I found precipitation correlates with latitude in Centrobolus millipede localities (R=0.6828, n=8, p=0.062011). Has a precipitation-latitude trend been published in South Africa?
Could you explain more about your question? like, what precipitation dataset you're using? is the relation annual mean, or specific season? A recent article on Cape Town drought is attached here that shows relation with large scale circulation and local drought.
The data are mean annual precipitation across South African forest biome and include the distribution records for two arthropod genera. Data sets at https://www.researchgate.net/publication/336252140 and https://www.researchgate.net/publication/335813264.