Pseudolunulites Cook and Voigt, 1986

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 : 1693-1694

Genus Pseudolunulites Cook and Voigt, 1986

( Figure 22 )

Type species

Discoescharites irregularis Roemer, 1863 , by original designation. Oligocene, Chattian, Bünde, North Rhine-Westphalia, Germany .

Diagnosis

Colony free-living ( Figure 22 (a)), discoidal, convex upper surface ( Figure 22 (b)), concave lower surface; basal wall exterior; regular overgrowths may spread radially from the centre of the colony on the upper surface. Autozooids squat subhexagonal ( Figure 22 (d,f)); zooidal boundaries grooved. Cryptocyst extensive, granular. Gymnocyst lacking. Opesia terminal, occupying about half of frontal surface; semi-elliptical with moderate to deep opesiular indentations and proximolateral opesiular constrictions. Ovicells unknown. Avicularia vicarious, symmetrical ( Figure 22 (e)), half or more of the length of an autozooid; opesia keyhole shaped; rostrum triangular, short, floor pustulose; autozooids proximolateral of avicularia oriented distolaterally outwards. Ancestrula ( Figure 22 (c)) budding a distal and a pair of distolateral autozooids plus a pair of proximolateral avicularia ( Cook and Voigt 1986).

Remarks

Despite its lunulitiform colony, Cook and Voigt (1986) argued that their new monospecific genus Pseudolunulites was unrelated to Lunulitidae , from which it differed in the structure of the colony and zooids, and instead belonged within a ‘polyphyletic’ Onychocellidae . A relationship with the common genus Lunulites was also discounted as all known species of this genus by the Oligocene had porous, cryptocystal basal walls of aragonite unlike the gymnocystal, seemingly calcitic basal walls of Pseudolunulites (and of earlier species of Lunulites ). We provisionally retain Pseudolunulites in Onychocellidae as the only free-living genus in this family, pending a better understanding of the relationships between onychocellids and the non-cupuladrian families with free-living colonies ( Lunulitidae , Lunulariidae , Otionellidae and Selenariidae ).

Range

Oligocene (Chattian).

Figures

Figure 22. Pseudolunulites irregularis (Roemer); NHMUK BZ 8220; Late Oligocene, Bünde-Doberg, North Rhine-Westphalia, Germany; (a) upper surface of free-living colony; (b) early astogeny; (c) ancestrula (lower centre) and periancestrular zooids; (d) characteristic arrangement of autozooids and avicularia; (e) avicularium; (f) autozooids and avicularia from late astogeny at edge of colony. Scale bars: a = 1 mm; b = 500 µm; c, d, f = 200 µm; e = 100 µm.