[New mermithid genera and species parasitic in fleas]

A new genus and a new species Imosmermis morosovi gen. sp. n. found in the flea Xenopsilla gerbilli minor Jordan are described. The genus Imosmermis differs from all known genera of Mermithidae by the absence of mouth and reduction of stihostome and the dorsal chord. Body is long and very thin. A new genus Aphanimermis comb. n. for the species Psyllomermis tshumacovae Rubzov is created. This genus is characterized with a stilet, with high developed lateral and ventral chord as well as with a tail which is absent in other genera infecting fleas.