This species had not been recorded in Britain at the time of Richards' (1980) RES handbook, but identification characters are given in Lomholdt (1984). It was first recorded in Britain in 1986 (Allen, 1987), although it may previously have been confused with S. solskyi.

A small, stem nesting solitary wasp. Identification keys are given in Lomholdt (1984) (as R. nigrinum), Richards (1980) and Yeo & Corbet (1995).

A small, black solitary wasp. Identification keys are given in Lomholt (1984), Richards (1980) and Yeo & Corbet (1995).

A small, ground-nesting red and black solitary wasp. Identification keys are given in Richards (1980), Lomholt (1984) and Yeo & Corbet (1995).

Probably the most common British species of Passaloecus, at least in the south.

A small, ground-nesting, red and black solitary wasp. The nomenclature of this species has been the subject of some confusion. Identification keys are given in Yeo & Corbet (1995) (as Psen bicolor); Lomholt (1984) (as Mimesa rufa), and Richards (1980) (as Psen bicolor). Prior to the publication of a paper by Spooner in 1948 the species was referred to as Psen equestris, so care is needed when citing older records of this wasp.

A species closely related to Passaloecus insignis, from which it is separable only with difficulty.

A small, black sphecid wasp, formerly placed within the genus Psen. It is one of ten species currently placed within the genus Mimumesa to be found in Europe, and is probably the most widespread of those species.

In the older literature this species has been placed in the genus Notozus, where it was known as scutellaris or constrictus. Identification keys and general biology are given in Morgan (1984) and Kunz (1994).