Setosella cyclopensis, Rosso & Martino & Gerovasileiou, 2020

Rosso, A., Martino, E. Di & Gerovasileiou, V., 2020, Revision of the genus Setosella (Bryozoa: Cheilostomata) with description of new species from deep-waters and submarine caves of the Mediterranean Sea, Zootaxa 4728 (4), pp. 401-442 : 409-412

publication ID	https://doi.org/ 10.11646/zootaxa.4728.4.1
publication LSID	lsid:zoobank.org:pub:3E4C6C25-3630-4842-A776-F87CF2E693FD
persistent identifier	https://treatment.plazi.org/id/0C3887F8-FF9F-FFEE-FF72-FF61EDFA7F9D
treatment provided by	Plazi
scientific name	Setosella cyclopensis
status	sp. nov.

Treatment

Setosella cyclopensis n. sp.

( Figs 3–7 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 ; Tables 1–3 View TABLE 1 View TABLE 2 View TABLE 3 )

Setosella vulnerata: Di Geronimo et al., 1990 View in CoL : table 1; Rosso, 2008a: figs 2B–F, 3I–J, O; Rosso, 2008b: fig. 1; Rosso et al., 2014: table 2, fig. 7A–E.

Type material. Holotype PMC. B24. 8.3.2018 a, Ciclopi 12E, 62 m: colony on the internal surface of a bivalve shell . Paratypes PMC. B24. 8.3.2018 b: Ciclopi 2000 2D, 47.5 m, one live and 51 dead colonies ; Ciclopi 2000 8H, 92.5 m, one living colony on a mollusc fragment ; Ciclopi 2000 8I, 95 m, one dead colony on a cyclostome fragment ; Ciclopi 2000 10G, 85 m, one dead colony ; Ciclopi 2000 12D, 53.5 m, two living and 46 dead colonies ; Ciclopi 2000 12E, 62 m, one dead colony. Ciclopi Island Archipelago , W Ionian Sea

Additional material. PMC. R.I.H. B1a, additional colonies from the cruises Ciclopi 2000 in the Ciclopi Islands Archipelago, and the PS/81 and Noto 1996 in the Gulf of Noto, W Ionian Sea. Live and dead colonies were found in the following samples: Ciclopi 2000: 2D, 2E, 3G, 3F, 3I, 8H, 8I, 10G, 12D, 12E, 12F, 12G and 18G, depth range 47.5–103 m; PS/81: 2B, 2C, 2XA, 2XB, 3XA, 4C, 4C1, 4X, 5X, 6D, 9B, 9C, 9D, 10C, 11E; CR1, Noto 1996: 7P, 9G, 9I and WP 123, depth range 44–162 m. Most of this material was first deposited as Setosella vulnerata (Busk) . PMC. R.I.H. B1b: sample 69. LCT.80, 90 m, Gulf of Catania , W Ionian Sea: dead colonies; PMC . R.I.H. B1c: samples “Minerva” 1D, 5D, depth range 30–40 m, Amendolara Bank, Gulf of Taranto , N Ionian Sea; PMC . R.I.H. B1d: Banco Apollo: one live and two dead colonies; PMC. R.I.H. B1e: sample CL74, 110– 150 m, off Calvì , Corse, NE Ibero-Provençal Basin: one living colony . PMC. R.I.M. B1f: sample 1 Benestare (Calabria), late Tortonian-early Messinian (one colony) PMC . R. I.Pl. B 1g: Diolo, Emilia, north Italy, Pliocene (five colonies from two samples) .

Etymology. Referring to the type locality, the Ciclopi Island Archipelago, off north of Catania, Ionian coast of Sicily.

