Cadosinopsis rehakovii sp. nov., a new calcareous dinocyst from the Jurassic-Cretaceous transitional interval of the Western Tethys

[摘要] Variegated limestones, a transitional series between red, Upper Jurassic radiolarite and whitish, Lower Cretaceous Maiolica limestone in the Pieniny Klippen Belt deposits in the Polish part of the Western Carpathians, have yielded rich microfossil assemblages with common calcareous dinoflagellate resting stages, hereafter, dinocysts. We found an undescribed dinocyst species in red-greenish limestone of a deep water, pelagic habitat in the Branisko succession of the Pieniny Klippen Basin and named it Cadosinopsis rehakovii sp. nov. The new species has a spherical to oval calcareous test ranging from 34 to 59 μm in length and 30 to 50 μm in width, with two layered wall. The inner layer is built of coarse–thick, plate-shaped calcite crystals and is white in transmitted light. The outer layer is built of fibrous crystals, vitreous (transparent) in transmitted light. The aperture is wide and seen only in the inner layer. We compared the detailed morphological characteristics of the new species with another species from the same genus in the Jurassic and Cretaceous Tethyan deposits. Specimens have been measured, grouped and interpreted using cluster analysis, principal component analysis (PCA) and canonical variate analysis (CVA). Among them, the new species shows a resemblance in cross-section to other species of Cadosinopsis , C . nowaki Borza, 1984, and C . andrusovi Scheibner 1967, previously described in literature. However, the two species are easily distinguishable by some features. Cadosinopsis . nowaki is bigger in size (length from 50 to76 μm and width from 43 to 67 μm), its inner layer is thicker and consists of vitreous-sparite calcite, and it has less centrically located chamber. C . andrusovi is much bigger in size as its length ranges from 68 to 108 μm and width ranges from 60 to 80 μm, and the cyst is more oval and its chamber less spherical. The new species is the third Cadosinopsis species described in the Tethyan realm and about two hundred and sixty-first fossil species (morphotype) described in the world so far.

[学科分类] 急救医学