Summary for Megabunus diadema (Opiliones)

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National Distribution

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Megabunus diadema Copyright: Peter Harvey
Identification difficulty rating: 1
Name: Megabunus diadema
Authority: (Fabricius, 1779)
Order: Arachnida: Opiliones
Family: Phalangiidae

Records: 1673
First Record: 1878
Latest Record: 2023

1992-on hectads: 389
Pre-1992 hectads: 396
Total hectads: 715

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About this species

Recorded altitude range
1m to 637m

Species text

This is a widespread species extending from the south of England to Shetland and the Western Isles. Despite being a very distinctive species, it is likely that it is under-recorded as a result of its cryptic colouration and secretive habits. There is some evidence of a decline in the far south-east with many old sites seemingly no longer occupied. This may be a recording artefact, but could be a consequence of climate change with the area now too dry and warm.

Megabunus diadema was first recorded in Britain by Meade (1855) as occurring in England and Wales. In Europe it is considered rare and reported from the Pyrenees in northern Spain, the coast of Normandy, the Faeroes, Iceland and coastal Norway.

Habitat and ecology
This species is most common in the cooler, wetter upland of Britain (see above) and is usually associated with the ground layers of heathland and woodland. Often collected from litter and from under rocks and logs, it is also found on tree trunks, especially in damper conditions. It is found at altitudes up to about 650m in Britain and to 2000m in the Pyrenees (Martens 1978).

The relatively few British records with adult/sex data show females present from March and peaking in June. Males have been recorded in May. Hillyard (2005) suggests that adults are present in most months of the year; some may live beyond 24 months. Females are much more abundant than males and there is evidence that many/most populations are parthenogenetic (i.e. females are able to produce viable eggs without males). Philipson (1959) recorded juveniles in all months. Eggs are laid in late summer and hatch in the same year.

Very little information seems to have been recorded on food items. Bristowe (1949) recorded M. diadema eating chironomids.

There is a great opportunity to explore the life history and ecology of this very distinctive species. Southern opilionologists may want to investigate the impact of climate change.

Widespread but apparently declining in south-east England.

Climate change - drought and increasing temperature.

Management & Conservation
Monitoring of south-eastern sites.

Text based on: Hillyard, P. D. 2005. Harvestmen: keys and notes for the identification of British species. Synopses of the British Fauna 4 (3rd edn). Field Studies Council, Shrewsbury.


Bristowe, W. S. 1949. The distribution of harvestmen (Phalangida) in Great Britain and Ireland, with notes on their names, enemies and food. Journal of Animal Ecology 18: 100-114.

Martens, J. 1978. Spinnentiere, Arachnida: Weberknechte, Opiliones. Die Tierwelt Deutschlands 64: 1-464. Fischer Verlag, Jena.

Meade R. H. 1855. XXXV. Monograph on the British species of Phalangiidae or Harvestmen. Annals & Magazine of Natural History 2nd Series 15(90): 393-416.

Philipson, J. 1959. The seasonal occurrence, life histories and fecundity of harvest spiders (Phalangida). Enomologists’ Monthly Magazine 95: 134-138


Adult Season

Adult Season Data (based on 55 records with adult season information)


background methodology

Broad Habitat Data (based on 428 records with habitat information)

Broad subhabitat Data (based on 18 records with subhabitat information)

Structural Habitat Data (based on 163 records with structural habitat information)

Habitat Detail and Method (based on 260 records with habitat detail and method information)

Recorded management for locations with Megabunus diadema

Recorded substrate and hydrology for locations with Megabunus diadema


Megabunus diadema Bernwood forest
Megabunus diadema Bernwood forest
Crowned Harvestman
Crowned Harvestman
Well hidden
Well hidden
Megabunus diadema harvestman
Megabunus diadema harvestman
Dorsal view - showing three spine-tipped apophyses on each femur
Dorsal view - showing three spine-tipped apophyses on each femur
Megabunus diadema Female
Megabunus diadema Female
Megabunus diadema
Megabunus diadema
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