Margaritopsis (Rubiaceae, Psychotrieae) Is a Pantropical Genus

Relationships among 40 species of the tribe Psychotrieae were estimated by cladistic analysis of nucleotide sequence variation in the rpsl6 intron (cpDNA). One strongly supported clade was found to include the genera Chazaliella, Chytropsia, Margaritopsis and Readea, and a number of species presently referred to Psychotria. It is suggested that this group should be treated taxonomically as one genus, the correct name of which would be Margaritopsis. The names Chazaliella, Chytropsia and Readea thus become synonyms of Margaritopsis. Margaritopsis in this broad sense is diagnosed by non-caducous stipules which are often marcescent, becoming papyraceous when old, by a greenish (rather than reddish or brownish) drying colour, planoconvex pyrenes with horny endocarp and distinct, marginal germination slits, and seeds with pale testa without an ethanol-soluble pigment. With this circumscription, Margaritopsis has ca. 10 species in the neotropics, ca. 25 in Africa, ca. 12 in New Caledonia and Fiji, and a few in SE Asia. It is doubtful if it occurs in The Philippines, New Guinea, Australia, Samoa or Hawaii. Three new combinations are made, Margaritopsis membranacea (Gillespie) L.Andersson, M. astrellantha (Wernh.) L.Andersson, and M. abrupta (Hiern) L.Andersson.