Proasellus cavaticus (Leydig, 1871)


  • Asellus cavaticus Leydig, 1871
  • Asellus cavaticus Schiödte, 1871


  • GB IUCN status: Least Concern
  • GB rarity status: Nationally Scarce

ID Difficulty


Proasellus cavaticus is distinguished from other British Asellids by entirely lacking eyes and pigmentation. However, care is needed since some underground populations of Asellus aquaticus may entirely lack pigmentation.  The shape of the male first pereopod is diagnostic.


Proasellus cavaticus is unique among British Isopods in being a specialist stygobite (i.e. entirely associated with subterranean aquatic habitats). It appears to be restricted to southern areas, with the majority of records from carboniferous limestone cave systems in the Mendip Hills and South Wales.  It has not been recorded from Ireland. 


It is typically recorded from underground streams, pools and wet surfaces in limestone caves and mines, where it tends to occur in small numbers in water films covering flowstones, within small seepages or in shallow pools. It has also been recorded from various interstitial and groundwater sites across southern England and Wales. 

This species is also covered by the Hypogean Crustacea Recording Scheme which provides more information about, and images of, this species.


Gregory, S. (2009) Woodlice and Waterlice (Isopoda: Oniscidea & Asellota) in Britain and Ireland.  Field Studies Council/Centre for Ecology & Hydrology.

BRC code