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

Abstract

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.

Morphological Characters of the Thickbody Skate Amblyraja frerichsi (Krefft 1968) (Rajiformes: Rajidae), with Notes on Its Biology

“…Chilean egg-bearing females were caught in deeper zones as well as deep-water corals (genus Antipathes and Bathypathes ), showing a positive correlation in the bycatch. Similarly, in the area is thought that the dusky catshark Bythaelurus canescens (Günther 1878) use deep-water coral branches as a substrate for egg-laying [45]. But as other Amblyraja species, A .…”

“…frerichsi may deposits its egg capsules on the sea bed and potentially use the coral gardens as oviposition shelter zones. Tendrils and curved horns are usually associated with oviposition into complex three-dimensional substrates, whereas egg cases without tendrils are generally deposited on bare substrate [45], [46]. The reason for female's apparent preference for deeper water is uncertain, but mature female could have a male-avoidance strategy [47] going deeper to lay her eggs, with young skates migrating to relatively shallow waters to reduce intraspecific competition [48].…”

Egg capsules of the yellownose skate Zearaja chilensis (Guichenot 1848) and the roughskin skate Dipturus trachyderma (Krefft and Stehmann 1974) (Rajiformes: Rajidae) from the south-eastern Pacific Ocean

“…The egg capsule is the tertiary egg envelope in oviparous cartilaginous fishes that protects the embryo throughout its development on the sea floor (Hamlett and Koob 1999) or any other type of substrate (Oddone and Vooren 2002;Treloar et al 2006;Concha et al 2009Concha et al , 2010. Comprehensive descriptions of capsules have been considered as a useful tool for systematics, reproductive behaviour and phylogenetic relationships (Clark 1922;Ishiyama 1958;Concha et al 2009;Ishihara et al 2012).…”

Trophic ecology of the dusky catshark Bythaelurus canescens (Günther, 1878) (Chondrychthyes: Scyliorhinidae) in the southeast Pacific Ocean

“…Inhabiting the upper continental slope, its geographic range stretches from southern Per u to the southernmost coast of Chile (Compagno et al, 2005), reaching a maximum length of 70 cm and inhabiting depths between 250-700 metres (Compagno, 1984). Despite this, the biology of deep-sea sharks off Chile is poorly known, although recent efforts have been made to study their trophic relationships and reproductive biology (Acuña and Villarroel, 2010;Concha et al, 2010;Hallet and Daley, 2011;Pethybridge et al, 2011). Despite this, the biology of deep-sea sharks off Chile is poorly known, although recent efforts have been made to study their trophic relationships and reproductive biology (Acuña and Villarroel, 2010;Concha et al, 2010;Hallet and Daley, 2011;Pethybridge et al, 2011).…”