Phylogenetic tree based on the partial nucleotide sequence of the Fusion gene of APMV-1. Viral sequences generated in this study (underlined) and previously published sequences are denoted by their GenBank accession number followed by isolate names. The reference strains were adapted from a recently suggested nomenclature for APMV-1 . Class I and class II viruses as well as genotype I to XV, including sublineages, within the class II clade are indicated by roman numerals. Statistical supports of ≥ 70% for inferred nodes are displayed. The branch between class I and class II clades of viruses has been truncated in order to limit the tree size.