Cladorhiza SARS 1872

CLADORHIZA SARS, 1872

Type species: Cladorhiza abyssicola Sars, 1872 (by monotypy).

Diagnosis, from Hajdu & Vacelet (2002): Cladorhizidae with anchorate/unguiferate anisochelae.

CLADORHIZA SEGONZACI SP. NOV.

(FIGS 2, 17F)

Type material

Holotype: NAUDUR ND 5 (7-1B), 10/12/1993, 17°23.11′S, 113°11.60′W, 2581 m. Muséum National d’Histoire Naturelle, Paris, no. MNHN D JV 79. Paratypes: NAUDUR ND 5 (7-1B), 10/12/1993, 17°23.11′S, 113°11.60′W, 2581 m. Muséum National d’Histoire Naturelle, Paris, no. MNHN D JV 80.

Etymology

Dedicated to Michel Segonzac who organized the sorting and distribution of the biological specimens from the Ifremer cruises.

Locality and habitat

East Pacific Rise, north of Easter Island, 10/12/1993, 17°23.11′S, 113°11.60′W, 2581 m on a dead smoker. The sample was collected from the top of the highest chimney (up to 6 m high) of an inactive site, a few metres from some active black smokers with a relatively dense population of the sea anemone Chondrophellia sp. The sponges were attached to the vertical face of the chimney comprising sulfide deposits. The sample fragment also bore the sponge Abyssocladia naudur sp. nov., some hydroids and about 20 specimens of small white sea anemones.

Description

Eleven specimens or fragments of a small erect sponge, attached to the solid substratum by an enlarged base 2–3 mm in diameter, and forming an unbranched slender spicular axis with numerous lateral processes, arranged at right angles around the entire main axis, more rarely arranged irregularly in two lateral rows. Holotype (Fig. 2A) 32 mm high with a 10-mm-long basal part of the axis devoid of lateral processes. Axis 0.4–0.5 mm in diameter, lateral processes conical, up to 0.9 mm long for 0.3–0.4 mm in diameter at the base. Paratypes (Fig. 2A) smaller, the largest 24 mm high with the same diameter as the holotype, with similar lateral processes up to 4.2 mm maximum length. On specimens observed in situ, axis with an abrupt end and long lateral processes more numerous than on preserved samples. No visible aquiferous system. Colour white in life, cream to clear brown in alcohol, most often darker in the basal portion of the stem, base blackish.

Skeleton: Axis of fusiform styles longitudinally arranged, the thinner styles generally at the centre of the axis, from which arises the skeletal axis of the lateral processes. Axis of the processes conical at the base, with the styles anchored by their head reaching the centre of the stem and the point outwardly directed. Living tissue poorly preserved, forming a thin layer around the axis of the lateral processes and at their base, containing a huge number of anisochelae dispersed without order in the present state of preservation of the specimens.

Spicules:

1. Styles (Fig. 2B) of the axis of the stem and of the lateral processes, straight or rarely feebly curved, slightly fusiform, with a short, acerate tip. Size 380– 990 × 14–23 µm, with a variable length/thickness ratio, some short and thick (for instance 380 × 22 µm) and others long and slender (930 × 15 µm). Some spicules, mostly localized in the centre of the skeletal axis, of same length but only 3–10 µm thick.

2. Anchorate/unguiferate anisochelae (Fig. 2D, E), extremely numerous, with a curved shaft, five lanceolate alae and well-developed fimbriae at the large end, three fang-like, sharply curved alae at the small end. Size 15–17.5 µm. Developmental stages (Fig. 2C) with two equal ends and alae appearing as small nodules.

3. Sigmas (Fig. 2F), moderately abundant, C or S shaped, very thin. Size 50–80 × 1–1.5 µm, the largest rare in the holotype.

4. Sigmancistras (Fig. 2G, H), uncommon, not observed in one specimen, contorted, with acerate tips, without notch. Size 20–25 µm × 2.0 µm.

Remarks

Underwater pictures taken from the submersible after collection of the tip of the chimney on which sponges were attached (Fig. 17F) probably represent this species, although it could be confused with Abyssocladia naudur sp. nov. described below, which was attached to the same rock sample. The two sponges are very similar in gross morphology (see Fig. 15A), and they were confused during the primary sorting operation and in the first spicule preparations. However, C. segonzaci is more irregular, with shorter and thicker filaments arranged in two opposite series, nonalternating along the axis, and has no lateral buds.

The sponge is very fragile, and many lateral filaments were broken upon examination in the laboratory. The filaments were most certainly longer in living specimens (Fig. 17F).

The species differs from most other representatives of Cladorhiza in the small size of the anisochelae. The only other species with anisochelae smaller than 20 µm, C. microchela Lévi, 1964, from the South China Sea (4330 m), has anisochelae not exceeding 13 µm and differs from the new species in the larger size of the styles, and the absence of sigmas and sigmancistras. The peculiar shape of the small end of the anisochelae, with three fang-like alae, is rather unusual, although it resembles that of the anisochelae of C. pentacrinus Dendy, 1887 (Dendy, 1887) from New Zealand. This species, however, differs in external shape, larger size of all spicule categories and absence of sigmancistra.