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Symbiotic relationships between silverfish (Zygentoma: Lepismatidae, Nicoletiidae) and ants (Hymenoptera: Formicidae) in the Western Palaearctic. A quantitative analysis of data from Spain
Molero-Baltanás, R., Bach de Roca, C., Tinaut, A., Diz Pérez, J. & Gaju-Ricart, M.
Abstract: A large dataset of various associations between silverfish (order Zygentoma) and Formicidae is presented; this was obtained from samples collected across continental Spain. Associations have been detected in 693 ant nests of 14 different genera of Formicidae, hosting two species of Zygentoma belonging to the family Nicoletiidae (subfamily Atelurinae) and 17 species of Lepismatidae (subfamily Lepismatinae). A high diversity of interactions has been found: Overall, 157 different associations (species of Zygentoma – species of Formicidae) have been recorded. Comparing our data with the existent literature, 41 of these pairs are reported here for the first time. A quantitative criterion is being followed to classify taxa of Spanish Zygentoma occurring in ant nests. According to their obligateness, three groups are distinguished: xenomyrmecophiles, occasional and strict myrmecophiles and, in the latter, at least two degrees of host specificity: generalist and specialist species. A cladogram of Spanish Lepismatinae places specialist silverfish as the more apomorphic taxa. Moreover, the number and type of guest species of the most frequent ant genera and the number of individuals and species per nest have been compared and the Zygentoma-Formicidae quantitative network has been analysed. In conclusion, more than one mode of association occurs between Zygentoma and Formicidae in the Western Palaearctic. Nests of Messor Forel, 1890 host a lot of species of silverfish, most of which are specialists that have likely developed a higher level of integration and are far from strict parasites. A second group of associations is represented by several common ant genera such as Camponotus Mayr, 1861, or Formica Linnaeus, 1758, which mostly host a few species of myrmecophilous Zygentoma (those that are considered generalists). The position of Aphaenogaster Mayr, 1853, is intermediate between these two opposite groups. In the latter two groups, silverfish are likely parasites.