Ontogenetic instars of Zygoribatula excavata, with remarks on juveniles of Oripodoidea (Acari: Oribatida)

Abstract

Information on the morphological ontogeny of oribatid mites of the family Oribatulidae is very scarce, and the juveniles of most species are unknown yet. In this work, the ontogenetic instars of the semicosmopolitan species, Zygoribatula excavata Berlese, 1916 are studied. The juvenile instars of this species are morphologically similar to those of the other species of Zygoribatula, and this genus can be included among those in which species are difficult to distinguish based on juvenile characteristics alone. As information on the morphological ontogeny of most species of Oribatulidae is still insufficient or unknown, a comparison on the juvenile characteristics of the families belonging to the superfamily Oripodoidea is given based on our own data and available literature sources. The major characteristics of juvenile instars of 10 families and 21 genera are presented. There are few characters, such as body shape and size, pattern of cuticle, excentrosclerites at gastronotic setae, size and morphology of setiform organs, such as bothridial as well as gastronotic setae that distinguish the families or genera of Oripodoidea.