Taxonomic name: Ctenophthalmus Euctenophthalmus congener congener (Flea Species)Interaction Type: ectoparasite ofLocation: HertfordshireReference: Ctenophthalmus (Euctenophthalmus) congener congener Roths., 1907: a flea new to Great Britain. Taxonomic name: Clethrionomys glareolus