A new conulariid from the Upper Mississippian (early Serpukhovian) of Central Russia (Moscow Basin): systematics, microstructure, and growth abnormalities

?Holoconularia rossica sp. nov. is described from interstratified shale and siltstone beds in the Dashkovka Member of the Upper Mississippian (early Serpukhovian) Gurovo Formation in the Moscow Basin, Central Russia. The status of the genus Holoconularia, originally described from the Devonian of Germany, is discussed, and it is argued that at least one species previously assigned to it may belong in Paraconularia instead. Another species, P. mosquensis from the Middle Pennsylvanian of Central Russia, may be more closely related to ?H. rossica than to species in Paraconularia. Comparisons are also made with Conularia, Ctenoconularia, and Tasmanoconularia, three genera that are very similar to certain species in Holoconularia. The well-preserved periderm of ?H. rossica sp. nov. exhibits microscopic circular pores (micropores) and (in one specimen) malformed, cleft or scalloped ornamentation. The micropores in this and other conulariids appear to be primary anatomical features that may have housed an extremely slender, very short pillar of non-mineralized (organic) periderm connecting successive microlamellae composed predominantly of organic material. Cleft and scalloped features may represent healed injuries inflicted by predators, possibly nautiloids and/or gnathostomes.