Using PCR-based methodologies, we surveyed triploid Crassostrea ariakensis (Fujita 1913), introduced in experimental trials in the Chesapeake Bay, for parasites endemic to the native oyster and for Bonamia ostreae. Perkinsus sp. was detected in all in C. ariakensis samples analyzed, reaching prevalences equivalent to or higher than in the native oyster. Bonamia sp. was detected in a small number of C. ariakensis individuals (2.7%) from the York River, and analysis of amplicon sequences revealed novel Bonamia-related sequences as well as those close to previously described Bonamia spp. (B. ostreae, B. exitiosa, and B. perspora). Bonamia ostreae cross-infection experiments based on cohabitation of B. ostreae-infected Ostrea edulis (Linnaeus 1758) with uninfected C. ariakensis revealed no evidence of B. ostreae transmission after four weeks. Although these results may appear inconsistent with the identification of Bonamia-infected oysters obtained from the York River, the relatively short duration of this cross-infection experiment may account for the lack of parasite transmission. In contrast, Perkinsus sp. infected C. ariakensis efficiently transmitted the parasite to uninfected Crassostrea virginica (Gmelin 1791) within two weeks, under similar cohabitation conditions.