Setosella margaritae, Reverter-Gil & Souto, 2021

Reverter-Gil, Oscar & Souto, Javier, 2021, Two new species of cheilostomate Bryozoa from Iberian waters, European Journal of Taxonomy 760, pp. 16-31 : 22-28

Setosella margaritae sp. nov.

urn:lsid:zoobank.org:act:E9976DD1-53EC-4547-A766-37B1DEE466DF

Figs 4–5 , Table 2

Setosella vulnerata – Reverter-Gil et al. 1992: 102, fig. 2; 2016: 28, fig. 4d. — Barcia Leal et al. 1993: 251. — Reverter-Gil 1995: 115, fig. 7. — Hayward & Ryland 1998: 298, fig. 103. — Reverter-Gil & Fernández-Pulpeiro 2001: 78 (shallow waters only). — De Blauwe 2006: 130, fig. 9; 2009: 252, figs 257–258.

Non Setosella vulnerata – Jullien 1882: 28, pl. 17 fig. 66. — Calvet 1907: 394. — d’Hondt 1973: 367; 1974: 38. — Hayward 1979: 60. — Reverter-Gil & Fernández-Pulpeiro 2001: 78 (deep waters only). — Templado et al. 2006: 208. — Reverter-Gil et al. 2014: 16. — Souto et al. 2016: 416 , figs 33, 38. — Rosso et al. 2020: 403 , figs 1–2 [= Setosella vulnerata ( Busk, 1860) ].

Non Setosella vulnerata – Templado et al. 2002: 203. (= Setosella cyclopensis Rosso, Di Martino & Gerovasileiou, 2020 ).

Differential diagnosis

Setosella with small, encrusting colonies. Autozooids small, oval, with opesia D-shaped or irregularly rounded, and two oval to tear-shaped opesiules, positioned close to opesia and directly beside lateral walls of zooid. Small interzooidal vibracula oval, positioned distolateral to each autozooid, always on the right side and often without exceeding distal edge of autozooid, especially in ovicelled ones. Ectooecium with transversely oval membranous window and granular endooecial surface underneath, with a small, central pore. Ancestrula oval, with cryptocyst occupying slightly less than half of the frontal area; opesia semielliptical, with straight or slightly concave proximal border.

Etymology

This species is dedicated to Margarita Salas Falgueras (1938–2019), Spanish scientist, medical researcher, and author in the fields of biochemistry and molecular genetics. She was a disciple of S. Ochoa (see above).

Material examined

Holotype

ATLANTIC SPAIN • colony on shell fragment; Galicia, Ría of Ferrol ; 43º45.889´N, 08º293.33´W; depth 20 m; 13 Sep. 1989; Reverter-Gil leg.; MHNUSC 10120 ; ( Fig. 4 A – B ).

Paratypes

ATLANTIC SPAIN • several small juvenile colonies on shell fragment; same collection data as for holotype; MHNUSC 10121 ( Fig. 4 C ) • colony on shell fragment; same collection data as for holotype; MHNUSC 10122 ( Fig. 5 C – D ) • small eroded colony on shell fragment; Galicia, Ría of Ferrol ; 43º45.500´N, 08º30.889´W; depth 12 m; 13 Sep. 1989; Reverter-Gil leg.; MHNUSC 10123 ( Figs 4 D , 5 B ) .

Other material

ATLANTIC SPAIN • colony on maërl; Galicia, Ría of Vigo; 42º23.889´N, 08º79.369´W; depth 16 m; 16 Sep. 1986; Fernández-Pulpeiro leg.; MHNUSC-Bry 93a (together with Setosella sp. ) ( Fig. 5A ) • colony on shell fragment; Galicia, Ría of Vigo; 42º23.139´N, 08º76.389´W; depth 9 m; 16 Sep. 1986; Fernández-Pulpeiro leg.; MHNUSC-Bry 93b • colony on shell fragment; Galicia, Ría of Vigo; 42º22.944´N, 08º88.056´W; depth 23 m; 2 Aug. 1985; Fernández-Pulpeiro leg.; MHNUSC-Bry 93c (together with Trypostega venusta ( Norman, 1864) and Microporella ciliata ( Pallas, 1766)) • colony on shell fragment; Galicia, Ría of Ferrol; 43º46.389´N, 08º26.333´W; depth 8 m; Jun. 2004; Reverter- Gil leg.; MHNUSC-Bry 656 (together with 12 spp. more).

Lectotype of Setosella vulnerata

NORTH SEA • UK, Shetland; Busk leg.; NHMUK 1899.7 .1.1487 (see also Souto et al. 2016).

Paralectotypes of Setosella vulnerata

NORTH SEA • several colonies; UK, Shetland; Busk leg.; NHMUK 1911.10 .1.760 (see also Souto et al. 2016) .

Other material of Setosella vulnerata

MEDITERRANEAN SPAIN • Alboran Island ; 35º83.550´N, 03º23.667´W; stn 313A; depth 118 m; 1996; Fauna Ibérica IV exped.; MNCN 25.03/3169 ( Fig. 6 ).

