Verification of cyprid size as a tool in the identification of two European species of Chthamalus barnacles using mtDNA-RFLP analysis

Adult barnacles of Chthamalus stellatus and Chthamalus montagui were collec ted in August 1998, from Garrettstown Co. Cork and Kilkee Co. Glare, in sou thwest and west Ireland, respectively. Attached cypris larvae were collecte d during the settlement season of C. stellatus and C. montagui, on 2 shores in Co. Cork and 1 shore on Glare Island, Co. Mayo in west Ireland. Cyprid collections were made during either August or September, in 1992, 1994 and 1998 and all cyprids were measured along their carapace length. Size-freque ncy histograms were produced for each sampling occasion. Total DNA was extr acted and the COI-COII mitochondrial genes were PCR amplified, both from se lected adults and cyprids of each species collected in 1998. Composite hapl otypes, produced by digesting PCR products with the restriction endonucleas es TaqI and RsaI, showed clear identification between the 2 species as adul ts and larvae. Of the 68 cyprids examined, those measuring 525 mu m and und er were found to have RFLP profiles corresponding with C. moniagui adults, while those of 550 mu m and larger were found to match C. stellatus adults. The findings verify previous length-frequency analysis. Carapace length is an important character in the identification of C. stellatus and C. montag ui cyprids. The PCR primers developed during this study will also amplify D NA from 4 other species of acorn barnacle.