Diagnosis. Colony typically encrusting sandy clasts with periancestrular zooids arranged in a double spiral and with the insertion of series of zooids in a clockwise budding pattern in the zone of astogenetic repetition. Autozooids rhomboidal; frontal area pear-shaped. Cryptocyst coarsely granular. Opesia transversely D-shaped with stout tubercles hanging distally. Opesiules paired, sharply denticulate on the inner side, beaded on the outer side. Vibracula disto-laterally to each autozooid, with arched rostrum, eight-shaped opesia and asymmetrical condyles. Kenozooidal ooecium of the terminal immersed ovicell crescent-shaped; ectooecium with a subcircular window exposing the endooecium. In older zooids ecto- and endooecium fuse showing pustulose cryptocystal shelf around the window and a small central pore, leading to the basal pore chamber of the kenozooidal ooecium. Ancestrula oval with smooth cryptocyst and trifoliate opesia, budding two vibracula distally and distolaterally, the distal vibraculum caudate. Kenozooids present, variable in size and shape with extensive, granular cryptocyst and a central opening. Intramural buds common.

Description. Colony encrusting, unilaminar, varying in size from small and spot-like (up to a dozen of zooids) to large and patch-like (up to one hundred zooids), typically found on sand or very fine gravel-sized clasts, usually covering a single side but often completely enveloping the substratum ( Figs 4 View FIGURE 4 , 6a View FIGURE 6 , 7 View FIGURE 7 ). Autozooids arranged in a double spiral in the periancestrular area ( Fig. 3a View FIGURE 3 ), and quincuncially in the area of astogenetic repetition of large colonies ( Fig. 4 View FIGURE 4 a–d), as the result of repeated insertions of arched series of zooids with a clockwise budding pattern, with new zooidal rows starting from a vibraculum. Autozooids irregularly rhomboidal, rounded (mean L/ W 1.46) ( Figs 3c View FIGURE 3 , 5d View FIGURE 5 ). Gymnocyst only partly exposed in frontal view and forming lateral and proximal walls steeply sloping towards the base. Frontal area often accounting for most of the zooidal length and width, ovoidal to pearshaped, outlined by a raised, thin rim. Cryptocyst coarsely granular, occupying at least three-fourth of the frontal area, depressed and relatively flat, gradually raising at the edges, especially distally, to form the straight to slightly concave proximal border of the opesia. Opesia transversely D-shaped, slightly wider than long, with rounded proximal corners and a distal shelf of stout tubercles, variable in length, leaning the operculum in shut position ( Fig. 5c View FIGURE 5 ). Spines absent. A pair of asymmetrical, elongate opesiules, the left one the wider, placed laterally at 35–60 µm from the proximal border of the opesia; the inner side with several (commonly five) sharp denticles, the outer side beaded owing to cryptocystal granulation. Elliptical, uniporous septula, c. 30 µm long by 10 µm wide, at about mid-length on each lateral wall and distally, slightly inclined towards the right, the distal septulum budding the vibraculum. Interzooidal vibracula globular, placed disto-laterally to each autozooid, occasionally distally ( Figs 3 View FIGURE 3 c–e, 5a, b, f, 6g); two circular uniporous septula, about 12 µm in diameter, on each proximal corner; opesia eight-shaped, constricted at mid-length by two blunt, asymmetrical, proximally directed condyles ( Fig. 5e View FIGURE 5 ). Rostrum arched and slightly flared, with a very narrow distal palate ( Figs 3c, d View FIGURE 3 , 5e View FIGURE 5 ); vibracular seta about twice as long as an autozooid. Terminal, immersed ovicell produced by the maternal autozooid, kenozooidal ooecium crescent-shaped; ectooecium smooth, in older zooids with pustulose cryptocystal shelf around the window fusing with endooecium; endooecium exposed through a large subcircular window, c. 65–75 µm in diameter, with a small, circular to transversely elliptical pore, c. 25–35 µm wide ( Figs 3d, e View FIGURE 3 , 5f View FIGURE 5 ). Ancestrula oval, smaller than autozooids; cryptocyst smooth, with faint growth lines, occupying the proximal half of the frontal area and tapering distally, forming two coarsely granular prominences laterally at about mid-length, and leaving a wide, gently trifoliate opesia ( Figs 3b View FIGURE 3 , 4b View FIGURE 4 ). Two vibracula budded from the ancestrula and oriented perpendicularly to each other: a caudate, small vibraculum budded distally; a larger vibraculum budded distolaterally on the left side ( Fig. 3a, b View FIGURE 3 ). Kenozooids occur on particularly uneven surfaces, in damaged areas of the colony ( Fig. 6 View FIGURE 6 a–d), and at the colony periphery, mostly at the encounter edges between different colonies or different abutting lobes of the same colony ( Figs 6f View FIGURE 6 , 7b, c View FIGURE 7 ); often small ( Fig. 6h View FIGURE 6 ), sometimes the same size as an autozooid ( Fig. 6e View FIGURE 6 ), round, oval or irregularly-shaped; cryptocyst extensive outlined by a raised smooth rim, slightly depressed and coarsely granular as in autozooids, with a small (compared to the size of the kenozooid) central opening variable in shape, from rounded to elliptical and triangular, with the granules of the cryptocyst projecting inwards giving a denticulate appearance. Intramural, reparative buds common in both autozooids and vibracula ( Figs 4f View FIGURE 4 , 5 View FIGURE 5 , 6b, c, h, i View FIGURE 6 ).

