'Draughtsman concentric rings' on culture are produced by the following organism:

Pneumococci form small round colonies, at first dome-shaped and later developing a central depression with an elevated rim which is viewed from above giving 'draughtsman' or 'carrom coin appearance' to colony. Other colonies may appear glistening because of capsular polysaccharide production. Pneumococci are -hemolytic on blood agar. Growth is enhanced by 5-10% CO2. Ref: Textbook of Microbiology By Ananthanarayan And Paniker, 7th editi