The strain was isolated in the years 1953-1955 from a patient in Malaysia by Alexander et al. (1957), who described it as a new sub-serovar named ricardi.
the strain appears for the first time in the list of 1959 (WHO, 1959) as a 'sub-serovar' of hamolytica. But in the 1967 list (WHO, 1967) it is given separate serovar status within the Hebdomadis serogroup. It was submitted to factor analysis by Kmety(1977) and placed in the newly established subgroup Saxkoebing of serogroup Sejroe.