Gary kindly sent me a single male specimen of M. buchanani. Unfortunately, I have no female specimen to compare the secondary (external) sexual differences in this species. Perhaps the literature addresses the differences, but I haven't checked. As in BugGuide photo 1903749, the first four protarsomeres of my male exhibit on their undersides two dense rows of "hairs" or "scales", somewhat curled in photo. Hard to say from the two photos if the male protarsomeres are truly proportionately wider than those of females. Readily observable expansion of protarsomeres among carabid males is the familiar rule, but there are many species exceptions. The more consistent rule is that only male protarsomeres show ventral vestiture (dense hairs/scales), but again there are exceptions.

The anal setation count is often useful for separating the sexes. My male specimen shows two long setae (one bilateral pair) near the apical edge of the abdomen. In many carabid species, the females will have four (or more) such anal setae (at least two bilateral pairs). I don't know if this rule applies to female M. buchanani but perhaps Gary will report back to us on this additional feature. Sometimes a long anal seta is broken off, but one can still see its associated puncture.

Incidentally, the ventral habitus photo (#1557398, July 12, 2018) shows two short "spikes" protruding from apical abdomen. It is likely these "spikes" represent the familiar bilateral female stylomeres, and so we are looking at a female in photo #1557398! Gary, please recheck this. Thanks. [Update: 1557398 was replaced by 1904122]

Moved from Metacolpodes.