Sarcocystis sp. from the herring gull (Larus argentatus) identity to Sarcocystis wobeseri based on cyst morphology and DNA results.

Having studied 11 herring gulls (Larus argentatus) Sarcocystis cysts were found in neck and leg muscles of 4 birds. One type of sarcocysts (cyst type I) that have a thin (∼1.0 μm), smooth, or slightly wavy cyst wall without clearly visible protrusions and small (6.0-8.0 μm) lancet- or banana-shaped cystozoites was identified by the light microscopy. Sarcocysts extracted from one herring gull were used for electron microscopy and DNA analysis. Ultrastructurally, Sarcocystis sp. from the herring gull had the same tissue cyst wall type-1 as S. calchasi, S. columbae, and S. wobeseri parasitizing in birds. According to first internal transcribed spacer (ITS-1) region, 18S rRNA and 28S rRNA gene sequences, Sarcocystis sp. from the herring gull belongs to S. wobeseri. Nevertheless, without evidences of cross-transmission experiment sarcocysts extracted from herring gull at present time are named as S. wobeseri-like.