Nudicella Schmidt and Bone, 2004

Taylor, Paul D., Martha, Silviu O. & Gordon, Dennis P., 2018, Synopsis of ‘ onychocellid’ cheilostome bryozoan genera, Journal of Natural History (J. Nat. Hist.) 52 (25 - 26), pp. 1657-1721 : 1688-1689

Genus Nudicella Schmidt and Bone, 2004

( Figure 18 )

Type species

Nudicella latiramosa, 2004 , by original designation. Middle Eocene to Early Oligocene, South Australia and Western Australia.

Diagnosis

Colony erect bifoliate, palmate with bifurcating branches ( Figure 18 (a,d)). Autozooids elongate hexagonal, distal edges rounded; zooidal boundaries grooved. Cryptocyst extensive, granular. Gymnocyst lacking. Opesia terminal, occupying less than one-third of frontal surface; semi-elliptical with opesiular indentations and an occlusor-lamina ( Figure 18 (b)), proximal edge straight or slightly concave. Ovicells immersed ( Figure 18 (e)); opesia in ovicellate autozooids enlarged, a transverse wall visible within the opesia separating the ovicell from the rest of the zooid. Avicularia vicarious, symmetrical ( Figure 18 (c)), about half the width of an autozooid but of similar length; opesia transversely semi-elliptical with a small foramen; rostrum acutely triangular. Kenozooids present along branch edges and in axils ( Figure 18 (f)).

Remarks

Five species were recognised by the authors of Nudicella , all from the Cenozoic of Australia ( Schmidt and Bone 2004). The key characters of the genus are the straight avicularia and occurrence of a small foramen in the proximal cryptocyst of the avicularia ( Figure 18 (c)). Most species of Nudicella have palmate erect colonies with narrow bifoliate branches that bifurcate. However, N. cribriforma Schmidt and Bone, 2004 has characteristically cribrate colonies (see Taylor 2012), and an unnamed species with an encrusting colony form was depicted by Schmidt and Bone (2004; fig. 9D).

The presence of a transverse wall between the main chamber of the maternal zooid and the ovicell ( Figure 18 (e)) is reminiscent of Cheethamia ( Figure 4 (d)). Both Nudicella and Cheethamia also have occlusor laminae, suggesting that the two genera may be closely related.

Range

Paleocene (Thanetian) to Miocene (Middle).

Figures

Figure 4. Cheethamia howei Shaw. (a) holotype, LSUMG-I 8237; Cretaceous, Campanian, Saratoga Chalk, Howard County, Arkansas, USA. (b–f) NHMUK BZ 4809; Cretaceous, Maastrichtian, Lake Ridge Apartments, Livingston, Alabama, USA; (b) ovicellate and non-ovicellate autozooids and an avicularium; (c) opesia of non-ovicellate autozooid showing occlusor lamina and a pair of closely spaced oral spine bases; (d) ovicellate autozooid with transverse wall visible in opesia; (e) avicularium; (f) ancestrula (lower centre) and first-budded autozooids. Scale bars: a, b, e, f = 500 µm; c = 100 µm; d = 200 µm.

Figure 18. Nudicella latiramosa Schmidt and Bone; Early Oligocene, Port Willunga Formation, South Australia; (a–c) NHMUK BZ 8216; (a) palmate colony; (b) autozooid opesia; (c) avicularium; (d–f) NHMUK BZ 8217; (d) bifurcating branch; (e) ovicellate autozooids; (f) non-ovicellate autozooids with a kenozooid in branch axis. Scale bars: a, d = 1 mm; b = 100 µm; c, e, f = 500 µm.