Chenmengella A. Zhuravlev, Liñán, and Gámez Vintaned

Zhuravlev, Andrey Yu., Liñán, Eladio, Vintaned, José Antonio Gámez, Debrenne, Françoise & Fedorov, Aleksandr B., 2012, New finds of skeletal fossils in the terminal Neoproterozoic of the Siberian Platform and Spain, Acta Palaeontologica Polonica 57 (1), pp. 205-224 : 219

Genus Chenmengella A. Zhuravlev, Liñán, and Gámez Vintaned nov.

Etymology: In honour of Professor Chen Meng’e, one of the discoverers of the Ediacaran skeletal fauna, and in order to modify the original generic name ( Chenella ).

Type and only species: Chenella laevis Zhang, Li, and Dong in Ding et al., 1992; China, southern Shaanxi Province, Yangtze Platform, Dengying Formation, Beiwan Member, upper Ediacaran ( Ding et al. 1992: 89, pl. 14: 3, holotype).

Diagnosis.—Cylindrical to weakly tapering, straight to slightly and irregularly curved, primarily calcareous tubicolous microfossil with circular to slightly oval cross−section and thin single−layered wall. Both wall surfaces are smooth.

Remarks.—The generic name is preoccupied by a foraminifer Chenella Miklukho−Maklay, 1959 and is thus replaced here (see Miklukho−Maklay 1959).

Although Chenmengella (= Chenella ) until now has been described only from South China ( Ding et al. 1992; Hua et al. 2000a, b; Zhang and Hua 2000) it is probably one of the most widespread Ediacaran skeletal fossils. It occurs in the La Ciénega Formation of northwestern Sonora, Mexico ( Cambrotubulus cf. C. decurvatus Missarzhevsky, 1969 and? C. cf. C. decurvatus in McMenamin, 1985: figs. 5.1, 5.4) and in the Turkut Formation on the northern Siberian Platform ( Cambrotubulus decurvatus Karlova, 1987 : fig. 1). Possibly, Cambrotubulus decurvatus commonly listed from the lowermost Nemakit–Daldynian part of the Ust’−Yudoma Formation on the southern Siberian Platforms (e.g., Khomentovsky and Karlova, 2005: 24) belongs to the same genus. By comparison with Cambrotubulus , Chenmengella lacks the thriradial symmetry of a cross−section and possesses straight to irregularly curved cylindrical tubes rather than regularly curved narrow conical shells.

In its morphology and dimensions, two other species of Chenmengella are similar to Chenmengella laevis (Zhang, Li, and Dong in Ding et al. 1992) from the Beiwan Member of the Dengying Formation of Shaanxi Province, South China. The species Chenmengella canaliculata Zhang et al. ( Ding et al. 1992: pl. 14: 10; Hua et al. 2000a: pl. 2: 9; Zhang and Hua 2000: pl. 1: 4) differs from the type species by the presence of a brittle fracture following the tube length, probably merely indicating a fragility of such thin−walled tubes. Similarly, Steiner et al. (2007) noted that in the case of C. canaliculata , a single specimen existed only which exhibits a longitudinal furrow and dumbbell−shaped cross−section, both resulting from compaction. In turn, Chenmengella regularis Zhang and Hua, 2000 ( Hua et al. 2000a: pl. 1: 2, 2000b: pl. 2: 11; McCall 2006: fig. 149.11) does not show any distinct feature other than a slightly different curvature of the longest tube fragments. As well, all these species co−occur in the same locality and are thus treated here as subjective synonyms.

Stratigraphic and geographic range.—Upper Ediacaran; Yangtze Platform ( China), Siberian Platform ( Russia) and Laurentia ( Mexico).