How are fleas classified in the order Siphonaptera?

Fleas are classified within the order Siphonaptera, a group of small, wingless, and laterally compressed insects that are ectoparasitic on warm-blooded vertebrates. While classification systems vary, a common approach divides modern fleas into 10 superfamilies, though some systems recognize as few as five or eight.1

An early classification system proposed in 1982 by Franciscus Gerardus Albertus Maria Smit identifies five primary superfamilies based on structural characteristics of the head, thorax, and abdomen:1

• Pulicoidea: Includes common species such as cat, dog, and human fleas.1
• Malacopsylloidea: Fleas found exclusively on rodents.1
• Ceratophylloidea: Includes fleas found on rodents and bats that do not fit into other categories.1
• Vermipsylloidea: Fleas that parasitize carnivores.1
• Hystrichopsylloidea: Primarily rodent fleas with a worldwide distribution.1

Phylogenetically, Siphonaptera are believed to have descended from an ancestor of the Mecoptera (scorpionflies), sharing several anatomical and physiological traits with them.23