文摘
Recent phylogenetic studies in the Vanguerieae adopted a narrow circumscription for Canthium characterized by the presence of supraaxillary spines. For a continuing project in Philippine Rubiaceae, an important focus was to resolve the disposition of spineless Philippine Canthium. In a collecting trip to key forested sites in the Philippines, two endemic Canthium species were collected: C.monstrosum and C. wenzelii. The absence of spines hinted at a deviation from Canthium sensu stricto (s.s.) and thus raised questions on their generic affiliation. Phylogenetic analysis of the combined ITS-trnL-F data sets showed a well-supported clade of Vanguerieae (PP = 1.00; BS = 100 %). The two endemic Canthium species seemed to have close affinity with Keetia (PP = 0.79; BS = 69 %), within a supported clade (PP = 0.99; BS = 80 %) containing Afrocanthium. Although the C. monstrosum–C. wenzelii-Keetia clade showed low BS support, it appears that morphological attributes shared by these taxa support this relationship. However, the Philippine endemics are morphologically distinct from Keetia by having a shorter calyx limb than the calyx tube, strictly pentamerous corolla, style ± same length with the corolla tube, wider than long stylar knob, glabrous disc, ellipsoid fruit and several features of pyrene such as strictly woody, an angular ventral side, presence of a longitudinal slit within the crest and the absence of a defined lid. To maintain homogeneity, taxonomic stability and distinct geographical distributions we proposed a new Philippine endemic genus Kanapia.KeywordsCanthiumITS (nrDNA)MalesiaRubiaceaetrnL-F (cpDNA)