Theonellidae Lendenfeld, 1903

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 : 880

Family Theonellidae Lendenfeld, 1903 Theonellidae indet.

Fig. 9A, D–H, L, O, P, R, U, X, Z .

Material.—Lower Eocene, middle–upper Eocene, Upper Cretaceous, Paleocene, south-central Ukraine.

Remarks.—The most common lithistid spicules reported by Ivanik (2003) seem to belong to the family Theonellidae . These are mostly ectosomal phyllotriaenes ( Fig. 9A, E, H, U ), as well as discotriaenes ( Fig. 9D, F, G ). Such spicules are characteristic for Discodermia du Bocage, 1869 (discotriaenes) and Theonella Gray, 1868 (phyllotriaenes) and closely related genera. Presence of one or more of these genera is also supported by occurrence of rare fragmentary preserved tetraclone desmas ( Fig. 9S, X, Z ) that are characteristic for this family.

The ectosomal phyllotriaenes with complex morphology of the cladome ( Fig. 9L, O, P ) resemble those found in an undescribed theonellid sponge taxon from the Salomon Islands (AP unpublished material).

Figures

Fig. 9. Spicule morphotypes from south-central Ukraine (A–V, X–Z) and Lithuania (W); Markovka, middle Eocene (A, D, E), Verhnee, lower Eocene (B, Z), Glâdov Âr, Upper Creatceous (C, J, K, P, Q, T, U, V, Y), Pesčanoe, upper Eocene (F, O), Kiselevka, middle Eocene (G, L, R), Markovka, upper Eocene (H, X), Nikol’skoe, upper Eocene (I, S), Lipcy, middle Eocene (M), Monastyrek, lower Eocene (N), and Neravai borehole, Paleocene (W). A, C, E, H, L, O, P, R. Phyllotriaenes. B. Sphaeroclone. D, F, G. Discotriaenes. I. Anchorate spicule. J, K, N, Q, S–W, Y. Megaclones. M. Siliceous plate. X, Z. Tetracrepid desmas. After Ivanik (2003); modified.