Material of Setosella cyclopensis

MEDITERRANEAN SPAIN • Columbretes Islands; 39º87.217´N, 0º63.400´E; stn 283A; depth 80– 85 m; 1996; Fauna Ibérica IV exped.; MNCN 25.03/3149 .

Description

Colony encrusting, unilaminar, forming small discoidal patches of alternating autozooids and vibracula. Autozooids irregularly oval, with well-developed smooth gymnocyst proximally that narrows and steepens distally, lateral walls slightly raised, framing an evenly granular cryptocyst that is flat and depressed proximally, gently rising distally to the opesiules to form the proximal border of the opesia. Opesia D-shaped or irregularly rounded, wider than long, distal margin with some blunt, irregularly spaced denticles. Two oval to tear-shaped opesiules (ca 20 μm long by 10 μm-wide), located in distal depressed area of the cryptocyst, positioned close to the opesia (mean 36 μm) and directly beside the lateral walls of zooid, their inner edges sometimes with several sharp denticles; the size of both opesiules unequal, the left one slightly larger. Small interzooidal vibracula oval, positioned distolateral to each autozooid, always on the right side and often without exceeding the distal edge of the autozooid, especially in ovicelled ones. Wide oval opesia, sometimes slightly narrower in the middle; seta long and slender, curved, up to twice length of the autozooid. Communication of zooids via small uniporous septula. Some autozooids and vibracula show evidence of breakage and regeneration associated with the intramural budding ( Fig. 5C–D ). Ovicells terminal, with a brood cavity immersed within the distal part of the maternal zooid. Kenozooidal ooecium roughly level with the colony surface, forming shallow hood covering distal end of the maternal zooid from which it is budded. Proximal ooecial margin forming the distal part of the zooidal orifice; ectooecium with transversely oval membranous window and granular endooecial surface underneath, with a small, central pore. Ovicellate zooids dimorphic, slightly wider distally, with orifices distinctly broader and campanulate in outline. Distal budding of autozooids and vibracula in ooecium-producing zooid retained. Ancestrula oval, with cryptocyst relatively smooth, occupying slightly less than half of the frontal area; opesia semi elliptical, with straight or slightly concave proximal border. Astogenesis beginning with one distal and two lateral autozooids; later zooids more irregularly arranged. The ancestrula also buds the two typical caudate vibracula of the genus: one short caudate, budded mid-laterally on the left side, and the other long caudate, budded distally, and sometimes curved to the right. On one occasion, however, this pattern was reversed, with the short vibraculum budded on the right side ( Fig. 4C ).

Remarks

The genus Setosella and all the species ascribed to it are at present well described under current standards. Setosella vulnerata , the type species of the genus, was redescribed by Souto et al. (2016). Rosso et al. (2020) redefined the genus itself as well as two known species ( S. cavernicola Harmelin, 1977 and S. spiralis Silén, 1942 ) and three new species ( S. alfioi Rosso, Di Martino & Gerovasileiou, 2020 , S. cyclopensis Rosso, Di Martino & Gerovasileiou, 2020 and S. rossanae Rosso, Di Martino & Gerovasileiou, 2020 ). Another species, S. folini Jullien, 1882 , was redescribed by Souto et al. (2011). Finally, an undescribed species was reported from Galicia (NW Iberian Peninsula) as S. aff. cavernicola (see Reverter-Gil et al. 2012; Rosso et al. 2020).

Setosella margaritae sp. nov. differs from S. vulnerata (see redescription by Souto et al. 2016) as well as from S. cyclopensis , quite a similar species, by several characters: the vibracula of S. margaritae sp. nov. are much smaller, about half the size, and characteristically shifted laterally on the right side, often without exceeding the distal end of the autozooid (especially in ovicelled zooids), instead being distal or only slightly distolateral. The autozooids are oval and clearly smaller in S. margaritae sp. nov. The opesiules are shorter, oval to tear-shaped, instead slit-like or elongated; moreover, the opesiules are located closer to the opesia and directly beside the lateral walls of the zooid, instead of away from the opesia and the lateral walls. The window of the ectooecium in S. margaritae sp. nov. is transversally oval, whilst in S. vulnerata and S. cyclopensis it is roughly circular, much smaller in the former species, much larger in the latter. Finally, the colonies of S. margaritae sp. nov. are very small, encrusting mainly shell fragments in shallow waters, as opposed to larger colonies encrusting mainly coarse sand, granules and fine pebbles in deeper waters in the other species.

At the same time, Setosella folini and S. alfioi differ from S. margaritae sp. nov. most obviously by their uniserial, free-living colonies. Setosella cavernicola , S. rossanae and Setosella sp. (as S. aff. cavernicola in Reverter-Gil et al. 2012) differ by their circular opesiules, four or even up to five in the latter two species. Finally, S. spiralis differs by the much larger autozooids and vibracula, with opesiules located further away from the opesia, and by colonies with spirally arranged zooids typically in a single rightcoiled row.

