Vulcanella aberrans Maldonado & Uriz 1996

Vulcanella cf. aberrans (Maldonado & Uriz, 1996)

(Figures 14–16)

Synonymy.

Vulcanella (Vulcanella) aberrans: Cárdenas et al. 2011, Table S1.

Material. ZMBN 80959, Traenadjupet, northern Norway, 66º58.22'N, 11º7.26'E, 320 m, bottom: mud with rare pebbles, boxcore.

Comparative material examined.

Vulcanella aberrans, CEAB-POR. BIO 021B, paratype, slope of Alboran Island, 35º54'- 35º52'N, 3º09'- 3º05'W, 70-120 m; ZMAPOR 21193, Gulf of Cadiz, 35º39.274'N, 07º20.013'E, 1390 m, tiny fragment; ZMAPOR 21170, Gulf of Cadiz, 35º39.274'N, 07º20.013'E, 1390 m; ZMAPOR 18012, Morocco, near Tanger, 35°17'39.66"N, 6°47'16.18"W, 531 m.

Vulcanella gracilis, ZMAPOR 18025, off Morocco, 529 m.

Outer morphology (Fig. 14 A). Massive sponge. Our specimen is broken up in several fragments. The largest, ficiform, attached to a small stone is 5 cm high and 4.5 cm wide. Color alive and in ethanol, of surface and choanosome, is whitish. Specimen is compressible. Surface is irregular, strongly hispid and dirty (due to trapped sediments). One damaged oscular basket was observed on top of the largest fragment (Fig. 14 E). Oscule openings in the sieve are fairly large (exhalant apertures are 0.5-2 mm). Pores were not found.

Skeleton (Fig. 14 B-D). Accumulation of spirasters and paratangential microxeas at the surface. This layer is ca 150 µm thick, thus invisible to the naked eye. Orthotriaenes and dichotriaenes are only present at the surface, albeit in low numbers. They are more or less positioned radially, with their cladomes beyond the surface (Fig. 14 D). Oxeas I and some oxeas II also cross the surface. Oxeas I are found all over the surface of the sponge but they are longer and wider around the oscula. The arrangement of the spicules in the choanosome is confused. Spirasters are more rare as one leaves the surface, they are nonetheless present around canals. Plesiasters on the other hand, are abundant in the choanosome, as well as microxeas. The oscular basket is surrounded by atrial oxeas I (Fig. 14 F). The oscular mesh is mainly a dense accumulation of paratangential microxeas I and streptasters. Under it, we still find microxeas, but in lower numbers. Foreign spicules in the choanosome are common (e.g. Sceptrella and Hamacantha).

Spicules (ZMBN 80959) (Fig. 15). (a) oxeas I, long and thin, isodiametric, length: up to 5000 µm; width: 3.0- 6.3 -14.5 µm. (b) oxeas II, stout, usually bent, smooth, length: 1921- 2789 -3473 µm; width: 21.0- 43.6 -70.0 µm. (c) ortho- and dichotriaenes, few, usually with deformities such as irregular or additional clads, rhabdome length: 152- 892 -1315 µm; rhabdome width: 23.0- 37.6 -62.0 µm; clad length for orthotriaenes: 183.0- 392.9 -566.0 µm (N=15); clad length for dichotriaenes: 70.0- 99.0 -129.0 µm + 72.0- 135.0 -194.0 µm (N=12). (d) microxea I, faintly microspiny, bent or straight, often centrotylote, length: 317- 397.8 -520 µm; width: 5.0- 6.0 -8.0 µm. (e) microxea II, faintly microspiny, bent or straight, length: 181- 239.2 -245 µm; width: 3.0- 3.2 -4.0 µm. (f) microxea III, faintly microspiny, straight or bent, length: 67.0- 116.2 -166.0 µm; width: 2.0- 2.0 -2.0 µm. (g) streptasters, all intermediates exist between spirasters, metasters, and plesiasters. Metasters and plesiasters often have a bow shaped shaft with the middle actines all on the same side, length: 14.0- 25.0 -39.0 µm.

Distribution. Northern Norway.

Depth. 320 m.

Discussion. If this specimen is conspecific with V. aberrans, this is only the second record of this species since its description, and its first record from the Norwegian coast. This specimen has been identified as V. cf. aberrans because it shows a few morphological and molecular differences with V. aberrans. Apart from (i) its shape (not plate-like) (Fig. 14 A), (ii) the wider oscules in the atrial sieve (Fig. 14 E), (iii) the additional category of microxea and (iv) the absence of thick-axis spiraters, the Norwegian specimen is very similar to the type material from the Alboran Island. All specimens from the Alboran Sea are plate-like (including the type and paratypes), but specimens from the Gulf of Cadiz growing on coral are more irregular in shape so the shape of our specimen could be related to the fact that it grows on yet another substrate (e.i. pebbles). The coarser atrial fenestration was also observed in ZMAPOR 18025 from the Gulf of Cadiz (Fig. 14 G), so atrial fenestration should not be considered a specific character of this species. Consequently, V. aberrans is even more similar to the poorly known Vulcanella cribrifera Sollas, 1886 from Cape Verde, which is notably characterized by coarse atrial fenestration. The only differences remaining between V. aberrans and V. cribrifera are (i) rare triaene malformations, (ii) atrial strongyles and (iii) only one size category of microxeas in V. cribrifera. Conspecificity of V. aberrans with V. cribrifera is not impossible but more specimens of the latter are needed to settle the issue. Microxeas II and III of our specimens have very close size ranges and they might represent a single category but more specimens are needed to confirm if they are true size categories. Maldonado & Uriz (1996) observe unusually thick-axis spirasters in the atrial ectosome. Although these were observed in ZMAPOR 18012 (Morocco), these were not found in the Norwegian specimen. Altogether, this makes very few morphological characters to consider our specimen not conspecific with V. aberrans and we need more material from Norway to show that these differences are consistent.

COI sequences of ZMAPOR 21193 (Gulf of Cadiz) and ZMBN 80959 (Norway) are identical. Conversely, alignment of the 28S (C1-D2) sequences of the Norwegian and the Moroccan specimens showed an 8 bp. difference, most of which is due to a 6 bp. single deletion in ZMBN 80959. This is a relatively important mutation event which raises once more the question whether the few distinctive morphological differences observed are characteristic of a new species. In our opinion, additional sequences are required to conclude.