Adrian Pont gave me this rather beautiful Costa Rican tachinid recently and it instantly reminded me of the Eucelatoria sp. that I had been working on from Bolivia and French Guiana. The deep matt velvety black contrasting with the yellow dusting stripes, combined with the elongate body and legs are all quite distinctive features. When keying this in Monty’s key though it fails to get to Eucelatoria (and goes on to Calolydella) because the excavation on T1+2 on this specimen does not quite reach the median marginals – it is as far away from them as they are from the posterior margin of T1+2.
EDIT (25/11/2010): On showing the photos to Monty Wood he has said that it is clearly one of the Calolydella geminata complex (which includes up to 12 species in Costa Rica alone!). Just goes to show – trust the key – don’t assume that it is a Eucelatoria just because it looks like one!! 😉