Cyclotrypa alexanderi Sakagami, 1963

Ernst, Andrej, 2016, Bryozoan fauna from the Permian (Artinskian-Kungurian) Zhongba Formation of southwestern Tibet, Palaeontologia Electronica (1946) 51 (9), pp. 1-59 : 13

Cyclotrypa alexanderi Sakagami, 1963

Figure 6.4-7 ; Table 7

1963 Cyclotrypa alexanderi Sakagami , p. 206, pl. 12, figs. 1-7.

1976 Cyclotrypa alexanderi Sakagami, 1963 ; Sakagami, pl. 25, figs. 1-2.

Material. SMF 23.053– SMF 23.066.

Description. Colonies branched ramose or encrusting. Branched colonies 7.5–9.6 mm in diameter, with 1.2–1.3 mm wide exozone and 5.1– 7.0 mm wide endozones. Encrusting colonies 1.3– 1.9 mm thick. In branched colonies, cylindrical autozooecia long in endozones, bending sharply in exozones, rounded–polygonal in transverse section. In secondary overgrowths and encrusting sheets, autozooecia growing from laminated epitheca. Epitheca 0.025 –0.030 mm thick. Autozooecial diaphragms few to common. Autozooecial apertures rounded to oval. Granular material well-developed at colony surface. Acanthostyles in granular material developed, 0.05–0.07 mm in diameter. Locally macrozooecia occurring. Vesicular skeleton well-developed. Vesicles small, separating autozooecia in 1–2 rows, 5–11 surrounding each autozooecial aperture, with rounded roofs, polygonal in tangential section. Autozooecial walls granular prismatic, 0.003 –0.008 mm thick. Low maculae without autozooecia regularly spaced on colony surface, 0.4–0.9 mm in diameter.

Remarks. Cyclotrypa alexanderi Sakagami, 1963 differs from C. uralica Nikiforova, 1939 from the Lower Permian (Artinskian) of Urals in smaller autozooecial apertures (aperture width 0.17–0.25 mm vs. 0.35 mm in C. uralica ). Cyclotrypa alexanderi differs from C. exposita Gorjunova, 1975 from the Lower Permian (Artinskian) of Pamir in smaller autozooecial apertures (aperture width 0.17–0.25 mm vs. 0.35–0.40 mm in C. exposita ).

Occurrence. Noonkanbah Formation, Lower Permian (upper Artinskian–Kungurian); Western Australia (unpublished data). Lower Permian (Artinskian); Malaysia. Zhongba Formation, Permian (upper Cisuralian–Guadalupian); Zhongba area of southwestern Tibet.

Figures

FIGURE 6. Thin section photographs of Eridopora uncata Yang and Lu, 1983, SMF 23.052 (1–3); Cyclotrypa alexanderi Sakagami, 1963 SMF 23.056 (4–5), SMF 23.061 (6), and SMF 23.056 (7); and Hexagonella kobayashii Sakagami, 1968, SMF 23.069 (8–9) and SMF 23.070 (10 and 11). 1–3, tangential section showing autozooecial apertures with lunarial ends indenting into the aperture (arrow); 7, tangential section showing autozooecia and macrozooecia (arrow); 8 and 9, branch transverse section showing autozooecial chambers and vesicular skeleton; and 10 and 11, longitudinal section showing autozooecial chambers and vesicular skeleton.

FIGURE 7. Thin section photographs of Hexagonella kobayashii Sakagami, 1968, SMF 23.067 (1–3) and SMF 23.072 (4); and Goniocladia aff. indica Waagen and Pichl, 1885, SMF 23.266 (5), SMF 23.077 (6), and SMF 23.073 (7). 1–3 and 6, tangential section; 7, mid-tangential section showing autozooecial chamber; 4, transverse section showing mesotheca with median tubules (arrow); and 5, external view of the colony form the reverse side.