Pycnogonids are completely unknown within Homeopathy. As such any provings or triturations whatsoever would be very useful. Pycnogonids may possibly represent one of the earliest extant arthropod lineages, and as such could have very useful information on the exploits of the arthropods during their early evolution, and the early history of their interact with the other, the earths energy which they are disharmonious with.
Many species are found in relatively shallow water, and would be quite easy to collect. Callipallene brevirostris is a small spider native to the East coast of North America, which is very common on docks. The largest sea Spider, Colossendeis colossea, would also be an excellent candidate.
Image credit: https://commons.wikimedia.org/wiki/File:Expl0892_-_Flickr_-_NOAA_Photo_Library.jpg.