Summary for Leiobunum sp. A (Opiliones)

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National Distribution

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Leiobunum sp. A males and female 003 Copyright: Ian Beddison
Identification difficulty rating: 4
Name: Leiobunum sp. A
Authority: (Schonhofer & Hillen 2008, Toss 2009, Wijnhoven et al. 2007)
Order: Arachnida: Opiliones
Family: incertae sedis

Records: 221
First Record: 2009
Latest Record: 2022

1992-on hectads: 25
Pre-1992 hectads: 0
Total hectads: 25

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About this species

Recorded altitude range
5m to 131m

Species text

This is an, as yet, unnamed species of Leiobunum (see Wijnhoven et. al. 2007) which has been spreading through Europe. It was first identified in Britain from Nottinghamshire in 2009 and this population appears to have persisted (see: Its UK range is expanding rapidly and has also been recorded in north-west England, the Midlands, London and South Wales. In August 2021 it was first recorded in Ireland (Dublin).

It Europe it was first found in the Netherlands (in Ooij, east of Nijmegen) in 2004. It also occurs in Germany, Austria and Switzerland.

Habitat and ecology
According to Wijnhoven (2009) Leiobunum sp. A is associated with stony ground. It is also found in ruderal places (e.g. disturbed areas) and around houses, on walls, under window sills and gutters, by former brickworks and old brick ovens, by rivers, under bridges, concrete blocks and the like.

Adults occur from late June to late December with the greatest activity in September. They probably overwinter in the egg stage. The obvious behavioural characteristic of this species is its gregariousness - forming roosting aggregations of between fifty and a thousand individuals. These roosts often occur on, and inside, buildings.

Little information has been published on the prey of this species but is likely to include a very wide range of invertebrates. A major concern is that it may (as in the case of Opilio canestrinii) pose a threat to native species of harvestmen.

This large invasive species would make a good candidate for studying species interactions as it establishes and spreads.

Recent introduction.


Wijnhoven, H., Schönhofer, A. L. & Martens, J. 2007. An unidentified harvestman Leiobunum sp. alarmingly invading Europe (Arachnida: Opiliones). Arachnologische Mitteilungen 34: 27-38.

Wijnhoven, H. 2009. De Nederlandse hooiwagens (Opiliones) Naturalis Biodiversity Centre - Entomologische Tabellen, The Netherlands. (translation available here:


 Account last edited by Meg Skinner at 18:11 on Fri 25th Nov 2022.

Adult Season

Adult Season Data (based on 61 records with adult season information)


background methodology

Broad Habitat Data (based on 8 records with habitat information)

Broad subhabitat Data (based on 2 records with subhabitat information)

Structural Habitat Data (based on 2 records with structural habitat information)

Habitat Detail and Method (based on 11 records with habitat detail and method information)

Recorded management for locations with Leiobunum sp. A

Recorded substrate and hydrology for locations with Leiobunum sp. A


Leiobunum sp. A Male 9990
Leiobunum sp. A Male 9990
Leiobunum sp. A Male 9998
Leiobunum sp. A Male 9998
Leiobunum sp. A Female 003
Leiobunum sp. A Female 003
Leiobunum sp. A males and female 003
Leiobunum sp. A males and female 003
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