Among 15 demodecid mite species (Acariformes: Demodecidae) recorded from carnivorans Carnivora, 3 species were described from mustelids Mustelidae. They are known only from single records, for which Demodex erminae has been described from the stoat Mustela erminea from Great Britain and New Zealand, D. melesinus from the European badger Meles meles known solely from Great Britain and D. lutrae discovered in the Eurasian otter Lutra lutra from Poland. The current record confirms the existence of D. melesinus, in badger from Poland, after close to one hundred years from its original description, as well as the first detection of the male for this species.

Despite the widespread belief that an extensive body of knowledge exists for the sucking lice (Anoplura), some of their common, Eurasian or even cosmopolitan species still lack complete taxonomic descriptions, especially those for their nymphal stages. This applies especially to the most common rodent parasites: the lice of the genus Hoplopleura. In Europe, only two of the five most common Hoplopleura species have full taxonomic characteristics with a description of the nymphal stages. This study enriches the current state of knowledge for another species, Hoplopleura longula and presents the first description of its nymphal stages. The study includes five rare louse specimens (two nymphs I, one nymph II, two nymphs III) of H. longula collected from 63 Eurasian harvest mice Micromys minutus. The collected lice were fixed and preserved in 70% ethyl alcohol solution and then placed in polyvinyl-lactophenol to form total preparations. Only two of the five species found in Eurasia (H. acanthopus, H. affinis, H. captiosa, H. edentula and H. longula) have been given full taxonomic descriptions, including immature stages. This paper presents a description of the nymphal stages of H. longula (described for the first time).

A greater understanding of mite biodiversity and ecology can explain their preference for microhabitats within host bodies, i.e., as ecto-, meso-, and endoparasites. Similarly, learning about the patterns formed by mite communities in wild animals can shed light on the mechanisms of parasitosis development in their domesticated counterparts. Hence, the present study examined the acarofauna of the mouflon, introduced to Poland in the early 20th century from a region of endemic occurrence. Forty-one individuals were examined for the presence of ectoparasites between 2010 and 2013; later, skin fragments were analysed for the presence of skin mites. A new species of Demodecidae, Demodex musimonis sp. nov., was discovered in the skin of the pasterns of 14.6% mouflons, as well as the ectoparasitic tick Ixodes ricinus (prevalence 29.3%) and ungulate-typical fly Lipoptena cervi (34.1%). However, no mites typical for ovine Ovis (Psorergatidae, Psoroptidae) were noted, nor any colonisation of microhabitats by species from local ungulates, resulting from the loss of original parasites during the introduction. A comparison of the acarofauna of the mouflon and domestic sheep Ovis aries aries suggests that a mite community with a complex structure and the co-occurrence of different families may be formed. However, it is not known whether the acarofauna of domestic sheep is derived from wild ancestors or the process of domestication. Even so, the peculiar Demodecidae must have been part of the natural parasitofauna of wild sheep, of which only D. musimonis sp. nov. has been recognised so far.

The genus Hoplopleura is the most speciose genus of sucking lice observed parasitizing rodents and lagomorphs (pikas). Despite the fact that the majority of Anoplura are believed to be monoxenic, many species within Hoplopleura may be oligoxenic. In addition, the occurrence of more than one parasite species per host species on individuals has been confirmed. As such, a precise species identification of the parasite, especially of the nymphs, is of high significance. The study is based on the material of 245 sucking louse specimens taken from 179 individuals of the striped field mouse Apodemus agrarius collected between 2008 and 2017. The study employs scanning microscopy to provide superior quality resolution of the studied traits. The study presents the first record of the characters of the nymphal stages of H. affinis, one of the common Eurasian species of the genus. Additional aspects of the biology and the host–parasite relationship of H. affinis are presented, e.g., female, male and nymphs of lice, showing different preferences in the choice of location (topography) on the host body. In addition, a global checklist has been made of all the species of Hoplopleura found parasitizing rodents of the genus Apodemus. Generally, the ranges of the occurrence of lice of this genus coincide with the geographic distribution of typical hosts, although this has not always been confirmed by local studies.

We present the first record of the characteristics of the three nymphal stages of Hoplopleura edentula, one of the common Eurasian species of the genus Hoplopleura. Lastly, a list of all species of Hoplopleura parasitizing the host genus Clethrionomys is provided. The descriptions of sucking louse species usually lack the features of the nymphal stages. In addition, it is impossible to determine whether the host is the main one or an accidental when there is a co-occurance of two or more lice species, unless we observe nymphs of the same species. As a result, data on the host cycle, the range of host specificity and other aspects of parasite-host system functioning, the possibility of transfer between hosts, and the possibility of transmission of pathogens, are incomplete. This study examines 114 specimens of the bank vole Clethrionomys glareolus, in which 38 Hoplopleura edentula were found.