It is very similar to other species such as Cylindroiulus londinensis, from which it can be reliably distinguished only by studying the shape of the telson.

[2] It occurs in Ireland, Britain, Spain, France, Benelux, Germany, Switzerland, Austria and the Czech Republic,[1] and is especially common on chalky and limestone soils.

[2] T. niger has a roughly cylindrical shiny black body, with around 100 pairs of contrasting white legs[3] on its 41–56 body segments.

[2] It lives in leaf litter, under bark or in moss, and feeds on encrusting algae, detritus[3] and sometimes fruit such as raspberries.

[5] Like many millipedes, T. niger coils itself into a spiral, with its legs on the inside and its head in the centre, when it is threatened,[2] but it can also flee with sidewinding movements.