Folsomia litsteri was described by Bagnall in 1939 who named the species after Jack Litster (often misspelled as Lister) who sent Bagnall many specimens from Ireland in the 1930s and 1940s. Lawrence (1973) sunk Folsomia litsteri as a junior synonym of Folsomia candida but I am convinced that it is a good species. Folsomia litsteri is a rare (but certainly under-recorded) white species with 0+0 ocelli which reaches a maximum length of 0.8 mm. The ratio of the length of the longest setae at the tip of the abdomen/length of mucro is between 2.5 and 3.0. The manubrium has 3+3 ventral (anterior) setae arranged in two longitudinal rows (Fig. 1). The dens has 15-17 ventral (anterior) setae and 4 dorsal (posterior) setae (3 at the base of the dens and one seta in the middle). The PAO is quite broad and elliptical and is shorter than the width of ant1 (Fig. 2). The ventral side of the third thoracic segment possesses 2+2 setae. At least one of Bagnall's specimens of Folsomia litsteri from Alnmouth is a mature female of 0.8 mm in length with 3+3 ventral manubrial setae. It appears to be identical in almost all respects to the paratype of Folsomia lawrencei Rusek, 1984 in the NHML collection (the only difference being the slightly shorter abdominal setae and shorter body length of Folsomia lawrencei). Thus Folsomia litsteri is probably a senior synonym of Folsomia lawrencei (ironic if true as Peter Lawrence was responsible for sinking Folsomia litsteri!).
Fig. 1 (above): Folsomia litsteri collected from Dulwich Wood Park, London in July 1934 by Bagnall. The manubrium (ma) has 3+3 ventral (anterior) setae arranged in two longitudinal rows (*). d, dens; mu, mucro.
Fig. 2 (above): Folsomia litsteri collected from Alnmouth in April 1937 by Bagnall. The post-antennal organ (PAO) is quite broad and elliptical and is shorter than the width of ant1.
