SUMMARY:In order to evaluate the use of parasites as biological tags to identify populations of the oceanic horse mackerel, Trachurus picturatus, two samples of 100 fish each, caught off the Madeira and Canary Islands from January to June 2009, were examined for the presence of anisakids, trypanorhynchs, acanthocephalans and liver coccidians. In T. picturatus from Madeira, prevalence of the coccidian Goussia cruciata reached 82%, whereas prevalence of the nematode Anisakis sp., the acanthocephalan Rhadinorhynchus cadenati and the trypanorhynch Nybelinia lingualis were 12.0%, 8.9% and 7.0%, respectively. In samples from the Canary Islands, prevalence of G. cruciata was 8.0%, Anisakis sp. and R. cadenati reached 5.0% and 42.0% respectively, and N. lingualis was not recovered. The absence of N. lingualis and the lower prevalence of Anisakis sp. appear to be related to the smaller size of the oceanic horse mackerels examined from the Canary Islands. Although significant differences in prevalence of two parasites, G. cruciata and R. cadenati, were found between the two regions investigated (χ 2 =125.13, df=1, p=0.000 and χ 2 =40.77, df=1, p=0.000), only G. cruciata was considered useful as a biological tag for the identification of populations of T. picturatus. In order to reach sound conclusions, an expansion of the temporal and spatial sampling strategy is recommended.

The helminth parasite fauna of the oceanic horse mackerel Trachurus picturatus Bowdich 1825, caught off the Madeira Islands was composed of six different taxa. Prevalence and abundance of larval Anisakis sp. (Nematoda: Anisakidae) and Nybelinia lingualis (Trypanorhyncha: Tentaculariidae), the most common parasite taxa, were 24.3%, 0.9 and 37.9%, 0.7, respectively. Bolbosoma vasculosum (Acanthocephala: Polymorphidae) and the monogeneans Heteraxinoides atlanticus (Monogenea: Heteraxinidae) and Pseudaxine trachuri (Monogenea: Gastrocotylidae) were comparatively rare. The depauperate helminth fauna of the oceanic horse mackerel at Madeira compared to other geographical regions of the north-eastern Atlantic, namely the Azores banks and the West African coast, may be attributed to the paucity of nutrients off oceanic islands and to a low density of the fish population.

The endohelminth parasite fauna of a deep water shark, the leafscale gulper shark, Centrophorus squamosus, examined from Madeiran waters, from September 2009 to January 2010, consisted of larval and juvenile cestodes of two orders, namely Trypanorhyncha and Tetraphyllidea, and L3 stages of Anisakis spp. Infection with Anisakis spp. could be due to the shark's opportunistic feeding on squids and black-scabbard fish, Aphanopus carbo, which is heavily parasitized by Anisakis spp. in Madeira waters. The occurrence of larval and juvenile cestodes only, in this shark, suggests that the leafscale gulper shark features as a paratenic or a dead-end host for the parasites.

Geographic variations in the diversity and prevalence of helminth parasites of fish can provide important clues as to the relatedness of fish populations. In the present work, the stomachs of 64 conger eels, Conger conger, collected during 1999 and 2000, were examined for the presence of parasites. Four fish were infected with L3 stages of the nematode Anisakis simplex s.l. (Anisakidae), 1 with the nematode Cristitectus congeri (Cystidicolidae), 1 with the acanthocephalan Rhadinorhynchus pristis, 17 with postlarvae of Sphyriocephalus tergestinus (Eucestoda: Trypanorhyncha), and 55 with Lecithochirium spp. (Digenea: Hemiuridae). The hemiurids were the most abundant parasites, with a total of 385 individuals recovered. Strong aggregated distributions were found for both the digeneans, Lecithochirium musculus and Lecithochirium fusiforme, with variance-to-mean ratios (s 2 /x) and index of discrepancy (D) 13.98 and 0.672 (for L. musculus) and 8.08 and 0.90 for L. fusiforme, respectively. Intensity of L. musculus, L. fusiforme, and S. tergestinus showed significant relationships with depth of capture. Differences in number of species and prevalence were found between Madeira and the Atlantic coasts of the Iberian Peninsula.

This paper describes a case of dirofilariasis in a two-year old, female grey wolf (Canis lupus lupus). The autopsy revealed the presence of 42 adult forms of Dirofilaria immitis in the pulmonary artery, right ventricle and right atrium, varying in length from 9.5 to 30 cm. This is, to the best of our knowledge, the second report of D. immitis in grey wolves in Serbia. Our finding confirms that the wolf, as a subspecies distinct from the dog, should also be considered as a very suitable definitive host for dirofilariasis.