Setosella, Hincks, 1877

Reverter-Gil, Oscar, Souto, Javier & Fernández-Pulpeiro, Eugenio, 2012, New and little known species of Bryozoa from Iberian Atlantic waters, Zoosystema 34 (1), pp. 157-170 : 164-169

Setosella sp.

( Fig. 4 ; Table 4)

Setosella vulnerata – Harmelin & d’Hondt 1992: 28 (part or whole).

MATERIAL EXAMINED. — MNHN 15487: BALGIM stn DW07, 36°46.1’N, 9°27.0’W, 1139-1144 m, 29/ V /84. One colony on grain of sand. — MNHN IB- 2009-1523: BALGIM stn DR71, 33°52.1’N, 8°07.4’W, 155 m, 06/ VII/84. One colony on grain of sand.

OTHER MATERIAL EXAMINED. — All material labelled as Setosella vulnerata (Busk, 1860) : MNHN 1981: Travailleur, D. 41, NE Atlantic, 1094 m. MNHN 1982: Travailleur, D. 2 (1 re sér.) NE Atlantic, 1068 m. MNHN 1983: Travailleur, D. 49, NE Atlantic, 3700 m. MNHN 2344 (part): Travailleur, D. 41, NE Atlantic, 1094 m. MNHN 6961 (part): Thalassa T 471, NE Atlantic, 562- 574 m. MNHN 962 (part): Thalassa T 471, NE Atlantic, 562- 574 m. MNHN 7002: Thalassa X343, NE Atlantic, 600- 655 m. MNHN 7023 (part): Thalassa X359, NE Atlantic, 605- 630 m. MNHN 7032 (part): Thalassa X374, NE Atlantic, 570- 582 m. MNHN 7098 (part): Thalassa W422, NE Atlantic, 700- 850 m. MNHN 7240 (part): Thalassa Y434, NE Atlantic, 620 m. MNHN 7302 (part): Thalassa 1968 , NE Atlantic, 695- 760 m. MNHN 7621 (part): Thalassa U852, NE Atlantic, 615- 645 m. MNHN 7634 (part): Thalassa W436, NE Atlantic, 499- 600 m. MNHN 8323 (part): Thalassa X362, NE Atlantic, 585- 600 m. MNHN 8324 (part): Thalassa X340, NE Atlantic, 860- 910 m. MNHN 8331: Thalassa X343,

FIG. 3. — A, B, Hincksina calpensis n. sp.: A, holotype ( MNHN IB-2009-1520 ) periancestrular area ; B, paratype ( MNHN IB-2009-1522 ) colony from Cassidaigne ; C -E, Hincksina sceletos ( Busk, 1858) ; C, holotype ( NHM 1899.7.1.1144), view of the colony ; D, same, detail of an autozooid with falciform spines; E, specimen NHM 1908.3.23.1, view of the colony. Scale bars: C, 300 µm; D, 100 µm; E, 500 µm. Photos C, D and E sent by B. Berning.

NE Atlantic, 600- 655 m. MNHN 8387 (part): Thalassa X352, NE Atlantic, 545- 580 m. MNHN 8363 (part): Thalassa X353, NE Atlantic, 635- 655 m. MNHN 8365: Thalassa X341, NE Atlantic, 800- 840 m. MNHN 8392 (part): Thalassa X348, NE Atlantic, 600-900 m MNHN 8395: Thalassa X342, NE Atlantic, 700 m. MNHN 8414 (part): Thalassa Y400, NE Atlantic, 800 m. MNHN 8415 (part): Thalassa Y405, NE Atlantic, 1170 m. MNHN 8454: Thalassa X345, NE Atlantic, 525- 550 m. MNHN 9334: Thalassa X345, NE Atlantic, 525- 550 m. MNCN 25.03/3126: Alborán Island, Mediterranean, 118 m. MNCN 25.03/3149: Columbretes Island, Levante, Mediterranean, 80 m. Dr Harmelin personal collection: Thalassa X313, NE Atlantic, 580- 525 m; SEAMOUNT 1, DW63, NE Atlantic, 630 m; SEAMOUNT 2, DW188, NE Atlantic, 310- 300 m; off Port-Cros Island & Gabinière Islet, Mediterranean, 300-350 m; off La Ciotat, L’Esquine Bank, Mediterranean, 100 m.

