TL;DR: Interestingly, not only colonization from Africa occurred but also long distance dispersal from the Neotropics shaped the current diversity of the Spermacoceae tribe on Madagascar.
TL;DR: A molecular phylogenetic study indicates that the Madagascan endemic members of Spermacoceae are the result of at least two independent colonization events, most likely by long-distance dispersal from the African mainland.
TL;DR: A phylogenetic reconstruction based on four plastid markers proves that Lathraeocarpa acicularis has its closest relatives among taxa of the Hedyotis-Oldenlandia group of the herbaceous tribe Spermacoceae sensu lato and a detailed survey of the morphology and anatomy of the genus based on recently collected material is presented, providing additional arguments for the new taxonomic position.
Abstract: Lathraeocarpa acicularis, a small woody Rubiaceae endemic to Madagascar, was rediscovered after more than 50 years. A phylogenetic reconstruction based on four plastid markers (atpB-rbcL, rps16, trnL-trnF, petD) proves that its previous position within the monogeneric tribe Lathraeocarpeae can no longer be supported. Our data clearly show that Lathraeocarpa acicularis has its closest relatives among taxa of the Hedyotis-Oldenlandia group of the herbaceous tribe Spermacoceae sensu lato. The taxon falls within the Pentanopsis clade and is sister to a group comprising the Madagascan genus Gomphocalyx and the Afro-Madagascan genus Phylohydrax. A detailed survey of the morphology and anatomy of the genus based on our recently collected material of Lathraeocarpa acicularis is presented, providing additional arguments for the new taxonomic position.