What was the last mathematical paper published in Latin?
Solution 1:
Zentralblatt lets you search by language of paper where I discovered this recent example.
Schechtman, Vadim New definition of a vertex algebroid. (Definitio nova algebroidis verticiani.) (Latin) A Bernstein, Joseph (ed.) et al., Studies in Lie theory. Dedicated to A. Joseph on his sixtieth birthday. Basel: Birkhäuser. Progress in Mathematics 243, 443-494 (2006).
In the preface, the editors note that Schechtman's paper is "linguistically refreshing"!