Plasmoporella xinjiangensis Lin and Wang

Cui, Yu-Nong & Wang, Guang-Xu, 2023, Early Katian, Late Ordovician, heliolitine corals from southern Kuruktag in northeastern Tarim Basin of China, Acta Palaeontologica Polonica 68 (2), pp. 273-295 : 276-282

publication ID	https://doi.org/ 10.4202/app.01023.2022
persistent identifier	https://treatment.plazi.org/id/03F35C14-FF8E-FFAB-885B-FAB083D842FD
treatment provided by	Felipe
scientific name	Plasmoporella xinjiangensis Lin and Wang
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Plasmoporella xinjiangensis Lin and Wang in Wang, 1981

Figs. 3 View Fig , 4 View Fig , 5 View Fig .

1981 Plasmoporella xinjiangensis sp. nov.; Lin and Wang in Wang 1981: 70, pl. 36: 2.

1986 Plasmoporella xinjiangensis Lin and Wang in Wang, 1981; Lin and Wang 1986: 52, pl. 8: 3a, 3b.

1990 Plasmoporella xinjiangensis Lin and Wang in Wang, 1981; Kong and Song 1990: 157, pl. 28: 2.

1990 Plasmoporella yuanbaoshanensis sp. nov.; Kong and Song 1990: 158, pl. 27: 3.

2015 Plasmoporella xinjiangensis Lin and Wang in Wang, 1981; Yang et al. 2015: 87, pl. 74: 3, 4.

Material.—Forty-five sectioned specimens, NIGP 200945– 200989 from the Yuanbaoshan Formation (lower Katian) of southern Kuruktag, Tarim Basin, China.

Emended diagnosis.— Plasmoporella with TaDs 1.60– 2.35 mm. Trabecular septa long some extending to corallite axis. Tabulae incomplete. Coenenchyme consisting of dissepiments, with vertical trabeculae present.

Description.—Eight almost complete coralla are measured, of low domical to high bulbous form, with the largest 80.24 mm wide and 33.96 mm high, and the smallest 44.12 mm wide and 16.72 mm high. Corallites rounded, 1.82–2.35 mm (average 2.14 mm) in diameter. Corallites outlined by 12 thick well-developed trabeculae, with walls of tabularia defined largely by downturned margins of coenenchymal dissepiments. Septa generally lachrymiform in transverse section, with a maximum width of 0.30– 0.65 mm (average 0.42 mm). The trabeculae may extend into corallites and coenenchyme, some extending to the corallite axis. Septa spinose in axial margin and appearing as numerous black dots in transverse section. Tabulae incomplete, slightly convex, Ta5 23–26. Corallite centers 2.10–3.20 mm apart (average 2.58 mm). Intercorallite spaces filled with coenenchyme of convex dissepiments. Dissepiments generally 0.16–0.49 mm (average 0.31 mm), 24–28 in 5 mm. A large number of trabeculae scattered in the coenenchyme, often passing through a few dissepiments.

Remarks.—Our specimens show closest resemblance to the holotype of Plasmoporella xinjiangensis Lin and Wang in Wang, 1981, documented from the Upper Ordovician Bulongor Formation of Hobuksar in northwestern Xinjiang, differing only in having longer septa. For this reason, we assign these specimens to P. xinjiangensis .

The specimens described as P. xinjiangensis by Lin and Wang (1986) from the same level and locality as the holotype and by Kong and Song (1990) from the Uligezitag Formation (lower Katian) of northern Kuruktag in northeastern Xinjiang are almost identical to the type material of the species, with the Uligezitag material having slightly smaller corallites (1.6–2.0 mm in diameter). Yang et al. (2015) also recorded P. xinjiangensis from the Sandbian Lianglitag Formation of Well 70 of central Tarim, the tabulae of which are more complete. Plasmoporella yuanbaoshanensis Kong and Song, 1990 , from the Yuanbaoshan Formation (lower Katian) of southern Kuruktag is attributable to P. xinjiangensis based on its comparable corallite size, which only differs in having weakly developed septa.

