Chapter 19.2, Problem 3RIA

The genus Salmonella was once thought to contain five species. Most scientists now consider only two species valid: S. bongori and S. enterica. The latter contains six subspecies, and S. enterica subspecies enterica is further subdivided into eight serovars. Three of these, Enteritidis, Typhi, and Typhimurium, were once considered Salmonella species. (a) Inspect figure 19.1 and construct a similar lineage for Salmonella. (b) What criteria do you think were used to make these taxonomic changes?