INTRODUCTION
The insect egg chorion plays a crucial role in protecting the developing
embryo and facilitating gas exchange during embryonic development (Lou
et al., 2018). It acts as a barrier against external agents while
allowing for the exchange of gases required for respiration (Pampolini
et al., 2020). The chorion contains structures that aid in fertilization
and can serve as a diagnostic feature for species identification (Gaino
et al., 1987). Additionally, the ultrastructure of different chorionic
modifications has demonstrated morphological, physiological, and
ootaxonomic importance in various insect orders (Hinton, 1981).
Dragonflies exhibit a variety of oviposition behaviors when it comes to
laying their eggs. These behaviors can be classified into three main
categories: exophytic, endophytic, and epiphytic (Rodrigues et al.,
2018). Exophytic species lay their eggs directly on the water surface,
while endophytic species lay their eggs inside plant tissue, either
aerial or underwater (Rodrigues et al., 2018; Corbet, 1983). Dragonflies
that exhibit exophytic oviposition, including Gomphidae, are capable of
laying eggs in water sources that lack plant or other materials (Ware et
al., 2012). This adaptation allows them to complete their egg-laying
process in a wider range of environments compared to species that lay
eggs endophytically or endosubstratically. The ability to lay eggs in
diverse aquatic habitats contributes to the ecological success and
distribution of Gomphidae (Ware et al., 2012).
Gomphidae eggs have received more attention than eggs from other species
that lay their eggs externally. However, research on gomphid eggs is
scarce. Currently, two types of eggs have been observed in Gomphidae.
Both types are generally elliptical in shape, and the eggs are enclosed
in a soft, jelly-like shell that is believed to come from accessory
glands (spumalin) in the female (Hinton, 1981). The first type is
surrounding with a thick jelly in the micropylar projection (Sahlen,
1995). The second type, found in a small number of species, lacks this
layer in the micropylar projection and instead carries a filament coil
the posterior pole (Gambles, 1956; Gambles & Gardner, 1960; Trueman,
1990; Andrew & Tembhare, 1992; Corbet, 1983). For example, studies have
been conducted using TEM on the species Onychogomphus forcipatus
unguiculatus , which is surrounded by a thick jelly in the micropylar
projection (Sahlen, 1995). Additionally, SEM and light microscopy
studies have been conducted on species Lestinogomphus africanus ,Ictinogomphus australis and I. rapax , which have a
filament coil the posterior pole (Trueman, 1990; Andrew & Tembhare,
1992; Gambles & Gardner, 1960).
L. tetraphylla is geographically distributed in Western and
Central Asia, as well as in Europe, including the Balkans and the
countries surrounding the Mediterranean. It is most commonly found in
northern Oman, along the Persian Gulf, and along the Euphrates and
Tigris rivers in Syria and southern Turkey (Schorr et al., 1998,
Steinmann, 1997; Boudot et al., 2021). There are records from Aydın,
Muğla, Hatay, Adana, Şanlıurfa, Adıyaman, Gökçeada in Turkey (Kalkman,
2006; Kalkman et al., 2004; Salur & Kıyak, 2007; Boudot et al. 2021;
Schorr et al., 1998). L.tetraphylla larvae breed in large
stagnant waters, slow-flowing rivers, and temporary ponds in both fresh
and brackish waters (Schorr et al. 1998).
Lindenia tetraphylla eggs are finding uncommon among dragonflies
due to the presence of a posterior filament coil. In this study, the
ultrastructure of Lindenia tetraphylla eggs was examined for the
first time using scanning electron microscopy (SEM).