Genetically determined color polymorphisms have a long history in the study of evolutionary change acting on populations. The Odonata exhibit relatively high levels of sex-specific color polymorphisms in mature adults. In Ischnura and Coenagrion, female-specific polymorphisms are known to be controlled by Mendelian genes. Nearly half of Enallagma species have polymorphic females, but the inheritance…
A three-year field study (January 2011–December 2013) of the Odonata of Curaçao, supported by photos and exuvial collections, recorded a total of 21 species from the island, almost doubling its previously known fauna. The lists of Odonata known from Aruba and Bonaire were also updated by specimen and photo records, and 24 species are now…
Hybridization between Calopteryx haemorrhoidalis and any of its congeners has not been reported until now. We observed spontaneous matings between male C. splendens and female C. haemorrhoidalis at a locality in Central Italy, together with some putative hybrid individuals that had a mixed phenotype. Here, we report the morphological and molecular characterization of five suspected…
The reproductive behaviour of the damselfly Neurobasis chinensis (Calopterygidae) was filmed at 300 and 600 frames per second in Thailand in spring 2009. This was subsequently viewed in slow motion for detailed analysis. Altogether we observed 26 matings at two different sites. Besides visual observations of behaviour of male–female encounters at the reproductive sites, we…
Although the sex ratio of Odonata at emergence has received much attention, we are still far from understanding the exact causes of its variability and imbalance. In this paper we studied the sex ratios at emergence in natural populations of two Gomphus species based on samples of exuviae taken from two European lowland rivers. We
Recent findings suggest that postmating prezygotic isolation (i.e. gametic barriers) could be an important factor preventing hybrid formation. Competitive gametic barriers emerge when a female is inseminated by a conspecific and a heterospecific male. We examined whether sperm proportions after double matings and copulation duration impede hybrid formation. For this, we used females of Ischnura…
The final instar larva of Heliaeschna idae Brauer is described and figured for the first time based on the exuvia from an advanced female larva collected in Sarawak, Borneo (East Malaysia). It is compared with the known larvae of the genus and is concluded to be most closely allied to Heliaeschna simplicia Karsch, with which…
Emergence studies in Odonata provide information on the behaviour, ecology and fundamental demographic parameters in population studies. This paper reports on a study of sex ratio at emergence, pattern and duration of the emergence season, and potential cohort splitting in Petalura gigantea. Sex ratio at emergence varied among years, habitat patches and swamp types. Across
Large numbers of migrating imagos of Anax ephippiger were observed from the end of January to March 2012 at Dakhla Bay, Southern Morocco, in an area where long-lasting fresh and brackish waters are lacking, and thus which is unfavourable for the reproduction of Odonata. This supports well the classical scheme of northward mass migration of…
The larva of Trineuragrion percostale is described and illustrated based on an exuvia collected with the teneral female. Four more exuviae sampled without imagines are added for comparison and discussion of morphological variations. This is the first time the larva has been associated with the correct species, although the larval description was given earlier. Lieftinck