CYSTOTHALAMIA VANDEGRAAFFI NEW SPECIES AND OTHER SPHINCTOZOAN SPONGES FROM THE UPPER CARBONIFEROUS OF SPAIN

Journal of Paleontology, Nov 2004 by Garc�a-Bellido, Diego C, Senowbari-Daryan, Baba, Rigby, J Keith

ABSTRACT-

New and previously described "Sphinctozoan" taxa have been collected from six different localities in northern Spain, all of them dated as Late Carboniferous, from Moskovian to Kasimovian in age. The sphinctozoans in the collection are all assigned to the Demospongiae: a new species of polyglomerate type, Cystothalamia vandegraaffi n. sp., and known species Amblysiphonella barroisi Steinmann, 1882, Amblysiphonella carbonaria (Steinmann, 1882), Discosiphonella mammilosa (King, 1943), Discosiphonella maior (Van de Graaff, 1969), and Sollasia ostiolata Steinmann, 1882. Some of these specimens present interesting paleoecological features, such as the use of a piece of calcareous algae as a hard substrate in a soft muddy bottom and a possible branching pattern determined by photophilic or negative geotaxic growth.

INTRODUCTION

THE SPHINCTOZOAN sponges described here came from six localities in the Cantabrian Ranges, which run east-west in the northwestern sector of the Iberian Peninsula, and constitute an important part of the senior author's doctoral thesis on the Paleozoic Porifera from the Iberian Peninsula (Garcia-Bellido Capdevila, 2002). However, this is not the first reference to the presence of sphinctozoan sponges in northern Spain, since the term Sphinctozoa was created by Steinmann (1882) based on Spanish specimens, among others, although he placed the group within the corals. These specimens had been collected by Barrois while working on the area (Barrois, 1882). Several decades later, Van de Graaff (1969) collected fossil sphinctozoans from one locality close to Vergano (Palencia, Spain) and mentioned two of Steinmann's taxa, Amblysiphonella barroisi Steinmann, 1882 and Sollasia ostiolata Steinmann, 1882, to which he added two other species of the genus Cystauletes King, 1943, presently regarded as Discosiphonella Inai, 1936. Since then, Truyols et al. (1980) mentioned other localities in northern Spain that have yielded a few sphinctozoan fossil fragments and Garc�a-Bellido Capdevila (1999) presented a preliminary study on the sphinctozoans from the Demu�s locality and their relative abundance compared with other fossil groups. Although the systematic position of sphinctozoans, or chambered sponges, has been extensively debated, they are now regarded as a polyphyletic group (Reitner, 1990; Senowbari-Daryan and Garc�a-Bellido, 2002), with representatives among the four established Porifera classes: Demospongiae (most sphinctozoans, including the ones described here), Hexactinellida (e.g., casearia Quenstedt, 1858 in Reitner, 1990; Pseucloverticillites Boiko, 1990), Calcarea (e.g., Sphaerocoelia Steinmann, 1882), and Archaeocyatha (e.g., Dictyosycon gravis Zhuravleva, 1960 in Reitner, 1990). The paleobiogeographic implications of the data presented here, together with thai of other Carboniferous sponges (Garc�a-Bellido and Rigby, 2004), and in particular the similarities between this sponge fauna and those from western North America, do not fall within the scope of the current paper and its discussion will be presented in a later essay. The data presented here, together with that from Garc�a-Bellido and Rigby (2004), shows the presence in Spain of eight sponge families within the dcmosponges and hexactinellids, with 14 genera and 16 species, making the Carboniferous the apex of poriferan diversity in the Paleozoic of the Iberian Peninsula.

LOCALITIES

Fossil sphinctozoan sponges have been collected from four localities in the province of Palencia, one in the province of Cantabria and one in the province of Asturias. The localities in Palencia are VRl, VR3, and VR4, at about 0.5, 1, and 4 km northeast of the town of Vergano (Fig. 1), and locality "Cv?," which corresponds to the general area where the holotype of C. vandegraaffi n. sp. was found, as inferred from Van de Graaff (1971). This region corresponds to the southeastern flank of the Cantabrian Ranges. The localities are included on the Geological Map of Spain (Scale 1:50,000) Sheet No. 107-Barruelo de Santull�n (Wagner et al., 1984) and their coordinates are 42�54'N, 4�24'W. Fossil sponges have been found in rocks assigned to the Verga�o Formation, which in this area is folded into the Castiller�a syncline. The hase of the Verga�o Formation lies over the massive sandstone beds of the upper Va�es Formation, and the top is defined by a fault that brings it into contact with the sediments deposited alter the Leonian Tectonic Phase, which are here represented by the Bra�osera Formation (Van de Graaff, 1971) or the Ojosa Formation (Wagner et al., 1984). The Verga�o Formation was defined by Van de Graaff (1971) to have a lower part of cross-stratified sandstones, shales with thin interbedded layers of mudstones and sandstones, limestones, and a turbidite bed, and an upper part, the Sierra Corisa Limestone Member, with 300 m of limestones, with some interbedded layers of marls and shales (Fig. 2). Fossil Porifera have been recently collected from marls located at the base of the second tongue of the Sierra Corisa Limestone Member of the Verga�o Formation, which corresponds to 1,600 m above the base of the section No. 4 by Van de Graaff (1971), but the holotype of C. vandegraaffi, is labeled as coming from 1,864 m above the base of the section No. 4, inside the Bra�osera Formation (Van de Graaff, 1971). Fossils in the Verga�o Formation include both marine and continental remains: foraminifera, sponges (including nonsphinctozoan demosponges: Coelodadia spinosa Girty, 1908 and Haplistion Young and Young, 1877, and hexactinellids: Stioderma perforata Garc�a-Bellido and Rigby, 2004), corals, gastropods, bivalves, brachiopods, and a diverse flora (Wagner et al., 1984). The date of the upper part of the Verga�o Formation was established by Van Ginkel (1965) as Myachkovsky, late Moskovian (Late Carboniferous). The study of new foraminifera samples (Villa, personal commun., 2000) provides greater precision, assigning these levels to the late Myachkovsky.