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A new genus and three new species of blood flukes (Aporocotylidae) are described from squirrelfishes (Holocentridae) from the Great Barrier Reef. Holocentricola rufus n. gen., n. sp. is described from Sargocentron rubrum (Forsskål), from off Heron Island, southern Great Barrier Reef, and Lizard Island, northern Great Barrier Reef, Australia. Holocentricola exilis n. sp. and Holocentricola coronatus n. sp. are described from off Lizard Island, H. exilis from Neoniphon sammara (Forsskål) and H. coronatus from Sargocentron diadema (Lacepède). Species of the new genus are distinct from those of all other aporocotylid genera in having a retort-shaped cirrus-sac with a distinct thickening at a marginal male genital pore. The new genus is further distinct in the combination of a lanceolate body, X-shaped caeca, posterior caeca that are longer than anterior caeca, a single, post-caecal testis that is not deeply lobed, a post-caecal, post-testis ovary that is not distinctly bi-lobed, and a post-ovarian uterus. The three new species can be morphologically delineated based on the size and row structure of the marginal spines, as well by total length, oesophagus and caecal lengths, and the position of the male genital pore, testes and ovary relative to the posterior extremity. The three species of Holocentricola are genetically distinct from each other based on cox1 mtDNA and ITS2 rDNA data, and in phylogenetic analyses of 28S rDNA form a well-supported clade sister to species of Neoparacardicola Yamaguti, 1970. This is the first report of aporocotylids from fishes of the family Holocentridae and the order Holocentriformes.Un nouvel ordre de poissons comme hôtes de digènes du sang (Aporocotylidae) ; description d’un nouveau genre et de trois nouvelles espèces infectant les poissons-écureuils (Holocentriformes, Holocentridae) de la Grande Barrière de Corail.Un nouveau genre et trois nouvelles espèces de digènes du sang (Aporocotylidae) sont décrits de poissons-écureuils (Holocentridae) de la Grande Barrière de Corail. Holocentricola rufus n. gen., n. sp. est décrit de Sargocentron rubrum (Forsskål), de Heron Island, au sud de la Grande barrière de corail, et de Lizard Island, au nord de la Grande barrière de corail, en Australie. Holocentricola exilis n. sp. et Holocentricola coronatus n. sp. sont décrits de Lizard Island, H. exilis de Neoniphon sammara (Forsskål) et H. coronatus de Sargocentron diadema (Lacepède). Les espèces du nouveau genre se distinguent de celles de tous les autres genres d’Aporocotylidae en ce qu’elles ont un sac du cirre en forme de cornue avec un épaississement distinct au niveau d’un pore génital mâle marginal. Le nouveau genre se distingue en outre par la combinaison d’un corps lancéolé, de caeca en forme de X, de caeca postérieurs plus longs que les caeca antérieurs, d’un seul testicule post-caecal qui n’est pas profondément lobé, d’un ovaire post-caecal et post-testiculaire qui n’est pas distinctement bilobé, et d’un utérus post-ovarien. Les trois nouvelles espèces peuvent être délimitées morphologiquement en fonction de la taille et de la structure des rangées des épines marginales, ainsi que de la longueur totale, de la longueur de l’œsophage et des caeca, et de la position du pore génital mâle, des testicules et de l’ovaire par rapport à l’extrémité postérieure. Les trois espèces d’Holocentricola sont génétiquement distinctes les unes des autres sur la base des données d’ADNr cox1 et d’ADNr ITS2, et forment un groupe-frère bien soutenu des espèces de Neoparacardicola Yamaguti, 1970 dans les analyses phylogénétiques de l’ADNr 28S. Il s’agit du premier signalement d’Aporocotylidae chez des poissons de la famille des Holocentridae et de l’ordre des Holocentriformes.

Recently, we found that liver of squirrelfish (Holocentrus rufus) from Bermuda contains remarkably high concentrations of metallothionein (MT) and Zn. To clarify the nature and cause of the Zn accumulation, four Holocentridae species from three genera (Neoniphon sammara, Sargocentron spiniferum, Myripristis violacea, and Myripristis murdjan) were collected from a totally different area, the Great Barrier Reef, Australia. The average hepatic Zn levels in these species ranged from 67 μg g-1 (S. spiniferum) to 1000 μg g-1 (N. sammara). The intraspecies variation in the hepatic Zn level was pronounced. In both N. sammara and M. murdjan, there was a 48-fold difference between the lowest and the highest Zn concentration. Zn accumulation was closely correlated to a dramatically elevated concentration of MT in liver. In N. sammara, which possessed the highest level of MT among the investigated species, the mean hepatic MT concentration was 19 500 μg g-1. Subcellular fractionation of the liver showed that MT was responsible for the binding of up to 74% of the hepatic Zn. The concentrations of MT and Zn in gills were low, suggesting that Zn storage in fish within this family is tissue-specific. The results further indicate that the high concentrations of MT and Zn in Holocentridae liver are linked to normal physiological processes. We suggest that the Holocentridae family may be a unique model for future studies of Zn metabolism and the function of MT.

Two nematode species of the family Cystidicolidae were collected from the digestive tract of marine fishes off New Caledonia, South Pacific: Ascarophis adioryx Machida, 1981 from the stomach of the speckled squirrelfish Sargocentron spiniferum and the sabre squirrelfish Neoniphon sammara (new host record) (both Holocentridae, Beryciformes), and a Spinitectus sp. female, morphologically similar to S. beaveri Overstreet, 1970, from the roundjaw bonefish Albula glossodonta (Albulidae, Albuliformes). Based on light and scanning electron microscopy examinations, A. adioryx is redescribed and a new subgenus Dentiascarophis subgen. nov., characterized by the presence of one dorsal and one ventral median protrusions in the mouth, is established to accommodate it; a key to subgenera of Ascarophis is provided. Ascarophis holocentri Parukhin, 1984 is considered a junior synonym of A. adioryx. The cephalic structure of Spinitectus sp. and S. beaveri is very different from those in other congeners and, therefore, a new subgenus Paraspinitectus subgen. nov., characterized by highly reduced pseudolabia, is erected to accommodate these species. The hemiurid digenean Lecithochirium cirrhiti (Manter et Pritchard, 1960) Yamaguti,1970 was found in the stomach of three species of squirrelfishes. Findings of A. (D.) adioryx, Spinitectus (P.) sp. and L. cirrhiti in New Caledonian waters represent new geographical records of these parasites.