Placospongia spp.

Łukowiak, Magdalena, Pisera, Andrzej & Stefanska, Tetiana, 2019, Uncovering the hidden diversity of Paleogene sponge fauna of the East European Platform through reassessment of the record of isolated spicules, Acta Palaeontologica Polonica 64 (4), pp. 871-895 : 884

Placospongia spp.

Fig. 1D, F .

Material.—Middle Eocene, south-central Ukraine

Remarks. —The bean-shaped to round, massive, 70–85 μm long microsclere spicules with polygonal plates between the grooves arranged on the spicule surface ( Fig. 1D, F ) are selenasters. This type of spicules is characteristic for clionaid genus Placospongia .

The nearly spherical spicule ( Fig. 5 AH) might also belong to this genus, except that it is considerably bigger than the spherasters typically found in Placospongia . As such, this assignment should be treated with caution.

Figures

Fig. 1. Spicule morphotypes from south-central Ukraine; Grigorevka borehole, upper Eocene (B), Glâdov Âr, Upper Cretaceous (A, G, J), Pogonovka borehole, upper Eocene (C), Russkie Tiŝki, middle Eocene (D, F, I, O, W, X, Z, AA), Markovka, upper Eocene (E, H, N), Nikol’skoe, upper Eocene (K, L, Q, T, U, V), Pesčanoe, upper Eocene (M, AB), Kantemirovka, upper Eocene (P), Harkov region, middle Eocene (S), Verhnee, lower Eocene (R), and Staroverovka, middle Eocene (Y). A, G, H. Aspidasters. B. Spheraster. C, E, J, N. Sterrasters. D, F. Selenasters. I. Triaene. K, X. Mesotriaene. L, O. Anatriaenes. M, AB. Dichotriaenes. Q. Centrotylote?oxea. R.?Triaene. S. Plagiotriaene. P, T, U. Triaenes. V. Irregular triaene. W. Style. Y– AA. Diaenes. After Ivanik (2003); modified.