To my knowledge there are no other recent responsa that address this Pri Maggadim vs. Chazon Ish dispute. Although the debate was not relevant here, there are certainly species where it would have ramifications. For example in 1993 a new species of animal was discovered in Vietnam. Despite its being Old World there is clearly no tradition regarding its kosher status. It seems to be an unusual antelope with long, straight horns.
Scientists are unsure even how to classify it.
Originally it was put in a new genus in the bovine group together with oxen and elands. Now some people are grouping it with goats. Either way, this odd, elusive creature that is possibly on the verge of extinction exhibits both kosher indicia and yet lacks a mesorah - a perfect test case for this debate.