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Weight-length relations of fishes are useful for estimation of biomass from length observations, e.g., in fisheries or conservation research. Here we provide some guidance to authors of such papers, in order to facilitate the publication and review process

One thousand three hundred seventy three fish specimens of eight different species from the vicinity of Kyiv, Ukraine, were examined for the presence of trypanosomes and 921 individuals were found to be infected. The prevalence of infection ranged from 24% in freshwater bream, Abramis brama, to 100 % in spined loach, Cobitis taenia. The level of parasitaemia also varied significantly between generally mild infections in pikeperch, Sander lucioperca, and heavy ones in C. taenia. In most cases the infections with trypanosomes were asymptomatic. Cases of co-infection with species of Trypanoplasma were documented for five out of eight examined host species. Molecular analysis of the 18S rDNA sequences revealed that four hosts, namely northern pike, Esox lucius, freshwater bream, spined loach and European perch, Perca fluviatilis, were simultaneously infected with two different trypanosome species. Our findings advocate the view that to avoid the risk posed by mixed infections, subsequent molecular taxonomic studies should be performed on clonal lines derived from laboratory cultures of fish trypanosomes.

Based on light and scanning electron microscopical studies, three new gonad-infecting species of Philometra (Nematoda: Philometridae) are described from marine fishes of the genus Lutjanus (Perciformes: Lutjanidae) in the northern Gulf of Mexico: P. longispicula sp. n. from the ovary of the northern red snapper L. campechanus (type host) and silk snapper L. vivanus; P. latispicula sp. n. from the ovary and rarely testes of the grey snapper L. griseus; and P. synagridis sp. n. (only males available) from the ovary of the lane snapper Lutjanus synagris. These species are mainly characterised by the lengths of spicules (378-690 microm, 135-144 microm and 186-219 microm, respectively) and spicule shapes, structure of the distal portion of the gubernaculum and the structure of the male caudal end. These are the first valid, nominal species of gonad-infecting philometrids reported from fishes of the family Lutjanidae in the western Atlantic region.

Based on molecular markers (COII and ITS1-ITS2) and morphological data, we describe three new Neotropical species of Gyrodactylus from Scleromystax barbatus and Scleromystax macropterus from southern Brazil. The three new species can be distinguished from each other by sequences of both molecular markers and morphology of hooks and anchors. Gyrodactylus bueni sp. n. is characterised by having hook with shaft curved, heel straight, shelf straight, toe pointed, anchor with superficial root slender, elongate and male copulatory organ armed with two rows of spinelets. Gyrodactylus major sp. n. presents hook with shaft, point curved, proximal shaft straight, heel convex, shelf convex, toe concave, anchor with superficial root robust and male copulatory organ armed with two rows of spinelets. Gyrodactylus scleromystaci sp. n. presents hook with shaft, point recurved, heel convex, shelf convex, toe pointed, anchor with superficial root curved and male copulatory organ armed with two rows of spinelets. These species appear to be closely related to other species of Gyrodactylus known from other species of Callichthyidae. These new species, however, differ by the comparative morphology of the haptoral hard structures and molecular data. Comparative analysis of sequences from these species of Gyrodactylus suggests that the COII gene may represent an important marker for the taxonomy of species of Gyrodactylidae and, perhaps, for species of other lineages of Monogenoidea.

Bentholebouria colubrosa gen. n. et sp. n. (Digenea: Opecoelidae) is described in the wenchman, Pristipomoides aquilonaris, from the eastern Gulf of Mexico, and new combinations are proposed: Bentholebouria blatta comb. n., Bentholebouria longisaccula comb. n., Bentholebouria rooseveltiae comb. n., and Bentholebouria ulaula comb. n. The new genus is morphologically similar to Neolebouria, but with a longer cirrus sac, entire testes, a rounded posterior margin with a cleft, and an apparent restriction to the deepwater snappers. Morphologically, the new species is closest to B. blatta from Pristipomoides argyrogrammicus off New Caledonia but can be differentiated by the nature of the internal seminal vesicle (2-6 turns or loops rather than constrictions), a longer internal seminal vesicle (occupying about 65% rather than 50% of the cirrus sac), a cirrus sac that extends further into the hindbody (averaging 136% rather than 103% of the distance from the posterior margin of the ventral sucker to the ovary), and a narrower body (27% rather than 35% mean width as % of body length). A Bayesian inference analysis of partial sequence of the 28S rDNA from Neolebouria lanceolata, Cainocreadium lintoni, Hamacreadium mutabile, Opecoeloides fimbriatus, Podocotyloides brevis, the new species, and previously published comparable sequences from 10 opecoelid species revealed two clades. One clade includes deep-sea (more or equal 200 m) and freshwater fish opecoelids + Opecoeloides Bremser, and a second clade included those opecoelids from shallow-water marine, perciform fishes.

