Goniocladia aff. indica Waagen and Pichl, 1885

Ernst, Andrej, 2016, Bryozoan fauna from the Permian (Artinskian-Kungurian) Zhongba Formation of southwestern Tibet, Palaeontologia Electronica (1946) 51 (9), pp. 1-59 : 14-16

Goniocladia aff. indica Waagen and Pichl, 1885

Figures 7.5-7 , 8.1-7 ; Table 9

aff. 1885 Goniocladia indica Waagen and Pichl , p.

805, pl. 93, fig. 3. aff.? 1929 Goniocladia indica Waagen and Pichl, 1885 ;

Bassler, p. 88. aff.? 1957 Goniocladia indica Waagen and Pichl, 1885 ;

Crockford, p. 38. aff. 1981 Goniocladia indica Waagen and Pichl, 1885 ;

Yang, Lu and Xia, p. 92-93, pl. 1, fig. 5, pl. 3,

fig. 4. aff. 1986 Goniocladia cf. indica Waagen and Pichl,

1885; Xia, pl. 11, figs. 1-2. aff. 1991 Goniocladia indica Waagen and Pichl, 1885 ; Xia, p. 191, pl. 7, fig. 10.

Material. SMF 23.073– SMF 23.080, SMF 23.266.

Diagnosis. Reticulate colony consisting of anastomosing bifoliate branches of intermediate width and thickness; fenestrules oval to circular, intermediate in size; autozooecia arranged in 4–6 rows on branches; autozooecial apertures with lunaria; vesicular skeleton well-developed, consisting of small vesicles; extrazooecial skeleton well-developed.

Description. Reticulate colony consisting of anastomosing bifoliate branches. Branches 0.88–2.00 mm wide and 0.63–1.26 mm thick. Fenestrules oval to polygonal (pentagonal to hexagonal), occasionally nearly circular. Autozooecia tubular, semicircular in transverse section at their bases, relatively short, budding in 4–6 rows from each side of thin mesotheca, opening on both sides of the median carina. Superior hemisepta positioned on the distal side of the autozooecial chamber near its bend; inferior hemisepta positioned on the proximal side (at mesotheca). Basal diaphragms rare. Mesotheca straight or slightly undulating, consisting of granular–prismatic material, with dark median layer, 0.02–0.04 mm thick, protruding on the obverse side as a median carina and as a sharp keel on the reverse side. Autozooecial apertures arranged regularly in 2–6 diagonal rows on both sides of the median carina, rounded to oval. Outermost parts of median lamina containing median rods, 0.010 –0.015 mm in diameter. Lunaria moderately developed, directed towards median carina. Autozooecial walls 0.02–0.04 mm thick, granular–prismatic. Extrazooecial skeleton (stereom) granular. Vesicular skeleton consisting of low small vesicles with flattened roofs, concentrated mostly in endozone.

Remarks. The present material superficially resembles the species Goniocladia indica Waagen and Pichl, 1885 , originally described from the Productus Limestone (?Kungurian–Wordian) of Salt Range, Pakistan. The original description of this species is based on external characters without use of thin sections. Only figure 3e from plate 93 ( Waagen and Pichl, 1885) shows a broken piece of branch, which reveals zooecial shape and vesicular skeleton typical for Goniocladia . Some important measurements such as aperture size and spacing of the original material are also unknown. Therefore, the assignment to this species by later authors was justified according to external parameters. Waagen and Pichl (1885, p. 805-806) provided the following measurements: branch width ca 1.5 mm, fenestrule length 3–7 mm, and fenestrule width 1–4 mm. They correspond in general with those of the present material. However, the present material possesses superior and inferior hemisepta, which were neither mentioned nor depicted in the original material.

The present species is, therefore, only tentatively assigned with Goniocladia indica Waagen and Pichl, 1885 . It differs from G. afghana ( Termier and Termier, 1971) from the Lower Permian of Afghanistan and Iran (Ernst and Gorgij, 2013) by larger fenestrules (fenestrule length 4.3–6.9 mm vs. 1.26–2.73 mm in G. afghana ; fenestrule width 2.4–3.7 mm vs. 0.75–1.56 mm in G. afghana ). Moreover, the present species has wider spaced apertures (average aperture spacing 0.60 mm vs. 0.45 mm in G. afghana ).

The present species differs from Goniocladia yongzhuensis Liu and Wang, 1987 from the Lower Permian (Artinskian) of Tibet in possessing smaller autozooecial apertures (aperture width 0.15–0.22 mm vs. 0.20–0.24 mm in G. yongzhuensis ) and larger fenestrules (fenestrule length 4.3–6.9 mm vs. 0.64–5.6 mm in G. yongzhuensis ).

Bassler (1929) and Crockford (1957) mentioned Goniocladia indica , but they did not provide either descriptions or illustrations of their material. Chinese citations of Goniocladia indica Waagen and Pichl, 1885 ( Yang et al., 1981; Xia 1986, 1991) seem to correspond to the species described here. However, no description mentioned hemisepta.

Occurrence.?Lower Permian; Tibet.? Productus Limestone (?Kungurian–Wordian) of Salt-range, Pakistan.?Lower Permian; Western Australia.?Lower Permian; Timor. Zhongba Formation, Permian (upper Cisuralian–Guadalupian); Zhongba area of southwestern Tibet.

Figures

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.

FIGURE 8. Thin section photographs of Goniocladia aff. indica Waagen and Pichl, 1885, SMF 23.076 (1 and 2), SMF 23.077 (3–5), and SMF 23.073 (6 and 7); and Liguloclema meridianus (Etheridge, 1926), SMF 23.093 (8). 1–2, and 6, branch transverse sections showing autozooecia chambers, mesotheca and hemisepta (arrow); 3–5, tangential sections showing autozooecial apertures; 7, longitudinal section showing autozooecial chamber with superior hemisepta (arrow); and 8, branch oblique section showing mesotheca, autozooecial chambers with hemisepta and vesicular skeleton.