Abstract: Internal transcribed spacer (ITS) and 5.8S of ribosomal DNA (rDNA) of 3 species (5 samples) of the genus Coronocyclus were amplified and sequenced using polymerase chain reaction (PCR) techniques. Sequence analysis demonstrated that the length of the ITS1-5.8S-ITS2 sequences ranged from 748 to 843 bp, and there were 119 variable sites (including gaps) and 18 parsimony informative sites. The length of the ITS1 sequences ranged from 367 to 370 bp, with 14 variable sites and 9 parsimony informative sites. The length of the ITS2 sequences ranged from 228 to 320 bp, with 105 variable sites and 9 parsimony informative sites. The 5.8S gene sequences of all 3 species were identical. For all 3 species, the G+C content was higher in the ITS1 (48.0% to 48.5%) than in the ITS2 (37.7% to 40.3%). Pairwise comparison in 5 sequences revealed inter specific differences ranged from 1.9% to 3.5% in the ITS1 and from 5.6% to 31.8% in the ITS2, however, intra specific variation was low (0 to 0.5% and 0 to 0.9%, respectively). Furthermore, the homology were 99.07% to 99.41% compared with the sequences in GenBank. The study demonstrated clearly that the internal transcribed spacer sequences provided genetic markers for the species identification of the genus Coronocyclus.

Key words: Coronocyclus; ITS; PCR; sequence analysis