Additions to the chigger mite fauna (Acariformes: Trombiculidae) of Saudi Arabia, with the description of a new species

Collections of chigger mites from murid rodents were performed in two bordering provinces of southwestern Saudi Arabia, Al Bahah and ‘Asir. A total of 561 chiggers belonging to 19 species were collected in 2020 and 2021 from 54 rodents of two species, Acomys dimidiatus (Cretzchmar) and Mus musculus L. One new species is described: Odontacarus thesigeri n. sp. Five species are recorded in Saudi Arabia for the first time: Microtrombicula abyssinica (Radford, 1947), Microtrombicula felis (Vercammen-Grandjean, 1965), Microtrombicula saperoi (Radford, 1954), Schoengastiella hypoderma Vercammen-Grandjean, 1956, and Schoutedenichia originalis Kudryashova, 1976. Among them, M. abyssinica and M. saperoi, are re-described based on type specimens and new materials.</jats:p

On the taxonomy of chigger mites (Acariformes: Trombiculidae) parasitizing birds in Thailand and Malaysia, with the description of a new species

Chigger mites were collected from 65 bird species in different regions of Thailand and Malaysia. In total, 21 species were recorded. The previously unknown fauna of chiggers parasitizing shorebirds of Thailand included one new species, Neacariscus (Whartonacarus) andamanensis n. sp. as well as Neacariscus (Neacariscus) pluvius (Wharton, 1945) previously recorded only in Oceania; Neacariscus (Whartonacarus) shiraii (Sasa, Kano and Obata, 1952) (known from Oceania and Japan); and Neacariscus (Whartonacarus) sulae (Oudemans, 1910) and Schoengastia archaea (Taufflieb, 1960), both described from West Africa. Toritrombicula kirhocephales Goff, 1982 described from Papua New Guinea was for the first time recorded in Asia (Thailand). Neoschoengastia gallinarum (Hatori, 1920) and Helenicula comata (Womersley, 1952) were for the first time recorded in Thailand. Ascoschoengastia lorius (Gunther, 1939) was for the first time recorded in Malaysia. Finally, Ericotrombidium cosmetopode (Vercammen-Grandjean and Langston, 1971) described from free larvae, was for the first time recorded on a host (bird Pellorneum ruficeps Swainson); and Leptotrombidium miculum (Traub and Audy, 1954) was for the first time recorded on a bird host. New host species were recorded for a large part of the collected chigger species.</jats:p

Automatic barcode gap discovery reveals diverse clades of Rhipicephalus spp. and Haemaphysalis spp. ticks from small mammals in 'Asir, Saudi Arabia

Abstract Background The ixodid tick genera Rhipicephalus and Haemaphysalis contain several species of medical and/or veterinary importance, but their diversity in some regions of the world remains under-explored. For instance, very few modern studies have been performed on the taxonomy of these genera on the Arabian Peninsula. Methods In this study, we trapped small mammals in the 'Asir Mountains of south-western Saudi Arabia and collected tick specimens for morphological examination and molecular barcoding, targeting three mitochondrial loci: cox1, 16S rRNA and 12S rRNA. Results We obtained a total of 733 ticks (608 Haemaphysalis spp. and 125 Rhipicephalus spp.) from 75 small mammal hosts belonging to six species. All tick specimens were immature except for nine adults recovered from a hedgehog (Paraechinus aethiopicus). Morphologically, the Rhipicephalus ticks resembled R. camicasi, but the Haemaphysalis ticks showed differences in palp morphology compared with species previously described from Saudi Arabia. Phylogenetic analysis and automatic barcode gap discovery identified a novel clade of Rhipicephalus sp. representing most of the nymphs. This was most closely related to R. leporis, R. guilhoni and R. linnaei. The adult ticks and a small proportion of nymphs clustered with R. camicasi sequences from a previous study. Finally, the Haemaphysalis nymphs formed two distinct clades that were clearly separated from all reference sequences but closest to some African species. Conclusions This apparent high level of tick diversity observed in a single study site of only ~ 170 km2, on a relatively small number of hosts, highlights the potential for the discovery of new tick species on the Arabian Peninsula. Graphical Abstrac

Molecular Detection of Candidatus Orientia chuto in Wildlife, Saudi Arabia

Scrub typhus is a zoonosis caused by 3 species of Orientia bacteria, including Candidatus Orientia chuto. This species is known only from a human case in Dubai and infections in wildlife in Kenya. We report molecular detection of Candidatus O. chuto in 2 wild rodent species from Saudi Arabia

Microbiome and mitogenomics of the chigger mite Pentidionis agamae: potential role as an Orientia vector and associations with divergent clades of Wolbachia and Borrelia

Abstract Background Trombiculid mites are globally distributed, highly diverse arachnids that largely lack molecular resources such as whole mitogenomes for the elucidation of taxonomic relationships. Trombiculid larvae (chiggers) parasitise vertebrates and can transmit bacteria (Orientia spp.) responsible for scrub typhus, a zoonotic febrile illness. Orientia tsutsugamushi causes most cases of scrub typhus and is endemic to the Asia-Pacific Region, where it is transmitted by Leptotrombidium spp. chiggers. However, in Dubai, Candidatus Orientia chuto was isolated from a case of scrub typhus and is also known to circulate among rodents in Saudi Arabia and Kenya, although its vectors remain poorly defined. In addition to Orientia, chiggers are often infected with other potential pathogens or arthropod-specific endosymbionts, but their significance for trombiculid biology and public health is unclear. Results Ten chigger species were collected from rodents in southwestern Saudi Arabia. Chiggers were pooled according to species and screened for Orientia DNA by PCR. Two species (Microtrombicula muhaylensis and Pentidionis agamae) produced positive results for the htrA gene, although Ca. Orientia chuto DNA was confirmed by Sanger sequencing only in P. agamae. Metagenomic sequencing of three pools of P. agamae provided evidence for two other bacterial associates: a spirochaete and a Wolbachia symbiont. Phylogenetic analysis of 16S rRNA and multi-locus sequence typing genes placed the spirochaete in a clade of micromammal-associated Borrelia spp. that are widely-distributed globally with no known vector. For the Wolbachia symbiont, a genome assembly was obtained that allowed phylogenetic localisation in a novel, divergent clade. Cytochrome c oxidase I (COI) barcodes for Saudi Arabian chiggers enabled comparisons with global chigger diversity, revealing several cases of discordance with classical taxonomy. Complete mitogenome assemblies were obtained for the three P. agamae pools and almost 50 SNPs were identified, despite a common geographic origin. Conclusions P. agamae was identified as a potential vector of Ca. Orientia chuto on the Arabian Peninsula. The detection of an unusual Borrelia sp. and a divergent Wolbachia symbiont in P. agamae indicated links with chigger microbiomes in other parts of the world, while COI barcoding and mitogenomic analyses greatly extended our understanding of inter- and intraspecific relationships in trombiculid mites. </jats:sec

Additional file 1 of Microbiome and mitogenomics of the chigger mite Pentidionis agamae: potential role as an Orientia vector and associations with divergent clades of Wolbachia and Borrelia

Additional file 1: Supplementary tables and figure