The "strongly ridge on the basis of the elytra" is in the definition of the subgenus : "les élytres pourvus chacun d'une crête longitudinale élevée au milieu de la base".
...but your specimen has a small lateral tuber in front of the pronotum; so, following Breuning (1938), it can't be a Mesosa (Metamesosa) sp. Specimen here seems the same.
Vietnam: Mesosa (Metamesosa) basinodosa?
Posted - 21/03/2018 : 10:40:28
The "strongly ridge on the basis of the elytra" is in the definition of the subgenus : "les élytres pourvus chacun d'une crête longitudinale élevée au milieu de la base".