A quantitative ecomorphological study was carried out on the sagitta otoliths of Antarctic and Subantarctic nototheniids, a particularly interesting family due to its fast adaptive radiation into different life strategies. We analyzed the otolith shape and size of 18 nototheniids to test the relationship between phylogeny, otolith characters and trophic niche. Relative size (area, length, width, perimeter and weight) and shape (biometric warp analysis based on homologous and pseudo-homologous landmarks) measurements were compared with phylogenic, habitat dwelling and food composition analyses. The results of the multivariate analysis of these factors indicate that there is a weak relationship between otolith shape of nototheniids and phylogeny; however, there is a clear correspondence between relative otolith size and shape and their trophic niche. The most benthic feeders of the family had the largest sagittae in relation to body size, and pelagic species had smaller and rounder shaped sagittae than benthic species. Consequently, in ecomorphological studies, it is useful to analyze the size and shape of sagittae. The discoidal shape of pelagic species, such as Pleuragrama antracticum, can be considered as a paedomorphic characteristic, converging to the juvenile sagittae of many species, which exhibit round sagittae that become elongated as they grow.

SUMMARY: A new species of the family Merlucciidae is presented, Merluccius patagonicus sp. nov., from the waters of the Argentine Sea. Besides the description of the new species, a brief diagnosis and a key to identification are added, with the purpose of easily separating the species from its similar relatives among the genus Merluccius Rafinesque, 1810 reported in the region: M. hubbsi and M. australis. -Se presenta una nueva especie Merluccius patagonicus sp. nov. perteneciente a la familia Merlucciidae, capturada en aguas del mar Argentino. En el presente trabajo, se adjunta además de la descripción, una breve diagnosis y una clave de identificación con el propósito de identificar fácilmente las especies similares del género Merluccius Rafinesque, 1810 citadas en la región: M. hubbsi y M. australis.

A new hake species, Merluccius tasmanicus sp. nov., is described from New Zealand waters and another species, Merluccius australis is redescribed. Merluccius tasmanicus sp. nov. differs from all other congeneric species in the following combination of characters: upper profile of the head slowly concave; lateral line slowly concave in the caudal region; body depth 4.9–5.9 times in standard length (SL); orbital diameter 6.1–7.1 times in head length, 2.1–2.2 times in snout length and 1.6–1.9 times in interorbital width; second dorsal fin rays, 42–43; anal fin rays, 42–44; lateral line scales ∼164. Merluccius australis is redescribed to clarify the identity of this species. Merluccius australis differs from all other congeneric species in the following combination of characters: upper profile of the head straight; lateral line straight in the caudal region; body depth 6.6–7.1 times in SL; orbital diameter 4.5–5.4 times in head length, 1.2–1.7 times in snout length and 1.0–1.3 times in interorbital width; second dorsal fin rays, 40–43; anal fin rays, 40–43; lateral line scales, more than 155. Merluccius tasmanicus sp. nov. is found in New Zealand and Patagonian waters and occasionally in Japanese waters; Merluccius australis is reported in both New Zealand and Patagonian waters.

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The feeding habits of the 4 most abundant macrourids that occur on the deep slope of the Catalan Sea (western Mediterranean) were examined for the first time for the Mediterranean at depths between 1000 and 2250 m. Diets of Chalinura mediterranea, Coryphaenoides guentheri, Coelorhynchus labiatus and Trachyrhynchus trachyrhynchus were analysed for 2 seasons (summer and autumn) and/or 3 different bathymetric strata. Coryphaenoides guentheri was the most euryphagous and T. trachyrhynchus the least. Chalinura mediterranea, Coelorhynchus labiatus and T. trachyrhynchus has a benthopelagic diet, whilst Coryphaenoides guentheri has a benthic diet. Coelorhynchus labiatus has a slight preference for bathybenthic prey (polychaetes, gammaridean amphipods) whereas Chalinura mediterranea and T. trachyrhynchus display a preference for bathypelagic prey (calanoid copepods, mysids). Chalinura mediterranea and Coryphaenoides guentheri have bathymetric differences in diet marked by the capture of different prey-items and also by a greater vacuity, a greater consumption of prey and a greater diversity at 1800 to 2250 m. A greater diversity in the diet is found in the Mediterranean populations of Chalinura mediterranea, Coryphaenoides guentheri and Coelorhynchus labiatus than in the Atlantic populations; this is probably an adaptation to the faunal paucity of the Mediterranean deep sea. General affinities among the diets of all macrourids are also analysed. The apparent coincidence between the diets of Chalinura mediterranea and T. trachyrhynchus could explain the bathymetric segregation of their respectives niches. Coelorhynchus labiatus, whose habitat width lies within those of the other 3 macrourids, has a dietary overlap intermediate to those of the other 3 macrourids. Ecological separation is maintained by a combination of differential depth distribution and feeding habits.KEY WORDS: Chalinura mediterranea · Coryphaenoides guentheri · Macrouridae · Feeding ecology · Western Mediterranean · Deep-sea ecology Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 234: [215][216][217][218][219][220][221][222][223][224][225][226][227][228] 2002 alimentary canal have been given by Morales-Nin (1990), Stefanescu et al. (1992b), Carrassón & Matallanas (1994) and Massutí et al. (1995). Diets of macrourids for depth ranges of 200 to 800 m have been studied by Macpherson (1979Macpherson ( , 1981, and some generic data on the diet of 1 specimen of Coryphaenoides guentheri and 1 Chalinura mediterranea from a depth of more than 2400 m have been reported by Geistdoerfer (1978). Apart from these 2 observations, no studies have been carried out on the diet of macrourids below a depth of 1000 m in the Mediterranean. In demersal deep-sea fishes in the western Mediterranean, a different behaviour in depth-size trends has been found compared to that in Atlantic waters; at the same time, a significant size reduction in Mediterranean populations of many species (among them the macrourids) has been...

The present study examines the feeding habits of Alepocephalus rostratus, the only species of the family Alepocephalidae in the Mediterranean Sea and the second most important fish species, in terms of biomass, inhabiting the deep slope of the Catalan Sea. Samples were obtained at depths between 1000-2250 m. Diet was analysed for two different size-classes (immature and mature specimens) at three different bathymetric strata during two different seasons. The feeding habits of A. rostratus included a narrow range of mobile macroplanktonic organisms (e.g. Pyrosoma atlanticum and Chelophyes appendiculata) and some material of benthic origin. Pyrosoma atlanticum was the preferred prey item in spring at 1000-1425 m, being very scarce in summer at the same depth as a consequence of its scarcity in the environment during this season. There were some ontogenic differences in the diet of A. rostratus at 1425-2250 m. Adults ingested more and larger prey than juvenile specimens. The scarcity of resources below 1200-1400 m fostered a more diversified diet, as well as passive predation of sedimented material.