Systematics ofPlagiochila sect.Glaucescentes Carl (Hepaticae) from tropical America: A morphological and chemotaxonomical approach

The systematics of theGlaucescentes Carl, a poorly known neotropical section of the large genusPlagiochila, is revised based on a large set of gametophytic, sporophytic and chemical characters. Three species are recognized,P. buchtiniana Steph.,P. longispina Lindenb. and Gottsche andP. diversifolia Lindenb. and Gottsche, the latter with two chemotypes. Twelve binomina are reduced to synonymy. The species occur in montane regions of tropical America, especially in the northern and central Andes. In addition,P. longispina is newly reported from the Azores, where it was previously known asP. allorgei Herzog and Perss. TheGlaucescentes are excellently characterized by morphological and chemical features and are clearly separated from theContiguae Carl, a group often confused with theGlaucescentes. Morphologically, theGlaucescentes stand apart by the brown oil bodies, thinwalled inner capsule wall cells and partly unequally bispiral elaters. Chemically, they are characterized by the accumulation of partially hydrogenated bibenzylderivatives (longispinone, longispinol), 3-benzylphthalides and various flavonoids, and by the low production of terpenoids.