Fenologia, morfologia floral e visitantes de Psychotria brachypoda (Müll. Arg.) Britton (Rubiaceae) em uma área de Floresta Atlântica, Sudeste do Brasil

Abstract

In this paper, the phenological pattern, floral biology, most frequent floral visitors and fruit set of Psychotria brachypoda are described. This study was carried out in Atlantic forest from October 2003 to September 2005. Flowering was annual and intermediate, occurring from August to January. Mature fruit production occurred from March to July 2004 and from February to June 2005. Corolla length and diameter of thrum flowers were larger than those of pin flowers. Although stigma length corresponded approximately to stamen length in each morph, exact reciprocal hercogamy did not occur. The nectar was more concentrated at 06:30h (33%) and more diluted at 14:30h (26%). Flowers in which nectar was collected throughout the day had about three times more nectar than flowers in which nectar was collected once at the end of the day. There were 24 plants with thrum flowers and 25 plants with pin flowers, indicating an isopletic population. The main floral visitors were females and males of the hummingbird Thalurania glaucopis, bees of the tribe Trigonini and of the genus Euglossa, three Lepidoptera species, one Diptera species and one Coleoptera. Fruit was produced in 13.7% of the total number of marked flowers, with similar production in both morphs. Thalurania glaucopis is probably the most important pollinator of P. brachypoda, because it often visits many flowers from different individuals of P. brachypoda, probably transferring pollen among them.