Rhabdomeson sp.

Ernst, Andrej, 2016, Bryozoan fauna from the Permian (Artinskian-Kungurian) Zhongba Formation of southwestern Tibet, Palaeontologia Electronica (1946) 51 (9), pp. 1-59 : 34

Rhabdomeson sp.

Figure 15.1-5

Material. SMF 23.158– SMF 23.160.

Description. Branched colonies with small axial cylinder. Branches 1.48–1.53 mm in diameter. Axial cylinder circular, 0.26–0.34 mm in diameter. Autozooecia budding in a spiral pattern from the axial cylinder, rhomboid in transverse section. Autozooecial apertures oval, arranged in regular diagonal rows, 0.15–0.19 mm wide. Two macroacanthostyles between each aperture present, 0.05– 0.08 mm in diameter. Microacanthostyles abundant, arranged in one row between macroacanthostyles, 0.015 –0.020 mm in diameter. Superior hemisepta present, curved proximally. Diaphragms absent. Autozooecial walls laminated, 0.010 –0.015 mm thick in endozone.

Remarks. Rhabdomeson sp. is similar to R. bispinosum Crockford, 1944 from the Lower Permian (Artinskian) of Western Australia, but differs in the presence of hemisepta and by having wider autozooecial apertures (aperture width 0.15–0.19 mm vs. 0.08–0.10 mm in R. bispinosum ). Rhabdomeson sp. differs from R. consimile Bassler, 1929 from the Upper Permian of Timor, by having wider apertures (aperture width 0.15–0.19 mm vs. ca 0.12 mm in R. consimile ).

Occurrence. Zhongba Formation, Permian (upper Cisuralian –Guadalupian); Zhongba area of southwestern Tibet .

Figures

FIGURE 15. Thin section photographs of Rhabdomeson sp. SMF 23.160 (1–4) and SMF 23.158 (5); and Primorella rotunda Gorjunova, 1985, SMF 23.163 (6) and SMF 23.162 (7–9). 1–3, branch oblique section; 4 and 5, longitudinal section; 6, tangential section; and 7–9, oblique section.