Diversity in mate-guarding types within the genus Anax 30. Juli 2012113 Diversity in mate-guarding types within the genus Anax (Odonata: Aeshnidae)
Andreas Martens 1, André Günther 2 and Frank Suhling 3
1) Biologie, Pädagogische Hochschule Karlsruhe, Bismarckstraße 10, D-76133 Karlsruhe,
Abstract
Observations of non-contact guarding in Anax guttatus, A. immaculifrons, A. indicus, and A. speratus are reported. In all four species males were observed following their mate and hovering above her intensively during oviposition. As a result, the genus shows a high di- versity in mate-guarding types, including contact-guarding (i.e., tandem oviposition), non- contact guarding and unguarded oviposition. A review on mate-guarding known to occur in the genus Anax worldwide is also provided.
Zusammenfassung
Unterschiedliche Typen der Partnerbewachung während der Eiablage bei der Gattung Anax (Odonata: Aeshnidae) – Vorgestellt werden Beobachtungen zur Bewachung der Partnerin ohne festen Körperkontakt bei Anax guttatus, A. immaculifrons, A. indicus und A. speratus. Bei allen vier Arten wurden die Männchen dabei beobachtet, wie sie ihrer Partnerin am Gewässer folgten und während der Eiablage ausdauernd über ihr rüttelten. Damit besitzt die GattungAnax die gesamte Vielfalt im Partnerbewachungsverhalten nach der Kopulation: die Eiablage im Tandem, die Bewachung ohne Körperkontakt und die un- bewachte Eiablage. Eine weltweite Übersicht aller Vertreter der GattungAnax und der von ihnen bekannten Formen der Partnerbewachung wird präsentiert.
Introduction
In odonates males often guard their female partners from copulation with other mates even after copulation and insemination. This behaviour offers benefits to the guarding male by reducing sperm competition and ensuring his sperm ferti- Libellula Supplement 12: 113-122 114 Andreas Martens, André Günther & Frank Suhling
lizes the female’s eggs, as well as benefits to the female by reducing male harrass- ment during oviposition. Post-copulatory mate guarding in Odonata is represent- ed by two different types: (1) grasping the female in tandem (contact guarding) and (2) following and guarding the female without physical contact and driving off other males (non-contact guarding). This phenomenom has been well-stud- ied in the Libellulidae and the Zygoptera (for reviews, see Conrad & Pritchard 1992; Corbet 1999; Fincke et al. 1997; Waage 1984; for a recent approach, see Schenk et al. 2004). Anax In theAeshna Aeshnidae, however,A. affinis mate-guarding has only been reported occasionally and inAnax single species, mostly as tandem-guarding in the genera (see below) and (especially : Klein 1932; Utzeri & Raffi 1983). In the ge- A. nus ephippi mostger A. general junius publicationsA. papuensis or detailedA. parthenope descriptions of adult reproduc- tive behaviour deal especially with cases of contact-guarding, as for example in , , , andA. imperator (Young 1967; Miller 1983; Jacquemin & Boudot 1986; Rüppell & Hadrys 1987; Rowe 1988; Günther & Mauersberger 1999). By contrast, in the females strictly oviposit unguarded and effectivelyA. immaculifrons repel males, which disturb them (Corbet 1957). Anax A single observation on by Busse (1993) in a faunistic paper suggests that non-contact guarding occurs in the genus . The first record was considered as unreliable by many odonatologists, who remained unconvinced even after additional proof was provided when that record was published as a photograph in a renowned field guide (Kalkman 2006: 172). Anax
Here we describe our own observations on non-contact guarding in species and review what is known about the mate guarding in the genus worldwide. Addi- tionally, to obtainAnax more details and a better overview, we reviewed the literature and interviewed experts worldwide about their own unpublished observations of ovipostion in species. Observations Anax guttatus
Mahé, Seychelles; pond of 30 m x 25 m in the garden of the Allamanda Hotel (04°46’36’’S, 55°31’23’’E), 18-viii-2004 (AM). – At 15:05 h local time (15:27 h solar time), a tandem pair arrived at the pond, crossed the water and landed as a tandem for oviposition in the emergent vegetation several times. After ca. 5 min- utes in tandem the male released her and began guarding her without physical contact while she continued oviposition. When the female changed oviposition sites, the male followed her at a distance of 20-30 cm, flying slightly higher. When- ever she landed again, he hovered closely above her and started flying in narrow circles, these becoming wider and wider in the course of time. In one instance he rested above her on the same stalk. Within the first 10 minutes after releasing Libellula Supplement 12: 113-122 Diversity in mate-guarding types within the genus Anax 115
her, he defended the female successfully from one rival. After a total of 5 minutes in tandem and 28 minutes of non-contact guarding she left the water with her abdomen curved. The male did not interfere with her and continued to patrol the pond. A. guttatus
More than 30 minutes before these observations, another pair of were seen at this pond. Oviposition also occurred in tandem before he released her and guarded her without physical contact. She moved oviposition sites several times, during which time he lost sight of her. A rival male detected her, grasped her and carried her in tandem, disappearing into a banana tree. It might be that both re- turned to the water and were the same pair described above.
