Microlicia pumila R.B.Pacifico & Almeda, 2023

Pacifico, Ricardo, Almeda, Frank & Kriebel, Ricardo, 2023, Microlicia delicata and Microlicia pumila (Melastomataceae), two new species from unprotected mountains with campo rupestr vegetation in eastern Brazil, Phytotaxa 599 (4), pp. 207-224 : 215-219

Microlicia pumila R.B.Pacifico & Almeda , sp. nov. ( Fig. 6 , 7A–B )

Type: — BRAZIL. Minas Gerais, Monte Azul, subida para o Pico da Formosa , 15°13’03’’S, 42°49’09’’W, 1512 m, 29 June 2022, fl., fr., R. Pacifico 725 & V.E. Bressan (holotype: HUEM!, isotypes: CAS!, HUEFS!, RB!) .

Diagnosis: — Differs from Microlicia karinae by the more delicate branches that are conspicuously verrucose (vs. only glandular-punctate), shorter leaf blades 2.8–5.2 mm long (vs. 5.8–14 mm long) that are more attenuate along the basal half, hypanthia 2.6–2.9 mm long (vs. 4–4.5 mm long), calyx lobes 2.6–2.9 mm long (vs. 3.5–4 mm long), petals 7–8 mm long (vs. 14–15 mm long), stamen filaments 2.2–2.7 mm long (vs. 5–5.6 mm long), and the 3-locular capsules [vs. (3–)4(–5)-locular] with apices not surpassing the hypanthial torus at maturity (vs. surpassing the torus by 1–1.2 mm).

Erect shrubs ca. 1 m tall, much-branched. Upper cauline internodes 0.7–1 mm long, light green (when fresh) becoming pale brown (when dry) and defoliated with age, quadrangular, not sulcate, unwinged, the surface verrucose and glandular-punctate, leaf scars evident on the lower part of the branches. Leaves decussate, ascending, concealing uppermost internodes (when dry), chartaceous, concolored and light green (younger leaves) to vivid green (older leaves when fresh), both leaf surfaces becoming pale green (when dry); petioles 0.6–1.2 mm long, light green to whitish (when fresh), rectangular; blades 2.8–5.2 × 2.2–3.7 mm, elliptic to obovate, apex acute to acuminate, base attenuate, margins entire on the basal half, crenellated on the upper half, flat, both surfaces densely glandular-punctate, 1-nerved to inconspicuously 3-nerved from the base (basal acrodromous), venation impressed on both leaf surfaces, the midvein not reaching the leaf apex, secondary venation not evident. Flowers 5-merous on pedicels 0.8–1 mm long, apical, solitary, ebracteolate. Hypanthia (at anthesis) 2.6–2.9 mm long, 2.1–2.4 mm wide at the torus, vinaceous (when fresh), campanulate, equaling or surpassing the capsule in length at maturity, densely glandular-punctate. Calyx tubes inconspicuous ca. 0.1 mm long. Calyx lobes 2.6–2.9 mm long, 1.1–1.4 mm wide at the base, red (when fresh) becoming brownish (when dry), oblong, apex acuminate, margins entire, externally glandular-punctate. Petals 7–8 × 5–6 mm, obovate, magenta, the base attenuate, apex acuminate, both surfaces glabrous, margins entire and glabrous. Stamens 10, dimetric and dimorphic; antesepalous (larger) stamens with filaments 2.4–2.7 mm long, glabrous, thecae (excluding rostra) 2.0–2.2 × 0.5–0.8 mm, oblong, smooth (tetrasporangiate), rostra 0.6–0.8 mm long, white, the ventrally inclined pores ca. 0.1–0.2 mm wide, nearly circular, pedoconnectives 3.5–3.7 mm long, appendages 0.7–0.8 mm long, apex truncate; antepetalous (smaller) stamens with filaments 2.2–2.5 mm long, magenta, glabrous, thecae (excluding rostra) 1.7–2.0 × 0.5–0.7 mm, oblong, smooth (tetrasporangiate), rostra 0.3–0.5 mm long, white, the ventrally inclined pores ca. 0.1 mm wide, nearly circular, pedoconnectives 1.3–1.6 mm long, appendages 0.3–0.4 mm long, apex truncate. Ovary (at anthesis) ca. 1.5 × 1 mm, superior, globose, glabrous, 3-locular, not adnate to the hypanthium; style 4–5 mm long, magenta, glabrous, stigma punctiform. Fruit at maturity a subglobose loculicidal capsule ca. 2.3–2.9 × 1.8–2.3 mm, pale brown, glabrous, 3-valvate, dehiscent from the apex to the base (basipetal), calyx lobes deciduous, enveloping hypanthia rupturing and flaking away with age, columellas tardily deciduous. Seeds ca. 0.7–0.8 × 0.3–0.4 mm, yellow or brownish, oblong, testa foveolate, raphal zone nearly circular, ca. 30% the length of the seed.

Paratype:— BRAZIL. Minas Gerais: Monte Azul, subida para o Pico da Formosa , 15°13’03’’S, 42°49’09’’W, 1512 m, 29 June 2022, fl., fr., R. Pacifico 724 & V.E. Bressan (CAS!, HUEFS!, HUEM!, RB!) .

Distribution, Habitat, and Phenology:— Apparently restricted to the Serra da Formosa, Monte Azul, Minas Gerais, Brazil ( Fig. 8 ). It was collected in campo rupestre at an elevation of 1512 m; flowering and fruiting in June. The municipality of Monte Azul is covered with vegetation that is transitional between Cerrado (Brazilian savanna) and Caatinga and is crossed by the Cadeia do Espinhaço in its Septentrional section, between Meridional Espinhaço and Chapada Diamantina ( Campos et al. 2017, Pacifico et al. 2021).

