Dicymbium nigrum/brevisetosum agg.


    Separation of these species can only be based on males, with females being indistinguishable from each other. The genitalia of the two species are identical. The British Arachnological Society record these two as separate species with females being grouped together as Dicymbium nigrum/brevisetosum and males needing detailed microscopic examination before acceptance to species level. Identification is made more difficult as there are intermediate specimens, and by the fact that the two species may be able to interbreed as they have identical genitalia. Any records of females, or of males which have not been microscopically examined and shown to be conclusively of one species should be recorded to this aggregate page.  

    Identification difficulty
    ID guidance
    • Prosoma (cephalothorax) 0.8-1.0 mm, inconspicuous, fovea clearly recognizable as a notch.
    • Opisthosoma (abdomen) plain, unremarkable.  
    • Tibial spines: 2-2-1-1.    
    • Metatarsus IV with trichobothrium.  
    • Front centre eyes significantly smaller than side eyes.
    • Sternum rough, extended backwards.  
    Recording advice

    Confirmation of conclusive microscopic features required for positive identification. 


    A common aeronaut which has been found in a wide variety of habitats including sphagnum bogs, grassland, damp woodland, heathland, marshes, wastelands and detritus.

    When to see it

    Adults have been recorded throughout the year with peaks in early summer and autumn.

    UK Status

    Common and widespread in Britain as an aggregate.

    VC55 Status

    Status in Leicestershire and Rutland is not known, but it would seem that the species are under recorded in our area. 

    Leicestershire & Rutland Map

    MAP KEY:

    Yellow squares = NBN records (all known data)
    Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

    UK Map