Mecodema is a genus of large flightless ground beetle (Carabidae) endemic to New Zealand.

The genus is very diverse in comparison to the other three New Zealand genera (Diglymma, Oregus, Orthoglymma) within the subtribe Nothobroscina (tribe Broscini).

Head, frons and vertex often rugose and / or punctate, microsculpture or macrosculpture absent in some species groups (e.g., curvidens species);[2][3] eyes prominent, almost hemispherical; a single supraorbital puncture on each side, bearing more than one setae; setose punctures of vertex absent; mandibles large, uniformly narrow to the pointed apex, sharply curved in the apical third, mandibles with a number of dorsal grooves and without a seta in the scrobe;[2][3] mentum with median process, which is notched to strongly indentate (bifid); usually with 2 setiferous punctures (may be absent) below the process and generally with 4–8 setose (setiferous) punctures along the submentum sclerite; labial palpi with setae on the penultimate segment; terminal segments of all palpi slightly compressed, sub-cylindrical, truncate; ligula chitinous with a median carina, 2 apical setae present; the membranous paraglossae extended well beyond the apex of the ligula; stipes with 2–3 basal setae; antennomeres I–II glabrous, III–V with apical ring, VI–XI setose throughout; antennomeres I–III subcylindrical, IV–VII subglobose and slightly compressed.

Prothoracic carina (pronotal lateral margin) distinct with an asymmetrical number of setae along each side, the last never at the posterior lateral sinuation (posterior angle); midline (median groove) and pronotal foveae (laterobasal depressions) always present; pronotal disc often with shallow depressions on each side of apical half.

Legs slender, the protibia with a pointed apical prolongation on the outer side, greatly distally expanded to distally expanded and shovel-like; male and female tarsi identical, the basal 4 segments of the anterior tarsi are as broad as they are long, usually slightly asymmetrical.