Molecular and statistical approaches to the delimitation of Eimeriidae species: a case of extreme polymorphism in eimerian oocysts from the plumbeous pigeon Patagioenas plumbea (Vieillot, 1818) (Columbiformes) in South America

The current work aimed to analyze, morphologically, statistically, and molecularly, oocysts shed from plumbeous pigeons, Patagioenas plumbea (Vieillot, 1818), from a locality at 2197 m of altitude near the Agulhas Negras peak, the highest point of the State of Rio de Janeiro, southeastern Brazil. The oocysts were extremely polymorphic, being subspheroidal, ovoidal, or ellipsoidal, in addition to having the random presence/absence of characteristic features associated with the oocyst wall, such as micropyle, micropyle cap, lateral micropyle, and outer veil/rough wall. Linear regression confirmed the extreme polymorphism of oocysts, showing that if all combinations of taxonomic characters in oocysts (morphotypes) were overestimated, 19 different species could be identified/described. In contrast, the means comparison analysis between oocysts with the presence/absence of characteristic features and the histograms showed equivalences and regularity in the distribution in the classes of measures, which indicate the presence of a single species in the measured oocysts. Molecular analyses were performed from the isolation of individual oocysts of different morphotypes, which had their genetic material extracted, amplified, and sequenced in 4 non-overlapping loci in the cox1 and cox3 genes and fragments of the small and large subunit rDNA of mitochondrial DNA. The sequences were 100