Fedora nodosa Silén, 1947a

Martino, Emanuela Di, 2023, Scanning electron microscopy study of Lars Silén’s cheilostome bryozoan type specimens in the historical collections of natural history museums in Sweden, Zootaxa 5379 (1), pp. 1-106 : 91-94

Fedora nodosa Silén, 1947a

( Fig. 50 ; Table 44)

Material examined. Lectotype (designated here) SMNH-Type-8735a ( Fig. 50A, B ; specimen figured in Silén 1947a, pl. 4, fig. 22) North Atlantic , Gulf of Mexico, Fort Pickens, Florida, United States; depth 415 m. Leg. Albatross 1885, Station 2398 . Paralectotypes SMNH-Type-8735b ( Fig. 50C–E ), SMNH-Type-8735c ( Fig. 50F, G ), SMNH-Type-8735d ( Fig. 50H, I ), and SMNH-Type-8735e (not figured), same details as lectotype.

Other species material for comparison: Fedora edwardsi Jullien, 1882 ( Fig. 51 , Table 45), North Atlantic Ocean, Josephine Bank, off Portugal, 38°7'N, 9°18'W, depth 1001 m, leg. Josephine Expedition 1869: SMNH-127677, three colonies ( Fig. 51H, I ); SMNH-128029, five colonies ( Fig. 51E–G ); SMNH-128030, 2 colonies ( Fig. 51A–D ).

Fedora ovum ( Smitt, 1873) ( Fig. 52 , Table 46). Lectotype (designated here) SMNH-Type-1799a ( Fig. 52H, I ), North Atlantic Ocean , off Tennessee Reef, Florida, United States, depth 209 m. Leg. Gulf Stream Explorations 1868–69, L.F. Pourtales 1869 . Paralectotypes SMNH-Type-1799b ( Fig. 52A, B ), SMNH-Type-1799c ( Fig. 52C–E ), SMNH-Type-1799d ( Fig. 52F ), SMNH-Type-1799e ( Fig. 52G ), same details as lectotype. Paralectotype SMNHType-9106, one colony (not figured), off the Pacific Reef , depth 426 m.

Description. Colony ovoidal, 2.44–2.66 mm long by 2.05 mm wide (L/ W 1.29 –1.19, N 2) ( Fig. 50A, C ); apical area occupied by ancestrular complex consisting of six radially arranged autozooids, similar in appearance (including the presence of an adventitious avicularium) and slender than later autozooids (mean L/ W 1.37) ( Fig. 50F, G ); antapical area occupied by polygonal kenozooids and avicularia ( Fig. 50H, I ).

Autozooids arranged in seven alternating whorls of 6–14 zooids each (the highest number of zooids at about colony mid-length), distinct with narrow grooves and a thin rim of smooth calcification when not obliterated by secondary calcification, hexagonal, almost equidimensional (mean L/ W 1.06); a basal pore chamber, rounded triangular, subelliptical or subcircular, 165–230 µm long by 135–180 µm wide, visible distal to each autozooid ( Fig. 50I , some arrowed).

Frontal shield imperforate and coarsely tubercular ( Fig. 50B, D, E ); an elliptical marginal areolar pore, 35–40 µm long by 25–45 µm wide, sometimes visible at the proximal zooidal corner and/or at the lateral corner ( Fig. 50D, E ).

Primary orifice cleithridiate, longer than wide (mean L/ W 1.24), a horseshoe-shaped anter separated from a bowl-shaped sinus by two robust rounded condyles proximomedially directed ( Fig. 50D, E ); oral spines absent also in early ontogeny. Closure plates tubercular as the frontal shield observed sealing the orifice up to the third generation of autozooids ( Fig. 50B, G ). Intramural budding observed in autozooids, visible as a series of concentric orificial rims ( Fig. 50D, E ).