DISTRIBUTION. — Setosella sp. has been collected in two NE Atlantic locations, off Cape St. Vincent ( Portugal) and off Casablanca ( Morocco).

DESCRIPTION

Colony encrusting, unilaminar, forming circular sheets of autozooids and vibracularia. Autozooids irregularly oval to sub-rhomboid; proximal extreme sometimes obliquely truncate, especially in periancestrular zooids. Lateral walls raised forming a fine, even rim. Frontal surface almost occupied by a finely granular cryptocyst, depressed, its distal third gently raised forming the proximal border of the opesia, straight or slightly concave. Opesia D-shaped, slightly wider than long, nearly coextensive with the operculum; with a distinct lunula in its distal border. Two long, slit-like opesiules in the deeper area of the cryptocyst, near the lateral walls of the zooid; the inner edge with some fine denticles; generally asymmetric, frequently the left opesiula longer. Small interzooidal vibracularia, oval, placed distal or disto-lateral to each autozooid, with a wide oval opesia, slightly narrower in the middle. Chitinous seta slender and long, even twice as long as an autozooid. Ovicell subimmersed, oval, with an oval depressed area with a central, circular pore. Ovicellate zooids tending to be shorter and wider distally; orifice of ovicellate zooids irregularly bell-shaped. Ancestrula oval, half the size of an autozooid; cryptocyst smooth occupying more than a half of the frontal surface, extending laterally; opesia irregularly trifoliated. Astogenesis beginning with two disto-lateral autozooids, each one giving rise to a clockwise spiral series, surrounding the ancestrula. Size of the autozooids increasing gradually, apparently losing the spiral arrangement; occasionally an autozooid giving rise to a left zooid, this producing a new clockwise whorl.

REMARKS

Harmelin & d’Hondt (1992) reported Setosella vulnerata from 11 stations in the Gulf of Cádiz. This genus, according to Bock (2000), only includes other four recent species: the Caribbean Setosella antilleana Weisbord, 1967 and the European Setosella folini Jullien, 1882 , Setosella spiralis Silén, 1942 and Setosella cavernicola . Setosella vulnerata , the type species of the genus, is purposely widely distributed and well-known, being reported from Norway and Shetland to Madeira and the Mediterranean, from shallow-waters to 3700 m depth. However, its type material has not been redescribed yet; moreover, the study of several material labelled as S. vulnerata , coming from different Atlantic and Mediterranean localities, reveals certain morphological variability which may correspond to different species. For instance, several colonies collected in a seamount near Madeira (Lion Seamount, 35°15,4’N, 15°34,6’W, 630 m depth), previously identified as S. vulnerata , fit well the description of S. spiralis , a species that doesn’t seem to have been recorded since its original description. To sum up, it will be necessary to redescribe S. vulnerata using SEM, establishing its diagnostic characters, its geographic and/or ecological variations, and describing new species, if it is justified.

We have revised two of the colonies originally reported as S. vulnerata by Harmelin & d’Hondt (1992). This material shows several differences with S. vulnerata as defined, for instance, by Prenant & Bobin (1966), Zabala & Maluquer (1988) or Hayward & Ryland (1998), so we have named it as Setosella sp. This species has larger autozooids, but with a smaller opesia which also exhibits a distinct lunula; on the contrary, the vibracularia are smaller and the ovicells are shorter. The autozooids of S. vulnerata are shorter and wider while in Setosella sp. they tend to be more elongated, with oval or subrhomboid outline. The opesiules in Setosella sp. are asymmetric and are very elongated. Moreover, the ancestrula of this species has a trifoliated opesia, while in S. vulnerata it is semi-elliptic.

The zooids of S. spiralis resemble those in S. vulnerata , but show larger opesiules. However, the main difference with this species as well as with Setosella sp. is the astogenesis as their zooids form an only whorl around the ancestrula instead of two whorls.

The autozooids of Setosella sp. are similar to those in S. folini , recently re-described by Souto et al. (2011a) as being proximally asymmetrical, exhibiting opesiules frequently asymmetrical. However, it differs from these species by exhibiting encrusting laminar growth, while the colonies of S. folini are uniserial and free.

