Emergence ecology and body size dimorphism in Sympetrum fonscolombii and S. meridionale (Odonata: Libellulidae)

Abstract

The study of dragonfly emergence provides insights into the understanding of their life history, ecology, and adaptation to abiotic and biotic factors. Here we investigate the emergence ecology and body size of two congeneric dragonflies (Sympetrum fonscolombii Selys, and S. meridionale Selys) in Northeast Algeria, highlighting the seasonal pattern, sex ratio at emergence, sexual size dimorphism (SSD), and vertical stratification. We found that both species, S. fonscolombii in particular, showed quite asynchronous emergence. In both species, and especially in the larger S. meridionale, sex ratio was found to be female-biased, which is in line with the hypothesis of a negative relationship between SSD and sex ratio. There was no seasonal pattern of body size observed in both species. In S. meridionale, SSD with regard to both body and wing sheath length was male-biased, while in S. fonscolombii, it was male-biased with regard to body length and female-biased with regard to wing length. Vertical stratification depended on support height (the higher the support, the higher the height of exuvia fixation) but had a complex relationship with the body size. The biological significance and implications of the vertical stratification-body size relationship are discussed.

Phenology of the regionally Critically Endangered dragonfly Urothemis edwardsii in the National Park of El Kala, Northeast of Algeria

“…In addition, the El Graeate site is also thought to host a larger population of U. edwardsii (Khelifa et al, 2018), suggesting distinct intraspecific competition. EM50 of U. edwardsii was quite different than those estimated for other Libellulidae studied in Northeast-Algeria, namely Sympetrum meridionale (Selys, 1841) (16 days) (Hadjadji et al, 2019), the Afrotropical Acisoma inflatum (25 days) (Baaloudj, 2020), and Orthetrum cancellatum (Linnaeus, 1758) (20 days) (Hadjoudj et al, 2014). The overall asynchronous emergence pattern was typical of a «summer species» (Corbet, 1954).…”