Polypora brouweri Bassler, 1929

Ernst, Andrej, 2016, Bryozoan fauna from the Permian (Artinskian-Kungurian) Zhongba Formation of southwestern Tibet, Palaeontologia Electronica (1946) 51 (9), pp. 1-59 : 40-42

Polypora brouweri Bassler, 1929

Figure 18.5-9 ; Table 25

1929 Polypora brouweri Bassler , p. 77, pl. 18, figs. 7-10.

1946 Polypora goldfussi Eichwald, 1860 ; Metz, p. 181, pl. 19, fig. 9.

Material. SMF 23.183.

Exterior description. Reticulate colonies composed of moderately wide branches jointed by moderately wide dissepiments. Autozooecia arranged in 4–5 alternating rows on branches. Autozooecial apertures rounded to oval, 4–10 spaced per length of fenestrule. Fenestrules long, oval to rectangular. Keels and nodes absent. Reverse colony surface smooth.

Interior description. Autozooecial chambers moderately long, generally rhombic to roughly hexagonal, irregularly polygonal at places of bifurcation in the mid-tangential section. Hemisepta absent. External laminated skeleton well-developed, traversed by abundant small microacanthostyles. Heteromorphs not observed.

Remarks. Polypora brouweri Bassler, 1929 differs from P. principalis Gorjunova, 1975 from the Lower Permian of Pamir in having wider branches as well as larger fenestrules. Polypora brouweri differs from P. remota grandis Trizna, 1939 from the Lower Permian of Urals in having narrower branches (branch width 0.72–1.13 mm vs. 1.11– 1.39 mm in P. remota grandis ) and wider apertures (aperture width 0.12–0.16 mm vs. 0.11–0.13 mm in P. remota grandis ). Polypora goldfussi Eichwald, 1860 , as described by Metz (1946) from the Permian of northern Tibet, corresponds to Polypora brouweri Bassler, 1929 . The original species of Eichwald (1860), however, possesses cyclozooecia ( Nikiforova, 1938).

Occurrence. Permian; northern Tibet. Lower Permian (Sakmarian-Artinskian); Timor. Zhongba Formation, Permian (upper Cisuralian –Guadalupian); Zhongba area of southwestern Tibet .

Figures

FIGURE 18. Thin section photographs of Polypora consanguinea Bassler, 1929, SMF 23.182 (1–4); and Polypora brouweri Bassler, 1929, SMF 23.183 (5–9). 1, oblique section; 2–5, tangential section showing autozooecial apertures, nodes and autozooecial chambers; 6, reverse side of the colony; and 7–9, tangential section showing autozooecial apertures and chambers.