Ovoviviparity in scutacarid mites (Scutacaridae, Heterostigmatina)?

Abstract

Scutacarid mites (Scutacaridae, Heterostigmatina) are oviparous and show a shortened developmental cycle, the larva being the only existing juvenile stage. Eggs inside of gravid females and freshly laid eggs generally show early stages of development and thus contain no differentiated embryo. However, findings of eggs already undergoing embryogenesis or even of larvae inside of gravid females in Thaumatopelvis reticulatus Ebermann and, as newly presented in this paper, Scutacarus eucomus Berlese, Scutacarus deserticolus Mahunka, Scutacarus longitarsus Berlese and Imparipes zicsii Mahunka suggest that ovoviviparity or larviparity caused by egg retention can also occur. Egg retention in the family Scutacaridae may be an age-related phenomenon or an adaptation to unfavourable environments.

Keywords:

• ovoviviparity
• egg retention
• Scutacaridae
• mixed parity
• reproduction

Acknowledgement

We are grateful to Dr. Gerhard Skofitsch for his help in preparing the photomicrographs.