Finospirifer 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 : 826

Finospirifer sp.

Fig. 26K .

Material.—One incomplete ventral valve from sample GB.

Remarks.—Although we have only one fragmentarily preserved ventral valve at our disposal ( Fig. 26K ) it is possible to determine it to the genus level quite convincingly. The valve is ornamented with about 20 simple costae on its flank. Sulcus is narrow, quite deep, with a few bifurcating costae. The median sulcal plication is very strong, disproportionally high, and carinate, extending much above the valve flanks in anterior profile. Although the specimen is incomplete and the general outline of the shell difficult to assess, the growth lines reveals that this form is characterised by strongly transverse outline. The latter feature precludes its assignment to the very similar Carboniferous genus Subspirifer Shan and Zhao, 1981 . According to Carter (2006: 1777) the genus Subspirifer may be a junior synonym of Finospirifer Yin, 1981 .

Finospirifer is a rare form found up to now only in Hunan and western Guizhou provinces, China ( Wu et al. 1974; Yin 1981; Tan 1986). Our specimen from Muhua (southern Guizhou Province) extends the geographic range of the genus. The ribbing pattern as well as the shape of the shell which can be traced according to the growth lines suggest that the specimens may represent F. taotangensis Yin, 1981 or F. shaoyangensis (Ozaki, 1939) , both from the early Carboniferous of Central Hunan ( Yin 1981). Tan (1986) described two other new species of Finospirifer from the early Carboniferous of central Hunan.

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).