Adventitious avicularia infrequent, present as early as the first generation of autozooids ( Fig. 50G ), single, placed laterally to the orifice at the same level as the condyles ( Fig. 50B ) or more distally ( Fig. 50D ), subcircular (mean L/ W 0.85), rostrum rounded, directed laterally or distolaterally, with complete crossbar ( Fig. 50D ); mandible semicircular ( Fig. 50I ). Interzooidal avicularia occupying the antapical area, similar in shape to adventitious avicularia, located centrally on a rectangular or irregularly polygonal cystid, 320–330 µm long by 285–310 µm wide, with the surface tubercular as the zooidal frontal shield, rostrum directed distally ( Fig. 50H, I ).

Kenozooids also present in the antapical area ( Fig. 50H, I ), rectangular or irregularly polygonal, 250–430 µm long by 175–270 µm wide, tubercular as autoozooids, either without openings or with central 8-shaped or elliptical opening, 100–110 µm long by 70–95 µm wide.

Ovicells not observed, likely absent.

Remarks. Silén’s (1947a) original material of Fedora nodosa consisted of 13 colonies. Unfortunately, only five were available in the type series studied here, including the colony figured by Silén (1947a, pl. 4, fig. 22) and here designated as the lectotype. The information on the type locality and legacy reported on the specimen label is consistent with that in the publication, except for the depth which is slightly deeper (i.e. 415 m versus 340 m).

The striated, chitinous tube observed in two of the colonies ( Fig. 50A, C ) was originally interpreted by Silén (1947a) as a kenozooidal attachment rootlet. However, upon closer examination of its peculiar morphology, exhibiting a narrow base of attachment to the colony (c. 130 µm) that widens towards the outer tip (c. 300 µm), the alternative interpretation of it as the polypide tube of a coronate scyphozoan seems to be equally plausible. While the original interpretation of the tube as a kenozooidal rootlet is supported by its presence in the exact same position in which the bryozoan rhizoid would be expected to emanate as well as by the absence of any other structures that could explain how the colony is actually attached to the substrate, the lack of evident scars from the ‘rootlet’ at its attachment point supports its alternative interpretation as a scyphozoan tube.

Eleven species are currently assigned to Fedora . Seven species are fossil: five are from the Eocene (Lutetian or Priabonian) of Europe ( France, Germany and Italy), one is from the Oligocene (Rupelian) of Mississippi ( USA), and one from the Miocene of Austria. Four species, including F. nodosa , are Recent, all found in North Atlantic waters, except for Fedora platydiscus Gordon & d’Hondt, 1997 , which was described from Mindoro Strait in the Philippines at 92–97 m depth. However, Gordon & d’Hondt (1997) were uncertain about the generic placement of the species given its flat discoidal colony form and the complete absence of avicularia, and forewarned the necessity to introduce a new genus, an action they did not undertake because only a single, infertile specimen was available.

Fedora nodosa is very similar in appearance to the type species of the genus, F. edwardsi (see Fig. 51 ), sharing all diagnostic features of the genus such as the autozooid distobasal pore chamber, the inconstant adventitious avicularia adjacent to the orifice, the cleithridiate shape of the orifice, the tubercular frontal shield, and the absence of ovicells. They can be distinguished based on the colony form, shape of condyles and type of frontal tuberculation. Fedora edwardsi has more cylindrical to pear-shaped colonies, with the highest number of zooids in a whorl usually located in the proximal third of the colony ( Fig. 51A, C ), pointed orificial condyles ( Fig. 51D ), and a finer and more prickly frontal tuberculation ( Fig. 51B, D, I ). The apical area is occupied by the ancestrular complex consisting of four radially arranged autozooids, with opposite pairs similar in size (365–375 × 300–330 µm versus 470–490 × 385–420 µm) ( Fig. 51E, G, H ).

