I have a draft key to Prioninae genera of US prepared....and I discovered a character that is very good for distinguishing Neomallodon from the other similar genera (Mallodon, Nothopleurus, Archodontes, etc.).

If there is no sutural spine present on the elytra, it is Neomallodon. All the others have a small but distinct spine at suture.

I can't be sure, but it looks as if this does have a spine which would mean it is not Neomallodon and most likely Nothopleurus.

Here's the relevant couplets of the key for these similar genera:

9(8’). Mandibles projecting partially downward, with their underside forming an angle with the ventral surface of the body that is less than 150 degrees (apices of mandibles not fully visible from dorsal view) …………….Archodontes
9’. Mandibles projecting more horizontally, with their underside forming an angle with the ventral surface of the body that is greater than 150 degrees (apices of mandibles usually fully visible from dorsal view)………………………10

10(9’). Metepisterna narrow, mesal margin extending less than one-third distance from elytral margin to ventral plane as viewed from lateral perspective. Gena coarsely, contiguously punctate and sculptured. Elytral suture with small spine………… Nothopleurus
10’. Metepisterna wide, mesal margin extending to nearly one-half distance between elytral margin and ventral plane as viewed from lateral perspective. Gena with very fine or moderate, but separately spaced, punctures. Elytral suture with or without small spine ... 11

11(10’). Elytral apex without spine at suture. Mandibles very thickened; bulging and rounded laterally. Gena with moderate punctures. Pronotum exhibiting little dimorphism--smooth and nearly impunctate on disk in both sexes…………………………Neomallodon
11’. Elytral apex with a small spine at suture. Mandibles not very thickened; not bulging and more straight laterally. Gena finely, sparsely punctate. Pronotum exhibiting dimorphism—disk smooth and nearly impunctate in females; with impunctate calli surrounded by small punctures in males……………………………………….12

12(11’). Mandibles densely pubescent along inner margin in male. Mandibles of both sexes generally shorter than head (much shorter in females)………………….Mallodon
12’. Mandibles mostly glabrous along inner margin in male. Mandibles of both sexes as long or longer than head (often much longer in males)…………………Stenodontes

Moved from Macrotomini.