Chromosome comparison and crossability tests compel relegating 6 of 10 Hopkins' Pissodes taxa to synonymy, namely, utahensis with similis Hopk., nigrae and alascensis with rotundatus Lec., fraseri and piperi with dubius Rand., and curriei with affinis Rand. Two, dubius and rotundatus, and possibly a third, affinis, of the four valid species revealed meiotic markers of semi-incompatibility not previously encountered; presumably, as in the strobi complex, the fourth, similis, is merely devoid of the necessary chromosomal diagnostic.