1	Elytra with series of deep to shallow punctures forming strongly to almost erased, excavated striae; additional series of punctures often present on the elytral intervals (Fig. 14A, B). Small size (6.9–12 mm)	2
–	Elytra without any trace of longitudinal series of punctures forming striae (Fig. 14C, D); if very weak striae are present, then interstriae show slightly raised longitudinal series of more or less developed and separated tubercles (Fig. 14D). Medium to small size (7.5–14 mm)	3
2	Anterior angles of pronotum slightly prominent (Figs 15A, 1C). Elytra with poorly marked striae, formed by longitudinal series of shallow to almost erased punctures; interstriae smoothly curved (Figs 7, 14A)	M. ramburii
–	Anterior angles of pronotum markedly prominent (Figs 15B, 16D). Elytra with strong to shallow striae, formed by longitudinal series of deep to shallow punctures; interstriae clearly convex (Figs 1, 14B)	M. gibbulus
3	Anterior angles of pronotum rounded, forming an open angle (Figs 16E, F). Elytra with shallow to almost erased striae, often showing longitudinal series of more or less developed elongated tubercles, or sometimes shallow fossae on the interstriae, better marked on the second half of the elytra and on the sides (Fig. 14D). Medium size (10–14 mm), long antennae (Fig. 3)	M. goudotii
–	Anterior angles of pronotum forming a widely acute to right angle (Figs 16A, B, 17). Elytra without any trace of striae or tubercles. Medium to small size (7.5–13 mm), relatively short antennae	4
4	Pronotum sculpture formed by deep large confluent punctures (Fig. 16A); the surface between punctures progressively transforms in irregular raised areas that become small irregular granules and wrinkles, giving a strongly rugose appearance to the pronotum sides (Figs 9, 16A). Medium size (11–13 mm)	M. scabricollis
–	Pronotum sculpture formed by deep to shallow, dense or sparse, never confluent, well-defined punctures which cover all the pronotal surface, including the lateral sides, which can present somewhat more confused punctation, but not forming rugose areas (Fig. 16B). Large to small size	5
5	Elytra covered by dense punctures somewhat confused or partially erased at the disc. Pronotum sculpture formed by deep, dense, well-defined punctation. Antennae relatively short, not reaching the base of pronotum (Fig. 5). Small size (7.5–8 mm)	M. lusitanicus
–	Elytra covered with very fine, shallow and sparse punctation that gave a silky shine to the elytral surface (Fig. 14C). Pronotum sculpture formed by shallow, spaced, and very fine well-defined punctation (Fig. 16B). Antennae usually reaching the base of pronotum (Fig. 11). Medium size (10–12 mm)	M. subglaber