Polytomy 

A polytomy, meaning many temporal based branches, is a section of a phylogeny in which the evolutionary relationships can not be fully resolved to dichotomies. In a phylogenetic tree, a polytomy is represented as a node which has more than two immediate descending branches. They present an analytical problem, but can usually be better studied by utilizing more flexible phylogenetic network software such as SplitsTree, which can represent some polytomies as median networks. Two types of polytomies are recognised, soft and hard polytomies. Soft polytomies are the result of insufficient phylogenetic information: though the lineages diverged at different times – meaning that some of them are closer relatives than others – the available data does not allow to recognize this. On the contrary, hard polytomies represents several speciation or lineage divergence events occurring at the same time, i.e. without their ancestral population, lineage or gene pool evolving in between, the resultant daughter species are equally distant from each other. While some researchers doubt that hard polytomies occur at all, there is little reason to assume that they don't. In particular situations they may even be not uncommon, for example when a species that has rapidly expanded its range and/or is highly panmictic undergoes peripatric speciation in different regions. (wikipedia)