Reproduction and description of a new genus and species of deep-sea asteriid sea star (Echinodermata; Asteroidea) from the southwestern Atlantic

Abstract

Bernasconiaster pipi gen. et sp. nov. is described from work carried out in deep waters off Argentina. It is a small species with six arms, which has only cross-type pedicellariae, among other particular characteristics. Some specimens were found brooding their offspring in the oral area with their arms arched. Up to seven different stages of development were observed, each located at a particular location within the egg masses, and supported by an individual cord. These are connected to a central and more robust primary cord by an oral extension. Eggs were found in the gonads, the initial stages of development were located along the arms to the oral area and some stages were protruding from the mouth, into the everted stomach. A hermaphrodite specimen was found with both types of gonads (male and female). The information obtained suggests a reproductive period of at least five months, continued reproduction should not be ruled out. This species supports the hypothesis that brooding condition predominates in the deep-sea. The present study represents the first record of this type of reproduction in the deep waters of the Southwest Atlantic.