First molecular identification of Vorticella sp. from freshwater shrimps in Tainan, Taiwan

Freshwater shrimps are the most common crustaceans kept in an aquarium. This study was a survey seeking parasites infecting cultured freshwater atyid shrimps at aquarium stores in Tainan, Taiwan. We observed that atyid shrimps were infested with Vorticella and Scutariella. Scutariella is a common shrimp parasite; thus, we focused on Vorticella infection in the atyid shrimps. Vorticella aequilata-like pop TW, a freshwater peritrich ciliate, was isolated from the atyid shrimps. The morphological characteristics were investigated using live observations. Specimens from the population showed identical arrangement of the infraciliature and identical ITS1-5.8SITS2 region sequences. The zooids are bell-shaped, 40-58 μm wide and 47-70 μm in long in vivo. The food vacuole is variable in shape and is located in the middle of the cell. ITS1-5.8S-ITS2 sequences of Vorticella aequilata-like pop TW did not match any available sequences in GenBank. Phylogenetically, Vorticella aequilata-like pop TW clusters with the other Vorticella within the family Vorticellidae and nests with Vorticella aequilata in the subclade. Above all, the morphological characteristics and molecular analyses show that the investigated Vorticella is a Vorticella aequilata-like species. The phylogenetic analyses of ciliates based on the ITS1-5.8S-ITS2 sequences reveal that the Vorticella genus consists of Vorticella morphospecies and that taxonomic revision of the genus is needed. Morphometric criteria and molecular analysis were used to describe and identify the Vorticella specie and this study presents the first molecular identification analysis of the Vorticella species in the cultured atyid shrimps in Tainan, Taiwan.