Dyscritella lii, Ernst, 2016

Ernst, Andrej, 2016, Bryozoan fauna from the Permian (Artinskian-Kungurian) Zhongba Formation of southwestern Tibet, Palaeontologia Electronica (1946) 51 (9), pp. 1-59 : 23

Dyscritella lii n. sp.

Figure 11.3-6 ; Table 13

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Etymology. The species is named in honour of Dr. Xianghui Li, who provided material for this study and helped during the manuscript preparation.

Holotype. SMF 23.235 .

Paratypes. SMF 23.236 and SMF 23.237 .

Type locality. Zhongba area of southwestern Tibet (E 84.31536, N 29.74233) .

Type stratum. Zhongba Formation, Permian (upper Cisuralian–Guadalupian).

Diagnosis. Encrusting colony; exilazooecia few; acanthostyles large, abundant, 8–14 surrounding each autozooecial aperture; exozonal walls thick.

Description. Encrusting colony, 0.99–1.05 mm thick, with 0.54–0.64 mm wide exozone. Autozooecial diaphragms absent. Autozooecial apertures rounded to slightly angular. Exilazooecia few, having rounded to polygonal transverse section, restricted to the exozone, 0.04–0.11 mm in diameter. Abundant acanthostyles in the walls of the exozone, originating from transitional zone between endozone and exozone, 8–14 surrounding each autozooecial aperture. Walls granular-prismatic, 0.02–0.03 mm thick in the endozone; laminated, regularly thickened, 0.08–0.13 mm thick in exozone. Maculae not observed.

Remarks. Dyscritella lii n. sp. differs from Dyscritella phetchabunensis Sakagami, 1975 from the Lower Permian of Thailand, by having larger and more abundant acanthostyles and fewer exilazooecia, as well as larger autozooecia (autozooecial aperture width 0.18–0.30 mm vs. 0.13–0.17 mm in D. phetchabunensis ). Dyscritella lii n. sp. differs from D. fida Morozova, 1991 from the Lower Permian of Mongolia in possessing more abundant acanthostyles (8–14 vs. 6–9 around each aperture in D. fida ), as well as larger autozooecia (autozooecial aperture width 0.18–0.30 mm vs. 0.18–0.20 mm in D. fida ).

Figures

FIGURE 11. Thin section photographs of Tabulipora xinjiangensis Yang and Lu, 1983, SMF 23.233 (1 and 2); Dyscritella lii n. sp., holotype SMF 23.235 (3, 4, and 6) and paratype SMF 23.236 (5); and Ulrichotrypella omanica Ernst et al., 2008, SMF 23.242 (7 and 8). 1, longitudinal section showing ring septa; 2, oblique section showing macroacanthostyles and tubules; 3 and 4, oblique section through the colony; 5 and 6, tangential section showing autozooecial apertures and acanthostyles; and 7 and 8, oblique section.