The sympatric occurrence of two genetically divergent lineages of sucking louse, Polyplax arvicanthis (Phthiraptera: Anoplura), on the four-striped mouse genus, Rhabdomys (Rodentia: Muridae)

Diversity and distribution of ectoparasite taxa associated with Micaelamys namaquensis (Rodentia: Muridae), an opportunistic commensal rodent species in South Africa

South Africa boasts a rich diversity of small mammals of which several are commensal and harbour parasites of zoonotic importance. However, limited information is available on the parasite diversity and distribution associated with rodents in South Africa. This is particularly relevant for Micaelamys namaquensis (Namaqua rock mouse), a regionally widespread and locally abundant species that is often commensal. To address the paucity of data, the aims of the study were to record the ectoparasite diversity associated with M. namaquensis and develop distribution maps of lice and mites associated with M. namaquensis and other rodents in South Africa. Micaelamys namaquensis individuals (n = 216) were obtained from 12 localities representing multiple biomes during 2017–2018. A total of 5591 ectoparasites representing 5 taxonomic groups – fleas, lice, mesostigmatid mites, chiggers and ticks was recorded. These consisted of at least 57 taxa of which ticks were the most speciose (20 taxa). Novel contributions include new host and locality data for several ectoparasite taxa and undescribed chigger species. Known vector species were recorded which included fleas (Ctenocephalides felis, Dinopsyllus ellobius and Xenopsylla brasiliensis) and ticks (Haemaphysalis elliptica, Rhipicephalus appendiculatus and Rhipicephalus simus). Locality records indicate within-taxon geographic differences between the 2 louse species and the 2 most abundant mite species. It is clear that M. namaquensis hosts a rich diversity of ectoparasite taxa and, as such, is an important rodent species to monitor in habitats where it occurs in close proximity to humans and domestic animals.

Phylogeography of the parasitic mite Laelaps agilis in Western Palearctic shows lineages lacking host specificity but possessing different demographic histories

Background

Laelaps agilis C.L. Koch, 1836 is one the most abundant and widespread parasitic mite species in the Western Palearctic. It is a permanent ectoparasite associated with the Apodemus genus, which transmits Hepatozoon species via the host’s blood. Phylogenetic relationships, genealogy and host specificity of the mite are uncertain in the Western Palearctic. Here, we investigated the population genetic structure of 132 individual mites across Europe from their Apodemus and Clethrionomys hosts. Phylogenetic relationships and genetic variation of the populations were analyzed using cytochrome c oxidase subunit I (COI) gene sequences.

Results

We recovered three main mtDNA lineages within L. agilis in the Western Palearctic, which differentiated between 1.02 and 1.79 million years ago during the Pleistocene period: (i) Lineage A, including structured populations from Western Europe and the Czech Republic, (ii) Lineage B, which included only a few individuals from Greece and the Czech Republic; and (iii) Lineage C, which comprised admixed populations from Western and Eastern Europe. Contrary to their population genetic differentiation, the lineages did not show signs of specificity to different hosts. Finally, we confirmed that the sympatric congener L. clethrionomydis is represented by a separated monophyletic lineage.

Conclusion

Differences in the depth of population structure between L. agilis Lineages A and C, corroborated by the neutrality tests and demographic history analyses, suggested a stable population size in the structured Lineage A and a rapid range expansion for the geographically admixed Lineage C. We hypothesized that the two lineages were associated with hosts experiencing different glaciation histories. The lack of host specificity in L. agilis lineages was in contrast to the co-occurring highly host-specific lineages of Polyplax serrata lice, sharing Apodemus hosts. The incongruence was attributed to the differences in mobility between the parasites, allowing mites to switch hosts more often.

Two New Species of Sucking Lice (Phthiraptera: Anoplura: Hoplopleuridae and Polyplacidae) from Grant's Rock Mouse, Micaelamys granti, in South Africa

Two new species of sucking lice (Phthiraptera: Anoplura), Hoplopleura granti n. sp. (Hoplopleuridae) and Polyplax megacephalus n. sp. (Polyplacidae), are described from Grant's rock mouse, Micaelamys granti (Wroughton), from Northern Cape Province, South Africa. Adults of both sexes are illustrated via line drawings and differential interference contrast microscopy images, and are compared with previously described related species that parasitize related hosts: Hoplopleura patersoni Johnson from Aethomys chrysophilus (de Winton) (red veld rat), Aethomys kaiseri (Noack) (Kaiser's aethomys), and Micaelamys namaquensis (A. Smith) (Namaqua rock mouse); Hoplopleura aethomydis Kleynhans from M. namaquensis; Polyplax praomydis Bedford from A. chrysophilus and M. namaquensis; and Polyplax solivaga Johnson from A. chrysophilus. It is not known if these new species of lice are vectors of any pathogens.

