the ventral face with two acute upward projections (horn-shaped) or with two rounded lobes and a rounded dorsal appendage, thecae 2.5–2.7 mm long; the antepetalous stamens with filaments 2.3–2.7 mm long, glabrous, connectives prolonged below the thecae, with two ventral lobes and a dorsal, rounded appendage, thecae ca. 2 mm long, all anthers with rounded apex, opening by a single, circular, apical pore. Ovary apex covered with dendritic hairs; style 5.5–6 mm long, filiform, glabrous, stigma clavate, papillose at the apex. Fruits 2–4 mm diam., seeds ovoid.

Distribution, ecology and phenology: ― Miconia renatogoldenbergii occurs in northern and central-western Brazil, in the states of Rondônia, Pará and Mato Grosso ( Fig. 3 ). The new species inhabits savanna areas on rocky or sandy soil. In the state of Rondônia, M. renatogoldenbergii occurs in the understory of terra firme forests on sandy soil. The studied material showed buds and flowers from April to June, and fruits in September.

Etymology: ― Miconia renatogoldenbergii is named after the botanist Renato Goldenberg who has studied Melastomataceae for the last two decades, published a vast amount of literature about the family, and mentored several students (including the authors). Furthermore, the new species was collected in 1997 by him.

Conservation status: ― Only seven specimens of Miconia renatogoldenbergii have been collected and none of them inside a conservation unit. According to IUCN (2014) criteria B1ab(ii), with EOO (Extent of Occurrence) = 24.000 km ² and B2ab(iv), with less than 10 collection locations and AOO (Area of Occupancy) = 237,442.150 km ², the species should be classified as “Endangered” (EN) and “Vulnerable” (VU), respectively. Since Miconia renatogoldenbergii has a wide AOO, it should be classified as “Vulnerable”(VU).

Comments: ― Following the traditional key to sections and subsections of Miconia ( Cogniaux 1891) , M. renatogoldenbergii would fit in sect. Miconia Candolle (1828: 183) due to the short and linear anthers, slightly attenuate apex with one or two pores, and ventrally biauriculate or bilobed connective appendages. Going ahead on this traditional classification, the new species also fits in subsect. Seriatiflorae Naudin (1850: 145) due to its inflorescence morphology, i.e., panicles or thyrses with secund-scoripiod branches.

The specimens of Miconia renatogoldenbergii have been misidentified as M. punctata ( Desrousseaux 1797: 50) Don (1823: 316) probably because both share large elliptic to obovate or lanceolate leaves, with the abaxial surface densely covered with rusty lepidote-stellate hairs ( Fig. 2 ), and inflorescences with secund scorpioid branches. However, the first has flattened young branches (vs. quadrangular branches in M. punctata ) and thyrses with a rectilinear and quadrangular main axis with four 4–8 whorls, and 2–4 subunits, with short and bifid scorpioid branches (vs. a panicle with two long lateral branches per node, the basal longer than the apical). Furthermore, the stamens of both species differ in shape and dehiscence. The new species has subulate anthers with a rounded apex and an apical circular pore, while M. punctata has clavate anthers with a truncate apex and an apical broadly triangular opening that is ventrally inclined. The presence of a mucron at the apex of most of M. renatogoldenbergii leaves is also remarkable, a feature that is always absent in M. punctata , according to observations done in several herbaria in the last years.

A similar mucron is often found in specimens of Miconia chrysophylla ( Richard 1792: 109) Urban (1910: 459) , which also shares with the new species, the discolorous leaf blades with rusty lepidote-stellate trichomes on the abaxial surface and scorpioid distal branches on the inflorescence. This species differs by the often verticillate leaves (vs. opposite in M. renatogoldenbergii ), thyrses with longer basal branches making it pyramidal (vs. thyrse with short lateral branches), and anthers oblong and rimose (vs. anthers subulate and poricidal).

Miconia amnicola Wurdack (1981: 243) also belongs to subsect. Seriatiflorae and shares with the new species the lepidote indument and the thyrses with scorpioid distal branches. Nevertheless, the new species can be distinguished by the rusty color of the indument (vs. whitish in M. amnicola ), the longer (4.4–10 cm), elliptic to obovate leaf blades (vs. shorter, 2.5–4 (6) cm, narrowly oblong, elliptic or lanceolate) and by the mucronate leaf apex (vs. gradually acuminate). According to Goldenberg et al. (2013), M. amnicola occurs in Colombia, Ecuador, Peru and north of Brazil (only in the state of Amazonas).

One additional closely related species from subsect. Seriatiflorae is Miconia cowanii Wurdack (1961: 37) . It shares with M. renatogoldenbergii the lepidote indument, the quadrangular young branches, and the scorpioid inflorescence distal branches. Miconia cowanii differs by the gradually acuminate leaf apex (vs. mucronate in M. renatogoldenbergii ), and the wider inflorescence branches. The flower measurements are also different between the two species: Miconia cowanii has a shorter hypanthium, 1.9–2.1 mm (vs. longer, 2.8–3 mm in M. renatogoldenbergii ), longer petals, 2.6–3.1 mm (vs. 1.8–2 mm), shorter style, ca. 3.5 mm (vs. longer style, 5.5–5.6 mm). Miconia cowanii is endemic to the state of Amapá, in northern Brazil ( Goldenberg et al. 2013; BFG 2015).

Paratypes: ― BRAZIL. Mato Grosso: “Expedition Base Camp”, 12˚49’S, 51˚46’W, 14 Sep 1968, Harley & Souza 10040 (K, NY, P) fr .; Querência, Estrada para Fazenda Tanguro , 3 Jun 1997, Goldenberg 444 ( NY, UPCB) bud. Pará: Altamira, Gleba Curuaé, 8˚45’S, 54˚ 57’W, Jul 2005, Sobral et al. 9911 ( BHCB, UPCB) fr .; Itaituba, BR 163, Km 171, 9˚35’S, 54˚35’W, 22 Apr 1983, Amaral 874 ( MG, NY) fl., fr. Serra do Cachimbo, estrada Santarém-Cuiabá, BR 163, km 780, com penetração de 1 km dentro da mata, 9º36’66’’S 54º9’W, 29 April 1983, Amaral 1042 ( INPA, MO, NY) bud., fl. Rondônia: Vilhena, Ponta de Pedra , Serra dos Parecis, 15 May 1984, Santos, J. U. et al. 767 ( MG) fl .

Figures

FIGURE 1. Miconia renatogoldenbergii. A. Apical branch with flowers. B. Detail of the indument on the abaxial leaf surface. C. Inflorescence branches. D. Flower. E. Hypanthium, external surface. F. Hypanthium and ovary in longitudinal section. G. Petal. H. Style. I. Antesepalous (left) and J. Antepetalous (right) stamens in lateral view. Drawn from Santos 767 (MG) by Alex Araújo.

FIGURE 2. SEM images of trichomes and a seed of Miconia renatogoldenbergii (A–B from Silva 190 [NY], C–D from Harley & Souza 10040 [NY].) A. Detail of the indument on the abaxial leaf surface. B. Detail of the main vein on the abaxial leaf surface with stellate trichomes. C. Seed, lateral view. D. Detail of the seed surface.

FIGURE 3. Distribution of Miconia renatogoldenbergii. A. Distribution in South America. B. Distribution in the Amazonian Forest and Savannas.