Microlicia pacificoi Almeda & Fidanza, 2020

Almeda, Frank & Fidanza, Karina, 2020, A new Microlicia (Melastomataceae: Microlicieae) from the Southern Cadeia do Espinhaço, Minas Gerais, Brazil, Phytotaxa 438 (3), pp. 182-188 : 183-186

Microlicia pacificoi Almeda & Fidanza , sp. nov. ( Figs. 1 , 2A )

Diagnosis:— Microlicia pacificoi can be recognized by its wiry habit, narrowly lanceolate sessile leaf blades that are 2.5–4 × 0.5–1 mm and resinous-punctate on both surfaces, delicate stalked gland-tipped trichomes on distal internodes and hypanthia, glabrous irregularly rugulate calyx lobes that are deciduous following anthesis, 5-merous flowers, and dimorphic, bicolored tetrasporangiate anther thecae.

Type:— BRAZIL. Minas Gerais: Municipio de Serro: Distrito of Milho Verde. About 2 km from Milho Verde on the road to Capivarí, 18º29.055’’ S, 43º29.936’W, 1040 m, 17 September 2005, fl. & fr., F. Almeda 9072, A. B. Martins, R. Belinello & M. B. Almeda (holotype UEC!; isotypes CAS-321362!, CAS-636976!, HUEM!, HUFU, K!, NY!, SPF!) .

Laxly branched shrubs with wiry branches to 0.5 m tall. Distal internodes 2–3 mm long, quadrangular, the angles with blunt green wings, the indumentum consisting of delicate spreading, incurved, or somewhat appressed gland-tipped beige trichomes mostly less than 0.25 mm long. Older branches mostly defoliated, gray to gray-brown, roundedquadrate to ± terete, glabrous and irregularly fissured longitudinally. Leaves crowded distally on the branches, erect to ascending when fresh, ± imbricate when dry, concolored, sessile; blades 2.5–4 × 0.5–1 mm, narrowly lanceolate, apex obtuse to bluntly rounded, base obtuse to truncate, the margin entire, 1-nerved, the abaxial surface moderately resinous-punctate, the adaxial surface also resinous-punctate but sparser and less conspicuous toward the blade base. Inflorescences consisting of solitary terminal flowers that appear ± axillary on older branches because of the elongation of lateral branches; flowers 5-merous, sessile or with short pedicels to 0.5 mm or less at anthesis and in fruit, subtended by a pair of bracteoles that are like the principal leaves in size, shape, and indumentum. Hypanthia (at anthesis) 3–4 mm long and 2–2.5 mm wide at the torus, dark red when dry, campanulate, copiously covered with delicate spreading to ± incurved gland-tipped trichomes 0.25–0.5 mm long and a sparse but inconspicuous understory of minute seemingly sessile glands; calyx tubes 0.25–0.5 mm long, calyx lobes (at anthesis) 2 mm long and 1 mm wide at the base, triangular, acute and tipped with an eglandular trichome 0.25 mm long that readily falls away, the adaxial surface glabrous, the external surface glabrous but irregularly rugulate and glutinous, deep red like the hypanthia, margin entire, caducous in post anthesis. Petals 8–12 × 4–6 mm, magenta, obovate, apex attenuate to acuminate, margin entire and lacking glands. Stamens 10, dimorphic, thecae tetrasporangiate: large (antesepalous) stamens 5, filaments 4–4.5 mm long, pink, ± compressed, thecae 3–3.5 mm long (including 0.75 mm long constricted rostra), dark red, oblong-subulate, the rostra white with a ventrally inclined apical pore, pedoconnectives prolonged 3.5 mm, pink, ± compressed dorsoventrally but tumid proximally when fresh, ventral appendages narrowly obcordate in outline when fresh, 1.5 mm long and 1.25 mm wide at the subtruncate to shallowly bilobed apex, the proximal two-thirds pink, the distal third yellow-white; small (antepetalous) stamens 5, filaments 4 mm long, pink, thecae 2.5 mm long (including the 0.5 mm long constricted rostra), yellow but brownish distally below the white rostra, oblong with a ventrally inclined apical pore, pedoconnectives prolonged 1 mm, yellow, ventral appendages 0.25 mm long, bluntly bilobed. Ovaries 2–2.5 × 1.5 mm, ellipsoid, glabrous, superior, 3-locular; style 7.5 × 0.5 mm, terete, glabrous, markedly declined to one side of the flower and conspicuously curved distally below the punctiform stigmas. Capsules ellipsoid, 3–3.5 × 2–2.5 mm, slightly exceeding the hypanthia in length, initially enveloped by the hypanthia then rupturing and flaking away with age, dehiscing into 3 valves from the apex to the base, columellas deciduous. Seeds 0.27–0.40 × 0.57–0.67 mm, oblong to subreniform, testa foveolate, grayish-brown, the raphal zone about 25–50 % the length of the seed.

