The diversity of Borrelia species discovered in California appears to be particularly high. A divergent group of Borrelia strains collected from Ixodes ticks in California was described by Postic and co-workers and designated ‘genomospecies 2’ (Postic D, Garnier M, Baranton G. Int J Med Microbiol 2007;297:263–271; Postic D, Ras NM, Lane RS, Hendson M, Baranton G. J Clin Microbiol 1998;36:3497–3504). We performed multilocus sequence analysis (MLSA) using eight housekeeping loci (clpA, clpX, nifS, pepX, pyrG, recG, rplB and uvrA) on 12 strains of this Borrelia genospecies to confirm that these strains form a distinct group within the Borrelia burgdorferi s. l. complex (Margos G, Hojgaard A, Lane RS, Cornet M, Fingerle V et al. Ticks Tick Borne Dis 2010;1:151–158). Phylogenetic and genetic distance analyses based on sequences of the MLSA housekeeping genes corroborated the distinctness of this group; genetic distances to all other members of the B. burgdorferi s.l. complex were 96 % or lower. We propose the name Borrelia lanei sp. nov. for this genospecies in honor of Professor Robert S. Lane, University of California Berkeley, for his contributions to Borrelia and tick research. The type strain for Borrelia lanei sp. nov., strain CA28-91T, has been deposited to two culture collections (=DSM 17992T=CIP 109135T).