Exploring nursery sites for oviparous chondrichthyans in the Southwest Atlantic (36°S–41°S)

The aim of this paper was to explore egg-laying areas of oviparous chondrichthyans occurring in the northern part of the Southwest Atlantic Ocean (36°S–41°S) at between 50 and 200 metres depth and the Mar del Plata Canyon (from 200 to 3447?m). A total of 515 capsules were collected corresponding to 10 species. Four species accounted for 87.6% of the total catch: Psammobatis normani, Bathyraja macloviana, Amblyraja doellojuradoi and Bathyraja brachyurops. The remaining corresponded to Schroederichthys bivius, Psammobatis rudis, Zearaja chilensis, Bathyraja albomaculata, Psammobatis lentiginosa and Bathyraja sp. Most hauls were monospecific and relatively few hauls contained four or five species (southern part of the area, in sites located at 75 and 94–105?m depth). No egg capsules were recorded between 1712?m and 3447?m. Highest densities (>3000 capsules/km²) were mainly found between 39°46.2′ and 40°29.9′S from 85 to 105?m and they were also recorded near the Mar del Plata Canyon at 37°59.7′S and at 852?m. The highest value recorded was 12,326 capsules/km² (located at 40°18.9′S and 85.4?m). The highest densities for each of the most abundant species are discussed. The finding of high densities of egg cases near the Argentine shelf-break front indicates that many skate species use this area as a nursery site. The egg-laying areas explored here are the first reported sites of this kind in the Southwest Atlantic Ocean. Recognizing and protecting egg-laying habitats may be important steps to a long-term conservation of oviparous chondrichthyan populations.     

Gymnocranius superciliosus and Gymnocranius satoi, two new large-eye breams (Sparoidea: Lethrinidae) from the Coral Sea and adjacent regions

Two related perciform fish species of the subfamily Monotaxinae (Sparoidea: Lethrinidae) Gymnocranius superciliosus sp. nov. and Gymnocranius satoi sp. nov. are described from specimens and tissue samples from the Coral Sea and adjacent regions. G. superciliosus sp. nov. is distinct from all other known Gymnocranius spp. by the following combination of characters: body elongated (depth 2.7–3.1 in standard length), caudal fin moderately forked with a subtle middle notch, its lobes slightly convex inside, distinctive blackish eyebrow, snout and cheek with blue speckles, and dorsal, pectoral, anal and caudal fins reddish. G. satoi sp. nov. is the red-finned ‘Gymnocranius sp.’ depicted in previous taxonomic revisions. While colour patterns are similar between the two species, G. satoi sp. nov. is distinct from G. superciliosus sp. nov. by the ratio of standard length to body depth (2.4–2.5 vs. 2.7–3.1) and by the shape of the caudal fin, which is more shallowly forked, its lobes convex inside and their extremities rounded. The two species are genetically distinct from each other and they are genetically distinct from G. elongatus, G. euanus, G. grandoculis, and G. oblongus sampled from the Coral Sea and adjacent regions.