Egg morphology update based on new chorionic data of Potamanthus luteus  (Linnaeus), Ephemera danica Müller and Oligoneuriella rhenana (Imhoff) (Insecta, Ephemeroptera) obtained by scanning electron microscopy

Abstract

The chorionic patterns of Ephemeroptera eggs are very diverse and these have often been used for taxonomic and systematic purposes. In a great number of species, including Potamanthus luteus, Ephemera danica and Oligoneuriella rhenana, these egg features have been studied using light microscopy. However, current trends in egg morphology studies use scanning electron microscopy (SEM), so that the eggs of these species need to be re-described in order to establish morphological comparisons. The general chorionic features which have already been described in these three species are confirmed in our SEM study, although a more detailed description of both the architecture and arrangement of these can now be offered. In addition, this study has allowed us to note new morphological data, such as the chorionic reticulation in P. luteus and the complex extrachorion-adhesive layer in E. danica; classification of the lateral attachment structure in P. luteus and O. rhenana has been changed; and the variability of the polar cap observed in P. luteus underlines the care that must to be taken when selecting chorionic structures for taxonomic purposes.

New type of egg attachment structure in Ephemeroptera and comparative analysis of chorion structure morphology in three species of Ephemerellidae

“…1995; Studemann and Landolt 1997). However, as in the case of the lateral attachment structures of the eggs of Potamanthus luteus (Linnaeus, 1767) (Potamanthidae), in which SEM studies revealed morphological characteristics that cannot be considered KCTs (Ubero‐Pascal and Puig 2007), the morphological characteristics of the lateral attachment structures of Ephemerellidae eggs also lead us to question the type to which they have traditionally been assigned.…”

“…1987, 1993; Kluge et al . 1995; Klonowska‐Olejnik 1997; Klonowska‐Olejnik & Jazdzewska 2003; Ubero‐Pascal 2004; Ubero‐Pascal and Puig 2007), although the number of species in which they have been studied in depth is still low.…”

“…Koss and Edmunds (1974) proposed a classification of Ephemeroptera attachment structures, although they also stated that this could change as the egg morphology of more species became known. Indeed, given their biological importance and morphological diversity, attachment structures have been the main focus in a large number of the studies on Ephemeroptera eggs (Gaino and Mazzini 1989; Gaino and Bongiovanni 1991, 1992; Gaino and Rebora 2001; Ubero‐Pascal 2004; Ubero‐Pascal and Puig 2007), the findings of which have provided more detail and shown the need to update Koss and Edmunds’ classification.…”

“…Compared with other Ephemeroptera, such as Potamanthidae, Ephemeridae and Oligoneuriidae, the egg morphology of Ephemerellidae has been studied in a considerable number of species (Ubero‐Pascal and Puig 2007). The characteristics of the chorion have been established both by optical microscopy and scanning electron microscopy (SEM) in approximately 32 species, belonging to 11 of the 22 genera forming this family according to Hubbard (1990); however, most of the descriptions given have been quite superficial (Bengtsson 1913; Smith 1935; Degrange 1956, 1960; Koss 1968; Koss and Edmunds 1974; Studemann and Tomka 1987; Gaino and Bongiovanni 1992; Kang and Yang 1995; Studemann et al .…”

The structure and ultrastructure of the egg capsules of stoneflies of the genusIsoperla(Insecta, Plecoptera, Perlodidae)

“…The structure and ultrastructure of insect egg capsules have been investigated by many authors (Biliński & Jankowska, ; Domínguez & Cuezzo, ; Gaino, Mazzini, Degrange, & Sowa, ; Gaino & Bongiovanni, ; Gaino & Mazzini, ; Gaino, Piersanti, & Rebora, ; Gaino, Sartori, & Rebora, ; Hinton, ; Kambysellis, Margaritis, & Craddock, ; Kaulenas et al, ; Kłonowska‐Olejnik & Jażdżewska, ; Krzysztofowicz & Kisiel, ; Margaritis, Kafatos, & Petri, ; Simiczyjew, ; Skudlik, Poprawa, & Rost, ; Ubero‐Pascal & Puig, ; Vogelgesang & Szklarzewicz, ; Wichard, Arens, & Eisenbeis, , b; Zawadzka, Jankowska, & Biliński, ). In the context of the great diversity of insects and their abilities to adapt to practically any environment on Earth, egg capsules, inside which the essential first step of development takes place continues to be of great interest.…”