A Monograph of Conostegia (Melastomataceae, Miconieae)

Birds optimize fruit size consumed near their geographic range limits

Animals can adjust their diet to maximize energy or nutritional intake. For example, birds often target fruits that match their beak size because those fruits can be consumed more efficiently. We hypothesized that pressure to optimize diet-measured as matching between fruit and beak size-increases under stressful environments, such as those that determine species' range edges. Using fruit-consumption and trait information for 97 frugivorous bird and 831 plant species across six continents, we demonstrate that birds feed more frequently on closely size-matched fruits near their geographic range limits. This pattern was particularly strong for highly frugivorous birds, whereas opportunistic frugivores showed no such tendency. These findings highlight how frugivore interactions might respond to stressful conditions and reveal that trait matching may not predict resource use consistently.

Untangling inflorescences in Miconieae (Melastomataceae): development, typology, and the systematic and evolutionary implications

This study aimed to describe the origin, position, development and typology of inflorescences in Miconieae through ontogenetic and morphological analyses using light microscopy. We observed three morphological character states: terminal, pseudo-axillary and axillary; and two ontogenetic states: terminal and axillary. The terminal and pseudoaxillary inflorescences originate from terminal reproductive meristems. Pseudoaxillary inflorescences result from unequal development of vegetative meristems which flank the terminal flowering unit, whereas in terminal inflorescences, both vegetative meristems develop equally. In axillary inflorescences, the terminal reproductive meristem is not involved, while axillary inflorescences originate from reproductive axillary meristems. The inflorescences range from heterocladic and thyrsoid to simpler types, such as botryoid and triad. Such characteristics can also be seen in paracladia, particularly those most distal. The terminal inflorescence is observed in all clades of Miconieae, and pseudoaxillary and axillary inflorescences should be apomorphic states in the tribe and derived from the terminal condition.

Miconia lucenae (Melastomataceae), a new species from montane Atlantic Forest in Espírito Santo, Brazil

We describe Miconia lucenae R.Goldenb. & Michelang., a new species from the montane Atlantic Forest in Santa Teresa in the state of Espírito Santo. Our analysis, based on three plastid spacers (atpF-atpH, psbK-psbl and trnS-trnG), one plastid gene (ndhF, not available for M. lucenae), and two nuclear ribosomal loci (nrITS and nrETS), showed that it belongs to a small clade with Miconia paradoxa (Mart. ex DC.) Triana (Minas Gerais) and M. michelangeliana R.Goldenb. & L.Kollmann (Espírito Santo). The three species in the “Paradoxa clade” can be recognized by the plants with glabrous or glabrescent branches and leaves, white petals and yellow stamens, these with the connectives not prolonged below the thecae, ventrally unappendaged, dorsally unappendaged or with a minute tooth, the latter bilobed or not, glabrous ovary, and the fruits with a persistent calyx. Miconia lucenae can be recognized, among the species in this clade, by the shrubby plants with terete young branches, short inflorescences, usually with red axes, and the 2-bracteolate, sessile, 4-merous flowers, with a ciliolate inner portion of the sepals, lanceolate petals, and 4-celled ovaries. This species can be considered as endangered according to IUCN criteria.

Morphological characterization of domatium development in Callicarpa saccata

BACKGROUND AND AIMS

Domatia are plant structures within which organisms reside. Callicarpa saccata (Lamiaceae) is the sole myrmecophyte, or 'ant plant', that develops foliar (leaf-borne) myrmeco-domatia in this genus. In this work we examined domatium development in C. saccata to understand the developmental processes behind pouch-like domatia.

METHODS

Scanning electron microscopy, sectioning and microcomputed tomography were carried out to compare the leaves of C. saccata with those of the closely related but domatia-less myrmecophyte Callicarpa subaequalis, both under cultivation without ants.

KEY RESULTS

Callicarpa saccata domatia are formed as a result of excess cell proliferation at the blade/petiole junctions of leaf primordia. Blade/petiole junctions are important meristematic sites in simple leaf organogenesis. We also found that the mesophyll tissue of domatia does not clearly differentiate into palisade and spongy layers.

CONCLUSIONS

Rather than curling of the leaf margins, a perturbation of the normal functioning of the blade/petiole junction results in the formation of domatium tissue. Excess cell proliferation warps the shape of the blade and disturbs the development of the proximal-distal axis. This process leads to the generation of distinct structures that facilitate interaction between C. saccata and ants.