| Summary: | The <i>Cedecea</i> genus is comprised of six rarely isolated species within the <i>Enterobacteriaceae</i> family. Representatives are Gram-negative motile bacilli, and are typically oxidase-negative, lipase-positive and resistant to colistin and cephalothin. In this study, a putative novel <i>Cedecea</i> species (designated strain ZA_0188<sup>T</sup>), isolated from the koala hindgut, was characterised using a polyphasic taxonomic approach. Maximum average nucleotide identity (ANI) and 16S ribosomal RNA (rRNA) similarity scores well below thresholds of species demarcation were reported, at 81.1% and 97.9%, respectively. Multilocus phylogenetic analysis indicated strain ZA_0188<sup>T</sup> was most similar to but divergent from recognised <i>Cedecea</i> species. The isolate’s genomic G+C content was determined as 53.0 mol%, >1% lower than previously reported in <i>Cedecea</i>. Phenotypically, strain ZA_0188<sup>T</sup> was distinct from recognised <i>Cedecea</i> species such as colistin- and cephalothin-sensitive, lipase-, sorbitol-, sucrose-, and Voges-Proskauer-negative, and melibiose-, arabinose-, arginine-, and rhamnose-positive. In preliminary experiments, strain ZA_0188<sup>T</sup> exhibited cellulase activity and high-level tolerance to eucalyptus oil compared to other enteric species surveyed. Collectively, these findings suggest that strain ZA_0188<sup>T</sup> represents a novel enteric species, for which the name <i>Cedecea colo</i> is proposed.
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