Plays a functionally redundant role in spermatogenesis and growth rate control. Required for the development of somatic gonad structures and for progression from larval stage to adulthood. 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. Rsp-2/rsp-6 RNAi caused severe abnormalities in somatic gonad structures and in some cases animals were arrested or dead at the larval stage. Belongs to the splicing factor SR family.