Many problems for a solo mother: maternal care efficiency of the ghost spider of new genus Eldar (Araneae: Anyphaenidae, Anyphaeninae) against new species Pseudogaurax Malloch (Diptera: Chloropidae)

Abstract

Parental care in nature can present itself in different forms and vary in intensities and strategies, being maternal care one of the widely observed patterns in animals. In spiders, parental investment is carried out mainly by females. Despite this, newly hatched eggs can still be targets of a series of natural enemies. In a remnant of Atlantic Forest in Brazil, females of the spider Eldar galadrielae sp. nov., family Anyphaenidae, build nests at the forest’s edge by folding plant leaves. However, information about the plants chosen for nest, the importance of maternal care by females in offspring survival, and predators are completely unknown. In this study, we (1) presented new information about the nest built by females of Eldar galadrielae sp. nov.; (2) compared the predation rate on eggs of the spider Eldar galadrielae in nests with and without the presence of the female; (3) provided morphological descriptions and distribution maps to the genus Eldar gen. nov. as well as presenting; and (4) the described Pseudogaurax vasconcellosi sp. nov. as the predator of the spider eggs. This is the first report on an interaction between Pseudogaurax flies and Anyphaenidae spiders. Our results support predation rates higher in female-less Eldar galadrielae sp. nov. nests. Although egg consumption was 100% in nests attacked by flies, overall nest predation rate was low, as flies were only recorded in three of the 12 nests that maintained female care, indicating that active protection of egg sacs by females can increase the offspring’s chances of survival.