Brachythyris sp.

Sun, Yuanlin & Baliński, Andrzej, 2011, Silicified Mississippian brachiopods from Muhua, southern China: Rhynchonellides, athyridides, spiriferides, spiriferinides, and terebratulides, Acta Palaeontologica Polonica 56 (4), pp. 793-842 : 832

Brachythyris sp.

Fig. 30A–E .

Material.—Five very fragmentary ventral valves from sample MH1 and one incomplete ventral valve from sample MH2.

Remarks.—Assignment of this scarce material to the genus Brachythyris is based on external characters, including the presence of a narrow sulcus, weak, rounded and simple radial costae, as well as on the absence of dental adminicula in the interior of the ventral valve ( Fig. 30A–E ). The median costa which can be observed in the specimens described below as Skelidorygma sp. does not occur in the form here described suggesting that it should be better placed in the genus Brachythyris .

Figures

Fig. 30. Brachythyrid brachiopods from the Tornaisian Muhua Formation, southern China. A–E. Brachythyris sp. A, B, E. Three incomplete ventral valves, PKUM02−0548 (A), PKUM02−0549 (B), and PKUM02−0550 (E), in exterior (A1, B1, E1), interior (A2, B2, E2), and posterior (A3, B3, E3) views. C. Incomplete ventral valve, PKUM02−0551, in exterior (C1) and interior (C2) views.D. Slightly broken ventral valve, PKUM02−0552, with heavily abraded surface costation in exterior (D1), lateral (D2), interior (D3), inclined interior (D4), and posterior (D5) views. F–I. Skelidorygma sp. F. Incomplete ventral valve, PKUM02−0553, in exterior (F1), interior (F2), and lateral (F3) views. G. Almost complete shell, PKUM02−0554, in dorsal (G1), ventral (G2), lateral (G3), posterior (G4), and anterior (G5) views. H. Ventral valve, PKUM02−0555, in exterior (H1), interior (H2), and posterior (H3) views. I. Umbonal region of a ventral valve, PKUM02−0556, in posterior (I1) and posterodorsal (I2) views, showing delthyrial cover and pedicle opening.Sample MH1 (A–C), MH2 (D), GB (E, G, H), and GT (F). Scale bars 5 mm.