Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 70. (Budapest 1978)

Vörös, A.: Viallithrys gen. n. (Terebratulida, Brachiopoda) from the Mediterranean Lower Jurassic

ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 70. Budapest 1978. Viallithyris gen. n. (Terebratulida, Brachiopoda) from the Mediterranean Lower Jurassic by A. VÖRÖS, Budapest Abstract - Viallithyris gen. n. with type-species V. gozzanensis (PARONA) is described from the Lower Jurassic of the Alpine segment of the Mediterranean province. The new genus is assigned to Gibbithyrididae on the basis of its horizontal outer hinge plates and crural bases given off dorsally. Its sulcate anterior margin and "brachidium support" render its systematic position unclear. With 5 figures and 1 plate. The Mediterranean palaeobiogeographic province can be characterized — among others — by a very diverse and rather indigenous Lower Jurassic brachiopod fauna (AGER 1967, VÖRÖS 1977). The Bakony Mts. of Hungary represent a geographically marginal but faunistically typical part of this province. The Hungarian Geological Institute carried out extensive excavations here in the last decades which resulted in a huge amount of Jurassic fossils collected bed by bed. The author has been entrusted with the study of Pliensbachian brachiopods by DR. J. KONDA, Director of the Geological Institute; this opportunity is gratefully acknowledged. A detailed monograph is planned to describe the whole brachiopod fauna; the aim of the present article is to present one of the new genera which have "ancient" (or recurrent) internal features apparently characteristic to many Mediterranean forms. Order TEREBRATULIDA WAAGEN, 1883 Suborder TEREBRA TULIDINA WAAGEN, 1883 Superfamily Terebratulacea GRAY, 1840 Family Gibbithyrididae MUIR-WOOD, 1965 [nom. correct. KATZ & POPOV 1974 (pro Gibbithyridae DAGIS, 1968, nom. transi, ex Gibbithyridinae MUIR-WOOD, 1965)] MUIR-WOOD (1965) founded her subfamily Gibbithyridinae on a few Upper Cretaceous genera. This subfamily was elevated to family rank by DAGIS (1968, p. 26.) without any explanation. KATZ & POPOV (1974a) gave a short diagnosis for the family Gibbithyrididae and this is accepted here: "Crural bases keeled, frequently with processes pendent into the dorsal umbonal cavity. Loop short, formed by simple transformation of echmidium ; wings (of the loop) poorly developed or missing." (I.e., p. 23.) Essentially on the basis of shell structure KATZ & POPOV (1974a, 1974b) placed this family into a newly created superfamily Centronellidoidea which was a member of a completely rearranged higher brachiopod systematics of the above authors. Although the Gibbithyrididae really bear certain ancient features resembling some Palaeozoic terebratulids, yet it seems more reasonable to keep this family within the superfamily Terebratulacea until convincing "connecting links" appear. KATZ & POPOV (1974a) differentiated two subfamilies: Gibbit hyridinae MUIR-WOOD (? TriassicRecent) and Dallithyridinae KATZ & POPOV (Lower Cretaceous - Recent) while a third was added by TCHORSZHEVSKY (1974) namely the Psebajithyridinae (Callovian - Oxfordian). The latter subfamily seems to be not quite distinct: it should rather be included into the Gibbit hyridinae. Subfamily GIBBITHYRIDINAE MUIR-WOOD, 1965 KATZ & POPOV (1974a) redefined this subfamily first of all by extending the stratigraphie range and the number of genera assigned. Viallithyris is only tentatively placed into this group since it has sulcate anterior commissure and "brachidium support"* in contrast to the other genera. These features perhaps would be important enough to erect a new subfamily but it seems advisable to wait until further representatives become known. * This new term is defined below, in the description of the species Viallithyris gozzanensis (PARONA).