The Enigmatic Schizoglyphid Mite gen. and sp. n. and Its Implications for Astigmatid Life Cycle Evolution.

A detailed morphological characterization is presented for gen. et sp. nov., a newly discovered modern representative of the relict family Schizoglyphidae, found in a nest of the termite in New Zealand. This is the second extant schizoglyphid species known from modern material, and its discovery provides rare insight into a transitional stage in the evolution of astigmatid life cycles. The phoretic stage appears to be a tritonymph-rather than the typical deutonymph-based on key morphological traits including three-segmented palps, three pairs of genital papillae, and the presence of a pharynx. These features suggest that early astigmatid mites evolved multiple ontogenetic routes to dispersal, including tritonymphal, deutonymphal, and possibly adult phoresy, before the canalization of life cycles around deutonymphal dispersal. The persistence of putatively ancestral traits in schizoglyphids, along with their apparent ecological conservatism in termite nests, indicates the role of environmental stability in preserving modes of life history that otherwise appear extinct. We also provide a key to describe Schizoglyphidae species and discuss the implications of this discovery for understanding the origins of phoresy-related metamorphosis in Astigmata.