BACKGROUND Birds of the family Laridae have not been intensively examined for infections with Sarcocystis spp. To date, sarcocysts of two species, S. lari and S. wobeseri, have been identified in the muscles of gulls. The aim of the present study was to evaluate the species richness of Sarcocystis in the herring gull, Larus argentatus, from Lithuania. METHODS In the period between 2013 and 2019, leg muscles of 35 herring gulls were examined for sarcocysts of Sarcocystis spp. Sarcocystis spp. were characterised morphologically based on a light microscopy study. Four sarcocysts isolated from the muscles of each infected bird were subjected to further molecular examination. Sarcocystis species were identified by means of ITS1 sequence analysis. RESULTS Sarcocysts were detected in 9/35 herring gulls (25.7%). Using light microscopy, one morphological type of sarcocysts was observed. Sarcocysts were microscopic, thread-like, had a smooth and thin (about 1 µm) cyst wall and were filled with banana-shaped bradyzoites. On the basis of ITS1 sequences, four Sarcocystis species, S. columbae, S. halieti, S. lari and S. wobeseri, were identified. Furthermore, it was demonstrated that a single infected herring gull could host two Sarcocystis species indistinguishable under light microscopy. CONCLUSIONS Larus argentatus is the first bird species found to act as intermediate host of four Sarcocystis spp. According to current knowledge, five species, S. falcatula, S. calchasi, S. wobeseri, S. columbae and S. halieti can use birds belonging to different orders as intermediate hosts.

中文翻译：

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立陶宛鲱鸥（Larus argentatus）中四种肉囊藻物种的分子鉴定。

背景技术尚未对拉达科（Lariidae）科的家禽进行深入检查，以检测是否患有肉孢杆菌属（Sarcocystis spp）。迄今为止，已经在海鸥的肌肉中鉴定出了两个物种的卵囊，即S. lari和S. wobeseri。本研究的目的是评估立陶宛鲱鸥（Larus argentatus）中石藻的物种丰富度。方法在2013年至2019年期间，对35只鲱鸥的腿部肌肉进行了Sarcocystis spp的囊肿检查。肉囊藻属 根据光学显微镜研究对形态进行了表征。从每只受感染禽类的肌肉中分离出的四个卵囊进行进一步的分子检查。通过ITS1序列分析鉴定了肉囊藻种。结果在9/35个鲱鸥中检出了囊肿（25.7％）。使用光学显微镜，观察到一种形态学的囊肿。囊肿是微观的，线状的，囊壁光滑且薄（约1 µm），充满了香蕉状的缓殖子。根据ITS1序列，鉴定出了四个石藻属物种，即哥白葡萄球菌，哈里提葡萄球菌，拉里葡萄球菌和沃氏葡萄球菌。此外，已证明，单个受感染的鲱鸥可以容纳在光学显微镜下无法区分的两个肉囊藻种。结论argentatus最早被发现是四个Sarcocystis spp的中间宿主。根据目前的知识，falcatula，S。calchasi，S。wobeseri，S。columbae和S. halieti这五个物种可以使用属于不同阶的鸟类作为中间宿主。囊壁光滑且薄（约1 µm），并充满了香蕉状的缓殖子。根据ITS1序列，鉴定了四种石藻属物种，S。columbae，S。halieti，S。lari和S. wobeseri。此外，已证明，单个受感染的鲱鸥可以容纳在光学显微镜下无法区分的两个肉囊藻种。结论argentatus最早被发现是四个Sarcocystis spp的中间宿主。根据目前的知识，falcatula，S。calchasi，S。wobeseri，S。columbae和S. halieti这五个物种可以使用属于不同阶的鸟类作为中间宿主。囊壁光滑且薄（约1 µm），并充满了香蕉状的缓殖子。根据ITS1序列，鉴定了四种石藻属物种，S。columbae，S。halieti，S。lari和S. wobeseri。此外，已证明，单个受感染的鲱鸥可以容纳在光学显微镜下无法区分的两个肉囊藻物种。结论argentatus最早被发现是四个Sarcocystis spp的中间宿主。根据目前的知识，falcatula，S。calchasi，S。wobeseri，S。columbae和S. halieti这五个物种可以使用属于不同阶的鸟类作为中间宿主。结果表明，单个受感染的鲱鸥可以容纳两种在光学显微镜下无法区分的肉囊藻。结论argentatus最早被发现是四个Sarcocystis spp的中间宿主。根据目前的知识，falcatula，S。calchasi，S。wobeseri，S。columbae和S. halieti这五个物种可以使用属于不同阶的鸟类作为中间宿主。结果表明，单个受感染的鲱鸥可以容纳两种在光学显微镜下无法区分的肉囊藻。结论argentatus最早被发现是四个Sarcocystis spp的中间宿主。根据目前的知识，falcatula，S。calchasi，S。wobeseri，S。columbae和S. halieti这五个物种可以使用属于不同阶的鸟类作为中间宿主。