A new species of Hepatozoon Miller, 1908 (Apicomplexa: Hepatozoidae) parasitizing Philodryas nattereri (Squamata: Dipsadidae) from the Caatinga, Brazil.

Brazil has a rich snake fauna with 435 species, 112 of which occur in the Caatinga biome. The genus Hepatozoon comprises over 300 species, with 40 described in Brazilian snakes. The objective of this study was to characterize morphologically and molecularly a undescribed species of Hepatozoon that infects Philodryas nattereri in the Caatinga, Pernambuco, Brazil. Between 2022 and 2025, five individuals of P. nattereri were collected. Blood samples were obtained for smear preparation, blood and liver samples were obtained and preserved in absolute ethanol, and viscera were collected for histopathological analyses; this material was used for the extraction of genetic material from the hemoparasites. Prevalence and parasitism indices were calculated. Amplification of the 18S rDNA gene was performed using the primers HepF300 and ER. All specimens (100%) were parasitized by Hepatozoon univasfensis sp. nov. Gametocytes in different stages of maturation were observed inside erythrocytes. Thus, based on morphological, morphometric, and molecular analyses, a new species of Hepatozoon is described from Philodryas nattereri collected in the municipality of Petrolina, Pernambuco, Northeast Brazil. Hepatozoon univasfensis sp. nov. represents the second Hepatozoon species described from a snake of the genus Philodryas and only the second species described from snakes and more broadly from the herpetofauna of the Caatinga.