Classification, origin, and patterns of diversification of Corynocarpus (Corynocarpaceae) inferred from DNA sequences

Sequences from the chloroplast-encoded gene rbcL and the nuclear-encoded in ternal transcribed spacer (TTS) region were analyzed independently and then combined to infer phylogenetic relationships of Corynocarpus. Relationship s obtained from the rbcL and ITS data sets are are largely congruent and we ll resolved. The combined data set provides even greater support for relati onships. The rhcL results support current placement of Corynocarpus in its own distinct family, the Corynocarpaceae, and suggest that this family is m ost closely related to the Anisophylleaceae, Begoniaceae, Coriariaceae Cucu rbitacene, Datiscaceae, and Tetrameiaceae, together comprising the order Cu curbitales. This contradicts traditional classifications, which have placed the Corynocarpaceae in the Celestrales. The file species of Corynocarpus a re genetically distinct, but comparison of ITS sequences shows little intra specific sequence variation within C. laevigatus and C. rupestris. The pres ent distribution, fruit morphology, and patterns of relationships inferred from the sequence data suggest a Palaeotropical center of origin and two in dependent radiations in the Corynocarpaceae. The first radiation comprises C. cribbianus and C. rupestris, which extend through New Guinea to Australi a, and the second radiation comprises C. dissimilis and C. laevigatus, whic h extend southwards through New Caledonia to New Zealand.