Coral-host specificity of Red Sea Lithophaga bivalves: interspecific and intraspecific variation in 12S mitochondrial ribosomal RNA.

Comparison of 12S mitochondrial ribosomal DNA sequences was used to approach the question of species specificity between boring bivalves of the genus Lithophaga and their coral hosts. A 450-bp long fragment was amplified by PCR from 13 individuals belonging to five subgroups of Lithophaga bivalves. These subgroups are defined according to their coral hosts species, and they belong to three currently recognized species: L. lessepsiana (1 host), L. simplex (2 hosts), and L. purpurea (2 hosts). All bivalves were collected from corals growing within an approximately 200-m section of the reef of Eilat, Red Sea. Sequence variation between members of the same species inhabiting different hosts (30-32%) was found to be very similar to the variation exhibited between recognized species. These results, when interpreted together with previously published data concerning variations among Lithophaga subgroups, support the notion of a very high degree of species specificity between Lithophaga bivalves and their coral hosts in the Red Sea.