Turbellarian black spot disease in bluespine unicornfish Naso unicornis in New Caledonia, caused by the parasitic turbellarian Piscinquilinus sp.

Turbellarian black spot disease is described in a bluespine unicornfish Naso unicornis (Perciformes, Acanthuridae) collected from the wild off Nouméa, New Caledonia, South Pacific. Each cyst contained a whitish worm, 2 to 4 mm in length, which was able to swim freely in seawater. Cyst walls consisted of fibrous tissue with a scattering of melanocytes. Worms had 2 eyespots at the anterior end, a pharynx at the posterior end and a largely undeveloped reproductive system. They were identified as Piscinquilinus sp. (= Ichthyophaga sp.), a genostomatid turbellarian. The disease spread within 2 wk from a single infected fish to 3 other unicornfish in the same tank, in spite of copper sulphate and diluted seawater treatment; however, other fish from several families kept in the same tank were not infected, suggesting specificity of these parasites. Praziquantel injections into the infected fish eliminated the infection. Other cases of turbellarian infections are reported from 7 fish species off New Caledonia; prevalence is very low (0.3%).

Moravecia australiensis n. g., n. sp. (Dracunculoidea: Guyanemidae) from the gills of the green porcupine fish Tragulichthys jaculiferus (Cuvier) in Australia.

A new dracunculoid genus and species, Moravecia australiensis, is described from gill-filaments of the green porcupine fish Tragulichthys jaculiferus (Cuvier) (Tetraodontiformes: Diodontidae) from Moreton Bay, Queensland, Australia. Abundant mobile larvae and a few adult males with females occurred in the gill-filament between the epithelial basement membrane and efferent artery. Gills of all 69 fish examined contained larvae. Eleven harboured adult nematodes of a previously undescribed species belonging to the family Guyanemidae. The new species is placed within a newly proposed genus because it differs from the four existing genera in the family in possessing fine cuticular transverse striations, two forward protruding cephalic elevations, a circumoral elevation, a small triangular mouth surrounded by six cephalic papillae arranged in two lateral clusters of three each and a pair of large lateral amphids. Males have two pairs of pedunculate caudal papillae supporting the caudal alae. A key to the genera of the Guyanemidae is presented.

First report of three Kudoa species from eastern Australia: Kudoa thyrsites from mahi mahi (Coryphaena hippurus), Kudoa amamiensis and Kudoa minithyrsites n. sp. from sweeper (Pempheris ypsilychnus).

Fish species around the world are parasitized by myxozoans of the genus Kudoa, several of which infect and cause damage of commercial importance. In particular, Kudoa thyrsites and Kudoa amamiensis infect certain cultured fish species causing damage to muscle tissue, making the fish unmarketable. Kudoa thyrsites has a broad host and geographic range infecting over 35 different fish species worldwide, while K. amamiensis has only been reported from a few species in Japanese waters. Through morphological and molecular analyses we have confirmed the presence of both of these parasites in eastern Australian waters. In addition, a novel Kudoa species was identified, having stellate spores, with one polar capsule larger than the other three. The SSU rDNA sequence of this parasite was 1.5% different from K. thyrsites and is an outlier from K. thyrsites representatives in a phylogenetic analysis. Furthermore, the spores of this parasite are distinctly smaller than those of K. thyrsites, and thus it is described as Kudoa minithyrsites n. sp. Although the potential effects of K. minithyrsites n. sp. on its fish hosts are unknown, both K. thyrsites and K. amamiensis are associated with flesh quality problems in some cultured species and may be potential threats to an expanding aquaculture industry in Australia.