Cladorhiza tenuisigma, LUNDBECK, 1905

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 : 34-36

CLADORHIZA TENUISIGMA LUNDBECK, 1905

( FIG. 28)

O r i g i n a l d e s c r i p t i o n: C l a d o r h i z a t e n u i s i g m a Lundbeck, 1905: 87.

Synonyms and citations: Cladorhiza abyssicola in part ( Hansen, 1885: 16); C. tenuisigma ( Topsent, 1909: 7, 1913: 49; Hentschel, 1929: 935; Burton, 1930: 492; Koltun, 1959: 82, 1964: 163); C. cf. tenuisigma ( Janussen, 2009: 50) .

Type material examined: Lectotype: ZMUC-DEM-161, the Danish Ingolf Expedition, st. 117 (24 July 1896, 69°13ʹN, 008°23ʹW, 1890 m), st. 105 (11 July 1896, 65°34ʹN, 007°31ʹW, 1435 m).

O t h e r m a t e r i a l e x a m i n e d: T h e D a n i s h I n g o l f Expedition, R/V ‘Johan Ruud’, R/V ‘Polarstern’ Ark

X-31-9, AB321/05, GeoBio 2009, IceAGE 2 (see Supporting information).

C o m p a r a t i v e m a t e r i a l e x a m i n e d: C l a d o r h i z a methanophila Vacelet & Boury-Esnault, 2002 , ‘Atlantis’ AT 21-02, J633-5.

D i a g n o s i s: E r e c t C l a d o r h i z a w i t h a r b u s c u l a r morphology consisting of branching stem with side branches. Stem and branches covered in a layer of softer tissue with filaments projecting in all directions. Branches typically end in a clearly visible swelling. Lower stem connected to the substrate with a root-like structure. Megascleres mycalostyles; microscleres one type of chela c. 16–32 µm, sigmas c. 31–54 µm and sigmancistras c. 42–58 µm.

Description: Specimens erect, up to 15 cm in length, with branching main stem, typically 2–5 mm in diameter. Numerous side branches with the same thickness as the main stem, and both stem and branches enclosed in soft tissue covered with thin, in ethanol whitish grey to light beige, with specimens kept in ethanol for a long time darker in colour, approaching reddish brown.

Skeleton : Skeleton of main stem and branches composed of spicule bundles forming a solid core surrounded by looser tissue at the surface. Filament skeleton originates in the centre of the main stem skeleton and is made up of overlapping mycalostyles, with a slight, softer outer layer ( Fig. 28D, E).

1- to 5-mm-long filaments in all directions ( Fig. 28A, B). Branches usually end in a clearly visible swelling ( Fig. 28C). Lower stem is bare and connects to the substrate with a number of rhizoid processes. Colour