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Two freshwater isolates (WB4.1-19 T and WB4.4-101), sharing 99.9 % 16S rRNA gene sequence similarity, were highly related to Aeromonas sobria (99.7 % similarity; 6 bp differences). A phylogenetic tree derived from a multi-locus phylogenetic analysis (MLPA) of the concatenated sequences of five housekeeping genes (gyrB, rpoD, recA, dnaJ and gyrA; 3684 bp) revealed that both strains clustered as an independent phylogenetic line next to members of Aeromonas molluscorum and Aeromonas bivalvium. The DNA-DNA reassociation value between the two new isolates was 89.3 %. Strain WB4.1-19 T had a DNA-DNA relatedness value of ,70 % with the type strains of the other species tested. Phenotypic characterization differentiated the two novel strains from all other type strains of species of the genus Aeromonas. It is concluded that the two new strains represent a novel species of the genus Aeromonas, for which the name Aeromonas rivuli sp. nov. is proposed, with the type strain WB4

Two clinical Aeromonas strains (A2-50 T and A2-67 T ) recovered from the wounds of two patients in Taiwan could not be assigned to any known species of this genus based on their 16S rRNA gene sequences, which showed similarities of 99.6-99.8 % to those of the type strains of Aeromonas caviae, A. trota and A. aquariorum. The rpoD phylogenetic tree allocated these strains to two novel and independent phylogenetic lines, the neighbouring species being A. caviae, the type strain of which showed 93.2 % similarity (56 bp differences) to strain A2-50 T and 92.2 % (63 bp differences) to strain A2-67 T . A multilocus phylogenetic analysis of five housekeeping genes (gyrB, rpoD, recA, dnaJ and gyrA; 3684 bp) confirmed that the two strains formed independent phylogenetic lineages within the genus. These data, together with phenotypic characterization and DNA-DNA reassociation results, revealed that these strains represent novel Aeromonas species, for which the names Aeromonas taiwanensis sp. nov. (type strain A2-50 T 5CECT 7403 T 5LMG 24683 T ) and Aeromonas sanarellii sp. nov. (type strain A2-67 T 5CECT 7402 T 5LMG 24682 T ) are proposed.The genus Aeromonas includes facultatively anaerobic, Gramnegative, non-spore-forming bacilli or coccobacilli that are generally motile, usually oxidase-and catalase-positive, able to reduce nitrate to nitrite and generally resistant to the vibriostatic agent O/129 (2,4-diamino-6,7-diisopropylpteridine) (Abbott et al., 2003;Martin-Carnahan & Joseph, 2005). The genus belongs to the family Aeromonadaceae, order Aeromonadales, class Gammaproteobacteria The taxonomy of this genus is complex because, despite each species apparently having specific phenotypic characteristics, biochemical identification is laborious and very imprecise, showing poor correlation with genotypic identification (Borrell et al., 1998;Soler et al., 2003;Figueras, 2005;Ormen et al., 2005). The 16S rRNA gene sequence similarity among species of the genus is very high, ranging from 96.7 to 100 % (Martínez-Murcia et al., 1992Saavedra et al., 2006). Furthermore, this gene presents microheterogeneities Martínez-Murcia et al., 2005;Morandi et al., 2005;Alperi et al., 2008) that reduce its usefulness for identification (Alperi et al., 2008); such was the case for Aeromonas culicicola Alperi et al., 2008), now considered a synonym of A. veronii (Huys et al., 2005). However, several housekeeping genes have proven to have Abbreviation: MLPA, multilocus phylogenetic analysis.The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA, gyrB, rpoD, recA, dnaJ and gyrA gene sequences of strains A2-50 T and A2-67 T are respectively FJ230077 and FJ230076, FJ807272 and FJ807277, FJ472928 and FJ472929, FJ472930 and FJ47931, FJ807270 and FJ807279 and FJ807274 and FJ807276. An unrooted 16S rRNA gene sequence-based maximum-parsimony phylogenetic tree, an unrooted MLPA minimum-evolution tree, details of differences in the 16S rRNA gene sequences of the novel strains and DNA-DNA hybridization results are available as supplementary material ...

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Three strains of Aeromonas hydrophila subspecies dhakensis, including the type strain, were subjected to phylogenetic analysis by sequencing gyrB, rpoD, and 16S rRNA genes and compared with all known Aeromonas species. The obtained gyrB and rpoD phylogenetic trees clearly suggested that these A. hydrophila subsp. dhakensis strains indeed belong to the species A. aquariorum. This finding may indicate that, at the time of "dhakensis" subspecies description, the strains were incorrectly identified as A. hydrophila by a polyphasic approach that included DNA-DNA hybridization.