Cyrtiopsis? cyrtiopsiformis ( Yang, 1977 )

Ma, Xue-Ping, Sun, Yuan-Lin, Hao, Wei-Cheng & Liao, Wei-Hua, 2002, Rugose corals and brachiopods across the Frasnian- Famennian boundary in central Hunan, South China, Acta Palaeontologica Polonica 47 (2), pp. 373-396 : 392-393

Cyrtiopsis? cyrtiopsiformis ( Yang, 1977)

Figs. 15F–J , 16 .

Arctospirifer cyrtiopsiformis Yang (sp. nov.); Yang et al. 1977: 434, pl. 172: 5

Material.—Fifteen complete specimens.

Remarks.—This species is characterized by a shell form almost identical with that of Cyrtiopsis graciosa Grabau, 1931 . They are similar in shell micro−ornamentation and shell outline and lateral profile. They are also identical in the structure of cardinalia, i.e., with a median cavity anterior to the cardinal process (compare fig. 16 with fig. 10 of Ma and Day 1999: 618). Differences lie in that the present species has a short delthyrial plate and has no pseudodeltidium. If there were sexual dimorphism in shell morphology of modern brachiopods, by analogy these two Devonian species would be taken as such an example. There have been indeed some reports of sexual dimorphism in fossil brachiopods such as Leiorhynchus ( Harrington 1969) .

Originally Yang et al. (1977) assigned this species to Arctospirifer Stainbrook, 1950 . However, Arctospirifer has no delthyrial plate ( Carter et al. 1994: 333 and X. P. Ma’s observations of Stainbrook’s type specimens) and has a median primary sinal plication instead of Cyrtospirifer − type sinal plications characteristic of the Cyrtospiriferidae ( Ma and Day 2000: 445) . Therefore Arctospirifer is not a cyrtospiriferid and Carter et al. (1994) reassigned it to the Echinospiriferidae of the Spinelloidea.

Occurrence.—Xinhua County (Upper Devonian); in the Jiangjiaqiao section (Qidong County), early Famennian.

Figures

Fig. 15. A–E. Platyspirifer paronai (Martelli, 1902), sample C−H.A. Interarea view of PUM 00026 showing the convex pseudodeltidium, × 2.75. B, C. Lateral and ventral views of PUM 00022; × 1.5. D, E. Dorsal and anterior views of PUM 00038; × 1.2. F–J. Cyrtiopsis? cyrtiopsiformis (Yang, 1977), sample C−H, anterior, ventral, dorsal, lateral, and posterior views of PUM 97011; all × 2 except I × 1.5. K–O. Sinospirifer subextensus (Martelli, 1902), sample C−H, anterior, posterior, dorsal, ventral and lateral views of PUM 00023; × 1.3. P, Q. Lamarckispirifer hayasakai (Grabau, 1931), sample C−H, anterior and posterior views of PUM 00028; × 1.3. R. Sinospirifer gortanioides Grabau, 1931; sample C−H, anterior view of PUM 98014, × 1.3.

Fig. 16. Transverse serial sections of Cyrtiopsis? cyrtiopsiformis from the Jiangjiaqiao section (sample C−H). Numbers refer to distance in mm from the ventral apex. Arrow indicates enlargement. Note the presence of a very short delthyrial plate and absence of a pseudodeltidium at the very posterior end of the ventral valve. Specimen PUM 00071 (97D).