Cryptic stasis during the development of Nothobranchius furzeri suggests new stages of dormancy outside of the typical three diapauses of annual killifishes.

Annual killifish live in temporary pools which completely lose water during the dry season. They bury their eggs in the muddy bottom where they stay through the entire dry season. The development of killifish embryos involves three strictly defined stages, where the embryo may go dormant and stop developmental progression. The system of the three facultative diapauses — diapause I, II, and III — was described in the 1970s and remained supported until now. Here, we report on the potential of the embryos of an African killifish species Nothobranchius furzeri Jubb to enter an additional developmental stasis occurring in between the stages defined for the diapause II and III. The stasis manifests as a full developmental halt in a stage previously regarded as non-diapausing or a markedly slowed down developmental rate. It occurs under usual laboratory incubation conditions, and the embryos that entered the stasis are capable of normal hatching after they exit the dormancy and complete their development. The aim of the study is to inform on the increased, cryptic complexity of the killifish diapause system while we discuss the possible reasons why the stasis, arguably occurring with some regularity, remained unnoticed for so long. [ABSTRACT FROM AUTHOR]