Morphological and molecular characterization of <i>Sarcocystis cooperii</i> n. sp. and related <i>Sarcocystis</i> species in three Colombian avian hosts.

Abstract

<h4>Background and aim</h4>Apicomplexan parasites of the genus <i>Sarcocystis</i> exhibit complex two-host life cycles involving birds as both intermediate hosts (IH) and definitive hosts (DH). Despite Colombia's exceptional avian diversity, knowledge of <i>Sarcocystis</i> species in its wild birds remains limited. This study aimed to characterize the morphology and genetic identity of <i>Sarcocystis</i> species infecting three Colombian birds, the Great Kiskadee (<i>Pitangus sulphuratus</i>), American black vulture (<i>Coragyps atratus</i>), and Andean condor (<i>Vultur gryphus</i>).<h4>Materials and methods</h4>Muscle samples from the three species were examined histologically using hematoxylin and eosin, periodic acid-Schiff, and toluidine blue staining. Transmission electron microscopy (TEM) was performed on <i>P. sulphuratus</i> samples to assess ultrastructural features. DNA was extracted and subjected to polymerase chain reaction amplification and sequencing of 18S ribosomal RNA, cytochrome c oxidase subunit 1, and internal transcribed spacer 1 region. Sequences were compared to GenBank data, and phylogenetic analysis was performed using the Maximum Likelihood method.<h4>Results</h4>Two <i>Sarcocystis</i> species were identified. A novel species, <i>Sarcocystis cooperii</i> n. sp., was described from the Great Kiskadee, representing the first record of this species in South America. TEM revealed thin-walled (<1 μm), flat cysts with knob-like blebs corresponding to type 1a morphology. Molecular data showed 99.9% similarity with <i>Sarcocystis</i> sp. ex <i>Accipiter cooperii</i>, confirming its identity as <i>S. cooperii</i> n. sp., with the Cooper's hawk acting as the putative DH. The <i>Sarcocystis</i> sp. detected in <i>C. atratus</i> and <i>V. gryphus</i> was genetically identical to isolates from Brazilian birds and closely related to <i>S. lari</i>, indicating a shared lineage among scavenging Cathartiformes.<h4>Conclusion</h4>This study expands current knowledge of avian <i>Sarcocystis</i> diversity in the Neotropics, documenting <i>S. cooperii</i> n. sp. in <i>P. sulphuratus</i> and the first record of <i>Sarcocystis</i> sp. in two Cathartiformes species in Colombia. These findings underscore the ecological importance of synanthropic and scavenging birds in <i>Sarcocystis</i> transmission dynamics and highlight the need for further research on host-parasite relationships and potential conservation implications for endemic avifauna.