Cribrilaria saginata ( Winston, 2005 ) Rosso & Beuck & Vertino & Sanfilippo & Freiwald, 2018

Rosso, A., Beuck, L., Vertino, A., Sanfilippo, R. & Freiwald, A., 2018, Cribrilinids (Bryozoa, Cheilostomata) associated with deep-water coral habitats at the Great Bahama Bank slope (NW Atlantic), with description of new taxa, Zootaxa 4524 (4), pp. 401-439 : 407-411

Cribrilaria saginata ( Winston, 2005) n. comb.

( Figs 2–9 ; Tables 1, 2)

Cribrilina radiata: Smitt, 1873: 22 (part), pl. 5, fig. 107; not fig. 108.

Puellina saginata Winston, 2005: 32 , figs 83–88.

Material examined. Great Bahama Bank slope, R/V Maria S. Merian Cruise MSM 20/4. Station GeoB16367-2 (three dead colonies on corals)—SMF-45.501; Station GeoB16376-1 (one dead colony on erect bryozoan)—SMF- 45.502; Station GeoB16377-1 (three dead colonies on corals)—SMF-45.503; Station GeoB16382-1 (one live and two dead colonies on corals)—SMF-45.504. Two dead colonies, one from Station GeoB16376-1 and one from Station GeoB16382-1, both on corals: PMC-Rosso-Bahama Collection Bah.H. B42a.

Description. Colonies encrusting, multiserial, unilaminar, but sometimes developing superimposed layers, even attaining sizes of 1 cm 2 or more in the examined material, and comprising tens to hundreds of zooids.

Zooids large and flat, distinct, of variable shapes but usually oval, longer than wide with few exceptions; the boundaries marked by shallow grooves ( Figs 2–5 ). Gymnocyst smooth or with faint radiating striations, narrow in the distal half and comparably wider in the proximal half of the zooid, usually with proximal and/or lateral extension(s) between neighbouring zooids ( Figs 3–5, 9 ). Interzooidal communication through basal pore-chambers with very wide windows, visible along lateral and distal walls of zooids at colony margins ( Figs 8, 9 ). Frontal shield circular or oval, occupying most of the frontal surface ( Figs 3–5 ). It is flat and consists of 20–24 wedgeshaped costae, each forming a low blunt bulge proximally and narrowing toward zooidal centre. Costae are connected by several intercostal bridges leaving 7–8, exceptionally nine, regularly spaced, 10–15 µm wide intercostal spaces, subrectangular to kidney-shaped. The largest peripheral pores are provided with papillae. Just 4– 5 intercostal pores, larger (15–25 µm wide) than the others, are seen proximally to the first suboral pair of costae ( Figs 6, 7 ). Suboral costae carinate and raised, merging along midline and forming a prominent shelf with a median suture ( Fig. 6 ). A pore may be sometimes present along the contact line where each costa ends with a prominent point. Orifice transversely D-shaped with a straight proximal border marked by an elevated rim, and a curved distal border with five equally spaced articulated oral spines ( Fig. 6 ), four persisting in ovicellate zooids ( Fig. 7 ).

Interzooidal avicularia large, common (with autozooid/avicularium ratio equalling three in several colonies), with a variably shaped but usually triangular cystid and long non-serrated, elongated triangular to almost parallelsided rostrum directed laterally or distolaterally, with paired pointed and down-curving pivotal denticles ( Figs 3, 8 ). Avicularium level with zooids, the rostrum usually embedded in between adjacent zooids, rarely slightly elevated.

Ovicells prominent, probably semi-cleithral. Ooecium formed by the distal autozooid [type 1 sensu Ostrovsky (1998, 2008, 2013) and type A sensu Bishop & Househam (1987)]. Ectooecium smooth, with a central longitudinal suture elevated into a keel ( Figs 4, 5, 7 ).

Ancestrula not observed.

Remarks. The characters in the examined colonies fit well with Winston’s (2005) description, although measurements of zooids and frontal shields are slightly larger, seemingly due to the occurrence of some irregularly shaped and particularly enlarged zooids, possibly caused by uneven substratum because our colonies usually encrust fragments of erect branching corals. It should also be mentioned that interzooidal avicularia have variably elongated rostra, usually straight and parallel-sided, but sometimes shorter and curving in our material.

Following discussion about ranking of Cribrilaria and Puellina (see above) we suggested the new combination Cribrilaria saginata n. comb. for Puellina saginata Winston, 2005 .

The studied colonies were collected in close vicinity to the type locality of this species, a century and a half after its first finding. Only one colony collected by Pourtales off Bahia Honda (Florida Keys), at about 322 m depth in 1868 is stored in Smitt’s collection. It was designated as the holotype by Winston (2005) when describing Cribrilaria saginata (as Puellina ).

As already mentioned by the latter author, C. saginata n. comb. can be easily distinguished from most other congenerics owing to the large zooidal size and very flat appearance of both zooids and colonies. Conspecificity of the specimens first described from off Florida by Smitt (1873) as Cribrilina radiata with the fossil Puellina (Cribrilaria) scripta ( Reuss, 1848) was suggested by Harmelin & Aristegui (1988) but has been rejected by Winston (2005) because Reuss’ species has smaller zooids with a narrower gymnocyst and comparably larger orifices than C. saginata [see also fig. 98 in Bishop & Househam (1987)]. Unlike Winston (2005), however, we question also the conspecificity of C. saginata with present-day populations of Puellina (Cribrilaria) scripta recorded by Harmelin & Aristegui (1988) from deep waters of the Ibero-Moroccan Bay and the Gibraltar Strait. These specimens show a prominent suboral umbo, which is lacking in colonies from the western Atlantic, and also have smaller orifices and interzooidal avicularia. Specimens from the Kermadec region recorded by Gordon (1984) as Puellina (Cribrilaria) innominata and synonymised by Harmelin & Aristegui (1988) with their Puellina (Cribrilaria) scripta , are even more different owing to the very narrow exposed gymnocyst, the frontal shield with less numerous costae ornamented by prominent spiny processes, and a serrated avicularian rostrum. All this material needs to be re-examined.

Distribution. Cribrilaria saginata n. comb. is known from shallow bathyal depths in the restricted area S and SE of Florida. The only live colony found in the present material originates from 658 m depth, but dead specimens occurred in the depth interval 641– 673 m. These findings extend the vertical distribution of the species, previously collected at 322 m, and confirm its confinement to deep waters, as also suggested by its absence in shelf habitats ( Winston 2005; Winston & Maturo 2009). Cribrilaria saginata n. comb. has been found preferentially to encrust deep-water corals, either exposed skeletons of live coral colonies, or fresh-looking to heavily corroded and oxidecoated dead coral fragments.

Figures

FIGURES 2–9. Cribrilaria saginata (Winston, 2005) n. comb., Great Bahama Bank slope, Station GeoB16377-1. 2, 3. SMF- 45.503a. 4–9. SMF-45.503b. 2. Group of autozooids with flat, round to oval frontal shield, and avicularia. Note the large windows of the basal pore-chambers (arrowed). 3. Close-up of a single autozooid with five oral spines and an avicularium. 4. Group of autozooids including one ovicellate. 5. Slightly inclined view of the ovicellate zooid to show the frontal carina. 6. Autozooidal orifice and suboral bar. 7. Distal part of an ovicellate zooid with four oral spines. Note the large intercostal spaces between the first pair of suboral costae. 8. Interzoecial avicularium showing pointed pivotal denticles. 9. Group of autozooids, some showing intramural budding along the edge of a damaged colony. Scale bars: 2, 9 = 500 µm; 3–7 = 200 µm; 8 = 100 µm.