Streblotrypa (Streblotrypa) parviformis, 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 : 27-30

Streblotrypa (Streblotrypa) parviformis n. sp.

Figures 12.8-10 , 13.1-3 ; Table 16

zoobank.org/ 5E091691-0A97-45F9-8BD6-091335B75870

Etymology. The species is named after its similarity with Streblotrypa (Streblotrypa) parva Morozova, 1965 .

Holotype. SMF 23.251 .

Paratypes. SMF 23.131 – SMF 23.142 , SMF 23.252 – SMF 23.261 .

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

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

Diagnosis. Thin branched colonies; axial bundle consisting of 3–7 axial zooecia; hemisepta absent; 12–20 metazooecia arranged between apertures; acanthostyles present.

Description. Branched colonies, 0.51–0.92 mm in diameter, with 0.09–0.17 mm wide exozones and 0.31–0.58 mm wide endozones. Autozooecia long, tubular, growing from a distinct axial bundle, rounded to slightly polygonal in transverse section. Axial bundle small, formed by 3–7 axial zooecia, 0.10–0.26 mm in diameter. Autozooecial apertures oval, arranged in regular diagonal rows. Autozooecial diaphragms locally present. Hemisepta absent. Metazooecia small, 12–20 of them arranged in three rows between apertures. Acanthostyles present, irregularly distributed between autozooecial apertures. Autozooecial walls laminated, 0.010 – 0.015 mm thick in endozone.

Remarks. Streblotrypa (Streblotrypa) parviformis n. sp. is similar to Streblotrypa (Streblotrypa) parva Morozova, 1965 from the Upper Permian of Caucasus, but differs from it by the presence of acanthostyles. Streblotrypa (Streblotrypa) parviformis differs from S. (S.) quadrata Liu, 1976 from the Lower Permian of China by the presence of acanthostyles and thinner branches (branch diameter 0.51–0.92 mm vs. 0.60–1.40 mm in S. (S.) quadrata ). Streblotrypa (Streblotrypa) parviformis differs from S. (S.) elegans Sakagami, 1970 from the Lower Permian of Thailand by possessing acanthostyles and lacking hemisepta.

Sub-genus STREBLOTRYPA ( STREBLASCOPORA ) Bassler, 1929

Type species. Streblotrypa fasciculata Bassler, 1929 . Upper Permian, Indonesia.

Diagnosis. Branched colonies. Clearly defined bundle of the axial zooecia in the endozone. Autozooecia budding from axial bundle, having long inflated proximal parts, rounded-polygonal in transverse section in the endozone, bending abruptly at the transition between endo- and exozone. Autozooecial apertures rounded to oval. Diaphragms rare. Inferior hemisepta commonly present, sometimes accompanied by superior hemisepta; in some species hemisepta absent. Metazooecia between the autozooecial apertures and beyond the distolateral margins of autozooecial apertures. Autozooecial walls laminated, without distinct autozooecial boundaries.

Remarks. Streblotrypa (Strebascopora) Bassler, 1929 differs from S. ( Streblotrypa ) Vine, 1885 by having a distinct axial bundle with more than 10 axial zooids.

Occurrence. Carboniferous to Permian; worldwide.

Streblotrypa (Streblascopora) delicatula Sakagami, 1961

Figure 13.4-8 ; Table 17

1961 Streblascopora delicatula Sakagami , p. 52, pl. 25, figs. 7-10, pl. 26, fig. 2-18, pl. 27, figs. 1-5.

1973 Streblascopora delicatula Sakagami, 1961 ; Sakagami, p. 84-85, pl. 8, figs. 1-4.

1984 Streblascopora delicatula Sakagami, 1961 ; Yang and Lu, p. 53-54, pl. 1, fig. 5b, pl. 2, 3a, b.

1997 Streblascopora delicatula Sakagami, 1961 ; Sakagami and Pillevuit, p. 212, figs. 4-(9-11), 5-1.

2008 Streblascopora delicatula Sakagami, 1961 ; Ernst, Weidlich and Schäfer, p. 692, figs. 9.1-9.2.

Material. SMF 23.143, SMF 23.205– SMF 23.208.

Description. Branched colonies, 1.3–2.0 mm in diameter. Axial bundle 0.45–0.67 mm in diameter. Axial zooecia arranged in 6–8 rows. Autozooecia budding from the axial bundle, having long inflated proximal parts, rounded to polygonal in transverse section in the endozone. Autozooecial apertures oval, arranged in regular diagonal rows. Superior hemisepta weakly developed; inferior hemisepta long. Terminal diaphragms common. Metazooecia small, oval to rounded, 6–9 of them arranged in 2– 3 rows between apertures. Autozooecial walls laminated, 0.005 –0.010 mm thick in endozone.

Remarks. Streblotrypa (Streblascopora) delicatula Sakagami, 1961 differs from S. (S.) marmionensis (Etheridge, 1926) in having wider and less closely spaced autozooecial apertures (average aperture width 0.16 mm vs. 0.10 mm in S. [S.] marmionensis ). Streblotrypa (Streblascopora) delicatula differs from S. (S.) germana Bassler, 1929 by the presence of hemisepta and wider autozooecial apertures (average aperture width 0.16 mm vs. 0.10 mm in S. [S.] germana ).

Occurrence. Lower Permian; Japan, Thailand. Aseelah Unit, Saal Formation (Lower–?Middle Permian); Batain Coast (eastern Oman). 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.

FIGURE 13. Thin section photographs of Streblotrypa (Streblotrypa) parviformis n. sp., paratype SMF 23.260 (1) and paratype SMF 23.256 (2 and 3); Streblotrypa (Streblascopora) delicatula Sakagami, 1961, SMF 23.205 (4, 6, and 7), SMF 23.206 (5), and SMF 23.143 (8); and Streblotrypa (Streblascopora) marmionensis (Etheridge, 1926), SMF 23.145 (9). 1 and 8, branch transverse section; 2, 3, 5, and 9, longitudinal section; 4, branch oblique section; and 6 and 7, tangential section.