Housekeeping genes such as translation elongationfactor-1a (EF-1a) and actin are frequently used as indepen-dently evolving markers because they do not appear tohave undergone horizontal transfer or gene duplication.Moreover, the rates of sequence substitutions in exons areconstrained by codon positions, which may determine thetaxonomiclevelofanalysis(Baldauf&Palmer,1993;Kretzer& Bruns, 1999).Beca