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.

Spatio-temporal patterns of genetic variations in populations of yellowtail kingfish Seriola lalandi from the south-eastern Pacific Ocean and potential implications for its fishery management.

The genetic population structure and genetic diversity of yellowtail kingfish Seriola lalandi from the coastal south-eastern Pacific Ocean (SEP) were evaluated at spatiotemporal scale in order to understand the ecology of this species. Between 2012 and 2015, temporal and spatial population genetic structure and a low genetic diversity were detected in S. lalandi from SEP. These results suggest that S. lalandi specimens arriving annually from offshore to the SEP coast could come from at least two genetically distinct populations, revealing a particular life strategy (i.e. reproductive or habitat segregation) for this fish species. Therefore, the SEP coast might constitute a point of population mixing for this species. Additionally, the low genetic diversity of S. lalandi in the SEP could be a result of a founder effect or overfishing. Regardless of the process explaining the genetic diversity and structure of S. lalandi in this geographical area, this new information should be considered in order to implement successful fishery management of this resource in the South Pacific.

Two new species of Encotyllabe (Monogenea: Capsalidae) based on morphometric and molecular evidence: parasites of two inshore fish species of northern Chile.

Two new species, Encotyllabe cheilodactyli and Encotyllabe antofagastensis (Monogenea: Capsalidae), have been found in the pharyngeal plates of Cheilodactylus variegatus and Anisotremus scapularis, respectively, in northern Chile (23°38'N, 70°24'W). Descriptions of the new species were based on morphometric and molecular evidence. Both species differ from previously described species of the genus by a combination of characteristics, including the size and relative position of the testes and the shapes of the major and small hamulus. In addition, E. cheilodactyli is unique among the known species of Encotyllabe due to the testes crossing the equatorial line of the body proper, and E. antofagastensis is unique among the known species of Encotyllabe due to its penis structure and anatomy leading to the genital pore. The analysis of the cytochrome c oxidase I gene as well as morphometric analyses demonstrated that the specimens belonged to 2 different species.