Taxonomia de Convolvulaceae a. Juss. Na região do Pajeú, semiárido de Pernambuco, Brasil

Abstract

Convolvulaceae includes 58 genera and about 1,880 species with cosmopolitan distribution, but with greater diversity in the tropics. In Brazil it is represented by 24 genera and 430 species. The Northeast of the country has a high number of family species and a great lack of knowledge about Convolvulaceae, although in recent years, several new species have been described, most of them endemic. Local studies have helped to narrow this gap, but little is known about the taxonomic and morphological diversity and geographic distribution of the family in some areas, especially in the semiarid. Thus, this study aims to perform a synopsis of the Convolvulaceae species in the Pajeú region, Pernambuco. The study area is located in the Caatinga phytogeographic domain and comprises 17 municipalities. The study was based on the collection and observation of field populations and analysis of collections belonging to the Semiarid Herbarium of Brazil (HESBRA). So far, 29 species have been recognized distributed in six genera, being Ipomoea the most representative with 19 species, followed by Jacquemontia, with four, Evolvulus with three, Merremia, Operculina and Turbina, with one species each. The recorded taxa can be differentiated mainly through characteristics of the habit, type and shape of leaves and sepals, dimensions and shape and color of the corolla and presence / absence of trichomes or types. All species are new records for area, as there were no family-specific taxonomic studies in the Pajéu region. Most species were found in caatinga vegetation, while I. alba, I. decipiens, I. indica and I. parasitica only in highland forests. Ipomoea alba, I carnea and I. indica are grown in the region as ornamental. Ipomoea bahiensis, I. brasiliana, I. rosea and Turbina cordata occur exclusively in Brazil and I. decipiens, I. marcellia and I. tenera are endemic to the Caatinga domain. Ipomoea decipiens is also here for the first time registered for Pernambuco. Identification keys and comments on geographic distribution, habitats, phenological data and distinctive character of the species are presented here. Endemism data and the new occurrence highlight the importance of preserving the environments found in the Pajeú region, especially the mountain forests, as well as reinforcing the need for further taxonomic studies in the area.