Cave dwelling "Baboon Spiders'' Anoploscelus lesserti, Citharischius crawshayi (Eumenophorinae) and Pterinochilus murinus (Harpactirinae) show stridulatory behaviour. Although morphology and relative position of stridulatory organs are important taxonomic tools, the behavioural context of stridulation is hardly known. In A. lesserti and C. crawshayi, the setae are located on coxa and trochanter of the pedipalps, 1st and 2nd legs. During stridulation both species lift their prosoma, moving pedipalps and 1st legs against each other, additionally striking against the assailant with pedipalps and 1st legs. P. murinus owns a field of setae only on the outer face of the chelicerae. For stridulation the trochanter of the pedipalps which also has a field of setae is moved transversally against the chelicerae. The durations of single sounds are variable in different species. In P. murinus a sound lasts 95-415 ms, the frequency reaches higher than 21kHz. A. lesserti shows the same range in frequency. C. crawshayi produces sounds with a period of 1200 ms reaching 17.4 kHz. Sonograms show species specific characteristics, so that species determination might be possible. The display may be a useful method signalling that a tube (cave) is occupied. It could also be useful defending enemies like parasitic wasps or small mammals [supported by Projekt Integrierter Naturschutz Ruanda/Rheinland-Pfalz].
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