Pelecitus fulicaeatrae (Nematoda, Filarioidea) of coots (Gruiformes) and grebes (Podicipediformes) - skin inhabiting microfilariae and development in Mallophaga

Pelecitus fulicaeatrae (Diesing, 1861) was found among tendons near the ankle (tibiotarso-tarsometatarsalis articulation) in 11 of 15 adult coots (Fulica americana) from Brooks, Alberta, Canada, in 6 of 9 adult coots from Delta, Manitoba, Canada, and in 2 of 4 adult red-necked grebes (Podiceps grisegena) from Brooks. Microfilariae of P. fulicaeatrae were found in skin of the feathered portions of the legs of infected birds, generally in the dermis around feather follicles; this is the first report of skin-inhabiting microfilariae among avian filarioids. Development of P. fulicaeatrae to the third stage in the chewing louse Pseudomenopon pilosum (Scopoli) (Mallophaga: Amblycera) is described. Microfilariae and developing first-stage larvae were found in nymphal and adult lice but third-stage larvae were found only in adults; prevalence of third-stage larvae was significantly higher in females than in males. Adult P. fulicaeatrae were recovered from an experimentally inoculated, laboratory-reared coot and from laboratory-reared coots that had been housed with infected and infested wild-caught coots. Pelecitus fulicaeatrae is the first filarioid in the Dirofilariinae known to be transmitted by lice and the third found in birds. Pseudomenopon pilosum was found on 40 (85%) of 47 coots of undetermined ages from Alberta and Pseudomenopon dolium (Rudow) was found on all of 5 juvenile red-necked grebes also from Alberta. Possibly, P. pilosum occasionally transfers to grebes and (or) P. dolium also transmits P. fulicaeatrae.