Mahé, Seychelles, the same pond, 20-viii-2004 (AM). – At 14:07 h solar time a tandem pair appeared at the same pond. During their first 11 minute long visit, the female curled her abdomen to oviposit 23 times, generally for less than one minute, once for 81 s. At 14:28 h the pair landed within a wider area of jumbled emergent vegetation for a longer stay. After 4:01 minutes of continuous oviposi- tion the male released the female, and flew in circles above her expelling one rival male. He continued to fly over the site, attacked and grasped the female again, 34 s after release. The pair formed a copulation wheel on the wing, ending in a tree with a copulation duration of 10:59 minutes. Afterwards the pair returned to the pond in tandem and resumed oviposition behaviour. After about 10 minutes they left the water in tandem.
TyphaThailand, Ban Bang Khaya Nai, flooded pit (08°43’57’’N, 98°14’30’’E), 9-iv-2009 (AG). – At 15.15 h local time an ovipositing female was observed inside an open reedbed. A male hovered continuously about 1 m above her. After 3 min- Anaxutes the immaculifrons female changed sites and the male followed her immediately.
India, Pench National Park, small tributary stream of the Pench river (21°38’15.67’’N, 79°13’34.41’’E), 13-xi-2008 (AG). – At 12.45 h local time a female was ovipositing into roots in the rocky bank of a pothole of about 5 m diameter wide. A male circled the pothole very low over the water and periodically hov- ered over or in front of the female for 5-120 seconds. Arriving rival males were attacked immediately and driven off by short chasing flights (n = 3). After the ter- ritory owner was captured, the female resumed oviposition for 3 minutes. About 2 minutes later another male arrived at the site. He formed a tandem and carried the female into the forest. 10 minutes later a female (the same individual?) was Anaxlaying indicuseggs at the same site, again non-contact guarded by a male.
India, lake west of Gondakhari (21°08’28.93’’N, 78°51’3.49’’E), 15-xi-2008 (AG). – At 11:15 h local time a single male was patrolling, inspecting a shallow lagoon Libellula Supplement 12: 113-122 116 Andreas Martens, André Günther & Frank Suhling
Ipomoea inside a floating Ipomoea stand by the lake shore. An arriving female was grasped within a few seconds. The copulation wheel was formed in flight, and copula- Ipomoeation completed in the mats after 4:30 minutes. Immediately afterwards they separated, both partners flew up and the female began ovipositing into the stems. The male followed her to several oviposition sites, flying 30-100 cm above or next to her. After 5 minutes of oviposition the female left the site Anaxtogether speratus with the guarding male.
Namibia, Naukluft Mountains; spring-fed pool of 3 m x 4 m at the Olive Trail (24°13’41.88’’S, 16°16’49.4’’E), 13-iv-2004 (FS). – On arrival at the spring, a pair in copula was spotted but then disappeared immediately. However, after a few minutes a female arrived, landed and started ovipositing. For most of the dura- tion of the oviposition a male hovered 20-30 cm above her and followed her when she changed sites. Non-contact guarded oviposition continued for about 10 min- utes. The oviposition substrates were dead as well as living leaves of terrestrial grass; no other vegetation was present.
