A distinct lineage of influenza A virus from bats has been identified in little yellow-shouldered bats in Guatemala. This virus is significantly divergent from known influenza A viruses, with a hemagglutinin (HA) that diverged at roughly the same time as known HA subtypes and was designated as H17. The neuraminidase (NA) gene is highly divergent from all known influenza NAs, and the internal genes of the bat virus diverged from those of known influenza A viruses before the estimated divergence of the known influenza A internal gene lineages. Attempts to propagate this virus in cell cultures and chicken embryos were unsuccessful, suggesting distinct requirements compared with known influenza viruses. Despite its divergence from known influenza A viruses, the bat virus is compatible for genetic exchange with human influenza viruses in human cells, suggesting the potential capability for reassortment and contributions to new pandemic or panzootic influenza A viruses. The bat virus is a potential sylvatic mammalian reservoir of influenza, and its genomic sequence provides insights into the ancestry and evolution of influenza A viruses. Phylogenetic analysis showed that the six internal genes of A/bat/Guat/09 diverged from those of known influenza A viruses after the split of influenza A and B but before the divergence of the internal genes of known influenza A viruses. The HA, on the other hand, diverged after the split of influenza A. The NA gene of A/bat/Guat/09 is extraordinarily divergent from known influenza viruses, suggesting it may descend from a much older ancestor than other genes. The bat virus's genome replication complex was able to function in human cells, indicating compatibility with human virus NCRs and suggesting that reassortants of bat and human viruses may not be incompatible. The identification of influenza A viruses in bats expands the repertoire of likely reservoirs of influenza viruses and raises further questions about how influenza viruses are maintained in bat populations and the public health and agricultural ramifications of this reservoir. The study highlights the importance of monitoring bat populations for influenza viruses and investigating their potential role in the emergence of new pandemic strains.A distinct lineage of influenza A virus from bats has been identified in little yellow-shouldered bats in Guatemala. This virus is significantly divergent from known influenza A viruses, with a hemagglutinin (HA) that diverged at roughly the same time as known HA subtypes and was designated as H17. The neuraminidase (NA) gene is highly divergent from all known influenza NAs, and the internal genes of the bat virus diverged from those of known influenza A viruses before the estimated divergence of the known influenza A internal gene lineages. Attempts to propagate this virus in cell cultures and chicken embryos were unsuccessful, suggesting distinct requirements compared with known influenza viruses. Despite its divergence from known influenza A viruses, the bat virus is compatible for genetic exchange with human influenza viruses in human cells, suggesting the potential capability for reassortment and contributions to new pandemic or panzootic influenza A viruses. The bat virus is a potential sylvatic mammalian reservoir of influenza, and its genomic sequence provides insights into the ancestry and evolution of influenza A viruses. Phylogenetic analysis showed that the six internal genes of A/bat/Guat/09 diverged from those of known influenza A viruses after the split of influenza A and B but before the divergence of the internal genes of known influenza A viruses. The HA, on the other hand, diverged after the split of influenza A. The NA gene of A/bat/Guat/09 is extraordinarily divergent from known influenza viruses, suggesting it may descend from a much older ancestor than other genes. The bat virus's genome replication complex was able to function in human cells, indicating compatibility with human virus NCRs and suggesting that reassortants of bat and human viruses may not be incompatible. The identification of influenza A viruses in bats expands the repertoire of likely reservoirs of influenza viruses and raises further questions about how influenza viruses are maintained in bat populations and the public health and agricultural ramifications of this reservoir. The study highlights the importance of monitoring bat populations for influenza viruses and investigating their potential role in the emergence of new pandemic strains.