Summary Growth and reproduction of Chelidonichthys lucerna is reported from Tunisian waters. A total of 286 specimens was collected from landings of bottom trawlers between January 2003 and November 2004. The total length ranged from 16 to 36 cm in females and from 17 to 26 cm in males. Marginal increment analysis of otoliths showed that the translucent zone was laid from October to May and the opaque zone laid from June to September. Females were from 0.5 to 9 years and males from 1 to 7 years old. Growth parameters of the von Bertalanffy growth function were TL∞ = 40.26; K = 0.06 and t0 = −3.03 in females and TL∞ = 46.16; K = 0.059 and t0 = −1.32 in males. The coefficient of the allometric length–weight relationships differed significantly by sex. Females with mature gonads were observed between October and May, with peaks in January and February. Length at which 50% of specimens were mature was 21.6 cm TL (estimated age about 3 years) in females and 19.2 cm TL (estimated age about 1.5 years) in males.

No abstract

Summary The most common gurnard species in the Gulf of Gabes (Tunisia) are Chelidonichthys lastoviza and C. obscurus. These two species were collected by trawl nets between February 2000 and July 2002 at depths ranging from 80 to 150 meters. In the laboratory the stomach contents were examined for diet assessment and to determine diet variation in relation to fish size, season and sex. The importance of different prey items was analysed utilising several feeding indexes, while diet overlap was tested using Schoener's index and the null model test. The two species showed similar diets, with the same qualitative and quantitative composition. Basic food consisted of crustaceans, mostly mysids and decapods. For Chelidonichthys lastoviza:Gastrosaccus sp. (F = 48.57%), Anchialina agilis (F = 30.57%) and Sicyonia carinata (F = 21.71%); for Chelidonichthys obscurus:Gastrosaccus sp. (F = 80.95%), A. agilis (F = 55.41%) and Pontocaris lacazei (F = 15.15%). A change in food composition based on fish size was observed in both species: mysids more frequently in the diet of small specimens, and decapods in the largest fishes. Seasonal variation in their diet was also recorded. The two fishes showed a significantly higher number of empty stomachs in late autumn and winter. Regardless of species and size class, a biologically significant diet overlap was observed between C. lastoviza and C. obscurus. This result may indicate a lack of competition among triglid species size‐class combinations or strong competition that has not yet led to resource portioning.

Abstract. Plectanocotyle major sp. n. (Monogenea: Polyopisthocotylea: Plectanocotylidae) is described from Chelidonichthys obscurus (Bloch et Schneider, 1801) collected from the Mediterranean coasts (Tunisia and France). The new species is compared to Plectanocotyle gurnardi collected on Chelidonichthys gurnardus and the only other valid species in the genus Plectanocotyle. The new species differs from P. gurnardi by the clamp size (137 µm vs 64 µm for clamp length and 110 µm vs 60 µm for clamp width, respectively) and the length of the male copulatory organ (107 µm vs 144 µm, respectively). Species of the Plectanocotylidae seem to be characterized by an oioxenic specificity. In a recent study of the biology of Triglidae in Tunisian waters, we found on the gills of Chelidonichthys obscurus (Bloch et Schneider, 1801) two species of Plectanocotylinae: Triglicola obscurum and another species belonging to Plectanocotyle that we considered as a new species. We also found this species in the collection of one of us (L. E.) collected at Sète in 1969, 1970 and 2003. This species is compared to P. gurnardi collected at Sfax (Tunisia) and Sète (France) on the type-host, C. gurnardus. This new species is described herein. MATERIALS AND METHODS Specimens of Chelidonichthys obscurus andChelidonichthys gurnardus caught by trawler were examined shortly after being landed. Gills were removed and placed in separate Petri dishes containing seawater, and examined for parasites using a stereomicroscope with incident light. Monogeneans were detached from the gills using a strong water current and transferred to a dish containing seawater. Some living parasites were studied, partially compressed beneath a coverslip, using a photonic microscope. Other specimens were transferred individually on a slide in a drop of ammonium picrate-glycerine after Malmberg (1957). The preparation was then covered with a round coverslip and sealed with Canada balsam. Some parasites, fixed in 70% ethanol, were stained with Semichon's acetic carmine and following dehydration through a graded ethanol series, and then were cleared in clove oil and mounted in Canada balsam. Some specimens mounted in Berlèse medium were used to study the morphology of the haptoral clamps and copulatory complex.Illustrations and measurements were made with the aid of a Leitz microscope with drawing tube. All measurements are given in micrometres. Ranges are given in the text followed in parentheses by the mean, standard deviation, and number of observations (n). Drawings (Figs. 2-6) were scanned and redrawn on a computer with CorelDRAW.After Llewellyn (1956), the following appellation for clamp skeleton, is used: a = median sclerite; b = anterior marginal sclerite; c = dorsal posterior, marginal sclerite; d = ventral posterior, marginal sclerite; e = median posterior plate (Fig. 2). Host identification and nomenclature follow Froese and Pauly (2005).

Lamellodiscus euzeti n. sp. (Monogenea: Diplectanidae) is described from the gills of two sparid fishes, Dentex canariensis (Steindachner) off Senegal and Ivory Coast and D. gibbosus (Rafinesque) off Senegal and Tunisia. The new species belongs to the “ignoratus” group, characterized by a lamellodisc with complete lamellae, a “lyre” shaped male copulatory organ type, and the “ignoratus” sensu stricto subgroup, characterized by a haptor with simple lateral dorsal bars. Lamellodiscus euzeti n. sp can be distinguished from all the congeneric species of the “ignoratus” subgroup by the presence of a prominent protuberance at the base of the curved part of the simple piece of the male copulatory organ (MCO), a large bulb at the base of the bifurcated piece of the MCO and the presence of 5-6 spines in the distal portion of the axial branch of the bifurcated piece of the MCO. Specificity and biogeography of Lamellodiscus species from sparid fishes are discussed.