The diagnosis of P. xinjiangensis is revised herein based on all the material now assigned to this species, with major revisions including an extension of the range of corallite size (1.60–2.35 mm) and the variation of septal length. Its comparison with similar species is shown in Table 1 and discussed below. Plasmoporella multitrabeculata Lin and Chow, 1977 , and Plasmoporella cystosa Lin and Chow, 1977 , both from the middle Sanqushan Formation (upper Katian) of Jiangxi, southeastern China, can be distinguished from P. xinjiangensis by their much smaller corallites (1.3–1.6 mm in diameter) and larger corallites (2.1–2.5 mm in diameter), respectively. Plasmoporella cystosa further differs in possessing much shorter septa.

Stratigraphic and geographic range.—The Yuanbaoshan Formation (lower Katian) of southern Kuruktag, northeastern Tarim, China; the Bulongor Formation (Katian) of Hobuksar, northwestern Xinjiang, China; the Uligezitag Formation (lower Katian) of northern Kuruktag, northeastern Tarim, China; the Lianglitag Formation (lower Katian) of Well 70 of central Tarim, Xinjiang, China.

Plasmoporella grandis Bondarenko, 1958

Figs. 6 View Fig , 7 View Fig .

1958 Plasmoporella grandis sp. nov.; Bondarenko 1958: 210, pl. 4: 3, 4.

Material.—Ten sectioned specimens, NIGP 200990– 200999 from the Yuanbaoshan Formation (lower Katian) of southern Kuruktag, Tarim Basin, China.

Emended diagnosis.—Species of Plasmoporella with TaDs 3.00– 4.50 mm. Septa long and thin, Tabulae complete to incomplete, strongly convex axially.

Description.—Ten complete coralla are measured, which are mostly low-domed, and sometimes bulbous or high-domed, with the largest 88.57 mm wide and 37.30 mm high, and the smallest 30.70 mm wide and 22.80 mm high. Corallites rounded and slightly stellated, with tabularium diameters varying from 3.02–4.11 mm (average 3.65 mm). Corallites walls outlined by edges of coenenchymal dissepiments. Septa of trabecular type, sometimes bifurcated, 12 in number, normally extending no more than one-eighth the TaD into tabularia, with maximum widths ranging from 0.53 to 0.87 mm (average 0.65 mm). Septa inclined upwardly and shown as dark dots in transverse section. Tabulae mostly complete, some strongly convex axially, closely spaced, with Ta5 13–17. Corallites separated by narrow cenenchyme, with their centers 4.26–4.35 mm apart (average 4.31 mm). Coenenchyme consisting of dissepiments, with vertical trabeculae observed. Dissepiments generally 0.68–1.16 mm wide (average 0.87 mm). Frequency of dissepiments similar throughout at 22–26 per 5 mm.

Remarks.—The present material is conspecific with Plasmoporella grandis Bondarenko, 1958 , from the Upper Ordovician Dulankara Formation of the Chu-Ili Terrane in southern Kazakhstan. Their major difference lies in the more complete tabulae of the former. On this basis, we include this feature in the diagnosis of this species. This species was assigned to Granulina by Bondarenko (1992), which was recently regarded as a synonym of Plasmoporella by Cui et al. (2022).

A comparison of Plasmoporella grandis with similar species is shown in Table 1 and discussed below. In the trabecular development P. grandis strongly resembles Plasmoporella bifida Bondarenko, 1958 , also from the Dulankara Formation of southern Kazakhstan. The major differences are smaller corallites (2.8–3.0 mm in diameter) and more incomplete tabulae of the latter. Plasmoporella gigantea Lin and Wang, 1986 , from the Upper Ordovician Bulongor Formation of Hobuksar in northwestern Xinjiang differs from P. grandis in having much larger corallites (4.2–5.0 mm in diameter) and sparser tabulae (6–7 per 5 mm). Plasmoporella qiakertensis Lin and Wang, 1985 , from the Upper Ordovician Gabosar Formation of Gabosar in northern East Junggar, Xinjiang, is distinguished by smaller corallite size (3.0– 3.5 mm in diameter) and more complete tabulae.

Stratigraphic and geographic range.—The Yuanbaoshan Formation (lower Katian) of southern Kuruktag, northeastern Xinjiang, China; the Dulankara Formation (lower Katian) of the Chu-Ili Terrane, southern Kazakhstan.