Cryptic species and their utilization of indigenous and non-indigenous intermediate hosts in the acanthocephalanPolymorphus minutus sensu lato(Polymorphidae)

Abstract

AbstractThe bird-infecting acanthocephalanPolymorphus minutushas been suggested to comprise different lineages or even cryptic species using different intermediate hosts. To clarify this open question, we investigatedPolymorphuscf.minutuscystacanths originating from amphipod intermediate hosts from 27 sites in Germany and France. Parasites and hosts were identified using integrated datasets (COI and/or morphology for hosts and COI + ITS1-5.8S-ITS2 for parasites).Mitochondrial and nuclear data (ITS1) strongly support the existence of three cryptic species inPolymorphuscf.minutus(type 1-3). These three types reveal a high degree of intermediate host specificity, withPolymorphustype 1 only encountered inGammarus fossarumtype B,Polymorphustype 2 inEchinogammarussp. andEchinogammarus berilloni, andPolymorphustype 3 inGammarus pulexandGammarus roeselii. Our results point to a so far neglected cryptic diversity of the genusPolymorphusin Central Europe. Furthermore,Polymorphustype 2 is most likely a non-native parasite in Germany that co-invaded withE. berillonifrom the Mediterranean area. Potentially, type 3 originates from South-East Europe and migrated to Germany byG. roeselii, where it might have capturedG. pulexas an intermediate host. Therefore, our findings can be seen in the context of ecological globalization in terms of the anthropogenic displacement of intermediate hosts and its impact on the genetic divergence of the parasites.