I'm not a Whiteman researcher; however, the name appears in conjunction with the Arnold line that I research. The reason that I particulary noticed this is because of a divorce record in Cass County, Missouri of Margaret Arnold (spelled Arnull in the record book) vs. Willis Arnold. The Arnolds had moved from Schuyler County, Illnois (1860) to Hamilton County, Iowa. Among several charges in the divorce petition was the following statement: "..during the whole year of 1870 in the State of Iowa and County of Hamilton, defendant was guilty of committing adultry with one Liddy Whitman since the month of December in the year aforesaid, plaintiff and defendant have lived separate and apart..."
The Arnolds lived at Dwelling #165-164. The Whitemans were next neighbors. At this moment I cannot lay my hands on that census record, but with the above info, I'm sure you can locate it. Sometime later I took another look at the Arnold census record in Schuyler County, Ill and stumbled upon Mathias Whiteman (48) PA and Lydia Whitman (36) Ohio also in Littleton Township of Schuyler Co. Dwelling #1223-1228. So, Willis and Margaret Arnold knew Mathias and Lydia Whiteman prior to Iowa. They probably moved together.