Julio Lamilla

Peces Chimaeriformes (Chondrichthyes, Holocephali) del Neógeno de la Formación Bahía Inglesa (Región de Atacama, Chile)

Se describen los primeros restos fosiles de peces condrictios holocefalos para el Neogeno de la Formacion Bahia Inglesa, Atacama, Chile. El material comprende una placa dental palatina y un mandibular que fueron recolectados al sureste de Caldera desde niveles fosiliferos asignados al Mioceno Medio-Mioceno tardio. Rasgos morfologicos caracteristicos y comparaciones con otras placas de quimeras callorrinquidas, actuales y fosiles, permiten designar el material como Callorhinchus sp.

Reproductive biology of Zearaja chilensis (Chondrichthyes: Rajidae) in the south‐east Pacific Ocean

Between 2000 and 2002, three artisanal landing sites were sampled in southern Chile, with data on population structure and reproductive development collected from 5477 yellownose skates Zearaja chilensis. Total length (L(T) ) ranged from 33 to 158 cm for females and 34 to 155 cm for males. No sexual dimorphism was evident in disc size (length or width) or in L(T)-mass relationships. The smallest mature female was 95 cm L(T) and the size at which 50% were mature (L(T50) ) was 109 cm. Males matured between 80 and 90 cm L(T) with a L(T50) of 88 cm. Although the largest Z. chilensis captured by the artisanal fishery was 155 cm L(T) , 89% of landings comprised relatively small, immature fish. This situation may compromise the stock integrity if intrinsic vulnerability and probable long-life span of Z. chilensis are considered. Consequences for the survival of the species and possible signs of a fishery collapse must be reviewed by management authorities by consideration of both artisanal and industrial landings in Chile.

Egg capsules of the dusky catshark Bythaelurus canescens (Carcharhiniformes, Scyliorhinidae) from the south-eastern Pacific Ocean

The external morphology of the egg capsule of Bythaelurus canescens and its fixation to the substratum are described. Bythaelurus canescens egg capsules are typically vase-shaped, dorso-ventrally flattened, pale yellow in colour when fresh and covered by 12-15 longitudinal ridges. The anterior border of the capsule is straight, whereas the posterior border is semicircular. Two horns bearing long, coiled tendrils arise from the anterior and posterior ends of the capsule. The presence of longitudinal ridges and long coiled tendrils at both anterior and posterior ends of the capsule readily distinguish these egg capsules from those of other chondrichthyans occurring in the south-east Pacific Ocean.

First record of Hydrolagus melanophasma James, Ebert, Long & Didier, 2009 (Chondrichthyes, Chimaeriformes, Holocephali) from the southeastern Pacific Ocean

The eastern Pacific black ghost shark, Hydrolagus melanophasma is reported from deep waters off Chile and is described from specimens collected off Valdivia at depths of 1150 to 1720 m. This species is distinguished from all other members of the genus by its large, curved dorsal fin spine, which extends beyond the dorsal fin apex; a second dorsal fin of uniform height along the caudal peduncle; large pectoral fins extending beyond the pelvic fin insertion; and a uniform black color of the body. Catch records of this species in Chile suggest a discontinuous distribution along the continental slope of the eastern Pacific Ocean, restricted to the Middle America and Atacama trenches. These observations elevate the number of chimaeroid fishes inhabiting Chile to five species.

Clave taxonómica del Superorden Squalomorphi de Chile (Pisces: Elasmobranchii)

espanolSe presenta una clave taxonomica para reconocer las especies chilenas de los tiburones del Superorden Squalomorphi, agrupadas en 16 familias: Hexanchidae, Chlamydoselachidae, Rhincodontidae, Pseudocarchariidae, Lamnidae, Cetorhinidae, Alopiidae, Scyliorhinidae, Triakidae, Carcharhinidae, Sphyrnidae, Dalatiidae, Centrophoridae, Squalidae, Echinorhinidae y Squatinidae. Para cada una de las 56 especies consideradas se indica la distribucion geografica. EnglishA taxonomic key to identify the Chilean species of the shark Superorder Squalomorphi, grouped in 16 families is presented. The families are: Hexanchidae, Chlamydoselachidae, Rhincodontidae, Pseudocarchariidae, Lamnidae, Cetorhinidae, Alopiidae, Scyliorhinidae, Triakidae, Carcharhinidae, Sphyrnidae, Dalatiidae, Centrophoridae, Squalidae, Echinorhinidae and Squatinidae. For the 56 currently considered species, the geographic distribution is indicated.

