Hydrobiologia 345: 109±116, 1997. 109
c 1997 Kluwer Academic Publishers. Printed in Belgium.
The life history of Boyeria irene (Fonscolombe, 1838) (Odonata: Aeshnidae) in the Sierra Morena Mountains (southern Spain)
Manuel Ferreras-Romero Departamento de BiologÂõa Animal (ZoologÂõa), Facultad de Ciencias, Universidad de Cordoba, Avda. San Alberto Magno s/n, ES-14004 Cordoba, Spain
Received 27 June 1996; in revised form 19 December 1996; accepted 13 February 1997
Key words: Odonata, life history, permanent stream, southern Spain
Abstract
The life history of Boyeria irene is inferred from size-frequency analyses of sweep-net samples taken during ®ve years in a permanent stream in the Sierra Morena Mountains. There the species is apparently mainly semivoltine, although a few larvae require three years to complete development. The instar distribution during winter is that of a `summer species' (sensu Corbet, 1954). Metamorphosis is con®ned to spring and there is a long ¯ying season. Similarities between B. irene and congeneric species in North America are discussed.
Introduction acterise the life history of an odonate with a relatively long generation time in a locality near the southern The term `voltinism' denotes the number of genera- limit of its distribution so that the species' voltinism tions completed within a year: thus a population com- there could be compared with populations at higher pleting one generation a year is described as univol- latitudes. tine, two generations a year as bivoltine, if one gen- The genus Boyeria comprises B. gra®ana eration requires two years to be completed as semi- Williamson, 1907 and B. vinosa (Say, 1839) in North voltine and more than two years as partivoltine. With America, B. maclachlani (Selys, 1883) in Japan, regard to their mechanisms of seasonal regulation,Cor- B. sinensis Asahina, 1978 in China, B. irene (Fons- bet (1954, 1964) recognized two major categories of colombe, 1838) in Europe (Davies & Tobin, 1985) and north-temperate Odonata: `spring species' that pos- B. cretensis Peters, 1991 in the Mediterranean island of sess a winter diapause during the last larval instar and Crete. B. irene ranges from northern Africa to Switzer- that typically show a brief, synchronised emergence land, central France, parts of Italy, and some Mediter- in spring or early summer; and `summer species' that ranean islands (Askew, 1988). lack a winter diapause in the last larval instar and that Information on the life history of species of Boy- typically show a less synchronised emergence later in eria is sparse. Preliminary observations have been the year. published on voltinism of B. irene in southern Spain Most studies of voltinism in European Odona- (Ferreras-Romero, 1994); and brief accounts exist of ta have been in north-temperate latitudes and have its egg development, diel periodicity, foraging and revealed regressions of voltinism on latitude (Norling, reproductive behaviour in southern France (Miller & 1984). The few corresponding studies of Odonata from Miller, 1985) and Spain (Wenger, 1955, 1963). In southern Europe reveal patterns of voltinism (Aguesse, North America observations on egg diapause (Walker, 1955, 1968; Ferreras-Romero, 1991) and phenology 1958) and voltinism (Paulson & Jenner, 1971; Smock, (Ferreras-Romero & Corbet, 1995; Ferreras-Romero 1988; Galbreath & Hendricks, 1992) contribute to our & Puchol-Caballero, 1995; Suhling, 1995) that are knowledge of B. vinosa. richly informative when considered against a latitude gradient. The objective of the present study was to char-
Article: hydr3668 GSB: Pips nr 135644 BIO2KAP
*135644 hydr3668.tex; 12/05/1997; 14:25; v.7; p.1 110
Methods In the laboratory the head width (maximum dis-
tance across the compound eyes) and the length of
0 0 The study site, Bejarano Stream (37 56 N, 4 52 W), metathoracic wing-sheaths were measured to the near- is ca. 400 m a.s.l. close to Sta. Maria de Trassier- est 0.1 mm using a Nikon binocular microscope with ra, Cordoba, Andalusia, Spain, in the Sierra More- an eyepiece micrometer; the number of abdominal seg- na Mountains. It is a small, permanent, mountain ments covered by the metathoracic wing-sheaths was stream with a closed canopy of alder (Alnus gluti- also recorded. On the basis of head width and wing- nosa (L.)), elm (Ulmus minor Miller), chestnut (Cas- sheath length each larva was assigned to one of the last tanea sativa Miller) and hazel (Corylus avellana three instars, these being designates as follows: last, L.) over most of its length. The stream where this F-0; penultimate, F-1; antepenultimate, F-2. The sex study was carried out supports secure populations of of each larva was determined according to the pres- B. irene, Cordulegaster boltonii (Donovan) and Ony- ence (female) or absence (male) of gonapophyses on chogomphus uncatus (Charpentier), and smaller pop- the ventral surface of the eighth and ninth abdominal ulations of Calopteryx haemorrhoidalis (Vander Lin- segments. den) and Aeshna cyanea (Muller)È (Ferreras-Romero, Presence of a thick coating of allochthonous parti- 1994; Ferreras-Romero & Corbet, 1995). The stream cles on the body surface, especially on the abdominal apparently contains no ®sh. At the sampling site, its venter (`clean' vs `dirty' larvae), and hardness and width is 2±5 m and mean depth is 35±50 cm. On darkness of the integument were also recorded in lar-
June 13, 1990 properties of the water were: conductivi- vae of the later instars.