In the past, we have considered our own material to be similar to typical Setosella vulnerata . That is why we have cited deep material as Setosella sp. (see Reverter-Gil et al. 2012). But after the redescription of S. vulnerata by Souto et al. (2016) the situation has turned out to be just the opposite. Our previous records of S. vulnerata from shallow waters of Galicia (NW Iberian Peninsula) are here assigned to S. margaritae sp. nov.: from the Ría of Ferrol at 8–20 m depth, and from the Ría of Vigo at 9–23 m depth, both on shell fragments ( Reverter-Gil & Fernández-Pulpeiro 2001 and present data). These colonies are very small, formed by very few autozooids, but are fertile because ovicells are formed even in the first or second generations of periancestrular zooids ( Figs 4A, C , 5A ). Moreover, the material of S. vulnerata reported and figured by De Blauwe (2006, 2009), collected on shells at 10–25 m depth in Belgium (North Sea), also belongs to S. margaritae sp. nov. These colonies are larger than the Galician ones, but present the same characters, also including ovicells in the first or second generations of zooids (see De Blauwe 2009: figs 257–258; accessible also through WoRMS 2020: http://www.marinespecies.org/photogallery.php?album=709&pic=25695#photogallery and http://www.marinespecies.org/photogallery.php?album=709&pic=25696#photogallery). Moreover, the description and figures of S. vulnerata in Hayward & Ryland (1998) fit the present description of S. margaritae sp. nov., at least the shallow-water material referred to there. Accordingly, the species is quite possibly distributed in shallow waters along the Atlantic coast of Europe, from the North Sea to at least the NW of the Iberian Peninsula. Its occurrence in other areas should be confirmed by reviewing previous citations of S. vulnerata . In a previous paper ( Reverter-Gil et al. 2012), we already suggested that previous records of S. vulnerata might correspond to several different species.

Conversely, previous records of Setosella vulnerata in Atlantic Iberian deep waters (Cachucho [= Le Danois Bank], Galicia, Portugal and Gulf of Cadiz) actually belong to this species (see Jullien 1882; Calvet 1907; d’Hondt 1973, 1974; Hayward 1979; Harmelin & d’Hondt 1992; Reverter-Gil & Fernández-Pulpeiro 2001 only deep waters; Reverter-Gil et al. 2014; Souto et al. 2016), as is also the case for records published as Setosella sp. by Reverter-Gil et al. (2012) (see also Souto et al. 2016; Rosso et al. 2020).

There are a few more previous records of Setosella vulnerata in Iberian waters: the record from Alboran Island, at 118 m depth, made by Templado et al. (2006) actually corresponds to S. vulnerata (see material examined and Fig. 6 ) as well as the recent records published by Ramalho et al. (2020) in a nearby area between 95 and 440 m depth. However, the record from Columbretes Islands (Mediterranean Spain), at 80 m depth, made by Templado et al. (2002) actually belongs to S. cyclopensis (see material examined; unfortunately, this sample is currently unavailable for photography). Thus, this is the first Iberian record of this Mediterranean species. We have no further information about the records published by Zabala et al. (1993) from the Blanes Canyon at 180–350 m depth and by Madurell et al. (2013) from Cap de Creus at 104–225 m depth (Catalonia), but based on the given depths these records may belong to S. vulnerata or to S. cyclopensis .

Following Souto et al. (2016) and Rosso et al. (2020), Setosella vulnerata is distributed in the Northeast Atlantic and the Mediterranean, although several Atlantic and Mediterranean occurrences still need to be checked. As already stated by Rosso et al. (2020) it is likely that S. vulnerata is actually restricted to deep habitats from the shelf break and the continental slope.

Figures

Fig. 4. Setosella margaritae sp. nov. A. Holotype (MHNUSC 10120). B. Same, optical photograph, together with a small, dead colony of Callopora discreta (Hincks, 1862) encrusting the inner part of a barnacle plate. C. Ancestrula with reversed astogenetic pattern (note the short vibraculum positioned on the right side) (MHNUSC 10121: paratype). D. Optical photograph of a damaged colony on a shell fragment (MHNUSC 10123: paratype).

Fig. 5. Setosella margaritae sp. nov. A. A colony of S. margaritae sp. nov. (left) together with the colony of Setosella sp. (right) (see text and Reverter-Gil et al. 2012 as S. aff. cavernicola) (MHNUSC-Bry 93a). B. Damaged autozooids (one ovicelled, another with a developing ooecium) with three vibracula with setae (MHNUSC 10123: paratype).C. A colony with a damaged periancestrular area; note the intramural budding in several zooids (MHNUSC 10122: paratype). D. Same, detail showing two ovicelled zooids and a vibraculum with intramural budding.

Fig. 6. A colony of Setosella vulnerata (Busk, 1860) collected at Alboran Island (Mediterranean Spain) (MNCN 25.03/3169).A. General view of the colony.B. The periancestrular area; note that the ancestrula was covered by a cryptocystal plate.