I do not know in which context they've used this primer, however, in maximum instances, dashes, hyphens and dots are used to indicate specific and deliberate mismatches. Hyphens within the PCR primers typically denotes the use of the identical base as in the template sequence. Dashes are normally used to denote the use of the alternative purine while dots refer to the use of the alternative pyrimidine. Silly to mention, generally these primers are so designed that they binds handiest to the conserved regions.