In a 2009 study of DNA sequences of 13 genes, 42 families were placed into 16 groups, ranging in size from one to 10 families.
Nun estudo realizado en 2009 de secuencias de ADN de 13 xenes, 42 familias puxéronse en 16 grupos, cun tamaño que abranguía dunha a dez familias.