Early Campanian (Late Cretaceous) Pleromidae and Isoraphiniidae (lithistid Demospongiae) from the Łódź‐Miechów Synclinorium (central and southern Poland): new data and taxonomic revision

Abstract

An abundant and diversified assemblage of early Campanian lithistid Demospongiae has been identified in the Miocene gravels exposed in the Bełchat ow lignite mine. Fourteen species of Pleromidae and one species of Isoraphiniidae have been distinguished in the assemblage. Among them, five species (Pachypoterion koeneni Schrammen; P. compactum Hinde; Gigantodesma aurita (Schrammen); Amphilectella piriformis Schrammen; and Heterostinia immanis Schrammen) have not been previously recorded from Poland. Moreover, one new genus and species, Stipesia belchatowiensis, assigned to the family Pleromidae, is described. Streptasters were found in the latter species and in Heterostinia immanis. They represent the first documented in situ microscleres in the fossil species of the Pleromidae. Due to the unique state of preservation of the sponges, significant new data on the choanosomal skeleton and ectoso-

Campanian (Late Cretaceous) Theonellidae and Phymaraphiniidae (lithistid Demospongiae) from the Miechów and Mogilno‐Łódź synclinoria (southern and central Poland): new data and taxonomic revision

“…The fossil lithistid sponges often show modification of desmas in the stalk and/or near the base (Pisera 2000; Świerczewska‐Gładysz 2016, 2017). Modified tetraclones with very elongated clones and without ring‐like swelling occur on the surface of the stalks of Phymaraphinia infundibuliformis and Cycloclema compressa .…”

“…2020) and only occasionally do they occur on soft floors (Pulitzer‐Finali 1993; Van Soest 2017). During the Cretaceous, when soft muddy sediment prevailed, numerous lithistid sponges colonized the sea floors (Świerczewska‐Gładysz 2006, 2017). This adaptation to a soft bottom is also evident in some of the theonellids and phymaraphiniids studied herein.…”

“…With the current state of research, it is difficult to determine whether the morphology of these additional spicules may be helpful in the taxonomy of Cretaceous theonellids. Additional subectosomal spicules, unknown in extant lithistid sponges, were noted in many Cretaceous species that are representative of other lithistid groups, such as Phymatellidae Schrammen, 1910 and Corallistidae Sollas, 1888 (Schrammen 1910; Reid 2004; Świerczewska‐Gładysz 2016, 2017), but have never been found in fossilized phymaraphiniids.…”

“…This redeposited assemblage of Cretaceous lithistid sponges ranks among the richest in Europe. To date, from this locality sponges representing only three families (Pleromidae, Isoraphiniidae and Corallistidae) have been studied in detail (Świerczewska‐Gładysz 2016, 2017). Additionally, specimens from the Kraków, Miechów, Pilica and Lelów areas (Miechów Trough, southern Poland) have been studied (Table 1); part of this material is contained in museum collections that were previously described by Bieda (1933) and Hurcewicz (1966).…”

“…In the lower part of the Campanian sequence, above the complex of marls, distinctive horizons of cherts with black flint cores have been documented (Rutkowski 1965; Pożaryski 1966; Jurkowska & Świerczewska‐Gładysz 2020 b ). Fossils are abundant and consist mainly of siliceous sponges (Bieda 1933; Barczyk 1956; Hurcewicz 1966, 1968; Świerczewska‐Gładysz 2016, 2017), bivalves, cephalopods and echinoids (Rutkowski 1965; Jurkowska 2016). Lithistid sponges, which are numerous in lower Campanian strata, usually are silicified and often form the black flint core in chert nodules (Jurkowska & Świerczewska‐Gładysz 2020 b ).…”