The autochthonous Lipoptena cervi and the allochthonous Lipoptena fortisetosa in Cervus elaphus in Central/Northern Italy were studied during autumn and winter 2018–2020 in order to evaluate the possible interactions between the two parasite species and the possible influence of geographical parameters on their abundance. This survey could help disentangling whether the coexistence between the two species will be possible or the competitive exclusion of L. cervi is to be expected. The results show that L. cervi is influenced by host sex and age and is more abundant at higher altitudes, while L. fortisetosa is more abundant in lower altitudes and in southern/eastern areas. The interaction between the two species is evident and symmetrical but mild at the component community level, while at the infracommunity level an asymmetric competition has been evidenced by the displacement of L. cervi when L. fortisetosa is present in the same body location. Geographical clusters of L. fortisetosa are evident in plains near urbanized areas, while L. cervi distribution appeared more scattered in all the Apennine ridge. Our observations indicate that the two deer ked species not only can coinfect the same host population but also the same host individual, avoiding strong direct interaction and competitive exclusion. All the observed patterns reflect different adaptations to environmental conditions and possible strategies to minimize competition. However, longitudinal surveys are needed to evaluate if the observed pattern is a constant feature or a result of the sampling seasons.
