Novel catalase-negative, Gram-stain-positive, beta-haemolytic, coccus-shaped organisms were isolated from Chacoan peccaries that died from respiratory disease. The initial API 20 Strep profiles suggested
Streptococcus agalactiae
with acceptable identification scores, but the 16S rRNA gene similarity (1548 bp) to available sequences of streptococci was below 98 %. Next taxa of the genus
Streptococcus
, displaying highest similarities to the strains from this study, were
S. bovimastitidis
NZ1587T (97.5 %),
S. iniae
ATCC 29178T (97.5 %),
S. hongkongensis
HKU30T (97.4 %),
S. parauberis
DSM 6631T (97.1 %),
S. penaeicida
CAIM 1838T (97.1 %),
S. pseudoporcinus
DSM 18513T (97.0 %),
S. didelphis
DSM 15616T (96.6 %),
S. ictaluri
707-05T (96.6 %),
S. uberis
JCM 5709T (96.5 %) and
S. porcinus
NCTC 10999T (96.4 %). All other
Streptococcus
species had sequence similarities of below 96.4 %. A sodA gene as well as whole genome-based core genome phylogeny of three representative strains and 145 available
Streptococcus
genomes confirmed the unique taxonomic position. Interstrain average nucleotide identity (ANI) and amino acid identity (AAI) values were high (ANI >96 %; AAI 100%), but for other streptococci clearly below the proposed species boundary of 95–96 % (ANI <75 %; AAI <83 %). Results were confirmed by genome-to-genome distance calculations. Pairwise digital DNA–DNA hybridization estimates were high (>90 %) between the novel strains, but well below the species boundary of 70 % for closely related
Streptococcus
type strains (23.5–19.7 %). Phenotypic properties as obtained from extended biochemical profiles and MALDI-TOF mass spectrometry supported the outstanding rank. Based on the presented molecular and physiological data of the six strains, we propose a novel taxon for which we suggest the name Streptococcus catagoni sp. nov. with the type strain 99-1/2017T (=DSM 110457T=CCUG 74072T) and five reference strains.