Plays a functionally redundant role in spermatogenesis and growth rate control. Extensively phosphorylated on serine residues in the RS domain. RNA-mediated interference (RNAi) of rsp-1 and rsp-2 result in reduced brood sizes and abnormal egg-laying behavior, and the presence of unusual vacuolated structures in some of the secondary spermatocytes, spermatids and spermatozoa. Belongs to the splicing factor SR family.