A genomic analysis of 18 cockroach and termite species has uncovered that these insects carry up to 4,900 fragments of bacterial DNA each, totalling 40,485 insertions across the group. Published in Proceedings of the National Academy of Sciences by researchers at the University of Sydney, the finding far exceeds the previous record of fewer than 300 horizontal gene transfers (HGT) documented in any complex organism. Many of the fragments, originating from the symbiotic bacterium Blattabacterium cuenoti, have persisted for at least 28.7 million years, indicating they may have acquired functional roles in the host’s survival.

A separate study, appearing in BMC Biology, examined the two-toed sloth (Choloepus didactylus) and compared its genome with dozens of other mammals. A team from the Leibniz Institute for Zoo and Wildlife Research in Germany, Hospital Sírio Libanês in Brazil, and the Wellcome Sanger Institute in the UK found that transposons—‘jumping genes’—have been unusually active in the sloth lineage for over 30 million years. Several of these elements are linked to mitochondrial and metabolic genes. The researchers hypothesise that the sloth’s extremely slow metabolism may be compensated by a genetic backup system that creates alternative pathways, allowing the animal to function with low energy demands. The work remains at the stage of genomic inference; functional validation is pending.

Field discoveries have simultaneously expanded the catalogue of known species. Argentine researchers described a new genus and species of ghost spider, Yagania chuanisin, from the remote Isla de los Estados in Tierra del Fuego, published in Diversity. The same country yielded the first new mammal genus collected in the field since 2000: the rodent Apnoctomys conicetorum, found in the Chaco Serrano of Córdoba and named in honour of Argentina’s national research council and parks administration. In Malaysia, a team identified the hyperparasitic fungus Pleurocordyceps cornusynnemata, which feeds on the ‘zombie-ant’ fungus Ophiocordyceps and exhibits a horn-shaped structure never before seen in its genus, as reported in the New Zealand Journal of Botany. Separately, palaeontologists in Argentina’s Río Negro province unveiled Antusuchus rionegrinus, a dog-sized terrestrial crocodile from the Cretaceous period, published in Historical Biology, adding a predator to the ancient Kokorkom desert ecosystem.

The Sydney group’s next objective is to determine whether any of the thousands of transferred bacterial DNA segments confer a measurable advantage. For the sloth study, the authors note that cell lines derived from these animals could eventually serve as models for human conditions involving mitochondrial dysfunction, though that remains a distant prospect. The taxonomic discoveries, meanwhile, reinforce the importance of protected areas and continued field surveys in under-explored regions.