GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE336nnn/GSE336355/primaryOK200TranscriptomicsHystrichopsylla talpae iberaExpression profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE336355GEOGSEfalseHystrichopsylla talpae ibera as a potential health risk of the endangered Iberian desman (Galemys pyrenaicus). Morphological, molecular, and phylogenetic characterization, pathogen profiling and microbiota analysis.The Iberian desman (Galemys pyrenaicus, É. Geoffroy Saint-Hilaire, 1811) is a critically endangered semi-aquatic mammal endemic to the Iberian Peninsula, and its recovery has been declared a top priority in Spain. Despite the progress made in understanding the ecological aspects, numerous clinical issues related to this endangered species remain unresolved, such as ectoparasites and associated pathogens. Here, we provide the first morphological and multilocus molecular characterisation of the flea Hystrichopsylla talpae ibera isolated from Iberian desmans in Central System (Ávila, Spain), and we clarify its phylogenetic position within Siphonaptera. Furthermore, we assessed the potential vector capacity of this flea species by analyzing its microbiota profile and detecting the presence of various bacterial and parasitic pathogens using Next-Generation Sequencing (NGS) and molecular techniques, respectively. Dipylidium caninum DNA was detected in all fleas examined, suggesting that sylvatic transmission of dipylidiasis cycles may involve Iberian desmans and their ectoparasites, with infection likely occurring through grooming and accidental ingestion of infected fleas. On the other hand, the microbiota of H. t. ibera was dominated by Pseudomonadota, with unusually high relative prevalence of opportunistic genera such as Serratia, Cupriavidus and Burkholderia–Caballeronia–Paraburkholderia. These results underscore the importance of monitoring ectoparasites and their associated pathogens in conservation planning of Iberian desman (capture and translocation programmes, captive breeding, etc). These findings indicate that desman fleas can act as minimally invasive sentinels for health monitoring in threatened freshwater mammals and highlight the need to integrate ectoparasite based surveillance into conservation planning for G. pyrenaicus.2026/10/01GSE336355GSM9833277GSM9833278GSM9833279GSM983328037137336355Hystrichopsylla talpae ibera