Distribution, habitat, and phenology:— Microlicia pacificoi is probably endemic to the Diamantina Plateau which is part of the southern sector of the Cadeia do Espinhaço in Minas Gerais, Brazil ( Fig. 3 ). At its only known locality, where it was locally common, M. pacificoi grows in white sand over and adjacent to seasonally dry (austral winter), eroded rocky quartzitic slopes exposed to full sun at an elevation of 1040 m ( Fig. 2B ). It was collected flowering and fruiting in September.

Conservation:—The portion of the Diamantina plateau where Microlicia pacificoi grows is not part of a protected area. Because only the type gathering was available for this study we were unable to calculate area of occupancy and extent of occurrence for a conservation assessment using IUCN guidelines and criteria ( IUCN 2017). The type locality appears to be relatively free of threats other than the occasional fire. Until other collections come to light we regard the conservation status of this species as Data Deficient (DD).

Etymology:— The specific epithet honors our student Ricardo B. Pacifico (1990–), a Ph.D. candidate in the Post-graduate program in Comparative Biology at the Universidade Estadual de Maringá in Paraná, Brazil. Ricardo’s comprehensive illustrated account of the tribe Microlicieae for the Flora of Serra do Cipó (Pacifico & Fidanza 2018) and other recent publications ( Almeda & Pacifico 2018a; 2018b; Carmo et al. 2019; Pacifico & Almeda 2018; Pacifico et al. 2018a; Pacifico et al. 2019a; 2019b) are important and welcome additions to the systematics of Brazilian Melastomataceae .

Affinities:— Microlicia pacificoi is morphologically most similar to the recently described Microlicia rugosa R. Romero & Versiane (2019: 2–3) which is apparently endemic to the Serra do Cipó, also in the southern sector of the Espinhaço range. Both species have an openly branched wiry habit with ascending leaves, quadrangular branchlets with blunt wings, narrowly lanceolate 1-nerved leaves with a moderate to dense glandular-punctate indumentum, solitary 5-merous flowers, magenta petals that are apically acuminate to apiculate, tetrasporangiate anthers, and 3- locular ovaries. Microlicia pacificoi differs most notably from M. rugosa in having a conspicuous indumentum of delicate spreading, incurved, or somewhat appressed stalked gland-tipped beige trichomes mostly less than 0.25 mm long on upper internodes and hypanthia (vs. a dense indumentum of spherical glands without evident stalks), smooth hypanthia (vs. conspicuously wrinkled or rugose hypanthia), sessile leaves (vs. leaves with short petioles 0.2–0.5 mm long), somewhat larger petals (8–12 × 4–6 mm) that lack glandular margins in bud [vs. somewhat smaller petals (6–9 × 2.5–4.5 mm) that are gland-margined in bud], and calyx lobes that are caducous in post anthesis (vs. calyx lobes that are persistent).

Microlicia pacificoi is also superficially similar to the narrow-leaved forms of M. isophylla DC. (1828: 120) , a more widespread species that ranges from the Brazilian states of Minas Gerais to Rio de Janeiro and São Paulo. In the latter the leaves are also sessile, linear-lanceolate, and 1-nerved but the upper internodes, hypanthia, and smooth calyx lobes appear glabrous with viscous impressed seemingly sessile trichomes, the floral pedicels at anthesis and in fruit are longer (1–2.5 mm), and the calyx lobes are persistent. Another Minas Gerais endemic that resembles Microlicia pacificoi is M. scoparia (A. St.-Hil.) DC. (1828: 120). It too has a habit and foliar morphology and indumentum similar to our new species but its quadrangular internodes are glabrous and lack developed wings, its uppermost internodes and hypanthia lack stalked gland-tipped trichomes, its floral pedicels are longer (1–2 mm), its petals are shorter (7–8 mm), and its anther thecae (excluding the rostra), although dimorphic in color, are nearly identical in size (ca. 1 mm long), and its calyx lobes are persistent.

Figures

FIGURE 1. Microlicia pacificoi. A. Habit. B. Representative leaf (adaxial surface). C. Representative leaf (abaxial surface). D. Cauline internode and associated leaves showing indumentum. E. Flower in profile view. F. Petal (adaxial surface) G. Small (antepetalous) stamen in profile view. H. Large (antesepalous) stamen in profile view. I. Fruiting hypanthium and calyx lobes in profile view. J. Capsule in cross section. K. Seed. L. Dehiscing capsule in profile view. Drawn from F. Almeda et al. 9072.

FIGURE 2. Microlicia pacificoi. A. Field photograph of a flower. B. The type locality (Almeda et al. 9072). Photographs by F.Almeda.

FIGURE 3. Distribution of Microlicia pacificoi.