A new species of carnivorous sponge (Porifera, Cladorhizidae) from Burdwood Bank, SW Atlantic Ocean

Carnivorous sponges have developed the ability to entangle, envelop, and digest small prey, mainly crustaceans. They represent an important exception to the filter-feeding behavior that characterizes the Phylum Porifera. These sponges are classified in the Family Cladorhizidae, currently with fifteen valid genera; among these, the genus Abyssocladia, with about 50 valid species worldwide, is characterized by pedunculate, disc-shaped, erect or plumose forms with abysochelae, cleistochelae, arcuate isochelae and/or sigmancistra as microescleres.

Sponge diversity at the Burdwood Bank (BB) is still poorly known, and carnivorous sponges remain understudied, with few records of this group in the area. This study describes a new species of Abyssocladia collected at the Marine Protected Area Namuncurá-Burdwood Bank at 54,83676667°S and 61,5137°W at a depth of 1000 m, during a research cruise in April 2016 aboard the RV ARA Puerto Deseado using a dredge. The new species is distinguished by its disciform shape, short filaments, irregular-smooth surface, and firm texture. The spicules are strongyloxeas, substyles, arcuate isochelae, abyssochelae, and sigmancistras. The morphological and spicular characteristics of the examined specimen do not match any previously described species in this genus, supporting its recognition as a new species (Abyssocladia chiesai sp. nov.), and contributing to the still-limited knowledge of Cladorhizidae diversity at Burdwood Bank and the broader SW Atlantic region. Also, this new species represents the first record of the genus Abyssocladia at the Burdwood Bank region.