Spiroplasma chrysopicola sp. nov., Spiroplasma gladiatoris sp. nov., Spiroplasma helicoides sp. nov., and Spiroplasma tabanidicola sp. nov., from tabanid (Diptera: Tabanidae) flies

Four spiroplasma strains, DF-1T, TG-1T, TABS-2T and TAUS-1T, all of which were isolated from Tabanidae, were serologically distinct from previously described spiroplasma species, groups and subgroups. Strain DF-1T originated from a Maryland, USA, deerfly (Chrysops sp.); strain TG-1T was isolated from a Maryland horsefly (Tabanus gladiator); strain TAUS-1T originated from a member of the T. abdominalis-T. limbatinevris complex of horseflies collected in Maryland; and strain TABS-2T was isolated from a horsefly (T. abactor) collected in Oklahoma. Cells of all of the strains appeared to be helical and motile when they were examined by dark-field microscopy. Cells of strain DF-1T growing in M1D medium were short helices with <6 turns; the helical cells of the other strains were long and usually had 6 or more turns. The short cells of strain DF-1T passed through 450- and 300-nm filter pores with no reduction in titre, but the longer cells of the other strains were partially retained by 450-nm-pore-size filters. Electron microscopy of all of the strains revealed wall-less cells surrounded only by a single cytoplasmic membrane. All of the strains grew well in SP-4 liquid media and in conventional mycoplasma or M1D media supplemented with horse or fetal bovine serum. Strains TABS-2T, TAUS-1T and DF-1T required serum or sterol for growth, but strain TG-1T was able to grow in the absence of serum or sterol. The optimum temperatures for growth of the 4 strains varied from 30 to 32°C, and growth occurred at 10 to 37°C. All of the strains catabolized glucose but did not hydrolyse urea. Only strain DF-1T hydrolysed arginine. The guanine-plus-cytosine contents of the DNAs of the strains were: DF-1T, 29±1 mol%; TG-1T, 26±1 mol%; TABS-2T, 27±1 mol%; and TAUS-1T, 26±1 mol%. The genome sizes of strains DF-1T and TAUS-1T were 1270 and 1375 kbp, respectively. Strain DF-1 (= ATCC 43209), the representative of spiroplasma Subgroup VIII-2, is designated the type strain of a new species, S. chrysopicola sp. nov. It is also proposed that strain TG-1T (= ATCC 43525T), the designated representative of Group XXIII, should be placed in a new species, S. gladiatoris sp. nov. In addition, Group XXXII spiroplasma strain TABS-2 (= ATCC 51746) is designated the type strain of S. helicoides sp. nov., and Group XXXIII representative strain TAUS-1 (= ATCC 51747) is designated the type strain of another new species, S. tabanidicola sp. nov.