Miconia dianae (Melastomataceae), a new species from Bahia (Brazil) with notes on leaf and hypanthium surfaces

Abstract

Miconia dianae is a new species described from four specimens collected in semideciduous forests in the municipality of Ribeirão do Largo, in the state of Bahia, Brazil. According to current data and based on IUCN criteria, this species should be qualified as “data deficient”, but we note that it should be actually considered as critically endangered, since the known habitat of M. dianae is reduced and subject of constant disturbance, which may perhaps lead to its extinction. The new species can be recognized by the inflorescences of pedunculate triads or seldom pauciflorous racemes with up to five flowers, these on a short pedicel topping an anthopodium 3–8 mm long, early caducous, filiform bracteoles, 5-merous flowers, terete hypanthia with verrucose projections on the abaxial surface, the calyx incompletely closed in bud, rupturing at anthesis in irregular lobes, white stamens with a dorso-basal hump and glandular trichomes on the connective, and a 3-locular, superior ovary with sparse glandular trichomes. The granulose surfaces of stems, leaves, inflorescences and hypanthia in dried specimens are caused by large druses, sometimes measuring half the thickness of the leaf mesophyll, that project themselves into hemispheric domes when the leaves are dried. The verrucose projections on the hypanthium develop from successive divisions of the ground tissue inside it. We were not able to explain its function, since they are not formed by crystals, nor seem to develop as pathogen or animal-induced galls, neither seem to store phenolic compounds nor starch. Since they fade away while the fruits ripen, they probably do not have any function related to dispersal either.