Cladorhiza kenchingtonae, Hestetun & Tompkins-Macdonald & Rapp, 2017

Hestetun, Jon Thomassen, Tompkins-Macdonald, Gabrielle & Rapp, Hans Tore, 2017, A review of carnivorous sponges (Porifera: Cladorhizidae) from the Boreal North Atlantic and Arctic, Zoological Journal of the Linnean Society 181, pp. 1-69 : 30-31

CLADORHIZA KENCHINGTONAE SP. NOV.

( FIGS 24, 25)

urn:lsid:zoobank.org:act:E9AB8B52-AAD8-4478-BC49-685D74132D2B

Type material: Holotype: CMNI 2016-0014 , CCGS ‘Hudson’ cruise HUD2010-029 (13 July 2010, The Flemish Cap, ROPOS dive 1336-16, 46°19.03ʹN, 044°33.46ʹW, 2935 m). The holotype was recovered using the ROPOS ROV system.

Diagnosis: Erect, fine, arching Cladorhiza with long, thin branches carrying filamentous projections on one side of main axis only. Megascleres mycalostyles, styles and acanthoxeas. Microscleres five-toothed anchorate anisochelae.

Description: Large and very fine, c. 2-m-long erect, arching sponge consisting of c. 1-m-long and 5-mm-wide stem branching off into three around 1-m-long and <5-mm-wide fine branches ( Fig. 24A, B). Each branch supported by a main axis with filaments up to several centimetre long set into two rows angled c. 90° to each other and facing downwards at oblique angles ( Fig. 24C). A couple of planktonic crustaceans were observed stuck to filaments. Recovered part consists of a branch fragment 16.5 cm long and 1.2–3.5 mm wide. Tissue is markedly concentrated on one side of axis only, between filaments and filament rows. Filaments are reduced or retracted into two series of distally oriented short projections ( Fig. 24D, E). Filaments become more reduced towards the distal end of the collected fragment and become slightly offset with clockwise torsion. Colour white freshly collected and off-white in ethanol.

Skeleton : The main axis consists of closely packed mycalostyles. The skeleton of the filaments are inserted into the main stem in an alternating pattern forming two oblique rows. The main part of the tissue, containing scattered mycalostyles and closely spaced microscleres, is found on the underside of the main stem and at the base of filaments. A thin surface layer, which appears to be continuous with the main tissue, also envelopes the entire branch, including the main stem, and is densely packed with chelae with their free ends pointing outwards. Small prey items were observed adhered to or partly embedded in the outer layer. The acanthoxeas are interspersed with chelae in the main and outer layer of tissue and are especially numerous at the base of the filaments ( Fig. 25A–C).