Microlicia rosanae 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 rosanae

description: Microlicia rosanae Almeda & R.B.Pacifico, sp. nov. (Fig. 1)
Type:— BRAZIL. Minas Gerais: Município de Catas Altas: RPPN Santuário do Caraça. Trilha subida para o Pico do Sol, 20 October 2016, fl., M. Castro 285 & J.N. Nakajima, A.F.A. Versiane (holotype: HUFU-00070110 -digital image!; isotypes: CAS!, UEC-138794 - digital image!).
Diagnosis:— Microlicia rosanae can be distinguished from M. pilosa by its internodes that are covered with spreading gland-tipped trichomes 0.5 mm long (vs. covered with a mixture of ascending to spreading glandular and eglandular trichomes 0.5–1 mm long), sessile leaf blades that are 1-nerved and glandular punctate adaxially [vs. leaves 1–3(–5)-nerved with eglandular trichomes], calyx lobes that are triangular, acute and lacking an apical trichome (vs. attenuate with a pungent apical trichome), and a 5–6-locular ovary that is ½ inferior (vs. a 6-locular ovary that is 4/5 inferior).
Shrubs with a much-branched upright habit 1–1.5 m tall. Distal branches inconspicuously quadrate to subquadrate and inconspicuously sulcate on opposing faces, the internodes copiously beset with spreading gland-tipped trichomes to 0.5 mm long, greenish-brown when dry, defoliating and becoming ± rounded and tardily decorticating with age; the upper internodes 2–5 mm long, nodes with a few spreading simple or gland-tipped trichomes 1 mm long that are tardily deciduous on older branches with distinct leaf scars. Leaves sessile, spreading, somewhat crowded and restricted to distal branches; blades 7.5–17 × 2–4(–6) mm, subcoriaceous, oblong to narrowly oblanceolate, base ± truncate to somewhat rounded, apex bluntly acute to obtuse, the margins entire and conspicuously revolute when dry, dark green and copiously glandular-punctate adaxially, pale green and moderately to copiously and minutely glandular puberulent abaxially on and beyond the central vein, 1-nerved, the secondary and higher order veins absent or not evident. Flowers 5–6-merous, solitary, terminal on primary and secondary branches, becoming pseudoaxillary with elongation of lateral shoots, subsessile with pedicels lengthening to 1.5–2 mm in fruit. Bracteoles 8–12 × 4–6 mm, sessile, elliptic-lanceolate, base obtuse, apex obtuse, 1-nerved, with indumentum on both surfaces like the mature leaves. Hypanthia (at anthesis) 3.5–4 × 2.5–3 mm, campanulate, copiously covered with a mixture of spreading inconspicuous short and longer (some gland-tipped) trichomes up to ca. 0.25 mm long. Calyx tube 1 mm long, flaring; calyx lobes (at anthesis) 1.5–2.5 mm long and ca. 2 mm wide at the base, triangular, acute at the apex, margins entire and deciduously glandular-ciliolate, the abaxial (outer) surface covered with an indumentum like the hypanthia, adaxially glabrous or deciduously puberulent with minute glandular trichomes. Petals 11.5–14 × 7–11 mm, pink with a creamy yellow base, obovate, apex rounded to somewhat oblique, base obtuse, margins entire and inconspicuously glandular-ciliolate. Stamens 10 or 12, dimetric and dimorphic, glabrous; large (antesepalous) stamens 5 or 6, filaments 6 mm long, anther thecae 4 × 1–1.5 mm (including 1 mm long rostrum), yellow, oblong, smooth (tetrasporangiate), pedoconnectives 5 mm long, strongly curved, appendages 1 mm long, blunt and ± truncate; small (antepetalous) stamens 5 or 6, filaments 5 mm long, anther thecae 3.5 × 1 mm (including 1 mm long rostrum), yellow, oblong, smooth (tetrasporangiate), pedoconnectives 1.5 mm long, appendages 0.5 mm long, blunt and ± truncate. Ovary 5–6-locular, ca. ½ inferior, oblong. Style 7–8 mm long, glabrous, somewhat curved distally and declinate at anthesis, stigmas punctiform. Fruiting hypanthia (excluding persistent calyx lobes) 5 × 5 mm, yellowish and conspicuously constricted into a short neck just below the torus. Capsules (at maturity) 5–6 × 5–6 mm, globose, glabrous, enveloped by the persistent hypanthia, dehiscence not observed. Seeds 0.50–0.91 × 0.33–0.46 mm, oblong to subreniform, yellow-brown, testa foveolate, raphal zone oblong, ca. 50–60 % the length of the seed.
Paratypes:― BRAZIL. Minas Gerais: Município de Catas Altas: RPPN Santuário do Caraça, trilha subida para o Pico do Sol, 20 October 2016, fl., M. Castro et al. 286 (BHCB, HUFU-00070109 -digital image!, SPF, UEC-138795 - digital image!); Serra do Caraça, trilha para o Pico do Sol, elev. 1500–1600 m, 19 January 2017, fr., R. Pacifico 299 & V.E. Bressan (CAS!, HUEM!, SPF-00232806!).
Distribution, Habitat, and Phenology:— Microlicia rosanae is known only from Serra do Caraça of the Espinhaço Meridional where it grows in campo rupestre with rocky outcrops at an elevation of 1500–1600 m (Fig. 2). It has been collected on two occasions along the trail to Pico do Sol where one of us (RP) noted a population of about 20 individuals growing one to two meters from one another. It was collected in flower in October and in fruit in January.
