Phylogenetic Placement of New Species with Fused Calyx Reveals Homoplastic Character in Eugenia (Myrtaceae)

Abstract

Abstract—The hyper-diverse Eugenia with ca. 1050 species currently includes Calycorectes, which fits the morphological delimitation of the latter except its calyx lobes are fused in the bud and tear at anthesis. Previous phylogenetic reconstruction demonstrates a single evolutionary event of calyx fusion in Eugenia. A new species, Eugenia petaloidea, found in remnants of submontane Atlantic Forest in northeast Brazil is morphologically unique with two external fused calyx lobes that split at anthesis and two internal free and petaloid calyx lobes. Only a few other Eugenia species share this condition, and Eugenia petaloidea can be distinguished from those by the externally glabrous hypanthium. The phylogenetic placement of Eugenia petaloidea based on three DNA markers (ITS, ETS, and psbA-trnH) indicates that this is the second clade of Eugenia known to have a fused calyx, indicating fusion of the calyx to be a homoplastic condition. The new species is here described, illustrated, and assessed according to IUCN criteria.