Friesea truncata is a bluish-grey moderately common and widespread soil-dwelling species with three, occasionally four (Fig. 1), or five anal spines. It was formerly known as Friesea mirabilis var. reducta. The largest specimen I have seen is 1.2 mm in length. Friesea truncata does not possess clavate setae and a mucro is absent from the dens (Figs. 2, 3, 4; this is the main feature which separates it from Friesea mirabilis). In fact, several specimens labelled Friesea 'mirabilis' in the NHML collection are Friesea truncata which is obviously more common and widespread than has hitherto been realised.
Some authors use chaetotaxy to separate Friesea mirabilis from Friesea truncata. Friesea mirabilis has been described as having seta a4 PRESENT on the dorsal side of the second thoracic segment (th2) whereas in Friesea truncata, seta a4 is ABSENT from th2. In Friesea mirabilis, seta A4 is supposed to be PRESENT on the tibiotarsi whereas in Friesea truncata seta A4 is ABSENT. However, these characters are not 100% reliable in UK/Eire material; asymmetry is frequent. The possibility still exists that Friesea truncata is simply a variety of Friesea mirabilis.
Species of Friesea have 8+8 ocelli but no post-antennal organ (PAO absent) or empodium on the foot.