Cryptosporidium homai n. sp. (Apicomplexa: Cryptosporidiiae) from the guinea pig (Cavia porcellus).

The morphological, biological, and molecular characterisation of a new Cryptosporidium species from the guinea pig (Cavia porcellus) are described, and the species name Cryptosporidium homai n. sp. is proposed. Histological analysis conducted on a post-mortem sample from a guinea pig euthanised due to respiratory distress, identified developmental stages of C. homai n. sp. (trophozoites and meronts) along the intestinal epithelium. Molecular analysis at 18S rRNA (18S), actin and hsp70 loci was then conducted on faeces from an additional 7 guinea pigs positive for C. homai n. sp. At the 18S, actin and hsp70 loci, C. homai n. sp. exhibited genetic distances ranging from 3.1% to 14.3%, 14.4% to 24.5%, and 6.6% to 20.9% from other Cryptosporidium spp., respectively. At the 18S locus, C. homai n. sp. shared 99.1% similarity with a previously described Cryptosporidium genotype in guinea pigs from Brazil and it is likely that they are the same species, however this cannot be confirmed as actin and hsp70 sequences from the Brazilian guinea pig genotype are not available. Phylogenetic analysis of concatenated 18S, actin and hsp70 sequences showed that C. homai n. sp. exhibited 9.1% to 17.3% genetic distance from all other Cryptosporidium spp. This clearly supports the validity of C. homai n. sp. as a separate species.