Loading...
4 results
Search Results
Now showing 1 - 4 of 4
- Refining the identification criteria for forma typica and brachycerca in exuviae of Boyeria irene (Odonata: Aeshnidae)Publication . Nunes, Luísa; Casanueva, Patricia; Santamaria, Tomás; Hernández, Maria Ángeles; Sánchez-Sastre, Luis Fernando; Campos, FranciscoIn female imagines of Boyeria irene, two forms are known according to the length of the cerci: forma brachycerca (short appendages) and f. typica (long appendages). Both forms are also recognisable in exuviae. Hitherto, no accurate measurements have been performed to distinguish between the two forms. Hence, we measured and analysed the absolute and relative length of the cerci in both sexes of exuviae from 11 populations originating from the centre and north of the Iberian Peninsula. We show that there are specimens intermediate between the two forms and that dimorphism is also present in males. The brachycerca form is more frequent in the north than in the centre of the Iberian Peninsula. Correct identification of both forms should always be based on accurate measurements of the length of the cerci.
- Patterns of variation in wing venation of Iberian Cordulegaster boltonii (Donovan, 1807) (Odonata: Cordulegastridae)Publication . Nunes, Luísa; Santamaria, Tomás; Casanueva, Patricia; Sánchez-Sastre, Luis Fernando; Ferreras-Romero, Manuel; Romero, Ángel; Campos, Francisco; Hernández, Maria ÁngelesSome structural characters, such as wing venation, have been used in odonates to differentiate taxa. In Cordulegaster boltonii, a species widely distributed throughout the western Palaearctic, the main characteristics of its wing venation have not been quantified until now. A six-variable analysis of wing venation (number of antenodal and postnodal cross-veins, number of cells in the anal triangle and in the anal loop) in specimens from several European countries was carried out. The results showed that: (a) females had a greater number of transversal veins and cells in the anal loop than males; (b) the values of these four variables were significantly lower in males from the Iberian Peninsula than in those from elsewhere; (c) within the Iberian Peninsula two groups of populations can be distinguished: one covers the north and the other the rest of the peninsula, the latter with two subgroups, one in the centre and one in the south and east. The number of cells in the anal loop is a valid variable for analyzing geographic differences in this species.
- Variation of larval size and adult emergence period of Boyeria irene (Fonscolombe, 1838) (Odonata: Aeshnidae) in the Francia River of western SpainPublication . Casanueva, Patricia; Hernández, Maria Ángeles; Nunes, Luísa; Sánchez-Sastre, Luis Fernando; Campos, FranciscoBoyeria irene (Fonscolombe, 1838) is a large dragonfly common in rivers and streams in southern Europe, but it is little known about the biometrical variations of their populations. In this paper, we test whether the time of the emergence period of this species differs in the same river, whether the larval size varies during the emergence period, and whether the distinct size variations are associated with the different river sections. Results have revealed that 1) female exuviae are larger than those of males, 2) except for the paraproct length, the exuviae have similar size across the entire river length, 3) size of the exuviae is larger in the first period of emergence than in the second one. A difference in emergence duration across the three river sections has been recorded.
- Predation by the common kingfisher Alcedo atthis of non-native fish species during the winterPublication . García, José Antonio; Hernández, Maria Ángeles; Nunes, Luísa; Sánchez-Sastre, Luis Fernando; Casanueva, Patricia; Campos, FranciscoCapsule:ThewinterdietofCommonKingfishersAlcedoatthisusingtworiversincentralSpainwas 94.9% fish, all of which were non-native species. Aims: To determine the composition Common Kingfisher diet in an area recently colonized by non-native fish species, and to compare estimated prey size during the winter to that of fish fed to nestlings during the breeding season. Methods: The diet was studied by analysis of pellets collected from the River Duero (lentic, still water) and River Pisuerga (lotic, riverine) in central Spain. Fish size (total length and biomass) calculated from paired remains contained in each pellet. Results:Prey itemswerealmost exclusivelyfish(94.9%ofallprey),withasmallproportionofnonnative Red Swamp Crayfish Procambarus clarkii (4.9%) and aquatic insects (0.2%). The diet consisted of only five species of fish, all of which were non-native. The Common Bleak Alburnus alburnus and Eastern Mosquitofish Gambusia holbrooki were theprey captured most often in the River Pisuerga and River Duero, respectively. Estimated length of fish prey ranged from 1.5 to 10.5 cm, but 53.6% of individuals were between 3 and 5 cm. Mean biomass of the fish consumed was also small (1.08 g per fish). Mean values of both fish total length and biomass were lower than the measurements reported elsewhere in Europe during the breeding season. Conclusion: Native fish species have disappeared from the diet of Common Kingfishers in our study area, probably because the non-native species are more common