Namibia, Naukluft Mountains; Tsams Ost Spring (24°15’16.2’’S, 16°06’34.2’’E), 13-iv-2004 (FS, together with participants of the pre-symposium tour of the 2007 Congress of Odonatology). – The site was a small stream, not more than 1 m in width and running, depending on year andDiceros season, bicornis along a stretch of about 500 m. Most parts of the stream were overgrown by reeds except for few open areas, some of them kept so by Black Rhinoceros and other game. On our arrival a pair in a copulation wheel was spotted. They flew up but re- mained sitting in a nearby bush. After about 10 minutes the pair separated and both immediately flew to an open part of the stream, where the female began ovipositing in floating reed stems. Again the male guarded the female by hovering above her an a distance of 10-50 cm and following her when changing oviposition sites.
Zambia, Lwamfumu River above Mumbuluma Falls (10°55’45.94’’S, 28°44’14.55’’E), 05-iv-2011 (AG). – At ca. 9:00 h local time a female appeared at the observation site and began ovipositing into root masses, floating grass and other plants. She changed sites frequently and disappeared from view several times. At 9:22 h a male appeared patrolling along the stream. He grasped the fly- ing female at 9:34 h. The mating took place in a tree near the bank but was not clearly visible. Both individuals returned at 9:45 h to the stream bank and the female started oviposition behaviour. She was guarded all the time by the male hovering an a distance of 20-50 cm. An approaching male was driven off by the guarding A. speratusmale at 9:53 h. Guarded oviposition was observed until 9:57 h, after which both individuals left my field of view. On 12-iv-2011 a single unguarded female of was seen ovipositing at the same site for about two hours.
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Discussion
Adult Aeshnidae are strong-flying and wide-ranging insects. Therefore, the most difficult problem is interpreting observations on their reproductive behaviour. As a result, the general overview of reproductive behaviour in odonates has been based mainly on observations of taxa other than Aeshnidae, such as Libellulidae and Zygoptera (for reviews, see Waage 1984; Conrad & Pritchard 1992; Fincke et al. 1997; Corbet 1999). Anax immaculifrons Our report confirmsAnax the observations of non-contact guarded oviposition of by Busse (1993). Furthermore, we describe non-contact guarding in three other species. In most of our observations, there is no doubt that the observed males were the mating-partners. Due to the low density of individuals and the open habitat, it was easy to observe that the males were accompanying the females during ovipositon. As a consequence,A. speratus one hasA. indicus to conclude that the males were guarding their own mates as they were following them and protected them from rival males. In two cases, in A. guttatus and , the sequence from mating to oviposition was directly observed, so that it is certain that the mating male was the guarding one. In one case in the phase of non- contact guarding lasted only about 30 s before the uncoupled male-grasped the female again. This case may show the limitation of the non-contact guarding sys- tem, suggesting that the guarding male also needs specific landmarks or an open, clearly defined habitatA. guttatus to relocate his mate once separated.
The observations on show that there is a high plasticity of guarding behaviour in that species. Tandem-oviposition and non-contact guardingSympetrum may appear in the same pair in Pantalathe sequence (1) tandem-guarding,Zygonyx (2) non-contact guarding. That sequence is also known from the libellulid genera (Uéda 1979; Singer 1987), (AM unpubl.) and (Martens 1991). UnguardedAnax oviposition takes place in these genera as well. Anax Hemianax The genus includes at least 29 extant species worldwide (Tab. 1). According to Peters (2000), including forms a well-defined monophyletic group. In two thirds of species, some reproductive behaviour has been observed (Tab. 1). However, more detailed systematic studies have not been made. There- fore there is a considerableAnax potential to gain new insights into their mating sys- tems. The compilation in Table 1 shows that all three types of mate guarding are present in the genus Anax. Whereas guttatus in nine species so far only unguarded oviposi- tion has been observed, six species perform tandem oviposition and four practise non-contact guarding. was the only species in which a switch in behaviour has been observed, although we have no doubt that in most species a change from contact or non-contact guarding to no guarding might occur, espe- cially towards the end of the oviposition.
