The A. astaci chitinases Chi2 and Chi3 possess an oomycete type-GH18 catalytic domain. Maximum likelihood phylogenetic analysis was performed with TreePuzzle using the diatom Thalassiosira pseudonana as an outgroup. Oomycete and fungal sequences are given in blue and grey, respectively. GenBank accession numbers of partial or complete amino acid GH18 domain sequences are indicated in parentheses. The scale bar represents 0.1 substitutions per site. The numbers at the nodes are quartet puzzling values indicating the frequencies of occurrence for 1,000 replicate trees and can be interpreted in much the same way as bootstrap values. The group A-V - one of six separate fungal groups classified [27, 28] - showing the closest homology to the sequences identified in this work, is represented by two members. An asterisk denotes partial sequences.