  An $r$-gentiling is a dissection of a shape into $r \geq 2$ parts which are
all similar to the original shape. An $r$-reptiling is an $r$-gentiling of
which all parts are mutually congruent. This article shows that no acute
tetrahedron is an $r$-gentile or $r$-reptile for any $r < 9$, by showing that
no acute spherical diangle can be dissected into less than nine acute spherical
triangles.
