Rickettsia are obligate intracellular bacteria often reported from hard ticks but more rarely from soft ticks. In this study, we detected in Northern Africa two putatively novel Rickettsia species in soft tick species of the Ornithodoros erraticus complex: Ornithodoros occidentalis from Morocco, Ornithodoros erraticus from Algeria and Ornithodoros normandi from Tunisia. We characterized these two novel Rickettsia species on the basis of comparative DNA sequence analyses and phylogenetics of four genes (gltA, 16S rRNA, coxA and ompB). These Rickettsia, provisionally named ‘Candidatus Rickettsia africaseptentrionalis’ and ‘Candidatus Rickettsia mauretanica’, differed in nucleotide sequence from those of other Rickettsia species by 0.38–21.43 % depending on the gene examined. Phylogenetics further showed that the two novel Rickettsia species are closely related to each other and represent sister taxa to R. hoogstraalii, R. felis and R. asembonensis within the transitional Rickettsia group. While Ornithodoros host species of ‘Candidatus Rickettsia africaseptentrionalis’ and ‘Candidatus Rickettsia mauretanica’ are among the most common soft ticks to bite humans, their pathogenicity remains to be investigated.

立克次体是专性细胞内细菌，通常从硬壁虱中报道，但从软壁虱中很少见。在这项研究中，我们在北部非洲的两个假定的新型检测立克次体的软蜱物种种类钝缘蜱erraticus复杂：钝缘蜱望江南来自摩洛哥，钝缘蜱erraticus阿尔及利亚和钝缘蜱normandi来自突尼斯。我们根据比较的DNA序列分析和四个基因（gltA，16S rRNA，coxA和ompB）的系统发育特征，对这两个新立克次体物种进行了表征。这些立克次体，暂时命名为“暂定立克africaseptentrionalis”和“暂定立克次体mauretanica”，在与其他的核苷酸序列不同立克次体通过0.38-21.43％，取决于该基因检测物种。系统发育进一步表明，这两种新立克次氏体物种是密切相关的，且表示姐妹群到R. hoogstraalii，R.蚤和R. asembonensis过渡内立克次氏体基团。虽然钝缘蜱的宿主物种“暂定立克次体africaseptentrionalis”和'暂定 毛立克次体是咬人的最常见的软壁虱，其致病性尚待研究。