Thelazioidea is a superfamily of spirurian nematodes in the large order Spirurida. Like all nematodes, they have neither a circulatory nor a respiratory system.Among the families placed here, only the Rhabdochonidae are notably diverse. though none is considered to be monotypic Consequently, the Thelazioidea are among the mid-sized superfamilies of Spirurida.The families of the Thelazioidea are: Pneumospiruridae Rhabdochonidae Thelaziidae↑