Proposal of Thorsellia kenyensis sp. nov. and Thorsellia kandunguensis sp. nov., isolated from larvae of Anopheles arabiensis, as members of the family Thorselliaceae fam. nov.

Two Gram-negative, rod-shaped strains, T2.1(T) and W5.1.1(T), isolated from larvae of the mosquito Anopheles arabiensis, were investigated using a polyphasic approach. On the basis of 16S rRNA gene sequence similarity studies, strains T2.1(T) and W5.1.1(T) were shown to belong to the genus Thorsellia, both showing 97.8 % similarity to the type strain of Thorsellia anophelis, with 98.1 % similarity to each other. Chemotaxonomic data supported the allocation of the strains to the genus Thorsellia: their major fatty acids were C18 : 1ω7c, C16 : 0 and C14 : 0 and they harboured a ubiquinone Q-8 quinone system and a polyamine pattern with the major compound 1,3-diaminopropane. Qualitative and quantitative differences in their polar lipid profiles distinguished strains T2.1(T) and W5.1.1(T) from each other and from T. anophelis. Average nucleotide identity (ANI), DNA-DNA hybridization, multilocus sequence analysis (MLSA) as well as physiological and biochemical tests allowed T2.1(T) and W5.1.1(T) to be distinguished both genotypically and phenotypically from each other and from the type strain of T. anophelis. Thus, we propose that these isolates represent two novel species of the genus Thorsellia, named Thorsellia kenyensis sp. nov. (type strain T2.1(T) = CCM 8545(T) = LMG 28483(T) = CIP 110829(T)) and Thorsellia kandunguensis sp. nov. (type strain W5.1.1(T) = LMG 28213(T) = CIP 110794(T)). Furthermore, phylogenetic analysis based on nearly full-length 16S rRNA gene sequences showed that the genus Thorsellia forms a separate branch, distinct from the families Enterobacteriaceae, Pasteurellaceae and Orbaceae. As a consequence, a new family Thorselliaceae fam. nov. is proposed. An emended description of Thorsellia anophelis is also provided.