No abstract

The genus Spiroplasma (helical mollicutes: Bacteria: Firmicutes: Mollicutes: Entomoplasmatales: Spiroplasmataceae) is associated primarily with insects. The Mycoplasma mycoides cluster (sensu Weisburg et al. 1989 andPettersson 2002) is a group of mollicutes that includes the type species -Mycoplasma mycoides -of Mycoplasmatales, Mycoplasmataceae and Mycoplasma. This cluster, associated solely with ruminants, contains five other species and subspecies. Earlier phylogenetic reconstructions based on partial 16S rDNA sequences and a limited sample of Spiroplasma and Mycoplasma sequences suggested that the genus Mycoplasma was polyphyletic, as the M. mycoides cluster and the grouping that consisted of the hominis and pneumoniae groups of Mycoplasma species were widely separated phylogenetically and the M. mycoides cluster was allied with Spiroplasma. It is shown here that the M. mycoides cluster arose from Spiroplasma through an intermediate group of non-helical spiroplasmal descendants -the Entomoplasmataceae. As this conclusion has profound implications in the taxonomy of Mollicutes, a detailed phylogenetic study of Spiroplasma and its non-helical descendants was undertaken. These analyses, done with maximum-parsimony, provide cladistic status; a new nomenclature is introduced here, based on 'bottom-up' rather than 'top-down' clade classification. The order Entomoplasmatales consists of four major clades: (i) the Mycoides-Entomoplasmataceae clade, which contains M. mycoides and its allies and Entomoplasma and Mesoplasma species and is a sister lineage to (ii) the Apis clade of Spiroplasma. Spiroplasma and the Entomoplasmataceae are paraphyletic, but this status does not diminish their phylogenetic usefulness. Five species that were previously unclassified phylogenetically are basal to the Apis clade sensu strictu and to Abbreviations: DF, deformation; MI, metabolism inhibition; PES, polyoxyethelene sorbitan; PHUH clade, Pneumoniae-Hominis-UreaplasmaHaemoplasma clade; SEM clade, Spiroplasma-Entomoplasmataceae-Mycoides clade. The GenBank/EMBL/DDBJ accession numbers for new Spiroplasma 16S rDNA sequences are: Spiroplasma sp. strain 277F, AY189312; Spiroplasma sp. strain LB-12, AY189313; S. insolitum, AY189133; S. floricola, AY189131; S. syrphidicola, AY189309; S. chrysopicola, AY189127; Spiroplasma sp. strain TAAS-1, AY189314; S. culicicola, AY189129; S. velocicrescens, AY189311; S. sabaudiense, AY189308; S. corruscae, AY189128; Spiroplasma sp. strain CB-1, AY189315; Spiroplasma sp. strain Ar 1357, AY189316; S. turonicum, AY189310; S. litorale, AY189306; S. lampyridicola, AY189134; S. leptinotarsae, AY189305; Spiroplasma sp. strain W115, AY189317; S. chinense, AY189126; S. diminutum, AY189130; S. alleghenense, AY189125; Spiroplasma sp. strain TIUS-1, AY189318; Spiroplasma sp. strain BIUS-1, AY189319; S. montanense, AY189307; S. helicoides, AY189132; Spiroplasma sp. BARC 1901, AY189320.

No abstract

Minimal standards for novel species of the class Mollicutes (trivial term, mollicutes), last published in 1995, require revision. The International Committee on Systematics of Prokaryotes Subcommittee on the Taxonomy of Mollicutes proposes herein revised standards that reflect recent advances in molecular systematics and the species concept for prokaryotes. The mandatory requirements are: (i) deposition of the type strain into two recognized culture collections, preferably located in different countries; (ii) deposition of the 16S rRNA gene sequence into a public database, and a phylogenetic analysis of the relationships among the 16S rRNA gene sequences of the novel species and its neighbours; (iii) deposition of antiserum against the type strain into a recognized collection; (iv) demonstration, by using the combination of 16S rRNA gene sequence analyses, serological analyses and supplementary phenotypic data, that the type strain differs significantly from all previously named species; and (v) assignment to an order, a family and a genus in the class, with an appropriate specific epithet. The 16S rRNA gene sequence provides the primary basis for assignment to hierarchical rank, and may also constitute evidence of species novelty, but serological and supplementary phenotypic data must be presented to substantiate this. Serological methods have been documented to be congruent with DNA-DNA hybridization data and with 16S rRNA gene placements. The novel species must be tested serologically to the greatest extent that the investigators deem feasible against all neighbouring species whose 16S rRNA gene sequences show .0.94 similarity. The investigator is responsible for justifying which characters are most meaningful for assignment to the part of the mollicute phylogenetic tree in which a novel species is located, and for providing the means by which novel species can be identified by other investigators.

No abstract