During a survey on the myxosporean fauna of gibel carp Carassius auratus gibelio in China, a species of Myxobolus, that did not conform to any known species was found. The species is characterised by the presence of round to ellipsoidal plasmodia of 2.6-4.0 mm in diameter in the palate of host. Mature spores are obovate in frontal view and lemon-shaped in lateral view, with the following range, mean and standard deviation of dimensions: 10.8-12.8 µm (11.7 +/- 0.4 microm) long, 8.2-9.9 microm (8.9 +/- 0.4 µm) wide and 6.0-7.5 microm (6.8 +/- 0.3 µm) thick. Two polar capsules are pyriform, 4.0-5.5 microm (4.8 +/- 0.3 microm) long by 2.9-3.6 microm (3.0 +/- 0.2 microm) wide. Polar filaments are coiled, with 5 to 6 turns. A small proportion of spores possesses a short caudal process. Scanning electron microscopy revealed discoid spores with a low sutural ridge and middle bulge. The small subunit ribosomal DNA sequence of this species did not match any available sequences in GenBank. Phylogenetically, this species is sister to M. nielii and M. hearti in a Henneguya-Myxobolus clade with robust support. Given the morphological and molecular differences between this species and other Myxobolus species, we propose the name Myxobolus oralis sp. n. for this parasite from gibel carp.

Parapedocotylinae, a new subfamily, is proposed to accommodate the gen. n. et sp. n. Parapedocotyle prolatili (Monogenea: Diclidophoridae), a gill parasite of the Pacific sandperch, Prolatilus jugularis (Valenciennes) (Pinguipedidae) from northern Chile. Among the Diclidophoridae the species of the Pedocotylinae are unique by bearing the first pair of clamps (most posteriorly) in a haptoral projection. Pedocotyle, the only genus in the Pedocotylinae, is characterised by the first pair of clamps non-pedunculate, modified and non-functional, without accessory suckers, and clamps of pairs 2-4 being pedunculate and functional. In contrast, the first pair of clamps in Parapedocotyle is well developed and functional at the terminal end of a long haptoral appendix and having clamp pairs 2-4 pedunculated, modified and apparently not functional. Seminal receptacle is preovarian in Parapedocotyle in opposition to its postovarian position in Pedocotyle. These differences justified the erection of the new subfamily Parapedocotylinae. The new subfamily is also supported by genetic analyses (18S rDNA, 28S rDNA and cox1 sequences) demonstrating that the Pedocotylinae and Parapedocotylinae belong to different clades in the Diclidophoridae.

Counting and sizing large farmed fish such as tuna is often performed during their transfer from one net cage to another. Dual-frequency-identification sonar (DIDSON) provides an automated fish counting and sizing tool. However, its counter and sizer are not suitable for measuring farmed fish because of net movements due to currents and subsequent frequent image breakups. This paper presents a fully automated acoustic method to count and size farmed fish during fish transfer by using DIDSON imaging. The background is subtracted from the image after being stabilized by an image phase-only correlation method. The segmentation of the fish is obtained by tracing the edges with a contour tracing method. To prevent recounting the same fish, a Kalman filter algorithm was designed and adapted to predict fish movements. Automated counting was performed by analyzing the spatiotemporal trajectory of the track. The separated fish images were searched for and body length was obtained by summing down the centerline segments from the head to the tail of the fish. The proposed system was verified using farmed yellowtail, Seriola quinqueradiata (mean total length 83.1 cm) to obtain a sizing error of mean total length within 2.4 cm.

In order to enhance the mass production of the house fly, Musca domestica, five aspects of its oviposition biology were analyzed. Oviposition substrate and the manner of its presentation, the composition of the diet of the adults, size of the pupae and numbers of flies in a cage were identified as critical. Females preferred to lay eggs on a substrate which was presented within a shelter and with increased linear edges against which the flies could oviposit. Different types of oviposition substrate resulted in comparable yields of eggs. The presence of an oviposition attractant (ammonia) in the manure was found to have a potentially positive effect on female fecundity. Egg yield increased when two protein sources (yeast and milk) were included in the adult diet. However, flies fed a mixture of sugar and yeast laid over 50% fewer eggs than those fed the same proportion of sugar and milk. The fecundity of flies decreased with increase in the number of flies per cage, but the highest total number of eggs per cage was obtained when the flies were most crowded (14.2 cm3 per fly). The size of the pupae did not significantly affect egg production.

We examined the relationship between body size and perceptual range (the distance at which an animal can perceive landscape elements) for a group of forest-dwelling rodents. We used previously published data on orientation ability at various distances for three sciurid species (gray squirrel, fox squirrel and chipmunk) and one murid species (white-footed mouse) to build a predictive model. We found a significant positive relationship between perceptual range and body mass. Although this model was built using a 15.5 m high horizon, we used this relation to predict the perceptual range of root voles (3.9-4.3 m) orienting towards a 0.5 m high horizon which was consistent with other empirical work suggesting a value of something less than 5 m. This model illustrates a relationship between perceptual range and body size and can be used to develop starting points for future investigations of perceptual range for similar organisms.