Microlicia obovatifolia R.B. Pacifico, Fidanza & Almeda, 2017

Pacifico, Ricardo B., Fidanza, Karina & Almeda, Frank, 2017, Two new species of Microlicia (Melastomataceae) from the Rupestrian Grasslands of Serra do Cipó, Minas Gerais, Brazil, Phytotaxa 316 (1), pp. 39-50 : 45-48

Microlicia obovatifolia R.B. Pacifico, Fidanza & Almeda , sp. nov. ( Fig. 5 ; Fig. 6. C, G–H )

Diagnosis:— Microlicia obovatifolia can be recognized by a combination of obovate leaves with 1–3 basal acrodromous veins, the veins impressed on both surfaces and blackened when dried, entire margin, rounded apex, surfaces sparsely glandular-punctate on both faces, flowers 5–(6)-merous, the hypanthium campanulate and glandular-punctate, calyx lobes triangular with an obtuse apex, and pink petals.

Type:— BRAZIL. Minas Gerais: Santana do Riacho, Km 132 on the road from Serra do Cipó (formerly Cardeal Mota) to Conceição do Mato Dentro, 19º15’12.2”S, 43º32’27.1”W, 1,381 m, 21 November 2004, F. Almeda et al. 8899 (Holotype: UEC!, Isotypes: CAS!, RB!).

Erect and much-branched shrub to 30 cm. Branchlets green, subquadragular, glandular-punctate, older branches becoming brown, terete and glabrescent towards the base. Leaves decussate, subsessile, approximately twice the length of the internodes and concentrated along the distal portions of the branches, the internodes with conspicuous leaf scars; blade 6.5–7.8 × 2.4–3 mm, light brown and concolorous (when dried), obovate, base attenuate, apex rounded, margin entire and glabrous, 1–3 basal acrodromous veins, blackened (when dried) and impressed on both faces, the midvein stout and enlarged at the base, lateral pair faint, leaves sparsely glandular-punctate on both faces. Flowers 5–(6)-merous, solitary, ebracteolate, born at apex of the branches; pedicels 1.3–1.5 mm long; hypanthium 3.0–3.2 × 2.3–2.5 mm, campanulate, glandular-punctate; calyx lobes 2.0–2.2 × 1.5–1.9 mm, triangular, apex obtuse, margin entire and glabrous, indumentum similar to the hypanthium; petals 8.5–9.1 × 6.1–6.3 mm, pink, obovate, margin entire, apex shortly acuminate, glabrous; stamens 10(–12), dimorphic: the longer (antesepalous) ones with filaments 4.5–5.2 mm long, pink, connective prolonged 4.8–5.0 mm long below the thecae, reddish-pink, appendage 1.3–1.4 mm long, yellow, apex truncate, thecae 1.3–1.4 mm long, red, broadly oblong, surface smooth, tetrasporangiate, rostrum 0.4–0.5 mm long, white, the pore widely circular; the shorter (antepetalous) ones with filaments 4.2–4.5 mm long, pink, connective prolonged 1.4–1.5 mm long below the thecae, yellow, appendage 0.4–0.5 mm long, yellow, apex very slightly bilobate, thecae 1.2–1.5 mm long, yellow, broadly oblong, surface smooth, tetrasporangiate, rostrum 0.2–0.3 mm long, white, the pore constricted; ovary 2.1–2.2 × 1.4–1.6 mm, subglobose, superior, 3-locular; style 5–5.2 mm long, pink, linear, glabrous, stigma punctiform. Capsules (immature) 2.6–2.9 × 1.6–1.8 mm, subglobose, 3-locular, initially enveloped by the brownish hypanthium.

Distribution and phenology:—This species is known only from southeastern Serra do Cipó, where it is probably endemic ( Fig. 7 ). It was collected at 1,381 m elevation near MG-010 highway ( Fig. 4. B ) in campo rupestre; flowering in November.

Etymology:—the epithet refers to the obovate shape of the leaves of this species.

Conservation status:—We have coordinates for the type and only known collection of this species but we are unable to assess the extent of its geographic range and abundance. Until additional distributional information is available we assign a classification of Data Deficient (DD) to this species.