Comparative phylogeography of parasitic Laelaps mites contribute new insights into the specialist-generalist variation hypothesis (SGVH)

Background

The specialist-generalist variation hypothesis (SGVH) in parasites suggests that, due to patchiness in habitat (host availability), specialist species will show more subdivided population structure when compared to generalist species. In addition, since specialist species are more prone to local stochastic extinction events with their hosts, they will show lower levels of intraspecific genetic diversity when compared to more generalist.

Results

To test the wider applicability of the SGVH we compared 337 cytochrome oxidase I mitochondrial DNA and 268 nuclear tropomyosin DNA sequenced fragments derived from two co-distributed Laelaps mite species and compared the data to 294 COI mtDNA sequences derived from the respective hosts Rhabdomys dilectus, R. bechuanae, Mastomys coucha and M. natalensis. In support of the SGVH, the generalist L. muricola was characterized by a high mtDNA haplotypic diversity of 0.97 (±0.00) and a low level of population differentiation (mtDNA F_st = 0.56, p < 0.05; nuDNA F_st = 0.33, P < 0.05) while the specialist L. giganteus was overall characterized by a lower haplotypic diversity of 0.77 (±0.03) and comparatively higher levels of population differentiation (mtDNA F_st = 0.87, P < 0.05; nuDNA F_st = 0.48, P < 0.05). When the two specialist L. giganteus lineages, which occur on two different Rhabdomys species, are respectively compared to the generalist parasite, L. muricola, the SGVH is not fully supported. One of the specialist L. giganteus species occurring on R. dilectus shows similar low levels of population differentiation (mtDNA F_st = 0.53, P < 0.05; nuDNA F_st = 0.12, P < 0.05) than that found for the generalist L. muricola. This finding can be correlated to differences in host dispersal: R. bechuanae populations are characterized by a differentiated mtDNA F_st of 0.79 (P < 0.05) while R. dilectus populations are less structured with a mtDNA F_st = 0.18 (P < 0.05).

Conclusions

These findings suggest that in ectoparasites, host specificity and the vagility of the host are both important drivers for parasite dispersal. It is proposed that the SGHV hypothesis should also incorporate reference to host dispersal since in our case only the specialist species who occur on less mobile hosts showed more subdivided population structure when compared to generalist species.

Electronic supplementary material

The online version of this article (10.1186/s12862-018-1245-7) contains supplementary material, which is available to authorized users.

Evidence of cryptic speciation in mesostigmatid mites from South Africa

Laelaps giganteus and Laelaps muricola (Mesostigmata; Laelapidae) are widespread and locally abundant host generalists on small mammals in southern Africa. The large host range and complex life history of these ectoparasites may allude to possible intraspecific cryptic diversity in these taxa. To assess genetic and morphological diversity in L. giganteus and L. muricola, we sampled 228 rodents at eight localities in South Africa. This sample included nine previously recorded host species and on these, L. muricola was only recorded from Mastomys natalensis and Micaelamys namaquensis while L. giganteus was found on Rhabdomys dilectus and Lemniscomys rosalia. Phylogenetic analyses of partial mtDNA cytochrome oxidase subunit I (COI) and nuclear ITS1 data strongly supported the recognition of L. giganteus and L. muricola, a scenario partly supported by the Tropomyosin intron. Strong support for evolutionary distinct lineages within L. giganteus is found: L. giganteus lineage 1 is confined to R. dilectus and L. giganteus lineage 2 is confined to L. rosalia. These host specific monophyletic lineages were also separated by 9.84% mtDNA sequence divergence and 3.44% nuclear DNA sequence divergence. Since quantitative morphometric analyses were not congruent with these findings, these two lineages more than likely represent cryptic species.