  A recent 15 parts-per-million (ppm) experiment on muonic hydrogen found a
major discrepancy with QED and independent nuclear size determinations. Here we
find a significant discrepancy in a different type of exotic atom, a medium-Z
nucleus with two electrons. Investigation of the data collected is able to
discriminate between available QED formulations and reveals a pattern of
discrepancy of almost 6 standard errors of experimental results from the most
recent theoretical predictions with a functional dependence proportional to Z^n
where n=4. In both the muonic and highly charged systems, the sign of the
discrepancy is the same, with the measured transition energy higher than
predicted. Some consequences are possible or probable, and some are more
speculative. This may give insight into effective nuclear radii, the Rydberg,
the fine-structure constant or unexpectedly large QED terms.
