Microlicia frankii R. Pacifico & Fidanza, 2018

Pacifico, Ricardo & Fidanza, Karina, 2018, Microlicia frankii (Melastomataceae: Microlicieae), a new species from Serra do Cipó, Minas Gerais, Brazil, Phytotaxa 361 (3), pp. 279-286 : 280-283

Microlicia frankii R. Pacifico & Fidanza , sp. nov. ( Fig. 1 ; Fig. 2 ; Fig. 3 , A–B)

Diagnosis:— Microlicia frankii can be recognized by its reduced habit (3–15 cm in height), leaves linear 2–5 mm long, glandular-punctate on both surfaces, flowers apical and solitary, calyx lobes narrowly-triangular 3.5–7 mm long, petals magenta, isomorphic stamens, and tetrasporangiate thecae.

Type:— BRAZIL. Minas Gerais: Congonhas do Norte, Serra Talhada (setor nordeste da Serra do Cipó), 9 km S de Congonhas do Norte na estrada para Conceição do Mato Dentro, entrada para Extrema seguindo ca. 11. km—Estrada para Lapinha, 18.937444ºS, 43.685027ºW, ca. 1,250 m, 20 January 2007, J. R. Pirani, M. F. A. Calió, B. P. F. Loeuille & E. G. Martins 5609 (holotype SPF!, isotypes CAS!, CEN-online image!, HUEM!, UEC!).

Small perennial shrub 3–15 cm in height, erect and much-branched. Underground system with a well-developed xylopodium. Upper cauline internodes 1.3–1.7 mm long, quadrangular, sparsely glandular-punctate. Leaves decussate with an inconspicuous petiole ca. 0.1 mm long, imbricate, ascendant (when fresh), blade 2–5 × 0.5–1 mm, linear, base attenuate, margin entire, apex rounded (shortly mucronate), light green (when fresh), glandular-punctate and covered with sessile glands on both surfaces (glands deciduous with age), inconspicuously 1-nerved from the base, secondary venation absent. Inflorescence reduced to solitary flowers born on pedicels 0.7–1.5 cm long in terminal positions on uppermost branchlets. Bracts and bracteoles absent. Flowers 5-merous, actinomorphic (even throughout anthesis). Hypanthium (at anthesis) 1.6–3.9 × 2–3.7 mm, campanulate, light green flushed with red (when fresh), externally glandular-punctate and covered with sessile glands (these deciduous with age). Calyx tube ca. 0.2 mm long. Calyx lobes 3.5–7 × 1–1.5 mm, narrowly-triangular, margin entire and glandular-punctate, apex acuminate and pungent, external surface similar to the hypanthium. Petals 6.7–7.2 × 4.5–5.2 mm, obovate, margin entire and glabrous, apex acuminate, magenta, both surfaces glabrous. Stamens 10, isomorphic in color, shape and size, positioned in a circle around the stigma (even throughout anthesis); filaments 2.8–3 mm long, pink, connective prolonged 1–1.7 mm below the thecae, yellow, appendage ca. 0.2 mm long, yellow, apex truncate, thecae 1.1–1.7 mm long (excluding the rostrum), yellow, oblong, externally smooth (tetrasporangiate), rostrum 0.2–0.3 mm long. Ovary 1.9–2.9 × 1.5–2.5 mm, subglobose, glabrous, superior, 3-locular. Style ca. 4.5 mm long, pink, stigma punctiform. Capsule ca. 7 × 5 mm long, dark-brown, 3-locular, dehiscent from the apex to the base, enveloped by the hypanthium constricted at the apex, then rupturing and flaking away with age. Seeds not seen.

Additional specimen examined (paratype):— BRAZIL. Minas Gerais: Congonhas do Norte, Serra Talhada (setor nordeste da Serra do Cipó), 9 km S de Congonhas do Norte na estrada para Conceição do Mato Dentro, entrada para Extrema seguindo ca. 11 km —Estrada para Lapinha, 18.940083ºS, 43.682138ºW, ca. 1,385 m, 3 February 2009, J. R. Pirani et al. 5709 ( CTES, HUEM!, RB!, SPF!).

Photographs:— On December 11th 2014, one M. frankii population was photographed at the Alto do Palácio (19.2641389ºS, 43.5362500ºW; Fig. 2 ), a campo rupestre moutaintop (ca. 1,300 m) located in Santana do Riacho. The voucher collected on that occasion was lost ( G. Camargo, pers. comm.) .

Distribution, habitat, and phenology:— Microlicia frankii is probably endemic to the Serra do Cipó ( Fig. 4 ) in the municipalities of Congonhas do Norte and Santana do Riacho. It occurs in quartzitic campo rupestre sites that are exposed to full sun, at elevations between 1,250 –1,385 m. Microlicia frankii was collected with flowers in January and February, and with fruits in January. The population from Alto do Palácio was photographed flowering and fruiting in December ( Fig. 2 ).

Conservation status:— The population from Alto to Palácio is afforded some protection, as this locality is included in the Serra do Cipó National Park. The populations from Congonhas do Norte are likely vulnerable, since there are no fully protected areas in that municipality. Over the past decades, the sampling effort differed greatly between Santana do Riacho and Congonhas do Norte ( Pirani et al. 2015). We suggest a classification of Data Deficient (DD) to M. frankii following the IUCN (2017) criteria.

