The L. impingens sub-group contains only L. impingens, a small to medium-size species with gray forewings and light yellow-brown hindwings. Th e male valve has a prominent costal lobe of the sacculus with a broad flattened apex (those of other Lasionycta species are conical or rounded). The vesica lacks subbasal cornuti and is relatively slen- der. Th e female bursa appears unisaccate due to minimal constriction similar to those in the L. staudingeri sub-group and the appendix bursae is small and curved distally. The male antenna is narrowly bipectinate, 1.46–2.0× as wide as the central shaft.

The L. impingens sub-group clusters with most of the species in the L. promulsa sub-group on CO1 distance analysis.