Phenology of the Odonata assemblage in a Mediterranean stream in the north-eastern Iberian Peninsula

摘要

We investigated the Odonata species composition of larvae, final instar (F-0) exuviae, and adults occurring in a sequence of two different mesohabitats - pool and riffle - in a short stretch of a Mediterranean stream running down the Catalan Pre-Coastal Range (north-eastern Iberian Peninsula). We sampled them during the period 2017-2018 and recorded adults of 26 taxa and confirmed by the presence of final instar exuviae that at least 21 were breeding successfully in that environment. We describe, for the first time for this region and habitat type, larval growth patterns, timings of adult emergence, and flight periods of the most abundant species and characterize the life cycles of some of them. These life cycles can be classified into three types: i) univoltine with overwintering in the larval stage and emergence taking place in spring or summer of the following year (Coenagrion mercuriale, C. puella, Ceriagrion tenellum, and Pyrrhosoma nymphula); ii) predominantly univoltine of the previous type with a small fraction of the population being semivoltine (Anax imperator and Orthetrum coerulescens, tentative conclusion); and iii) univoltine with overwintering in the egg stage, a short larval growth period in the following spring, emergence in early summer, a long maturation period, and reproduction postponed until late summer or early autumn (Chalcolestes viridis and Sympetrum striolatum). Our results may contribute to fill in gaps in the knowledge of voltinism and phenology of the life cycles of Odonata in correlation with latitude, geographical area, and habitat type.