Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 20. 2002. (Budapest, 2002)

FRAGMENTA PALAEONTOLOGICA HUNGARICA 20, BUDAPEST, 2002 A new euomphalomorph gastropod genus in the faunula, listed by VADÁSZ (1915) from Alsórákos (Per§ani Mts, Romania; PEarly Jurassic) by János SZABÓ Abstract — Five species are distinguishable from the available, most probably Early Jurassic material, consisting of a few poorly preserved inner casts and a specimen with shell. The latter one preserved also the original shell microstructure that was different from that of the comparable genera just like some of the megascopic characters. These gave a basis for establishment of Valamidiscus persanyensis n. gen. & n. sp. Short descriptions of the steinkerns are also given in the systematic part of the paper. Because Valamidiscus n. gen. cannot be fitted into the existing families without objection, its accommodation has been tentatively chosen (PDiscohelicidae, PCirroidea). Key words — Euomphalomorpha, PCirroidea, PDiscohelicidae, shell structure, Persani Mts, PEarly Jurassic. SZABÓ, J.: A new euomphalomorph gastropod genus in the faunula, listed by VADÁSZ (1915) from Alsórákos (Persani Mts, Romania; PEarly Jurassic). — Fragmenta Palaeontologica Hungarica, 20: 61-67. Introduction A few, most probably Early Liassic gastropod specimens provided the occasion to publish the information below. Recendy their locality area has became mghlighted because of a possible occurrence of fossil bearing, marine Triassic-Jurassic boundary sequence. Therefore a preliminary revision of the museum materials from this region has been started (PÁLFY 1999) and the rediscovery of the gastropods is a consequence of these studies. PODEK, F. and JEKELIUS, E. collected the studied specimens in the initial years of the 20

th century. The gastropods constitute only a minor part of the complete fauna (9 srjeamens among hundreds of other fossils, mainly cephalopods). Their preservation is rather poor; eight specimens are inner moulds and only a single one has shelly preservation. However, the shelly specimen seems to be an important document to the knowledge of the euomphalus-shaped gastropods. The material is now deposited in the Museum of the Hungarian Geological Institute. In the faunal list of VADÁSZ (1915, p. 237), two names refer to these gastropods: Discohelix transsylvanicus n. sp. Trocbus epulus D'ORBIGNY. Because VADÁSZ did not give systematical description and figure, the species name "transsylvanicus" remained "nomen nudum". The generic identification also needs a correction. In an earlier publication, VADÁSZ (1908, p. 287, pl. VI: 8,9) reported two additional Lower Liassic gastropod species from this area: Pleurotomaria reticulata SOW. Pleurotomaria cfr. sulcata SOW. The specimens of the latter two species have not been studied in detail, however, the figures in VADÁSZ (1908) and the applied names suggest a need of a taxonomical revision. Plmmtornaria reticulata SOW. = Trocbus reticulatus]. SOWERBY, 1821 = (the valid name:) Batbrotomaria reticulata (SOWERBY J., 1821) strongly differs both in its shape and age (Late Jurassic). The case with Pleurotomaria cfr. sulcata SOW. is similar: Trocbus sulcatus SOWERBY J., 1818 = (the valid name.) Leptomaria sulcata (SOWERBYJ., 1818) is an Aalenian species. The poor preservation of the inner moulds does not permit a detailed systematic analysis, therefore the paper will concentrate to the single shelly srx^cimen, representing a new genus and species that increases the number of the euomphalusshaped genera. Formerly this group of Palaeozoic-Mesozoic gastropods has been regarded as belonging to a single family or surx^rfamily, Euomphalidae or Euomphaloidea, respectively (see e.g. KNIGHT et al. 1960). However, recent studies have demonstrated their polyphyletic origin (MORRIS & QJEEVELY 1981; BANDEL

1988, BANDEL& GELDMACHER 1996, BÄNDEL & FRYDA 1998, WAGNER 2002). The genera got into several families belonging sometimes to different subclasses. Because the Persani Mts new form has preserved a curious shell rnicrostructure that has not yet been reported and this character is usually regarded as having high classification value, the possibility to establish another new family must be also considered.