Spirifer (Mesochorispira), 1992

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 : 826

Spirifer (Mesochorispira) sp.

Fig. 26L .

Material.—One fragment of anterior part of ventral valve and two small fragments of ventral umbonal part from sample MH1.

Remarks.—This species is extremely rare in the Muhua’s fauna being represented by three very incomplete specimens. The best preserved of them is a fragment of a large ventral valve showing well developed median sulcus, short tongue, and numerous radial costae which bi− or trifurcate ( Fig. 26L ). Growth lines preserved on the specimen indicate rather rounded, not angular cardinal extremities in the adult stage. All these features suggest that this material represents a species of the subgenus Spirifer (Mesochorispira) .

Figures

Fig. 26. Spiriferide brachiopods from the Tornaisian Muhua Formation, southern China. A–J. Parallelora sp. A. Incomplete dorsal valve, PKUM02−0516, in exterior (A1), interior (A2), and inclined interior (A3) views. B. Incomplete dorsal valve, PKUM02−0517, in exterior (B1) and interior (B2) views, and enlargement of cardinalia (B3). C. Incomplete dorsal valve, PKUM02−0518, in exterior (C1), interior (C2), and enlarged exterior (C3) views showing surface micro−ornamentation. D. Incomplete ventral valve, PKUM02−0519, in exterior (D1), interior (D2), and posterior (D3) views. E. Incomplete ventral valve, PKUM02− 0520, in exterior (E1) and interior (E2) views, and enlarged posterior region (E3). F. Interior of incomplete ventral valve, PKUM02−0521, showing partly preserved muscle scars. G. Incomplete ventral valve, PKUM02−0522, in exterior (G1) and interior (G2) views. H. Incomplete ventral valve, PKUM02−0523, in posterior (H1; showing subrectangular interarea), fragmentary interior (H2; showing denticulate hinge line), and exterior (H3) views. I. Incomplete ventral valve, ZPAL V.XXVI/71, in exterior (I1), interior (I2), and posterior (I3) views. J. Interior of incomplete ventral valve, PKUM02−0524, showing accessory denticulation. K. Finospirifer sp., incomplete ventral valve, PKUM02−0525, in anterior (K1) and exterior (K2) views. L. Spirifer (Mesochorispira) sp., exterior of incomplete ventral valve, PKUM02−0526; note numerous ctenostomate borings. Samples GB (A–H, J, K), GT (I), and MH1 (L).