The unusual life history of a southern Iberian Peninsula population of Torleya major (Ephemeroptera: Ephemerellidae)

Abstract The nymphal biology of a population of Torleya major (Klapálek) in southern Iberian Peninsula was studied. An atypical life cycle pattern is described, with eggs hatching in August producing a fast‐developing cohort with adults emerging in autumn and a second slow‐developing cohort with adults emerging in spring of the following year. Nymphal growth occurred primarily in summer–autumn (in the first cohort) and in spring (in the second). The origin of such a life history is discussed. Nymphs were collector‐gatherers, consuming mainly detritus. Although ontogenetic shifts on the use of trophic resources were detected, similar food was utilized during the months when both cohorts cohabited, eliminating the possibility that the rapid growth of the first cohort could be related to the utilization of different food resources.