Janulum spinispiculum Carter 1876

Janulum spinispiculum (Carter, 1876)

(Fig. 2; Table 1)

Isodictya spinispiculum Carter 1876: 310, Pl. 15, Fig. 42.

Metschnikowia spinispiculum, Lundbeck 1902: 52, Pl. 12, Fig. 4; Topsent 1904: 243, Pl. 5, Fig. 1; Hentschel 1929: 901, 987.

Janulum spinispiculum, de Laubenfels 1935: 79; Boury-Esnault et al. 1994: 132, Fig. 102; Vacelet 1969: 210, Fig. 54; Calcinai et al. 2013: 6, Fig. 3.

Lithoplocamia spinispiculum, Hooper 2002: 506 (with question).

Material examined. ZMA Por. 19460, 19461: BIOSYS/HERMES 2005, boxcore 24, southeast Rockall Bank, 55.506° N, 15.786° W, 680 m, 27 Jun 2005, collected by 50 cm boxcore from RV Pelagia; ZMA Por. 19579, BIOSYS/HERMES 2005, boxcore 60, southeast Rockall Bank, 55.444° N, 16.076° W, 780 m, 30 Jun 2005, collected by 50 cm boxcore from RV Pelagia; ZMA Por. P. 8676, slide, Porcupine Seabight, southwest of Ireland, 852 m, coll. L.A. Hendry, Scottish Association for Marine Science, Jun 2003; ZMA Por. P. 8672, 8673, East of Iceland, from Copenhagen Museum’s Lundbeck collection; BELUM Mc7745, Mc7798, Mc7812, West Coast of Ireland, RV Celtic Explorer Cruise CE10004, 54.063° N, 12.413° W, 1469 m, 26 May 2010, collected by ROV Holland I; BELUM Mc7816, West Coast of Ireland, RV Celtic Explorer Cruise CE10004, 54.058° N, 12.547° W, 1350 m, 27 May 2010, collected by ROV Holland I. Other material. Janulum filholi (Topsent, 1890), MOM 0 4 0078: Holotype, Campagnes de l' Hirondelle Stn 105 (1892), 927 m.

Distribution. Northeast Atlantic region: southern Portugal, Azores, Rockall Bank; Mediterranean Sea: Alboran and Ionian Seas, Canyon de la Cassidaigne; North Atlantic: Iceland; Arctic Ocean: Barents Sea, northern Norway and Spitzbergen.

Description. Very thinly to relatively thickly encrusting, often very small, 1–2 cm 2, 1– 2 mm thick, with a smooth, porous, membranous surface (Fig. 2 A), or erect, almost cylindrical, irregularly lobate with an encrusting base (Fig. 2 B), about 25 mm thick, texture firm, friable. Colour in life white, pale cream, dull yellow. BELUM Mc7745 was a pale cream crust on coral, with a pattern of channels on the surface (Fig. 2 A).

Skeleton. Choanosome, a regular, areolate, multispicular isodictyal reticulation of spined strongyles with no fibre or tract development, spongin limited to the skeletal nodes (Fig. 2 D). Ectosome a tangential isodictyal reticulation of individual spicules.

Spicules. Strongyles, (Fig. 2 C, E; Table 1) with sparse, distinctive, prominent sharp concave spines concentrated in the middle of the spicule in short linear arrays, smooth at the extremities. Spicules may

Locality Strongyles (µm) Janulum spinispiculum (Carter, 1876)

Northeast Atlantic (Portugal)

Carter (1876) Type species North of Cape St Vincent, southern 208 x 8 Portugal, 136–680 m

Topsent (1904) Princess-Alice Bank, Azores, 200 m — (As Metschnikowia spinispiculum) (Campagne of 1897), Pico et São Jorge

Islands, 1250 m (Campagne of 1902)

Northeast Atlantic (Ireland)

Mediterranean Sea

North Atlantic (Iceland)

Lundbeck (1902) East of Iceland, 307 m and Denmark Strait, 208–238 x 10–12 (As Metschnikowia spinispiculum) 567 m

ZMA Por.P.8672 and 8673 slides East of Iceland, 307 m 235 (222–252) x 13 (12–14), n=10 from Lundbeck (1902)

Arctic Ocean

Janulum princeps sp. nov.

Note 1. Hentschel (1929: 901) Part I listed specimens of Metschnikowia spinispiculum from Spitzbergen but did not provide any spicule dimensions. In an overview (Part 2) of Arctic species he includes a fuller description of the species with spicule dimensions that appear to be taken directly from Lundbeck (1902).

have slightly swollen ends and may be straight or slightly bent at one or both ends, to the same or opposite sides. Immature spicules may be entirely smooth and may occasionally have mucronate ends. Spicule lengths and widths range from 159–267 x 8–17 µm in the Northeast Atlantic, 100–230 x 3–10 µm in the Mediterranean Sea, 208–252 x 10–14 µm to the east of Iceland, and 208–252 x 8–14 µm in the Arctic Ocean (Table 1).

Substrate, depth range and ecology. Found on stones (Carter 1876) and on the interstices of dead corals at 550 m depth at Gibraltar (Boury-Esnault et al. 1994). Collected from red and white corals on deep Mediterranean coral bank habitats at 623 and 539 m depth by Calcinai et al. (2013). Rockall Bank samples were all from cold water coral reefs, growing on dead branches of Lophelia and Madrepora, at depths of 680– 780 m. Porcupine Seabight material came from 852 m. West coast of Ireland samples collected from cold water coral reefs, overgrowing dead Lophelia, 1350 –1470 m.

Remarks. Janulum spinispiculum has a North Atlantic – Arctic Ocean distribution and varies considerably in depth from about 140 m off the coast of Portugal to about 1500 m on the Rockall Plateau region in the Northeast Atlantic. Spicule lengths and thickness vary accordingly (Table 1), with the shortest spicules being found in specimens in the Western Mediterranean, and the longest in specimens collected from the Rockall Bank area and east of Iceland region. The sponge also has a variable gross morphology that ranges from thinly encrusting patches to thickly encrusting with lobes.

Bukry (1978) figured a spined strongyle from a Neogene deep sea core (3–23 Ma) from the west of Iceland (Fig. 2 F) that is more heavily spined and longer and thicker (Bukry 1978, Pl. 7, Fig. 20: spined strongyle 288 x 20 µm) than any spicule recorded from J. spinispiculum from Iceland (Fig. 2 E) (Lundbeck 1902, Pl. 12, Fig. 4 a–b: 208–238 x 10–12 µm), and the largest spicule measured from J. spinispiculum is 267 µm (ZMA 19461) which is somewhat smaller than the microfossil spicule. The microfossil spicule is considerably longer than the average length of spicules for J. spinispiculum for the general region (about 200–240 µm), suggesting that Janulum was present in the North Atlantic sometime during the Neogene but likely to be a species distinct from J. spinispiculum.