Finally, S. cavernicola differs from all the other species of the genus by basically exhibiting much smaller size, by the rounded opesiules, often more than two, and by the ovicell shape.

As we have just revised samples from two stations out of the 11 where Harmelin & d’Hondt (1992) reported S. vulnerata , we are not certain if all of them refer to Setosella sp. or if at least part of the material actually corresponds to S. vulnerata .

Setosella aff. cavernicola Harmelin, 1977 ( Fig. 5 ; Table 5)

? Setosella cavernicola Harmelin, 1977: 1064 , figs 16, 17. — Zabala 1986: 299, fig. 82. — Zabala & Maluquer 1988: 93, fig. 134.

MATERIAL EXAMINED. — Ría de Vigo: 42°14’20’’N, 8°47’47’’W, 16 m, 16/IX/86.One colony on Phymatolithon calcareum (Pallas) W. H. Adey & D. L. McKibbin.

DESCRIPTION

Colony encrusting, unilaminar, forming a small whitish crust. Autozooids piriform. Lateral walls sloping; basal surface much larger than the frontal membranous surface, bordered by a thin frontal rim. Almost the whole frontal surface covered by a depressed cryptocyst, finely granular, occupying ⅔of the area; distally raised forming the proximal border of the opesia, slightly concave. Opesia D-shaped. Two pairs of lateral opesiules, small and circular. One or two large uniporous septulae in each lateral wall. Interzooidal vibracularia, oval, inconstant, each one placed in the right distolateral extreme of an autozooid. Avicularia and spines absent. Ovicell hyperstomial, subimmersed, oval, about 0.10 mm diameter; with a small, circular depressed area with a central, circular pore. Ancestrula oval, smaller than an autozooid; cryptocyst occupying a half of the frontal area, extending laterally but not reaching the distal edge of the opesia.

REMARKS

Setosella cavernicola was originally described by Harmelin (1977) from a Mediterranean cave, near Cassis ( France) (see Fig. 6) and is also known from a cave of the Medes Islands (Catalonia, Spain), 14 m depth (Zabala 1986). This species seems to inhabit exclusively in the dark areas of submarine caves. Setosella cavernicola was also reported from the north of the Canary Islands (WWF 2006), but this report might be due to confusion, as the description of the Mediterranean material was published in an article on the Bryozoa from Banco de la Concepción (N Canaries).

The only colony we have observed was collected in the Ría de Vigo, 16 m depth on maerl. This colony shows minor differences with the description of S. cavernicola . While the size is similar, the autozooids from the material from Vigo tend to be piriform and not oval as in the material from France; thus, the ratio length/width is not the same. However, Zabala (1986) describes the autozooids of his material from Catalonia as piriform. The lateral walls of the autozooids from our material are much angled to the inner side, in such way that the basal surface of the zooid is much larger than the frontal surface. Finally, the cryptocyst spreads gradually on its edge to the frontal ring, while in the material from Tremies the limits between cryptocyst and frontal rim are very distinct.

To these morphologic differences we should also add the habitat, very different to the dark caves where the species had previously been collected, as well as the geographic distance. Therefore, it would not be impossible that these minor morphological differences were due to geographic and/or ecological variations. However, the scarce material studied does not let us know up to what point these differences match in the range of variation of the species or if they have any taxonomic significance. The current

FIG. 6. — Setosella aff. cavernicola Harmelin, 1977 (cave of Trémies): A, view of a colony; B, autozooid and vibracularia (scale aprox.). Photos sent by J.-G. Harmelin. Scale bars: A, 500 µm; B, 100 µm.

observation would, therefore, be the first Atlantic of S. cavernicola , furthermore coming from a very different environment from the originally described for the species.

Figures

FIG. 4. — Setosella sp. (MNHN 15487): A, view of the periancestrular area; B, detail of the ancestrula; C, autozooids; D, ovicellate zooids. Scale bars: A, D, 500 µm; B, 200 µm.

FIG. 5. — Setosella aff. cavernicola Harmelin, 1977 (Ría de Vigo), view of the colony;left down,ovicellate zooid of Setosella vulnerata (Bust, 1860).