San Martin (2005: 63) used a recombination of Sphaerosyllis bilineata into Prosphaerosyllis in text flow, not formally signified as a new usage, when discussing his recombination of Hartmann-Schröder's, 1979 Australian Sphaerosyllis species, as Prosphaerosyllis longipapillata. It is evident that if Prosphaerosyllis is recognised as a full genus (it was a subgenus of Sphaerosyllis), then that is where Sphaerosyllis bilineatea should be placed.
Faulwetter et al. (2011: 301) compared Prosphaerosyllis bilineata with Prosphaerosyllis longipapillata (Israel specimens, originally described from Australia) and infer they are very similar, a conclusion in line with discussions by previous authors. They state that: "To determine the identity of the Mediterranean material and whether P. bilineata and P. longipapillata are different species or not, careful examination of all type material is needed."