DAO 67:115-124 (2005)  -  doi:10.3354/dao067115

Systemic infection of Kudoa lutjanus n. sp. (Myxozoa: Myxosporea) in red snapperLutjanus erythropterus from Taiwan

Pei-Chi Wang1,2, Ju-ping Huang1, Ming-An Tsai1, Shu-Yun Cheng1, Shin-Shyong Tsai1,3 Shi-De Chen1, Shih-Ping Chen4, Shih-Hau Chiu5, Li-Ling Liaw5, Li-Teh Chang6, Shih-Chu Chen1,3,*

1Department of Veterinary Medicine, 2Department of Tropical Agriculture and International Cooperation, and
3Graduate Institute of Animal Vaccine Technology, National Pingtung University of Science and Technology, Pingtung 912, Taiwan, ROC
4Division of Animal Medicine, Animal Technology Institute Taiwan 300, Taiwan, ROC
5Bioresource Collection and Research Center, Food Industry Research and Development Institute, Hsinchu 300, Taiwan, ROC
6Basic Science, Department of Nursing, Meiho institute of Technology, Pingtung 912, Taiwan, ROC
*Corresponding author. Email:

ABSTRACT: A new species of Kudoa lutjanus n. sp. (Myxosporea) is described from the brain and internal organs of cultured red snapper Lutjanus erythropterus from Taiwan. The fish, 260 to 390 g in weight, exhibited anorexia and poor appetite and swam in the surface water during outbreaks. Cumulative mortality was about 1% during a period of 3 wk. The red snapper exhibited numerous creamy-white pseudocysts, 0.003 to 0.65 cm (n = 100) in diameter, in the eye, swim bladder, muscle and other internal organs, but especially in the brain. The number of pseudocysts per infected fish was not correlated with fish size or condition. Mature spores were quadrate in apical view and suboval in side view, measuring 8.2 ± 0.59 µm in width and 7.3 ± 0.53 µm in length. The 4 valves were equal in size, each with 1 polar capsule. Polar capsules were pyriform in shape, measuring 3.62 ± 0.49 µm in length and 2.2 ± 0.49 µm in width. Mild inflammatory responses or liquefaction of host tissue were associated with K. lutjanus n. sp. infection. The junction of shell valves appeared as overlapping, straight lines. The polar filament formed 2 to 3 coils. A general PCR (polymerase chain reaction) primer for Kudoa amplified the small subunit (SSU) rDNA sequences, and the amplified gene was sequenced. It was evident from the phylogenetic tree that the 3 strains tested, AOD93020M, AOD93028M and AOD93028B, were identical and belonged to the Kudoa SS rRNA subgroup. The evolutionary tree showed that these strains form a unique clade, at a distance from other Kudoa species and myxosporeans. The spore’s morphological and ultrastructural characteristics, as well as the SS rDNA properties of the isolates, were also essentially identical and served to distinguish them from representative Kudoa. It is, therefore, proposed that the strains isolated from the diseased red snapper be assigned to a new species.

KEY WORDS: Myxosporea · Kudoa lutjanus n. sp. · Brain · Red snapper · Lutjanus erythropterus

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