Microlicia septentrionalis Almeda & R. B. Pacifico 2023, sp. nov.
Creators: name: Almeda, Frank
name: Pacifico, Ricardo
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Myrtales
Melastomataceae
Microlicia
Microlicia septentrionalis

description: Microlicia septentrionalis Almeda & R.B.Pacifico, sp. nov. (Figs. 3, 4C– F)
Type:— BRAZIL. Minas Gerais: Município de Monte Azul. Pico da Formosa e arredores, 15°14’17”S, 42°49’15”W, 1792 m, 29 July 2022, fl., fr., R. Pacifico 730 & V. E. Bressan (holotype: HUEM!; isotypes: CAS!, HUEFS-264540!, RB-1469244!, SPF!).
Diagnosis:— Microlicia septentrionalis can be distinguished from M. mellobarretoi (Markgraf 1940: 220 221) by its shorter upper internodes 3–4 mm long (vs. 5–17 mm long), smaller ovate-lanceolate leaves 13–32 × 6– 4 mm (vs. larger oblong to lanceolate leaves 35–80 × 7–30 mm), shorter hypanthia at anthesis that are 6–7 mm long from base to torus with trichomes 1–2.5 mm long (vs. hypanthia 10–14 mm long with trichomes mostly 4–5 mm long), petals that are pink throughout on the adaxial surface (vs. pink with distinctly yellow base), and ovary apex beset with spreading glandular trichomes (vs. ovary apex glabrous).
Shrubs or small trees 1–3 m tall, dichotomously branching. Distal branches subquadrangular to sub-rounded, sulcate and deeply furrowed longitudinally on two opposing faces, glabrous, defoliating and decorticating with age; the upper internodes 3–4 mm long with knobby thickenings just below each leaf scar, the nodes with conspicuous leaf scars and a persistent pectinate fringe of brownish glandular trichomes ca. 0.5 mm long just above each scar. Leaves ± crowded on the branches distally, concave and reduced in size distally toward the inflorescence, some uppermost leaves sparingly punctate abaxially, sessile, antrorsely spreading on uppermost branches; blades 13–32 × 6–14 mm, chartaceous when dry, ovate-lanceolate, base truncate, apex bluntly acute, margin entire, conspicuously callose-thickened (0.5 mm wide), prevailingly glabrous on both surfaces (rarely sparingly punctate on the distal abaxial surface), dark green on both surfaces when fresh, typically red on callose-thickened margins and midvein abaxially (when fresh and dry), 1-nerved on abaxial surface but secondary and higher order veins not evident. Flowers 5-merous, aggregated in congested, mostly 3–5-flowered terminal dichasia, sometimes reduced to solitary flowers. Bracteoles closely enveloping flower buds, sessile and concave, blades 8–15 × 5–10 mm, chartaceous, ovate, rounded at the base, bluntly acute at the apex, margins entire and sometimes sparsely beset with trichomes 0.5 mm long, commonly flushed red on both surfaces. Hypanthia (at anthesis) ca. 6–7 × 3–4 mm, campanulate, somewhat constricted distally above the ovary just below the torus into a neck 1–2.5 mm long, glabrous basally and distally with a sparse ring (sometimes interrupted) of gland-tipped trichomes mostly 0.5 mm long just below the constricted neck. Calyx tube 1–2 mm long; calyx lobes (at anthesis) 7–8 mm long and 3–3.5 mm wide at the base, chartaceous, red, persistent, triangular, apex acute, margins entire and glandular-ciliate, mostly glabrous but sparingly beset distally with gland-tipped trichomes to 1.5 mm long on both surfaces. Petals 26–27 × 15–16 mm, pink throughout with somewhat darker venation on adaxial surface and an asymmetrical red band on one side of the petal on the abaxial surface, obovate, apex shallowly emarginate to truncate, base obtuse to truncate, margins entire and inconspicuously glandular-ciliolate. Stamens 10, dimetric and dimorphic, yellow throughout: large (antesepalous) stamens 5, filaments 10 mm long, anther thecae 6 × 2 mm (incl. 1 mm long rostrum), oblong, smooth (tetrasporangiate), constricted distally into a rostrum with a ventrally inclined pore, pedoconnectives 7 mm long, appendages 2 mm long, shallowly bilobed; small (antepetalous) stamens 5, filaments 9 mm long, anther thecae 5.5 × 1.5 mm (incl. 1 mm long rostrum), oblong, smooth (tetrasporangiate), constricted distally into a rostrum with a ventrally inclined pore, pedoconnectives 1.5 mm long, appendages 1 mm long, shallowly bilobed. Ovary 5-locular, 2/3 inferior, oblong, with glandular trichomes up to 0.5 mm long distally around the base of the style. Styles 11–12 mm long, glabrous, declinate, stigmas punctiform. Fruiting hypanthia (excluding lobes) 7–8 × 5 mm, constricted above the ovary apex into a distinct neck ca. 2 mm long. Capsule s (at maturity) ca. 5 mm long, enveloped by the persistent hypanthia and calyx lobes, greenish flushed with red, dehiscence not observed but vascular strands persisting after capsule walls have fallen away. Seeds 0.69–0.98 × 0.27–0.42 mm, oblong, yellow-brown, testa foveolate, raphal zone about 70% the length of the seed.
