Synonymies. See Turrisi et al. (2009: 53).
The genus Pristaulacus has been redefined by Turrisi et al. (2009) within a cladistic framework and is represented in all zoogeographic regions excepting Antarctica. It can be distinguished from Aulacus by the following combination of characters: occipital carina present (Figs. 6, 7, 23) (absent in Aulacus); frons not sculptured above antennal sockets (Figs. 5, 7) (sculptured in Aulacus); tarsal claws with three or four tooth-like processes along inner margin (Fig. 15) (with only one weak basal process in Aulacus); petiole slender, at least 2.5 times as long as wide (Figs. 1, 2, 22) (at most 1.0 times as long as wide in Aulacus) (Turrisi 2007; Turrisi et al. 2009).
The Japanese species of Pristaulacus can be distinguished by the following key, updated after Turrisi & Konishi (2011) and Turrisi & Watanabe (2011).