Phylogenetic affinities of Monimiaceae based on cpDNA gene and spacer sequences

Nucleotide sequence data from the chloroplast rbcL gene and the trnL-trnF intergenic spacer of 58 species in 38 genera were used to infer the phylogenetic affinities of Monimiaceae to other Laurales, and to assess whether the family in the traditional wide sense is monophyletic. Besides Monimiaceae, the Laurales comprise Calycanthaceae, Gomortegaceae, Hernandiaceae, and Lauraceae. Magnoliaceae and Myristicaceae were used as outgroups. Based on recent molecular data, Amborellaceae and Chloranthaceae, which have sometimes been included in the order, do not belong in the Laurales, and indeed trnL-trnF sequences of Amborella (Amborellaceae) and Hedyosmum (Chloranthaceae) were too different to be unambiguously aligned with the remaining sequences. Parsimony analyses of the trnL-trnF and trnL-trnFrbcL data groups the genera into five major clades, Calycanthaceae, Atherospermataceae, Gomortega, Siparunaceae, and a weakly supported Monimiaceae s.str.-Lauraceae-Hernandiaceae clade. RbcL data alone provide no resolution at the family level. Many aspects of traditional intra-familiar classification of Monimiaceae are supported except that the sole perfect-flowered member of the family, the monotypic Sri Lankan Hortonia, is not basal (13 of 15–22 genera sampled). Instead, there are two major clades in Monimiaceae. One comprises the functionally dioecious monospecific Peumus from Chile plus the morphologically and functionally dioecious small genera Monimia from the Mascarenes and Palmeria from eastern Australia and New Guinea. The other consists of Hortonia and all remaining genera. The atherospermatoids are supported in their traditional circumscription (14 species, 7 genera, of which 10 and 6 were sampled). The neotropical genus Siparuna, different from recent classifications that have stressed its isolation, is genetically and morphologically very close to the West African species Glossocalyx longicuspis. Both taxa have unisexual flowers of the same general morphology, and both have unitegmic ovules. From the current data it seems that monoecy is basal in Siparuna, but more complete sampling of species with a faster evolving genetic marker is needed for a fuller understanding of the evolution of monoecy and dioecy in this genus.