Remarks. Setosella cyclopensis n. sp. closely resembles S. vulnerata in colony morphology, zooidal arrangement and dimension. However, colonies of S. cyclopensis n. sp. are usually larger than those of S. vulnerata ; autozooidal opesiules are larger than in S. vulnerata , with more prominent spiny processes on their internal margins; ooecial windows are wider than in S. vulnerata ; cryptocyst is homogeneously finely granular, whereas it is coarser or tessellated in S. vulnerata ; the ancestrular opesia is widely semielliptical and with prominent lateral indentations in S. cyclopensis n. sp., whereas it is initially ovoidal, with a widely concave proximal margin, and becomes trifoliate with marked lateral indentations in S. vulnerata ; the caudae of the ancestrular vibracula are markedly shorter in S. cyclopensis n. sp. compared to S. vulnerata . Interzooidal kenozooids of different shapes and sizes often occur in S. cyclopensis n. sp. ( Fig. 6 View FIGURE 6 ) but have never been observed in S. vulnerata . The presence of kenozooids is a remarkable feature of S. cyclopensis n. sp., and required the emendation of the diagnosis of the genus. Breakage and reparative regenerations as well as subsequent intramural buds (up to three) are common in autozooids, vibracula and ovicells of this species.

Distribution. Setosella cyclopensis n. sp. is known from several sectors of the present-day Mediterranean. It was originally reported as S. vulnerata from the type locality, the Ciclopi Island Archipelago ( Rosso 2001; 2008a; Rosso et al. 2014), and other areas of the Ionian Sea (Poluzzi & Rosso 1989; Rosso 1989, 1996 a, 1996b; Di Geronimo et al. 1998), the Banco Apollo, near Ustica Island in the S Tyrrhenian Sea ( Di Geronimo et al. 1990), and off NW Corsica in the north-eastern Ibero-Provençal Basin ( Rosso 1989). Rare living and abundant dead colonies were collected in mid- to open-shelf areas at a depth range of 30– 162 m. The identity of S. vulnerata colonies reported from Mediterranean localities (e.g. Gautier 1962; Harmelin 1976; Zabala & Maluquer 1988) and the Aegean Sea ( Hayward 1974) needs to be confirmed. The record of S. vulnerata by d’Hondt (1981) from the Sirte Gulf possibly relates to a different species (see Remarks to S. alfioi n. sp.).

The fossil record of Setosella cyclopensis n. sp. ranges back to the late Tortonian-early Messinian of southern Italy (Di Geronimo et al. 2002). It also occurred in the Pliocene sediments of some localities in northern Italy, but there are no reports from Pleistocene deposits.

Ecology. Setosella cyclopensis n. sp. seems particularly adapted to colonise heterometric sandy bottoms swept by moderate currents in the mid- to open-shelf ( Rosso 2008a). Colonies of this species preferably encrust very coarse sand (in the range of 1–2 mm), more rarely granules and fine pebbles up to 7–8 mm wide, usually reaching 3x 5 mm in size ( Rosso 2008a). Colonies cover only one side of the substratum or tend to completely envelop it. Likely, these Setosella colonies are able to clean themselves and to slightly adjust their position in respect to neighbouring clasts using the long, vibracular, bristle-like setae ( Rosso 2008a).