Taxic diversity: Vane-Wright et al., 1991 and May 1990 which accounts for polytomies by counting the number of branches descending from each node that lies on the path from a spp tip to the root (not just counting the number of nodes).
tax.distinctiveness(tree, type = c("Vane-Wright", "May"))
an object of class phylo
specify "Vane-Wright" or "May"
Vane-Wright, R.I., Humphries, C.J. and Williams, P.H. (1991). What to protect? - Systematics and the agony of choice. Biological Conservation, 55, 235-254.
May, R.M. (1990). Taxonomy as destiny. Nature, 347, 129-130.
Mark Vellend, William K. Cornwell, Karen Magnuson-Ford, and Arne Mooers. In press. Measuring phylogenetic biodiversity In: Biological diversity: frontiers in measurement and assessment. Edited by Anne Magurran and Brian McGill.