All the possible combinations for cob primers designed based on dinoflagellate cob (Table 2 ; [12] , [23] , [24] ) were tested but failed to PCR amplify any products. BLAST searching using cob aa sequences from apicomplexans and dinoflagellates against the P. marinus whole genome shotgun sequencing database (tblastx) hit one contig (860 bp, AAXJ01022806) containing the 59 end of a cob-like sequence. The corresponding mRNA of this sequence and its 39 end were obtained for both species of Perkinsus by PCR and 39 RACE using Perkinsus-specific primers paired with the GeneRacer3 primer (GenBank accession numbers HQ670239, HQ670241; Figure 4 , Table 2 ).