Natantesprifmata rogersi, Hussain & Rogers & Blackburn, 2022

Hussain, Rowshi, Rogers, Steven L. & Blackburn, Joel A., 2022, Ovummuridae (calcareous microfossils) from the Much Wenlock Limestone Formation, Shropshire, UK, Palaeontologia Electronica (a 27) 25 (2), pp. 1-24 : 12-14

Natantesprifmata rogersi sp. nov.

Figure 6 A-D zoobank.org/ 46757E61-FE70-4101-BF76-D970E3BCCA63

Derivation of name. After Steven Rogers, University of Keele, geologist who initiated the studentled sedimentological and micropalaeontological study of the off-reef tract limestones from the Much Wenlock Limestone Formation, Wenlock Edge, Shropshire, UK; genus masculine.

Holotype. LST7/0057, Longville Stanway Track, Nodular Packestones of the Off-reef Tract, Much Wenlock Limestone Formation, Homerian.

Paratype. 1MQ/0023, Moorwood Quarry, Nodular Packestones of the Off-reef Tract, Much Wenlock Limestone Formation, Homerian.

Material. 214 specimens

Diagnosis. Same as for genus.

Description. Test composed of two asymmetrical chambers separated by a pseudo-septum. The dorsal chamber is larger and pyramidal and sometimes a cylindrical areal aperture may be present within the central axial plane posterior of the dorsal chamber. The ventral chamber is smaller and pyramidal/conical shaped and extends to terminate at a sharp apex. The walls thicken at the edges of the dorsal chamber. The walls are calcitic and lamellar resembling a brick-like arrangement. The chambers occasionally host clastic grains and pyrite.

Dimensions. Overall test height of 44–126 μm and an overall test width of 34–120 μm long. Large dorsal chamber height of 5–71 μm and a diameter of 7–61 μm with a surrounding wall thickness of 0.9– 15 μm. The smaller ventral chamber has a height of 3–48 μm and a width of 5–50 μm and the thickness of the wall surrounding the chamber is 0.5–11 μm. A septum thickness of 0.5–10 and an aperture width ranging from 0.9–10 μm.

Remarks. Specimens of Natantesprifmata rogersi appear quadrilateral or resemble kites in cross-section. Their walls can include pyrite as can their chambers. Sometimes clastic material is present within their dorsal or ventral chambers.

Stratigraphical range. Lower Silurian (Homerian).

Figures

FIGURE 6. Photomicrographs of Natantesprifmata rogersi (A-D) and Hartonella oblonga (E-H) within the MWL Fm., these specimens are from Longville Stanway (A), Longville Stanway Track (B), Eaton Top (C), Moorwood Quarry (D) and Harton Hollow (E-H). (A) = N. rogersi with a prismatic dorsal chamber (DC) separated from the conical ventral chamber (VC) by a septum-like structure (ss). Apical aperture is present in the DC. (B) = N. rogersi with pyrite within the walls (pyw) of the test. Thickened walls (tw) are present around DC. Note quartz grains (qtz) within the DC infill. (C, D) = N. rogersi showing the typical kite-like shape. (E, F) = H. oblonga showing a large elongated dorsal chamber (DC) separated by a septum-like structure (ss) from its smaller globular ventral chamber. (G) H. oblonga with a pointed VC and a smoother, more oval DC. Bivalve fragment (bv) (top right). (H) An H. oblonga with a thicker than normal wall and elongated ss. Specimen of mg is neighbouring H. oblonga (bottom centre). Sparitic matrix (sp); Biosparitic matrix (bsp). All scale bars equal 50 µm.