Distribution, Habitat, and Phenology:— Microlicia septentrionalis was collected on the summit of Pico da Formosa (ca. 1792 m) in municipality of Monte Azul of the Espinhaço Septentrional in northern Minas Gerais, Brazil (Fig. 2). It formed a small population of about 10 to 20 individuals on the rocky summit in campo rupestre. It was collected in flower and fruit in July.
Informal Conservation Status:— Microlicia septentrionalis is known only from the type gathering so calculations of EOO and AOO values were not possible. Based on IUCN (2022) guidelines and criteria we assign a Data Deficient status (DD) to this species at this time. Pico da Formosa and immediate surroundings are still little-known botanically and have no formal protected status, so this species is potentially vulnerable.
Etymology: — The specific epithet septentrionalis highlights both the distribution of this species in the Espinhaço Septentrional and its distribution that is to the north of its closest relative, Microlicia mellobarretoi, that is restricted to the Serra de Gr„o Mogol of Minas Gerais, Brazil (Fig. 2).
Affinities:— Microlicia septentrionalis also appears to be related to a small group of morphologically similar species in the Lavoisiera s.s. clade of Microlicia that includes M. mellobarretoi and M. gentianoides (Martius & Schrank ex Candolle 1828: 104) Versiane & R.Romero in Versiane et al. (2021: 53). All of these species share an openly branched shrubby habit, 5-merous flowers with well-developed elongate calyx lobes, hypanthia with a well-developed constricted neck above the ovary apex, spreading glandular trichomes on the hypanthia and calyx lobes, and a 5-locular ovary (see Martins & Almeda 2017).
Microlicia septentrionalis appears to be closest to M. mellobarretoi (see diagnostic illustrations in Martins & Almeda 2017: 127), a species also known only from the state of Minas Gerais but restricted to the Serra de Gr„o Mogol in the northeastern part of the state. In addition to the differences enumerated in the diagnosis, M. septentrionalis has hypanthia with a narrow continuous or interrupted line or band of short spreading trichomes (Figs. 3F, N) below the distal constriction (vs. a wide band of longer trichomes that covers much of the length of the hypanthia), abaxial petal surfaces that have a distinctive asymmetrical red band on one side that is also visible in maturing floral buds (Fig. 4D), and hypanthia that are 6–7 mm long from the base to the torus at anthesis (vs. hypanthia 10–14 mm long). The two species are allopatric (Fig. 2) with Microlicia mellobarretoi growing at lower elevations (750–1100 m).
The more widespread, but not particularly common, Microlicia gentianoides (Fig. 2), is also similar to and appears to be another close relative of M. septentrionalis. It differs in having larger (45 –100 × 10–25 mm) elliptic-lanceolate to oblong-lanceolate leaves that are ± reflexed or perpendicular to the stems [vs. smaller leaves (13–32 × 6–14 mm) that are ovate-lanceolate and antrorsely spreading on the branches], and petals that are uniformly white with yellow-green venation on the adaxial surface (vs. pink with darker pink venation). The hypanthial length from base to the torus (at anthesis) in M. gentianoides is also longer (11–13 mm), opposed to the shorter ones in M. septentrionalis (6–7 mm). The petals of M. gentianoides are entire and tipped with a terminal glandular trichome (vs. entire and inconspicuously glandular-ciliolate along the entire margins), and its ovary summit is glabrous (vs. beset with spreading glandular trichomes around the style base). Another more distant relative is the rare and little-collected M. punctata (Martius & Schrank ex Candolle 1828: 104) Versiane & R.Romero in Versiane et al. (2021: 54) which has similar crowded concave leaves on distal branches with bright red callose margins. The latter is readily distinguished by its prominently fluted hypanthia, modally 8-merous flowers, pink to pink-magenta petals with a yellowish-green or white base adaxially, and a 6–8-locular ovary. For a diagnostic illustration of M. punctata, see Martins & Almeda (2017: 148).
description: Published as part of Almeda, Frank & Pacifico, Ricardo, 2023, New species of Microlicia (Melastomataceae) from the Espinhaço Meridional and Septentrional of Minas Gerais, Brazil, pp. 184-194 in Phytotaxa 600 (3) on pages 189-192, DOI: 10.11646/phytotaxa.600.3.5, http://zenodo.org/record/8080850