Two new Neotetraonchus species (Dactylogyridea, Dactylogyridae) parasitising the Peruvian sea catfish Galeichthys peruvianus (Siluriformes, Ariidae), including molecular data.

As part of a parasitological survey, several specimens of two new monopisthocotylean species, Neotetraonchus celsomanueli sp. nov. and N.peruvianus sp. nov. (Dactylogyridea, Dactylogyridae), were collected from the gill filaments of the Peruvian sea catfish Galeichthys peruvianus (Siluriformes, Ariidae) off Puerto Pizarro, Tumbes region, Peru. Neotetraonchus celsomanueli sp. nov. is characterised by an MCO with a T-shaped distal end and an accessory piece that is ribbed and expanded proximally with a worm-shaped termination. Neotetraonchus peruvianus sp. nov. is typified by its MCO, which has a sledgehammer-shaped distal end and an accessory piece with a claw-shaped distal end. Additionally, N.peruvianus sp. nov. is characterised by its jellyfish-shaped onchium. A partial 28S rDNA sequence was obtained from N.celsomanueli sp. nov., and a phylogenetic analysis was conducted. This analysis revealed the phylogenetic position of Neotetraonchus celsomanueli sp. nov. within a clade comprising monopisthocotylean parasites of diadromous and marine ariid catfishes, including Hamatopeduncularia spp., Chauhanellus spp., Thysanotohaptor Kritsky, Shameem, Kumari & Krishnaveni, , and Neocalceostomoides spinivaginalis Lim, 1995. This finding brings the number of known Neotetraonchus species to seven and represents the first described Neotetraonchus species infecting marine catfishes from Peru.

Acanthocotyle gurgesiella n. sp. (Monogenea: Acanthocotylidae) from the deep-sea skate Gurgesiella furvescens (Rajidae) in the south-eastern Pacific.

Little is known about the diversity of parasites of the deep-sea fish of the world's oceans. Here, a new species of monogenean parasite of the deep-sea skate Gurgesiella furvescens is described. Specimens of parasites were obtained from the skin of two specimens of the dusky finless skate, G. furvescens (Rajidae), in the vicinity of Valparaiso (33°S, 72°W), central Chile, from midwater trawl fishing at depths of 350-450 m. Both morphological and molecular analyses were conducted to provide a full description of the new species, named Acanthocotyle gurgesiella. For the molecular analyses, nuclear large subunit (LSU) rDNA and the mitochondrial gene cytochrome c oxidase 1 (COI) were used. From the morphological analysis and a comparison with the known species of the genus, A. gurgesiella can be identified by a combination of morphological characteristics, including the number of testes, number of radial rows of sclerites in the pseudohaptor, aperture of the genital pore and shape of the vitelline follicles. The results from the DNA analysis indicated that A. gurgesiella has a genetic divergence of 3.2-3.7% (LSU rDNA gene) from A. urolophi, the only congener species for which molecular data are available.

Metazoan parasites of Brama australis from southern Chile: a tool for stock discrimination?

The metazoan parasites of 403 specimens of the southern ray's bream Brama australis from three localities in southern Chile (Lebu 36° 70' S; 73° 40' W, Calbuco 41° 50' S; 73° 08' W and Punta Arenas 53° 10' S; 70° 50' W) were recorded. More than 23 400 parasite specimens belonging to 12 taxa were registered. Metazoan parasites were dominated by the copepod Hatschekia conifera, constituting 97% of the total number of parasites; the larval cestode Hepatoxylon trichiuri was the second most important parasite (2·1% of the total number of parasites). The remaining 10 species constituted <1% of the metazoan parasites. Parasitological evidence, based on univariate and multivariate analysis, does not support the existence of discrete stocks in the studied zone.