This species may be distinguished from the related A. caviventris and A. concinnus by the triangular rather than quadrilateral third submarginal cell of the forewing and the shorter setae, or hairs, on the thorax and abdomen.

[2] A. nigerrimus is a Holarctic species found from Northern and Central Europe eastwards across Asia to the Pacific Coast and in North America from the Yukon[3] to Newfoundland.

[5] The flight period in Great Britain is May to September,[5] although in northern California adults have been collected in May, June and July.

[6] Prey collected by A. nigerrimus include spiders from the families Lycosidae, Gnaphosidae and Pisauridae.

[5][6] One nest of four cells was found under a stone on moorland at an altitude of 400 m in Glen Tilt, near Blair Atholl, Perthshire.