Description of immatures and ontogenetic development of Africoseiulella flechtmanni Kreiter, type species of the enigmatic family Africoseiulellidae (Acari: Mesostigmata: Phytoseioidea)

[EN] The genus Africoseiulella Kreiter was established to accommodate a species initially included in the family Phytoseiidae. Four species of this genus are currently known, and a recent study has examined its phylogenetic position, placing it within the newly proposed family Africoseiulellidae. All four species have been described based on adult forms, with immature stages remaining unknown or poorly known. In the present work, all developmental stages of the type species, A. flechtmanni Kreiter, are described, and the ontogenetic sequence of setal development on the dorsal and ventral idiosoma, palps, and legs is documented. The development of leg chaetotaxy is compared with the commonest pattern in Phytoseiidae. In addition, the patterns of appearance of cuticular organs, including pores and poroids, are reported. A complementary description of the adults, based on specimens collected in the Canarian Island of Fuerteventura, is also provided.