 Taxonomic sequences are essentially heuristic devices that help in arrangements of linear systems such as books and information retrieval systems.Since phylogenetic relationships are complex and non-linear, there is no unique way to define the sequence, although they generally have the more basal listed first with species that cluster in a tight group included next to each other.The organization of field guides and taxonomic monographs may either follow or prescribe the taxonomic sequence; changes in these sequences are often introduced by new publications.