Flora de Pernambuco (Brasil): Lythraceae J. St.-Hil.

Abstract

Lythraceae is comprised in Myrtales as sister group of Onagraceae. Lythraceae comprises about 30 genera and 600 species being widely distributed in tropical and subtropical regions. In Brazil, 11 genera and 216 species are recognized, with 160 endemic. The Northeast region is the third with the highest recorded richness (57 spp. in 7 genera). In Pernambuco four genera and 16 species are found, representing the second richest state of the region. Despite the family's representativeness for the region, there is a lack of studies about the family, compromising the knowledge related to the taxonomic richness and geographical distribution of its species. This work aimed to perform the taxonomic study of Lythraceae species occurring in Pernambuco (Brazil). For this, field expeditions and analysis of the materials from CEN, HESBRA, HST, HTSA, HUEFS, HVASF, IPA, JPB, PEUFR and UFP herbaria between 2018 and 2020 were conducted. Were recognized 12 species and five genera ( Ammannia L., Cuphea P. Br., Lafoensia Vand., Pleurophora D. Don. and Rotala L.). The species found predominate in Caatinga environments in the state. Complete morphological descriptions, an identification key, phenological period information, geographical distribution, taxonomic notes, photographs and illustrations of the diagnostic characters are presented. The morphological characters relevant to the identification of the species are: branch indumentum; leaf insertion and phyllotaxy, blade, base and apex shapes, indumentum type and venation; inflorescence type and position, presence or absence of bracteoles; presence or absence of spur, as well as the shape of this structure; presence or absence of petals, as well as their color and size. Also presented is the article entitled “Flora of Usina São José, Igarassu, Pernambuco (Brazil): Lythraceae J. St.-Hil. and Onagraceae Juss.”, which is about the families in the Atlantic Forest fragments of Usina São José, Pernambuco, which undergo anthropic actions, resulting in implications for conservation. The taxonomic treatment identified six species and three genera, Cuphea , Rotala (Lythraceae) and Ludwigia L. (Onagraceae). Rotala ramosior (L.) Koehne is a new record for Brazil. The characters considered for the delimitation of the species were: phyllotaxy, branch indumentum, leaf shape and indumentum, petal color and apex, capsule shape, seed arrangement and raphe size. Results of these works provide subsidies for understanding the ecological importance of these species, in addition to helping to reduce the taxonomic impediment and serve as a basis for future studies of evolution, ecology and conservation of Brazilian flora.