A new group of microfossils: Middle Miocene (Badenian) opercular caps (calottae) of the tube-dwelling polychaetes Vermiliopsis SAINT-JOSEPH, 1894

Abstract

A new group of microfossils, consisting of the calcareous opercular caps, or calottae, of tube-dwelling polychaetes of the genus Vermiliopsis SAINT-JOSEPH, 1894; is entertained to describe a Middle Miocene (Badenian) material derived from the Korytnica Basin, southern slopes of the Holy Cross Mountains, Central Poland. The updated reports on any fossil opercula of the tube-dwelling polychaetes are reviewed, to indicate their difference from the studied material. The opercular system in the present-day species of the genus Vermiliopsis is shown, to accentuate the structural setting of the studied ancient calottae, among which three morphological groups are distinguished. These groups are described, in the open nomenclature, as the calottae comparable to those of the present-day species, viz. Vermiliopsis infundibulum (PHILIPPI, 1844), V. Iabiata (O.G. COSTA, 1861), and V. monodiscus ZlBROWIUS, 1968. The noted differences are discussed, and such factors as various stratigraphic age (thus, phylogeny), preservation and/or taphonomic loss (? abrasion), and biotope conditions (environmental stress, various bioprovince connections) are thought to have influenced differences in morphology and/or biomineralization of the studied Middle Miocene calottae and of their present-day counterparts.