Reductoniscus costulatus Kesselyák, 1930


GB IUCN status: Not applicable (non-native)

ID Difficulty


Reductoniscus costulatus is a very small woodlouse, reaching 2 mm body length, and is capable of rolling into a sphere when disturbed.  The head and body are covered in characteristic broad rounded tubercles (confusion is only likely with Buddelundiella cataractae). However, the telson of R.costulatus has a characteristic ‘hour-glass’ shape (also seen in Venezillo parvus) and it has truncated 'square' uropods typical of the family.

A brief description of this species, with figures, is given in Gregory (2014).

Andy Murray
Andy Murray
Keith Lugg
Keith Lugg
Keith Lugg
James Harding-Morris


Reductoniscus costulatus has been collected from Kew Gardens on several occasions and more recently at Eden Project (Rainforest Biome), Cornwall, where it has proved quite numerous in 2009 and 2010. A few additional sites are reported by Gregory & Lugg (2020).


Specimens have been found beneath dead wood, among leaf-litter, peaty soil or detritus and under leaf sheaths of 'palms' and bananas. 

Elsewhere it has been recorded in 'the wild' in Seychelles, Mauritius, Malaysia and Hawaiian Islands.


Gregory, S. (2014) Woodlice (Isopoda: Oniscidea) from Eden Project, Cornwall, with descriptions of species new to Britain, and poorly known British species. Bulletin of the British Myriapod & Isopod Group 27: 3-26.

BRC code