Etymology:— The specific epithet makes reference to the reduced leaves and floral parts of the new species, when compared to its closest relatives.

Notes:— Microlicia pumila is apparently related to M. karinae , M. nervosa , M. naudiniana and M. obovatifolia , all of which share obovate leaves, magenta petals, and dimorphic stamens with well-developed connectives, somewhat truncate ventral appendages, and tetrasporangiate thecae. All probable relatives occur in central Minas Gerais state, on the Serra do Cipó and/or the Diamantina plateau, whereas M. pumila is apparently restricted to the extreme north of the state, at the Serra da Formosa ( Fig. 8 ). Microlicia karinae , M. nervosa and M. obovatifolia may occur sympatrically at the Serra do Cipó, at or around the Alto do Palácio (Santana do Riacho), whereas Microlicia nervosa and M. naudiniana are probably sympatric at some point along the Diamantina plateau. All of these species can be separated by the diagnostic characters in the following key:

1. Leaves sessile or on inconspicuous petioles up to 0.2 mm long ........................................................................................................2

- Leaves on conspicuous petioles 0.8–2.2 mm long .............................................................................................................................3

2. Leaves widely obovate ( Fig. 1F ); leaf margin, hypanthia and calyx lobes covered with gland-tipped trichomes 0.1–0.3 mm long; calyx lobes linear, ca. 0.2 mm wide.................................................................................................................. Microlicia naudiniana

- Leaves narrowly obovate ( Fig. 1D ); leaf margin, hypanthia and calyx lobes glandular-punctate; calyx lobes triangular, 1.5–1.9 mm wide ................................................................................................................................................................. Microlicia obovatifolia

3. Leaf midvein stout and prominent on the abaxial surface; leaf margin entire along the upper half; leaf surfaces, margin, hypanthia and calyx lobes covered with gland-tipped trichomes 0.1–0.3 mm long; calyx lobes linear, up to 0.5 mm wide, persistent in fruit.. ............................................................................................................................................................................... Microlicia nervosa

- Leaf midvein flat and impressed on the abaxial surface; leaf margin crenellated along the upper half; leaf surfaces, margins, hypanthia and calyx lobes glandular-punctate; calyx lobes oblong, 1.1–2 mm wide, deciduous in fruit ..........................................4

4. Branchlets only glandular-punctate; leaf blades 5.8–14 mm long, hypanthia 4–4.5 mm long, calyx lobes 3.5–4 mm long, petals 14–15 mm long, stamen filaments 5–5.6 mm long, capsules (3–)4(–5)-locular, apically surpassing the hypanthial torus by 1–1.2 mm at maturity (Serra do Cipó).............................................................................................................................. Microlicia karinae

- Branchlets conspicuously verrucose and glandular-punctate; leaf blades 2.8–5.2 mm long, hypanthia 2.6–2.9 mm long, calyx lobes 2.6–2.9 mm long, petals 7–8 mm long, stamen filaments 2.2–2.7 mm long, capsules 3-locular, apically not surpassing the hypanthial torus at maturity (Serra da Formosa)..................................................................................................... Microlicia pumila

Figures

FIGURE 1. A summary of the elliptic Fourier analysis of leaf shape. A. Two main PC axes associated with variation in leaf shape. Each row represents variation in shape explained by each of the first two PC axes, whereas the columns correspond to the mean shape ± 1.5 standard deviations on each side. B. PCA ordination of the elliptical Fourier analysis showing ranges of variation in leaf shape associated with each species. C–G. Photos of representatives leaves of species sampled in the elliptic Fourier analysis. C. Microlicia pumila (R. Pacifico 725 & V.E. Bressan). D. Microlicia obovatifolia (F. Almeda et al. 8899). E. Microlicia karinae (F. Almeda et al. 9705). F. Microlicia naudiniana (R. Pacifico 321). G. Microlicia nervosa (F. Almeda et al. 9124). H. Heatmap highlighting regions that differ in mean leaf shape between M. pumila (outlined in red) and M. karinae (outlined in light blue). Scale bars: 2 mm.

FIGURE 6. Microlicia pumila. A. Habit. B. Detail of the verrucose internodes. C. Apical vegetative branch. D. Leaf (abaxial surface). E. Leaf (adaxial surface). F. Floral bud. G. Antesepalous stamen. H. Antepetalous stamen. I. Capsule enveloped by the hypanthium. J. Capsule. K. Seed in lateral view. Voucher: R. Pacifico 725 & V.E. Bressan. Scale bars: A, 2 cm; B, 1 mm; C, 4 mm; D–J, 2 mm; K, 0.4 mm.

FIGURE 7. Microlicia pumila. A. Fruiting branches. B. Branchlet terminating in a floral bud. C. Type locality, Serra da Formosa, Monte Azul, Minas Gerais, Brazil. Photos by R. Pacifico. Voucher: R. Pacifico et al. & V.E. Bressan 725.

FIGURE 8. A. Map of Brazil with Minas Gerais state highlighted in black. B. Minas Gerais with distributions of Microlicia karinae, M. nervosa, M. naudiniana, M. obovatifolia and M. pumila. C. Satellite image of Serra do Cipó with distributions of M. karinae, M. nervosa, M. naudiniana and M. obovatifolia. D. Satellite image of Serra da Formosa with the distribution record of M. pumila.