Informal Conservation Status:—The distribution of M. rosanae is within the borders of Reserva Particular do Patrimônio Natural do Caraça (RPPN-Santuário do Caraça), a private reserve which is located in the ‘Quadrilátero Ferrífero’ (Iron Quadrangle) of the Espinhaço Meridional in southern Minas Gerais. The RPPN-Santuário do Caraça was established in 1994 to protect a total area of 11,233 ha, of which 10,187 ha are devoted to biodiversity conservation (Talamoni et al. 2014). The RPPN-Santuário do Caraça encompasses an elevational range of 850–2072 m. The native vegetation within the reserve consists of Atlantic Forest at lower elevations and along water courses, and campo rupestre and high elevation grasslands (campos de altitude) in the higher rocky areas (Vasconcelos & Melo 2001). Landscapes with vast reservoirs of iron ore in Brazil and elsewhere are environmentally threatened because of the high value this mineral has in the international market (Salgado & Carmo 2015). The vegetational cover of the Serra do Caraça is presently intact and appears to be one of the few protected areas inside the Iron Quadrangle. The population of M. rosanae appears to be afforded a good measure of protection from destructive mining practices but fires are always a potential threat in campo rupestre habitats. Too few collections of M. rosanae are known to calculate EOO and AOO values using GeoCAT and none of them are georeferenced. We therefore assign a Data Deficient (DD) status to this species based on IUCN criteria.
Etymology: — The specific epithet honors Dra. Rosana Romero, Professora titular at the Federal University of Uberlândia (Minas Gerais) and Curator of the HUFU herbarium, in recognition of her long-time research on Brazilian Melastomataceae, especially Microlicia, who first brought this distinctive species to our attention.
Affinities:— Microlicia rosanae is readily distinguished by its sessile oblong to narrowly oblanceolate 1-nerved leaf blades, 5 6-merous flowers, hypanthia that are copiously covered with a mixture of inconspicuous spreading short and longer (some gland-tipped) trichomes that are up to ca. 0.25 mm long, and 5 6-locular ovaries that are ca. ½ inferior. In having an ovary that is partly inferior, Microlicia rosanae is part of the Lavoisiera s.s. clade of Microlicia (see Fig. 2, Microlicia sp. 3, in Pacifico et al. 2022c) but it does not appear to be particularly close to any described species in that group, nor is it similar to any other described species of Microlicia s.l. It is superficially similar to Microlicia pilosa Versiane & R.Romero in Versiane et al. (2021: 54) which was originally described as Lavoisiera vestita Almeda & A.B.Martins in Martins & Almeda (2017: 171–172). The two species share petals that are pink with a well-defined creamy yellow or greenish-yellow base on the adaxial surface. In addition to the differentiating characters provided in the diagnosis, M. rosanae differs from M. pilosa in having leaf blades that are oblong to narrowly oblanceolate and 2–4(–6) mm wide (vs. oblong to elliptic-lanceolate and 6–10 mm wide). The two species are also allopatric. Microlicia rosanae appears to be restricted to Serra do Caraça and M. pilosa is restricted to the summit of Pico do Itambé (Fig. 2).
There are three other species in the Lavoisiera clade of Microlicia that share with M. rosanae exclusively 5–6- merous flowers, 5–6-locular ovaries, prevailingly pink petals, and stamens that are all fertile. These species are M. australis (A. St.-Hilaire ex Naudin 1844: 151) Versiane & R.Romero in Versiane et al. (2021: 52), M. crassifolia (Martius & Schrank ex Candolle 1828: 104) Versiane & R.Romero in Versiane et al. (2021: 53), and M. minensis Versiane & R.Romero in Versiane et al. (2021: 52). Microlicia rosanae differs from all of these species in having mature hypanthia that are strongly constricted distally just below the torus (vs. not constricted). This character difference and many others involving vegetative and indumentum details suggest that a close relationship to any of them seems unlikely. Diagnostic illustrations and detailed descriptions for all of these species are included in Martins & Almeda (2017) together with field photographs. In Martins & Almeda (2017) see Lavoisiera pulchella Chamisso (1834: 370 371) for M. australis, L. crassifolia Martius & Schrank ex Candolle (1828: 104) for M. crassifolia, and L. canastrensis Almeda & Martins in Martins & Almeda (2017: 60) for M. minensis. For flower images of M. rosanae (as Microlicia sp. nov.) see Figures 7D & 7E in Brito (2022: 13).
A species of Microlicia that grows sympatrically with M. rosanae on the trail to Pico do Sol at RPPN Santuário do Caraça is M. calycina (Chamisso 1835: 430) Versiane & R.Romero in Versiane et al. (2021: 52). This latter species, which is a member of the Trembleya s.s. clade of Microlicia (Pacifico et al. 2022c), has 5-merous flowers and 5- locular ovaries. Its leaves are also narrow with margins that are revolute when dry like M. rosanae; the two species can be confused when encountered only in fruiting condition. In M. calycina the distal internodes are quadrate with angles that are distinctly winged (vs. internodes subquadrate with unwinged angles), the leaf blades are elliptic to narrowly elliptic, 3-nerved from the base, with petioles 0.8–1.8 mm long and a base that is attenuate (vs. blades oblong to oblanceolate, 1-nerved, sessile and with a base that is ± truncate to rounded). The hypanthia of M. calycina are glandular-punctate (vs. copiously covered with a mixture of spreading short and longer smooth and gland-tipped trichomes), and the petals are apically acuminate (vs. rounded to somewhat oblique). For an illustration of M. calycina, see Pacifico et al. (2022c: 43).
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 185-188, DOI: 10.11646/phytotaxa.600.3.5, http://zenodo.org/record/8080850