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Table 1. Extant Anax species of the world, with a comparison of their known mate-guard- ing behaviour during oviposition. Crosses indicate that the respective guarding behaviour was observed at least once. The category ‘no guarding’ is likely present in all species. Here we only list species under this category if no other guarding behaviour has been observed. – Tabelle 1. Die Liste der bekannten Anax-Arten der Welt, mit einem Vergleich ihres Part- nerbewachungsverhaltens durch das Männchen während der Eiablage; ENG Exclusively no guarding, grundsätzlich ohne Bewachung; NCG Non-contact guarding, Bewachung ohne Körperkontakt; CG Contact guarding, Eiablage im Tandem.
Species ENG NCG CG References Distribution
Anax amazili (Burmeister, 1839) x x Esquivel (2006), S & Central America, Texas W. Piper unpubl., and Florida to Brazil, J. Hoffmann un- Galapagos Isl. publ. Anax bangweuluensis Kimmins, 1955 Central Africa Anax chloromelas Ris, 1911 Africa from Sierra Leone and Uganda to Zambia and Mozambique Anax concolor Brauer, 1865 x Paulson (2009) Texas to Brazil Anax congoliath Fraser, 1953 Congo Basin Anax ephippiger (Burmeister, 1839) x Miller (1983), Jac- Africa, W Palaearctic quemin & Boudot (1986), Günther & Mauersberger (1999) Anax fumosus Hagen, 1867 x AG unpubl – Asia from Japan to ssp. celebense Indonesia Anax georgius Selys, 1872 Timor Anax gibbosulus Rambur, 1842 x A.G. Orr unpubl. Australia Anax guttatus (Burmeister, 1839) x x this study, Seychelles to Japan and Orr (2001) N Australia, Pacific Islands Anax immaculifrons Rambur, 1842 x Corbet (1999) S/SE Asia to E Mediterra nean Anax imperator Leach, 1815 x (x)1 Corbet (1957) Africa, W Palaearctic Anax indicus Lieftinck, 1942 x this study India, Sri Lanka Anax julius Brauer, 1865 x Peters (1987) E Asia Anax junius (Drury, 1773) x Young (1967) North America Anax longipes Hagen, 1861 x Paulson (2009) E United States Anax maclachlani Förster, 1898 New Guinea, Bismarck Archipelago Anax mandrakae Gauthier, 1988 Madagascar Anax nigrofasciatus Oguma, 1915 x K. Wilson unpubl. Himalaya to Japan Anax panybeus Hagen, 1867 x K. Wilson unpubl. Japan to Myanmar and Indonesia Anax papuensis (Burmeister, 1839) x Rowe (1988) Australia, New Zealand, New Guinea, Indonesia
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Species ENG NCG CG References Distribution
Anax parthenope (Selys, 1839) x Miller (1983) Palaearctic Anax pugnax Lieftinck, 1942 New Guinea Anax selysi Förster, 1900 New Guinea Anax speratus Hagen, 1867 x this study Sub-Saharan Africa, Arabia Anax strenuus Hagen, 1867 Hawaii Anax tristis Hagen, 1867 x AM, AG, FS unpubl. Sub-Saharan Africa, Madagascar Anax tumorifer McLachlan, 1885 Madagascar Anax walsinghami McLachlan, 1882 x R. Novelo-Gutierrez California and Texas to unpubl. Honduras
1) There exists a description of a single tandem-oviposition inA. imperator (Balança & Visscher 1989). We regard this as a rare exception. It is common knowledge among odonatologists in Europe that females of A. imperator oviposit alone.
Anax A. junius A. parthenope A. julius A. ephippiger A. papuensis All species that areA. guttatus known to show migratory behaviour (sensu Corbet 1999: 408) – , , , , and – oviposit in tandem, and switches between contact and non-contact guarding. All these species may occur in high densities at the oviposition site when migratingA. immaculifrons swarms arrive.A. speratus The high intensity guarding may be an adaptation to temporary high densities at oviposition sites. At least two of the non-contact species, and , are typical running water species. Most probably, non-contact guarding is highly efficient at streams. Males are able to drive off rivals by chasing flights. Presumably this would be much easier along a linear habitat thanA. imperator on a broad lakeA. tristis were rivals would approachA. imperator from all direc- tions. In species that do not guard, individual males often dominate a pond tem- porarily, such as and . Interestingly, in females are able to repel males very effectively.
