Chengxianoproductus cf. changxingensis Liao and Meng, 1986

Chen, Zhong-Qiang, Campi, Monica J., Shi, Guang R. & Kaiho, Kunio, 2005, Post-extinction brachiopod faunas from the Late Permian Wuchiapingian coal series of South China, Acta Palaeontologica Polonica 50 (2), pp. 343-363 : 358

Chengxianoproductus cf. changxingensis Liao and Meng, 1986

Figs. 7K, 10B , 14 .

cf. Waagenoconcha palliata (Kayser) ; Chao 1927: 90, pl. 7: 3, 4, not 5, 6. cf. “ Waagenoconcha ” palliata (Kayser) ; Wang et al. 1964: 286, pl. 40:

22–24. cf. Chengxianoproductus changxingensis n. sp.; Liao and Meng 1986: 80.

Locality and horizon: Daijiagou section; 1 st member of the Lungtan Formation.

Material.—Of five studied specimens, NMV P309626 and NMV P309640 are figured.

Description.—Large size for genus; subquadrate in outline; nearly circular in lateral profile; widest at midlength of shell; ears broad, flat, well−demarcated from umbo. Ventral valve strongly convex; beak small, distinct, incurved, slightly overhanging hingeline; lateral slopes steep; median sulcus broad, distinct; dorsal valve slightly concave, flattening posteriorly; median fold low, originating anterior to umbo. Ventral exterior with broad, flattened concentric bands, bearing 6–7 rows of circular spine bases tending to be alternatively arranged; row of spines along hinge. Dorsal ornament similar to that of ventral valve. Ventral interior with dendritic muscle scars, without median septum. Cardinal process bilobed with cardinal process a shallow, circular alveolus; lateral ridges extending from base of cardinal process, curving down inside ears; median septum low, extending over half disc length ( Fig. 14 ).

Remarks.—When they established the present species, Liao and Meng (1986) questionably assigned parts of Kayser’s (1883: pl. 27: 9–12) specimens to their new species C. changxingensis . However, as stated in the above generic discussion, the specimens figured by Chao (1927) and Wang et al. (1964) are not conspecific with the type specimens of Parapulchratia palliata Kayser, 1883 . Accordingly, C. changxingensis only includes parts of the figured materials by Chao (1927: pl. 7: 3, 4). Of these, the specimen figured by Chao (1927: pl. 7: 3) and Wang et al. (1964: pl. 40: 22–24) was selected as the holotype of the species by Liao and Meng (1986).

The Daijiagou materials are comparable with the Changxing type in size, shell outline, spine arrangement and observed internal features. However, the conspicuous, smooth grooves separating lamellae are not preserved in Chao’s original specimens. Consequently, the assignment of the Daijiagou materials to C. changxingensis is tentative. In addition, the specimen NMV P309640 also approaches C. nitens Liao and Meng, 1986 in many aspects, but C. nitens can not include the described material as it is smaller and has a greater number of lamellae and fewer rows of spines on each lamella. The Changhsingian species C. intercedens Liao and Meng, 1986 is differentiated from the described specimen (NMV P309640) by its deeper ventral median sulcus and a greater number of lamellae. Tschernyschewia sinensis ( Chao, 1927) is also characteristic of the Lungtan Coal Series and morphologically indistinguishable from C. changxingensis , from which the T. sinensis differs in possessing a more elongate outline and the absence of conspicuous bands.

Figures

Fig. 10. A. Meekella kueichowensis (Huang, 1933), dorsal (A1), ventral (A2), and lateral (A3) views of NMV P309622. B. Chengxianoproductus cf. changxingensis Liao and Meng, 1986, ventral (B1), posterior (B2), lateral (B3), and dorsal (B4) views of NMV P309640 (B); B5, enlargement of fine, densely arranged spine bases of B1. C, D. Spinomarginifera alpha Huang, 1932, lateral (C1), posterior (C2), ventral (C3), and dorsal (D) views of a complete specimen NMV P309643 and a dorsal external mold NMV P309644. E–H. Transennatia gratiosa (Waagen, 1884), ventral (E1, G, H1), anteroventral (E2, H2), posterior (E3, H3), lateral (E4, H4), and internal (F) views of a ventral internal mold NMV P309639 (E), and latex replica NMV P309638 (F) of the ventral internal mold (E –E), a ventral internal mold NMV P309636 (G) and a dorsal external mold NMV P309637 (H –H). A, E, F, G, from the 4th member of the Lungtan For1 4 1 4 mation of Daijiagou; B, from the 1st member of the Lungtan Formation of Daijiagou; C, D, H, from the 5th member of the Lungtan Formation of Daijiagou.

Fig. 14. Cardinal process of Chengxianoproductus cf. changxingensis Liao and Meng, 1986 (based on specimen NMV P309640).