Affinities:— Microlicia obovatifolia is most similar to Microlicia naudiniana R.Romero in Romero et al. (2015: 1013) ( Fig. 6. D–E ). Both species share the obovate leaf blade, attenuated at base and rounded at apex, 3 basal acrodromous veins, pink petals, bilocolored tetrasporangiate anthers, and staminal filaments and appendages with similar shapes.

Although M. naudiniana is its closest probable morphological relative, M. obovatifolia is easily distinguished by its glandular-punctate young branches, hypanthia and calyx lobes, the entire glabrous leaves, the triangular calyx lobes, and anthers with less elongate thecae (1.2–1.5 mm long) In turn, M. naudiniana has short glandular hairs (0.1–0.2 mm long) covering its young branches, hypanthia and calyx lobes, the leaves with crenulate margins and covered by glandular emergences, linear calyx lobes, and oblong anthers that are more elongate (1.8–1.9 mm long). Although M. naudiniana occurs in the region around Diamantina and also in Serra do Cipó, these two species are known only from few populations and there is no evidence of sympatry.

Microlicia nervosa R. Romero (2013: 1) ( Fig. 6. A ), Microlicia avicularis Martius ex Naudin (1845: 176) ( Fig 6. B, F ) and Microlicia riedeliana Cogniaux (1883: 80) , all of which are known from Serra do Cipó, are somewhat similar to the new species. One can easily differentiate M. obovatifolia from M. nervosa by its subsessile leaves and triangular calyx lobes (vs. petiolate leaves and linear calyx lobes in M. nervosa ), and from M. avicularis by its obovate leaves with the margin entire (vs. narrowly elliptical leaves with the margin crenulate in M. avicularis ). A few populations of M. riedeliana have slightly obovate leaves, with the margin entire and glabrous, resembling those of M. obovatifolia . The new species differs by its consistently obovate leaves, shorter calyx lobes, and smaller petals ( Table 1). Microlicia riedeliana is known only from central (Lapinha da Serra and Pico do Breu) and northwestern Serra do Cipó (Santana de Pirapama and Congonhas do Norte), while M. obovatifolia is known only from southeastern Serra do Cipó, along the MG-010 highway.

From the northern Serra do Espinhaço, Microlicia torrendii Brade (1962: 252) also has entire leaves that are glandular-punctate on both surfaces, hypanthia that are also glandular-punctate, and triangular calyx lobes. Microlicia obovatifolia differs by the obovate leaves (vs. ovate to suborbicular in M. torrendii ), that are 3-nerved (vs. mostly 1- nerved in M. torrendii ), and petals 8.5–9.1 mm long. (vs. 13–14 mm long. in M. torrendii ). Additional comparative features are given in Table 1.

Figures

FIGURE 4. A. Landscape of Preto River Valley, Congonhas do Norte, Minas Gerais, the type locality of Microlicia nortecipoana. B. Landscape of southwestern Serra do Cipó, near highway MG-010, Minas Gerais, the type locality of Microlicia obovatifolia. (All by C.A. Rossi).

FIGURE 5. Microlicia obovatifolia. A. Habit. B. Detail of an apical flowering branch. C. Adaxial (left) and abaxial (right) leaf surfaces. D. Floral bud. E. Antepetalous (left) and antesepalous (right) stamens.F. Gynoecium. G. Immature capsule enveloped by the hypanthium. (All from F. Almeda et al. 8899).

FIGURE 6. A–G. Abaxial leaf surfaces and floral buds of M. obovatifolia and some of its probable relatives.A. M. nervosa (R. Pacifico & A. Carmo 155). B, F. M. avicularis (R. Romero et al. 8640). C, G. M. obovatifolia (F. Almeda 8899). D–E. M. naudiniana (D.C. Zappi et al. 3312). H. Microlicia obovatifolia, close-up of a flower from the type collection. (H by Frank Almeda). Scale bars: 2 mm.

FIGURE 7. Southeastern Brazil. Geographic distribution of Microlicia nortecipoana and Microlicia obovatifolia in Minas Gerais state, at elevations above 1,000 m.