Fedora ovum ( Fig. 52 ) was originally assigned to Myriozoum by Smitt (1873) based on some similarities with Myriapora truncata ( Pallas, 1766) and species of Leieschara , and re-assigned to Fedora by Silén (1947a). In this species, however, autozooids lack a distobasal pore chamber, avicularia with condyles (incomplete crossbars) are numerous and placed along autozooidal boundaries (e.g. Fig. 52A, C, F–H ), the orifice although cleithridiate is cormidial and formed by both the zooid it belongs to and the distal zooid ( Fig. 52B, E ), the frontal is pitted, and large ovicells, occupying the entire length of the frontal shield of the distal zooid, are present ( Fig. 52A, F, H, I ). All these features were observed in the genus Sphaerulobryozoon d’Hondt, 1981 , which appears as a better fit for F. ovum . The new combination Sphaerulobryozoon ovum ( Smitt, 1873) is therefore suggested. Silén (1947a) acknowledged the absence of the distobasal pore chamber in S. ovum n. comb., and justified the re-assignment of the species to Fedora , interpreting the avicularia as special lateral chambers homologous with the distobasal chamber of F. edwardsi and F. nodosa . In his diagnosis of the genus Sphaerulobryozoon , with type species S. pedunculatum from bathyal western Atlantic waters, d’Hondt (1981) described two types of zooids with opercula, i.e. normally functioning autozooids (“autozoécies”) and microzooids (“microzoécies”). The microzooids(e.g. Fig. 52B, E ) are here re-interpreted as interzoooidal avicularia with condyles and semicircular mandibles (see d’Hondt 1981, pl. 7, fig. 3).

The type specimens of Paleogene and Neogene species attributed to Fedora also need to be revised.Unfortunately, in most cases the quality of the illustrations and/or images available from the original publications prevent any meaningful re-interpretation.

Figures

FIGURE 50. Fedora nodosa Silén, 1947a. Gulf of Mexico, Florida, United States. A, B. Lectotype (designated here) SMNH- Type-8735a. C–E. Paralectotype SMNH-Type-8735b.F, G. Paralectotype SMNH-Type-8735c.H, I. Paralectotype SMNH-Type- 8735d.A. Lateral view of the colony. The nature of the chitinous tubes here and in (C) is unclear. It can either be interpreted as a kenozooidal attachment rootlet or as the polypide tubes of a coronate scyphozoan. B. Close-up of autozooids with operculum or closure plate. C. General view of the colony. D. Close-up of autozooids with adventitious avicularia. E. Close-up of two orifices with and without operculum, and additional orifice rims due to subsequent intramural budding. F. General view of the proximal end of the colony (i.e. ancestrular region). G. Close-up of the proximal end of colony with emanation point of zooidal rows. H. General view of the distal end of the colony. I. Close-up of the distal end of colony with kenozooids. Scale bars: A = 2 mm; B = 400 µm; C, F, H = 1 mm; D, G, I = 500 µm; E = 200 µm.

FIGURE 51. Fedora edwardsi Jullien, 1882. North Atlantic Ocean, Josephine Bank. A–D. SMNH-128030.A, C. Lateral views of two colonies. B. Group of zooids with operculum, some also with an adventitious avicularium. D. Close-up of two zooids showing the orifice. E–G. SMNH-128029. E, G. Proximal view of two colonies with emanation point of zooidal rows. F. Closeup of the proximal end with?ancestrula. H, I. SMNH-127677. H. Proximal view of a colony with?ancestrula. I. Group of autozooids with adventitious avicularia. Scale bars: A, C = 1 mm; B, E = 400 µm; D, F = 200 µm; G, I = 300 µm; H = 500 µm.

FIGURE 52. Sphaerulobryozoon ovum (Smitt, 1873) n. comb. North Atlantic Ocean, off Tennessee Reef, Florida, United States. A–G. Paralectotypes SMNH-Type-1799b-e. H, I. Lectotype (designated here) SMNH-Type-1799a. A, C, F–H. Lateral views of the four paralectotypes and the lectotype. B. Close-up of two zooids showing the terminal, cormidial orifice and interzooidal avicularia along the zooidal margins. D, E. Close-up of orifices and avicularia. I. Ovicellate zooid. Scale bars: A, C, F, H = 500 µm; B, D = 200 µm; E = 100 µm; G = 1 mm; I = 300 µm.