The phylogenetic position of the roughskin skate Dipturus trachyderma (Krefft & Stehmann, 1975) (Rajiformes, Rajidae) inferred from the mitochondrial genome

Abstract The complete mitochondrial genome of the roughskin skate Dipturus trachyderma is described from 1 455 724 sequences obtained using Illumina NGS technology. Total length of the mitogenome was 16 909 base pairs, comprising 2 rRNAs, 13 protein-coding genes, 22 tRNAs and 2 non-coding regions. Phylogenetic analysis based on mtDNA revealed low genetic divergence among longnose skates, in particular, those dwelling the continental shelf and slope off the coasts of Chile and Argentina.

Southernmost record of Isurus paucus Gitart Manday, 1966 (Elasmobranchii: Lamnidae) in the southeast Pacific Ocean

Se informa sobre el registro mas austral del marrajo de aleta larga Isurus paucus Gitart Manday, 1966 en el Pacifico suroriental. El ejemplar correspondio a una hembra de 310 cm de longitud total, capturada por un pesquero artesanal frente a la costa de Valparaiso, Chile, por un pesquero artesanal cuya especie objetivo era el marrajo de aleta corta, I. oxyrinchus. Los principales caracteres taxonomicos utilizados en la identificacion del marrajo de aleta larga que permitieron distinguirlo de la otra especie del genero Isurus (marrajo de aleta corta), fueron la forma de la cabeza y hocico, la longitud de las aletas pectorales, la posicion relativa de la primera aleta dorsal con respecto al margen posterior de las aletas pectorales y la posicion relativa de la segunda aleta dorsal con respecto de la anal. Los antecedentes recopilados indican que la presencia de Isurus paucus no se restringiria a zonas de aguas calidas, sino que tambien se distribuye en aguas templadas-frias

Morphological characters of the thickbody skate Amblyraja frerichsi (Krefft 1968) (Rajiformes: Rajidae), with notes on its biology

Detailed descriptions of morphological features, morphometrics, neurocranium anatomy, clasper structure and egg case descriptions are provided for the thickbody skate Amblyraja frerichsi; a rare, deep-water species from Chile, Argentina and Falkland Islands. The species diagnosis is complemented from new observations and aspects such as colour, size and distribution are described. Geographic and bathymetric distributional ranges are discussed as relevant features of this taxońs biology. Additionally, the conservation status is assessed including bycatch records from Chilean fisheries.

Spatial overlap of shark nursery areas and the salmon farming industry influences the trophic ecology of Squalus acanthias on the southern coast of Chile

Abstract Potential interactions between marine predators and humans arise in the southern coast of Chile where predator feeding and reproduction sites overlap with fisheries and aquaculture. Here, we assess the potential effects of intensive salmon aquaculture on food habits, growth, and reproduction of a common predator, the spiny dogfish—identified as Squalus acanthias via genetic barcoding. A total of 102 (89 females and 13 males) individuals were collected during winter and summer of 2013–2014 from the Chiloé Sea where salmon aquaculture activities are concentrated. The low frequency of males in our study suggests spatial segregation of sex, while immature and mature females spatially overlapped in both seasons. Female spiny dogfish showed a functional specialist behavior as indicated by the small number of prey items and the relative high importance of the austral hake and salmon pellets in the diet. Immature sharks fed more on pellets and anchovies than the larger hake‐preferring mature females. Our results also indicate that spiny dogfish switch prey (anchovy to hake) to take advantage of seasonal changes in prey availability. Despite differences in the trophic patterns of S. acanthias due to the spatial association with intensive salmon farming, in this region, there appears to be no difference in fecundity or size at maturity compared to other populations. Although no demographic effects were detected, we suggest that a range of additional factors should be considered before concluding that intensive aquaculture does not have any impact on these marine predators.

Morfología del sistema mecanosensorial de la línea lateral de Zearaja chilensis (Batoidea: Rajidae)

The mechanosensory system of the lateral line in Zearaja chilensis , is composed by a series of sensory canals located at both the ventral and dorsal surface...