Diversity and phylogeny of the order Halymeniales (Rhodophyta) on the Brazilian Coast

Algae of Halymeniales (Rhodophyta) present a wide ecological and economic importance, as primary producers and bioactive compounds producers, and include invasive species worldwide. Its taxonomy is quite problematic, with reports of misidentifications and nomenclatural changes. Therefore, studies have included molecular tools to assist the morphological taxonomy of this order. This study aims to investigate through molecular and morphological techniques the diversity of Halymeniales along the Brazilian coast, in order to contribute to the knowledge of native marine flora. Three molecular markers were sequenced, UPA, COI-5P and rbcL, whose data were allied to morphological characters and resulted in 26 delimited species. There are 11 new species to science: Corynomorpha cf. clavata, two taxa morphologically identified as \"Cryptonemia\" crenulata, two taxa morphologically identified as Cryptonemia seminervis, Halymenia ignifera, Halymenia pinnatifida, Halymenia silviae, Grateloupia cf. dichotoma, Grateloupia cf. filicina 1 and Grateloupia cf. filicina 2. At least seven new genera were found, represented by the following taxa: \"Cryptonemia\" bengryi, representatives of \"Cryptonemia\" crenulata complex, \"Cryptonemia\" delicatula, \"Halymenia\" elongata, \"Halymenia\" floridana, Halymeniales sp. 1 and Halymeniales sp. 2. Three species whose type locality is Asia were detected: Grateloupia orientalis, Grateloupia turuturu and Grateloupia yangjiangensis. Among taxa previously recorded to Brazilian coast, nine were not found. If those taxa constitute valid species, the diversity of the order in Brazil will be represented by 35 species. Phylogenetic analyses showed that Cryptonemia, Halymenia and Grateloupia constitute non-monophyletic groups. Results demonstrated the existence of wide cryptic and pseudo-cryptic diversity as well as novel species and genera, and revealed the presence of non-native species (AU)