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| Merianthera calyptrata R.Goldenb., Bochorny & Fraga, in Goldenberg, Bochorny, Amorim, Ziemmer et Fraga, 2023. |
ABSTRACT
Merianthera is a genus of flowering plants with up to now seven species occurring in eastern Brazil, in the states of Bahia, Espírito Santo, and Minas Gerais. It belongs to the tribe Pyramieae (Melastomataceae), and can be recognized by its shrubby or treelet habit with caducous leaves, 5-merous flowers with a strongly zygomorphic androecium, the latter with dimorphic stamens bearing complex dorsal connective appendages, as well as an inferior ovary and capsular fruits. We describe here a new species of Merianthera from two collections and a photographic record, all from the same locality, an inselberg in the Municipality of Jacinto, in northeastern Minas Gerais. Its candelabriform habit, with a fistulose stem, and solitary, axillary or cauliflorous flowers are only shared with M. burlemarxii. However, Merianthera calyptrata R.Goldenb., Bochorny & Fraga sp. nov. has at least three characters that are absent in M. burlemarxii and all other species in the genus: the total absence of both a peduncle and bracteoles, the calyptrate calyx and the fruits developing from inferior ovaries and dehiscing through longitudinal slits. The first character appears to be unknown in other species in the family.
Keywords: Cambessedesieae, inselbergs, Pyramieae, xerophytic plants
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| Field photographs of Merianthera calyptrata R.Goldenb., Bochorny & Fraga sp. nov. A. Fertile branch. B. Branch apex, longitudinal section showing the fistulose structure of the stem, with the chambers filled with parenchyma. C–E. Sequence of flower anthesis, showing the calyptrate calyx with its circumscissile dehiscence. F. Flowers, frontal view. G. Stamens and style, lateral view. H. Old flower, lateral view; this photo shows the single, ebracteolate flower and the absence of a peduncle. I. Mature fruit. From: Fraga & Couto 4144 (A–H), Amorim et al. 11854 (I). Photos by C.N. Fraga (A–H) and Y. Gouvea (I). |
Merianthera calyptrata R.Goldenb., Bochorny & Fraga sp. nov.
Diagnosis: Merianthera calyptrata sp. nov. differs from Merianthera burlemarxii by the acute or slightly cuneate leaf base (vs obtuse to rounded in M. burlemarxii), rounded to seldom obtuse apex (vs acuminate or abruptly acuminate), the solitary flower on a single, ebracteolate pedicel, borne directly on the stem, i.e., not borne on a peduncle (vs solitary, bibracteolate, pedicellate flower borne on a short peduncle), calyx closed in bud, calyptrate, dehiscing through a transversal, circumscissile slit that releases a single, conical cap (vs open in bud, with five regular sepals), fruits opening regularly through (3–)4 longitudinal slits running from the apex to almost the base of the fruit (vs fruits opening irregularly, with no apparent line of dehiscence, and the seeds are dispersed as the hypanthium and ovary walls decay and open; fide Goldenberg et al. 2012).
Etymology: The epithet refers to the flowers with a calyptrate calyx, a unique feature of M. calyptrata sp. nov., and otherwise unknown in the genus and tribe.
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| Illustration of Merianthera calyptrata R.Goldenb., Bochorny & Fraga sp. nov. A. Fertile branch. B. Detail of the branch showing leaf and flower scars plus two lenticels, each at one side of the leaf scar. C. Branch tip with leaves, flower buds, an open flower and a fruit. D. Flower opening sequence, from left to right: flower bud, with the calyptrate calyx still attached to the hypanthium; flower bud, with a circumscissile dehiscence, but the calyptra still holding the petals together; and young flower, with the calyptrate calyx falling from the petal tips. E. Petal, adaxial surface. F. Flower in longitudinal section (calyx, petals and stamens removed) with detail of trichomes at the base of style. G. Antesepalous stamens, from bud (left) and mature flower (right). H. Antepetalous stamens, from bud (right) and mature flower (left). I. Antepetalous stamen, detail of the pore. From Fraga & Couto 4144 (all drawings). Drawn by Diana Carneiro. |
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| Merianthera calyptrata R.Goldenb., Bochorny & Fraga sp. nov. in its habitat. A. Inselberg and granitic outcrops where the plant can be found. B. Vegetation cluster growing on a cleft, on a granitic outcrop, with M. calyptrata to the right and front, with flowers. C. Three individuals with spreading crowns, behind some Alcantarea (É.Morren ex Mez) Harms (Bromeliaceae). From Fraga & Couto 4144. Photos by C.N. Fraga. |
Renato Goldenberg, Thuane Bochorny, André Márcio Amorim, Juliana Klostermann Ziemmer and Claudio Nicoletti de Fraga. 2023. Merianthera calyptrata sp. nov. (Melastomataceae, Myrtales), A New candelabriform Species from Minas Gerais, Brazil. European Journal of Taxonomy. 888(1), 64-76. DOI: 10.5852/ejt.2023.888.2209