Browsing by Author "Cordero-Rivera, Adolfo"
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- Larval development and growth ratios of Odonata of the AzoresPublication . Lamelas López, Lucas; Florencio, Margarita; Borges, Paulo A. V.; Cordero-Rivera, AdolfoTo fully understand odonate life cycles, it is vital to analyse the patterns of larval growth, which are tightly associated with variations in environmental factors. However, the identification of larval instars is often difficult, especially for early development stages. We hypothesise that pond hydroperiod influences odonate larval growth, and test this idea with novel information about the environmental characteristics of 12 study ponds in Terceira Island (Azores). This study, which represents the first analysis of larval development of Odonata in the Azores, involved determining the instars of development and growth ratios. We measured the morphological characteristics of 898 Odonata larvae, and found that they significantly differed between temporary and permanent ponds. To estimate the larval instars, we used two methods: frequency distribution methods and correlation diagrams between body characteristics. The first method was the most effective, allowing the estimation of 17 instars for Anax imperator, 13 for Sympetrum fonscolombii and 10 for Ischnura hastata, as well as growth ratios between instars for head width, total length, abdomen length, wings and antenna length. Our results also suggest that a combination of the two methods is the most appropriate strategy for estimating the number of instars and growth ratios during larval development.
- New data on the Odonate fauna from Graciosa Island (Azores)Publication . Vieira, Virgílio; Cordero-Rivera, Adolfo[…]. Currently, four odonate species are known from the Azores archipelago (Valle 1940; Gardner 1959, 1960; Belle 1992; Cordero-Rivera et al. 2005; Lorenzo-Carballa et al. 2009), namely, Anax imperator Leach, 1815 (Aeshnidae), Sympetrum fonscolombii (Selys, 1840) (Libellulidae), Ischnura pumilio (Charpentier, 1825) and Ischnura hastata (Say, 1839) (Coenagrionidae). The first three species belong to the European fauna, whereas the last one is native to the Americas (Belle & van Tol 1990; Lorenzo-Carballa et al. 2009; Weihrauch 2011). In a previous paper we found that all four species were known from all islands except Santa Maria and Graciosa, but we proposed that this was due to a lack of sampling and suggested that it is likely that all four species are present in all of the nine islands (Cordero Rivera et al. 2005). Further sampling confirmed the presence of these four species in Santa Maria Island (Lorenzo-Carballa et al. 2009; Tavares et al. 2010). Very few records of odonates have been published for Graciosa. The first was a female S. fonscolombii observed on July 17, 1938 (Valle 1940). No indication of the relevant locality was given. To our knowledge, only A. imperator and S. fonscolombii species were further recorded for Graciosa (Cordero-Rivera et al. 2005; Lorenzo-Carballa et al. 2009), but again without localities. So, the present contribution deals with new odonate records for this island. Given that I. hastata is of great interest in every island of the archipelago due to its unique parthenogenetic reproduction in all its Azorean localities, the first author made two visits to Graciosa in 2004 and 2007, in order to survey the local odonate fauna.