LONG-LEGGED SAC SPIDERS - Family
Cheiracanthium Sac Spiders usually have a cream or straw-coloured body, with very black chelicerae and face. The black face and chelicerae are the most indicative feature of these spiders. They have long front legs that are often held out forward and bent. They build temporary sac-like silken retreats in leaves, folds in curtains, and in the corners of rooms. They often venture indoors to hunt at night.
Of all the commonly encountered spiders in East Africa, these are the ones to be the most wary of.
Cheiracanthium sac spiders are found throughout most of Sub-Saharan Africa and, as they are not web-bound, wander around looking for prey. As such, they are encountered often, especially at night, and account for about 75% of all spider bites in Sub-Saharan Africa. Cheiracanthium venom is cytotoxic, and therefore destroys tissue cells. The initial bite is not painful, so often goes unnoticed until later when it becomes swollen, red, and itchy. This develops into a boil-like sore and can cause great pain and fever that can last up to two weeks. There is not much first aid that can be applied other than treating the symptoms like pain and fever.
Similar specie: There are other, similar looking, types of Sac Spiders from the family Clubionidae that are completely harmless and should not be confused with the Long-Legged Sac Spiders from the family Miturgidae.
LIFESTYLE: Free-running, ground-living, plant-living
HABITAT: on or under bark; in webbing, scrapes, or free-running, under stones; on bushes and plants; in and under leaf litter.
BODY SIZE (excluding legs): 3-12.5 mm
DANGER: Venomous (See above)
(Info - Kenyan Spiders Blogspot)
Reply: I agree with your ID, 7 January, 2016:
I would be most obliged if you could ID the attached spider.
They were found in 13 plant galls of a sample of 138. The galls were only on the plant Osteospermum oppositifolium. These grow naturally on our farm in Namaqualand, Northern Cape Province, South Africa.
If I could be so bold as to have a guess, I think they might be Miturgidae (sac spiders), and possibly the genus Cheiramiona (long-legged sac spiders). But I would really prefer the opinion of someone who actually knows something about spiders!
The purpose of my exercise was to try to determine what is causing the galls (which I havenít been able to do yet). I suppose the spiders are using the galls as a convenient habitat and possibly feeding on larvae (of which I found many) in the galls?
Hope you can help!