A new carnivorous sponge, Chondrocladia robertballardi sp nov (Porifera: Cladorhizidae) from two north-east Atlantic seamounts

Carnivorous sponges (Porifera: Cladorhizidae) are a particularly interesting group of species typically occurring in deep-sea habitats. In this study a new species, Chondrocladia (Chondrocladia) robertballardi sp. nov., is described from specimens collected on two large north-east Atlantic seamounts - the Gorringe and Galicia Banks - located off the Iberian Peninsula. The holotype, collected on the Gorringe Bank by ROV, is a large, dichotomously branched and stalked sponge with translucent spheres in the middle of secondary axes and a rhizoid basal fixation system. Direct observations on the habit of the new species were made from the ROV. The paratypes, collected on the Galicia Bank by dredge and trawling, are fragments of different sizes. The skeleton is composed of a single class of styles and isochelae. All specimens were collected at similar depths (1400-1738 m) within the upper bathyal, and at the same longitude but separated by 670 km. A synthesis of the geographic as well as bathymetric distribution of this genus is presented. The species is compared with all known species of this genus worldwide.