Redescription of the feather mite Ingrassia aequinoctialis (Trouessart, 1899) (Acariformes: Xolalgidae) with notes on systematics and host associations of the Ingrassia genus-group

The feather mite Ingrassia aequinoctialis (Trouessart, 1899) (Xolalgidae: Ingrassiinae), never previously illustrated, is redescribed based on recently collected specimens from the Red-tailed Tropicbird Phaethon rubricauda Boddaert, 1783 (Phaethontiformes: Phaethontidae). Additionally, we provide an updated checklist of species of the genus Ingrassia Oudemans, 1905 and three closely related ingrassiine genera, Leptosphyra Hull, 1934, Tectingrassia Gaud, 1972 and Vingrassia Vasyukova and Mironov, 1991, which together form the Ingrassia genus-group. Taxonomic characteristics of these four genera, their host associations and possible relationships are briefly discussed. The name Vingrassia latior (Trouessart, 1899) comb. n. is proposed for the mite species Megninia centropodos latior Trouessart, 1899 transferred herein to the genus Vingrassia.