Besides the male’s benefit of protecting his mate against rivals andAnax sperm remov- al, there are some specific clues which may help us also understand the female’s perspective by being guarded. The females within the genus , as in some other aeshnid species, often have damaged, dented compound eyes. This damage is caused by the male’s epiproct (Ris 1910; Calvert 1920; Dunkle 1979) when the female is being grasped by the male. In general, this damage may occur during pre-copula, when the male grasps the female, during the copulation wheel, and also in post-copula tandem. The amount of damage should increase especially during oviposition in tandem, when both mates have to synchronously change oviposition sites several times. What could be the female’s strategies to reduce the risk of, or the trade-off from eye damage? One option may be for females to have a smaller body size and mass which may reduce the mechanical stress in the tandem-linkage. The alternative trend would be the size extension in cases without tandem guarding. We suppose that the larger body size and mass in fe- Libellula Supplement 12: 113-122 120 Andreas Martens, André Günther & Frank Suhling
Anax A. tristis A. walsinghami males may beAnax helpful in effectively repelling males. As known so far, the very large species in , such as and , do not show mate guarding. The genus is a phylogenetic young and modern clade within the Aeshnidae (Peters 1987, 2000). The members are persistent long-distance fliers (Peters 2000) and have a high dispersal ability. Most species have the potential to colonise a wide variety of habitats and have a short life-cycle, comparedAnax to other aeshnids (Corbet et al. 2006). They are even successful in aridA. imperator areas, which are otherwise dominated by libellulids (Suhling et al. 2003). The ability of females to de- posit A. ephippigertheir eggs in the smallest piece of plant tissue ( : many observa- tions from rock pools in the Mascarene Islands and Namibia; AM unpubl.), or wet soil ( : Miller 1983) reduces the limitations of endophytic oviposi- tion. The tendency to be a habitat opportunist is indicated in the diversity and flexibilty of reproductive behaviour. On oneAnax hand, amazili we suppose that sexual conflict is a driver for an opportunistic choice of habitat, when females swerve to sub-op- timal habitats to avoid male harassment. females were observed ovi- positing without guarding males in suboptimal (saline) habitats, whereas in typi- cal habitats they were guarded (J. Hoffmann pers. comm.). Females may seek such suboptimal habitats as a trade-off for not being bothered by males. On the other hand, opportunism needs behavioural adaptations to the wide range of popula- tion densities,Anax caused by the high variance in breeding success in time and space.
The genus shows high variabilty in reproductive behaviour. To our knowl- edge it is the only genus of the Aeshnidae in which all three types of guarding oc- cur. We suggest that intense guarding may be finally associated with the various effective densities that prevail at the oviposition habitat in the different species. No guarding may indicate that the females have evolved effective repellent be- haviour. In such a species guarding may occur never or very rarely. In species that otherwise show intense guarding, no guarding may be observed when females avoid male harassment by selecting suboptimal habitats and opportunistic choice of a wide spectrum of waters. However, it is far too early for conclusions. On the Anaxone hand, more detailed observations on guarding behaviour are needed, as well as information about female male-repelling behaviour, preferably in all species of . On the other hand, a phylogeny to the species level is required to assess the phylogenetic background of the guarding behaviour. Acknowledgements
Günther Peters had an enormous impact on the development of our scientific style and work. Therefore, we are proud to have a birthday present in his special Anaxfield. We would like to thank Rodolfo Novelo-Gutierrez, Joachim Hoffmann, Jens Kipping, Albert G. Orr, Werner Piper and Keith Wilson for their information on behaviour. Special thanks to Albert G. Orr for comments on the manuscript and improving the English. Libellula Supplement 12: 113-122 Diversity in mate-guarding types within the genus Anax 121
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