No person claiming any interest in real property under or through a person named as a defendant in an action concerning real property to which the Colorado rules of civil procedure are applicable need be made a party to such action unless his interest is shown of record in the office of the county clerk and recorder in the county where such real property is situated, and the decree shall be as conclusive against him as if he had been made a party. If such action is for the recovery of actual possession of the property, the party in actual possession shall be made a party.L. 41: p. 605, § 2. CSA: C. 40, § 117(2). CRS 53: § 118-6-14. C.R.S. 1963: § 118-6-14.