Renato Goldenberg

Studies on the reproductive biology ofMelastomataceae in “cerrado” vegetation

Controlled pollinations and observations of pollen tube growth, pollen fertility and cytological data were studied in 11 species ofMelastomataceae growing in “cerrado” in SE Brazil. Seven species produced apomictic fruits with viable seeds. Four species were not apomictic, with two self-incompatible (gametophytic SI) and two self-compatible, one showing spontaneous self-pollination. The apomictic species had lower pollen fertility than sexual ones — although in some cases differences were not significant — showing that low pollen fertility may be a useful indicator of apomixis if analysed using careful sampling supplemented by emasculation experiments. The apomictic species also showed meiotic irregularities, probably related to hybridization, polyploidy and the cause of low pollen fertility. Apomixis in this group probably is more associated with taxonomy and phylogeny than habitat or habit, since 85% of the apomictic species reported in the literature belong to the tribeMiconieae and occur in a wide range of vegetation types and have diverse habits. This suggests the existence of very extensive apomictic complexes comparable to those reported in mainly temperate genera ofAsteraceae andRosaceae.

Pattern of tree species diversity in riparian forest fragments of different widths (SE Brazil)

Width is an essential element of the spatial configuration of riparian forests and may be fundamental in determining their corridor function. In the present study we tested the effect of forest width on floristic structure (tree species composition and diversity) in 15 fragments of riparian forest in an agricultural fragmented landscape of SE Brazil. All these fragments were chosen in a geomorphological homogeneous river reach under similar soil, topographic and human disturbance conditions in order to minimize the influence of these factors. The forest widths considered ranged from 30 to 650 m. The results showed that total species richness and climax species richness were significantly greater when we consider larger fragments, as has been observed in other studies. Nevertheless, species diversity and evenness were not significantly correlated with forest width. The analysis of species composition showed that the narrowest fragments were characterized by species well adapted to temporary flood conditions, while medium and wide fragments showed a composition typical of drier upland areas. Therefore, the effect of forest width on floristic structure appears to be more strongly linked to the effect of river floods in the case of the fragments studied. The existence in riparian corridors of a drier forest, in general richer and more diversified than the annually flooded forest, seems to favor the maintenance of regional species diversity in fragmented landscapes.

O gênero Miconia Ruiz & Pav. (Melastomataceae) no Estado de São Paulo

The present paper deals with the species of Miconia occuring in the Brazilian State of Sao Paulo. The 53 species listed and described here probably represent all taxa of the genus collected in this State.

Rupestrea: A New Brazilian Genus of Melastomataceae, with Anomalous Seeds and Dry Indehiscent Fruits

Abstract The genus Rupestrea is described to include two species previously described in Miconia. Rupestrea carvalhoana and R. johnwurdackiana are restricted to Campos Rupestres at the northern portion of the Chapada Diamantina in Bahia, Brazil. The genus can be recognized by the dry and indehiscent fruits that may be hydrochorous, and by the orthocampylotropous, monoembryonic seeds, each incompletely divided into two cavities by a septum. The genus is sister to a large clade that includes the capsular-fruited tribes Melastomeae, Microlicieae, and Rhexieae.

Miconia papillosperma (Melastomataceae, Miconieae): a new species from Amazonas, Brazil

Abstract Miconia papillosperma, a new species of Melastomataceae shrubs from Northern Brazil is described and illustrated. This new species is characterized by elliptic lanceolate leaves with the only pair of secondary veins running close to the margin. It is also unique in having seeds with a papillose testa, a character until now unknown in the Miconieae. The description of this new species from a relatively well collected area near a major road north of Manaus, Amazonas, Brazil, is further evidence of our lack of knowledge on plants in many Neotropical areas.

Increased Sampling in Under-Collected Areas Sheds New Light on the Diversity and Distribution of Bertolonia, an Atlantic Forest Endemic Genus

Abstract Information regarding conservation actions and species distribution are based on specimens collected and deposited in scientific collections and taxonomic studies. In the tropics, these data might be biased for several reasons. Even in well-explored regions, such as the Atlantic Forest, there is still a lot to learn regarding distribution and evolution of genera and species. Intense sampling effort during the last 15 yr in the central Atlantic Forest has led to the description of six new species of Bertolonia (Melastomataceae). Bertolonia angustipetala, B. cuspidata, B. linearifolia, B. reginatoi, and B. vitoriana are endemic to southern Bahia, and B. kollmannii also occurs in Minas Gerais, near the border between both states. These and other recent discoveries in Bertolonia shift the diversity center of the genus from the southern to the central region of the Atlantic Forest, and provide a new context to understand morphological and biogeographical variation within the genus.

Nomenclatural novelties in Miconia (Melastomataceae: Miconieae)

The Miconieae (Melastomaceae) are a strictly Neotropical group comprising over 1900 species. The tribe is characterized by inflorescences that are terminal or axillary, but not cauliflorous (except a few species of Charianthus, Clidemia, and Mecranium), flowers subtended by only one pair of bracteoles (or none at all), with anthers that lack a pedoconnective, leaves without long acicular raphides, and berry fruits. Generic delimitations within the Miconieae have been notoriously complex, and phylogenetic analyses have shown that Miconia is paraphyletic with many other genera embedded within it. These nested genera include Anaectocalyx, Calycogonium, Catocoryne, Charianthus, Clidemia, Conostegia, Killipia, Leandra, Maieta, Mecranium, Necramium, Ossaea, Pachyanthus, Pleiochiton, Sagraea, Tetrazygia, and Tococa. In the absence of a workable solution that allows the subdivision of the tribe into smaller, morphologically recognizable and monophyletic genera, it has been previously proposed that only one genus be recognized in the tribe. Here we present the necessary taxonomic and nomenclatural changes necessary to recognize Miconia as the sole genus within Miconieae.