Species of Tetracanthella are characterised by possession of four prominent anal spines. Tetracanthella brachyura is a moderately common species found in bogs and mountains. It is black or dark blue, reaches a maximum length of 1.3 mm and has a mucro with two teeth (Fig. 1). The empodial appendage of the foot is only about 0.2 to 0.3 times as long as the claw.
The map below also includes all records for Tetracanthella britannica Cassagnau, 1959 and for Tetracanthella pilosa Schött, 1891. Tetracanthella britannica was sunk as a junior synonym by Deharveng (1987), while Tetracanthella pilosa is a good species but without confirmed UK records. There are slides in the NHML labelled Tetracanthella pilosa, but Steve Hopkin found these to by T. brachyura. Indeed on many of Bagnall's slides, he has crossed out pilosa and written 'brachyura' on the label. In his 1949 paper, Bagnall states in the first sentence of the description of Tetracanthella brachyura sp. n. 'This species has been confused with I. pilosa Schott'.