Smithicyathus cinctus ( Smith, 1945 )

Wrzołek, Tomasz, 2007, A revision of the Devonian rugosan phillipsastreid genus Smithicyathus, Acta Palaeontologica Polonica 52 (3), pp. 609-632 : 616-618

Smithicyathus cinctus ( Smith, 1945)

Figs. 5A , 6A.

1945 Phillipsastrea cincta sp. nov; Smith: 43, pls 22: 4a–c, 23. non 1952 Pachyphyllum cinctum (Smith) ; Soshkina 1952: 86, pl. 20: 74

(possibly to Chuanbeiphyllum ) non 1962 Phillipsastrea cincta Smith ; McLaren and Norris 1962: pl.

11: 28, 29 (to Smithicyathus mcleani sp. nov., see Fig. 6C) 1986 Smithicyathus cinctus (Smith) ; Sorauf and Pedder 1986:pl. 5: 1, 4. 1994 Smithicyathus cinctus ( Smith, 1945) ; McLean 1994b: 80–82

(partim), pl. 3: 1–4 (non pl. 2: 2–5 = S. mcleani sp. nov.).

Material.— Besides the holotype ( GSC 9244 ) there are two other, possibly topotypical colonies listed by McLean (1994b: 81) from the Uppermost Frasnian of Alberta, Canada: GSC 98205 , 98206 .

Diagnosis.—The massive species of Smithicyathus with septa present only at the inner boundary of the dissepimentarium, i.e., in the vicinity of the vertical series of horseshoe dissepiments, with very large corallites (DIC is over 7.7 mm), commonly with more than one tabularium within a single intercorallite wall.

Discussion.—This species is geographically isolated from others of the genus. Two morphotypes: massive and phaceloid, were included into the species by McLean (1994b), with massive specimens indicated as topotypic. Measurements and the numerical analysis by me ( Tables 1, 2 and Appendix 2) suggest that; (1) massive and phaceloid colonies should be regarded as separate species (different CO and DIC parameters); and (2) comparison with the other species (Appendix 2) indicates that the tabularium diameter (TM and TW), and consequently L1 and L2, are larger in the Canadian material (both in massive S. cinctus and in phaceloid S. mcleani sp. nov.), than in any other species of Smithicyathus , with the exception of the two Siberian species S.? emendatus and S.? russakovi . Further comparison with the two latter species will be possible when more Siberian material is available. Among the best−known species of the genus, S. cinctus is morphometrically and morphologically most similar to S. smithi and its closely related species, S. lubliniensis , but the latter two typically have smaller corallites (lower values of DIC, TM, lower septal number). Pachyphyllum cinctum of Soshkina (1952; mentioned under “dubious species” above; see also Appendix 3, column “o”) possibly represents a distinct species of the phillipsastreid genus Chuanbeiphyllum He, 1978 (as suggested by McLean 1994b: 81).

Stratigraphic and geographic range.—Uppermost Frasnian of the District of Mackenzie, western Canada: Kakisa Formation ( McLean 1994b: 81).

Figures

Fig. 5. Wall and septal microstructures in the Upper Frasnian Smithicyathus. A. The holotype of massive Smithicyathus cinctus (Smith, 1945), Western Canada, GSC 9244, with non−cerioid, locally discontinuous intercorallite walls; for details of sampling location see McLean 1994b: 80, 81 (A1 transverse, A2 longitudinal section). B. Smithicyathus lacunosus (Gürich, 1896), Panek quarry, GIUS 384P 54, densely phaceloid colony with cerioid (tripartite) intercorallite walls predominating, but also with pseudocerioid segments, mainly between parent and offset corallites close to offsetting area, note also presence of 3rd order septa at some corallite peripheries (B1 transverse, B2 longitudinal section). C. Smithicyathus smithi (Różkowska, 1953), Zgórsko quarry, GIUS 382ZS 14, massive pseudocerioid colony with occasional intercorallite voids, bordered by epithecate walls (C1 transverse, C2 longitudinal section).Scale bar 2 mm for all items.