Morphology of dry-resistant eggs in parthenogeneticHeterocypris incongruens(Ramdohr, 1808) (Ostracoda, Crustacea)

Abstract

It has been known that many organisms evolved to survive in temporary or ephemeral inland waters. Many of them have dry-resistant eggs against desiccation. The structural feature of egg shell is important because only this will ensure to survive the dry period. Structural features of egg shell in the parthenogenetic Heterocypris incongruens (Ramdohr, 1808) was investigated by scanning electron microscope. Results showed that egg shell structure consists of two distinct layers; an outer layer with holes or alveoli and an inner layer consisting of two dense sublayers. Also, structural similarities in egg-shell of H. incongruens and some other crustaceans which combat desiccation problem will be discussed.

Neonicotinoids thiamethoxam and clothianidin adversely affect the colonisation of invertebrate populations in aquatic microcosms

“…Our data show that field-realistic concentrations of two commonly used neonicotinoids, thiamethoxam and clothianidin, significantly impact on populations of invertebrates (Diptera and Ostracoda) colonising aquatic microcosms, with some differences between the effects of the two chemicals. The aquatic microcosms were colonised mainly by flying Diptera ( Culex and Chironomidae) which oviposited in the water, and also by Ostracoda, which may have originated from the soil added to each microcosm (they can survive for long periods in soil as desiccation-resistant eggs) (Özuluğ and Suludere 2012 )). Organisms were found to differ in their sensitivity to both the concentration and particular class of neonicotinoid.…”

First ultrastructural description of an apomictic opsiblastic egg in freshwater Gastrotricha

“…The importance of resting eggs in these taxa is well documented (e.g., reviewed in Fryer, 1996; Incagnone et al, 2015; Pourriot & Snell, 1983; Ruttner‐Kolisko, 1983), but in most species the structure of the eggshell is poorly known and an understanding of how cellular ultrastructure changes during diapause or after emergence from diapause is incomplete (e.g., Reed et al, 2021). Among crustaceans, some copepods (Williams‐Howze, 1997; Winding Hansen, 2019), nonmarine ostracods (Horne & Martens, 1998; Rossi et al, 1996), and branchiopods (Lavens & Sorgeloos, 1987) are parthenogenetic, but only select species of Ostracoda (e.g., Heterocypris incongruens (Ramdohr, 1808); Özuluğ & Suludere, 2012; Vandekerkhove et al, 2013) and Branchiopoda (e.g., species of Daphnia : Tucker et al, 2013) can produce resting eggs via parthenogenesis. To date, there are no studies that show if the eggshells of embryos derived via amphimixis differ from those produced via parthenogenesis.…”