Neoeridotrypella astrica ( Linskaya, 1951 )

Ernst, Andrej, 2016, Bryozoan fauna from the Permian (Artinskian-Kungurian) Zhongba Formation of southwestern Tibet, Palaeontologia Electronica (1946) 51 (9), pp. 1-59 : 25-27

Neoeridotrypella astrica ( Linskaya, 1951)

Figure 12.2-7 ; Table 15

1951 Rhombotrypella astrica Linskaya , p. 150, pl. 3, figs. 3-4.

Material. SMF 23.243- SMF 23.250.

Description. Ramose colonies, 4.10–5.40 mm in diameter, with 0.54–0.82 mm wide exozone and 3.02–3.76 mm wide endozone. Autozooecial diaphragms absent. Autozooecial apertures rounded to slightly angular. Exilazooecia few, having rounded to polygonal transverse section shape, restricted to the exozone, 0.04–0.11 mm in diameter. Abundant stellate acanthostyles in the walls of the exozone, originating from transitional zone between endozone and exozone, strongly varying in size. Usually 1–4 macroacanthostyles and 5–10 microacanthostyles surrounding each autozooecial aperture. Walls granular-prismatic, 0.018 –0.025 mm thick in the endozone; laminated, regularly thickened, 0.15–0.26 mm thick in exozone. Tubules and spherules abundant in exozonal walls.

Remarks. Neoeridotrypella astrica ( Linskaya, 1951) differs from N. pulchra Morozova, 1970 from the Upper Permian (Kazanian) of Russia, in having slightly larger autozooecial apertures (aperture width 0.17–0.26 mm vs. 0.16–0.20 mm in N. pulchra ). Neoeridotrypella astrica differs from N. schilti Gilmour et al., 1997 from the Upper Permian (Wordian) of Nevada, USA, in having smaller autozooecial apertures (average aperture width 0.22 mm vs. 0.25 mm in N. schilti ). Furthermore, Neoeridotrypella astrica has no diaphragms instead of the few present in N. schilti , and stellate acanthostyles instead of normal ones.

Occurrence. Cisuralian (Artinskian–Kungurian); Northern Urals, Russia. Zhongba Formation, Permian (upper Cisuralian–Guadalupian); Zhongba area of southwestern Tibet.

Figures

FIGURE 12. Thin section photographs of Ulrichotrypella omanica Ernst et al., 2008, SMF 23.242 (1); Neoeridotrypella astrica (Linskaya, 1951), SMF 23.245 (2 and 3), SMF 23.246 (4–6), and SMF 23.249 (7); and Streblotrypa (Streblotrypa) parviformis n. sp., holotype SMF 23.251 (8–10). 1, 6, 7, and 10, tangential section; 2–5, oblique branch section; and 8 and 9, longitudinal section.