PHENETIC ANALYSIS OF 28 SPECIES PANGASIID CATFISHES FROM ASIA

Abstract

A great variation in the external morphology of pangasiid catfishes and it is difficult to give a standard definition of their external appearance. The degree of similarity, known as phenetic analysis, is generally one of the criteria on which the recognition of taxa has been based. The objective of this phenetic analysis was to determine the degree of similarity. A measure of dissimilarity was computed from the coordinates of the first two axes of the Correspondence Analysis, using Euclidean distance. The distances were used to produce coefficients of similarity between each species pair. Distances are  non-negative and low values indicate similarity. Distance values for the matrix were then clustered with the unweighted pair-group method using the arithmetic average and summarized in a phenogram. The results showed that all species analysed for proposed genera aggregated. Analysis on 28 species supports that they should belong to four genera.