Etymology:— The new species is named in honor of our friend Dr. Frank Almeda (1946–), who is Curator Emeritus of the California Academy of Sciences Herbarium (CAS) and a renowned Melastomataceae specialist. Frank Almeda has made significant contributions to the family’s taxonomy.

Notes:— Microlicia frankii was initially confused with M. juniperina ( Fig. 3 , C–D). Microlicia juniperina shares with M. frankii the sessile leaves, narrowly-triangular calyx lobes, magenta petals, and reduced size (e.g., J.R. Pirani et al. 5206; 5588, SPF). Microlicia frankii can be distinguished by its non-amplexicaul leaves (vs. semi-amplexicaul in M. juniperina ), glandular-punctate on both faces (vs. glabrescent), rounded at the apex (vs. acuminated), and isomorphic stamens (vs. dimorphic). The only other species with which M. frankii might be confused is M. ericoides ( Fig. 3 , E–F). The latter is a small shrub (15–20 cm in height) with imbricated leaves, glandular-punctate on both surfaces, and margenta petals. Microlicia frankii differs by its leaf blades that are linear (vs. lanceolate in M. ericoides ), rounded at the apex (vs. acute), and isomorphic stamens (vs. dimorphic). To our knowledge, M. frankii is the only species of Microlicia with isomorphic stamens that occurs in Minas Gerais. Other comparative features and the distribution of the compared species are given in Table 1.

Melastomataceae exhibits extraordinary variation in staminal form ( Wilson 1950) and isomorphic stamens occur commonly in several tribes [e.g., Miconieae Candolle (1828: 152) , Blakeeae Bentham & Hooker (1867: 727)] ( Goldenberg et al. 2008; Penneys & Judd 2013). In the last comprehensive monograph on Microlicia, Cogniaux (1891) defined this genus by having stamens that are very unequal between the two cycles. Later, isomorphic stamens were described in eight Bahian species [ Microlicia minima Markgraf (1927: 46) , Microlicia isostemon Wurdack (1983: 122) , Microlicia subalata Wurdack (1983: 125) , Microlicia comparilis Wurdack (1984: 136) , Microlicia morii Wurdack (1995: 822) , Microlicia catolensis Woodgyer & Zappi (2005: 436) , Microlicia aureoglandulosa Woodgyer & R. Romero in Romero & Woodgyer (2018: 5), and Microlicia curticalycina R. Romero & Woodgyer (2018: 9) ].

A striking feature of M. frankii is the orientation of its stamens during the anthesis, in which all 10 stamens are positioned in a circle around the stigma ( Fig. 2 , B). In most species of this genus, the anthers of the antesepalous stamens lie in a sub-parallel or outward-pointing orientation that serves as a “landing platform” for the pollinators [as described for Lavoisiera Candolle (1828: 102) by Martins & Almeda (2017)], which in turn results in a floral symmetry that has been described as “zygomorphic due to the position of stamens and style” (e.g., Romero et al. 2015, 2016, 2017; Romero & Versiane 2016; Diniz-Neres & Silva 2017, 2018). In Melastomateae Bartling (1830: 329) , the stamen dimorphism was presumably lost in a few species of Melastoma Linneaus (1753: 359) , in which all 10 stamens are disposed in a circle around the stigma ( Meyer 2001; Luo et al. 2008). The loss of stamen dimorphism in Melastomataceae lineages could be a result of complex interactions between bee size and stamen size ( Luo et al. 2008), and/or the incorporation of other groups of pollinators to improve pollination associated with a lower demand for pollen grains by bees ( Brito et al. 2016).

In the Microlicieae treatment for the Serra do Cipó, M. frankii is cited as Microlicia sp.4 (Pacifico & Fidanza, in press).

Figures

FIGURE 1. Microlicia frankii. A. Habit. B. Leaf abaxial surface. C. Floral bud. D. Flower. E. Petal adaxial surface. F. Stamen. G. Gynoecium. Scales: A. 5 mm. B. 1 mm. C. 2 mm. D–E. 3 mm. F–G. 1 mm. Drawn from J.R. Pirani et al. 5609 (SPF).

FIGURE 2. Microlicia frankii. A. Habit. B. Close-up on two flowers. C. Fruiting branch. Photographs by G. Camargo.

FIGURE 3. A–B. Microlicia frankii. A. Leaf blade (abaxial view). B. Floral bud. C–D. Microlicia juniperina. C. Leaf blade (adaxial view). D. Floral bud. E–F.Microlicia ericoides. E. Leaf blade (abaxial view). F. Floral bud. Scales: 2 mm.A–B from J.R. Pirani et al. 5609 (SPF); C–D from C.S. Sato et al. 3 (SPF); E–F from F. Almeda et al. 8563 (CAS).

FIGURE 4. Distribution of M. frankii. A. Map of South America highlighting Brazil. B. Hypsometric map of southeastern Brazil. C. Satellite photograph of the Serra do Cipó. D. Satellite photograph of the type locality.