Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 23. 2005. (Budapest, 2005)

FRAGMENTA PALAEONTOLOGICA HUNGARICA 23, BUDAPEST, 2005 Badenian (Middle Miocene) Polyplacophora from the Central Paratethys (Bánd and Devecser, Bakony Mountains, Hungary) by Alfréd D LILA I Abstract — The isolated valves of Polyplacophora species are rare elements of the Hungarian Miocene fossil assemblages. This paper provides description of a rich and well-preserved chiton fauna from Bánd and Devecser (Bakony Mts) collected by two amateur collectors. Eight species of six genera were identified in this Early Badenian (Middle Miocene) fauna: Fepiclopleurus (Eepidopleurus) cajetaniis, Fepidochitona sp., Ischnochiton rissoi, Chiton corallinus, Chiton (RJjyssoplax) olivaceus, Acanthochitona faluniensis, Cryptoplax weinlancli, Cryptoplax margitae. Up to now, this is the most diverse Polyplacophora assemblage known from the Hungarian Miocene (and also Cenozoic) formations. Four of the eight species were recognized for the first time from Hungary: L. cajetanus, 7. rissoi, C. corallinus and C. olivaceus. The widespread Central Paratethyan species, C. weinlandi is represented by particularly rich and variable material, rendering the study of ontogenetic changes. The taxonomic composition of this chiton material corresponds well to the other Polyplacophora faunas known from the Central Paratethys (e.g. Poland, Austria, Romania). Keywords — Polyplacophora, chitons, Middle Miocene, Badenian, Hungary, Central Paratethys, l^epidopleurus, I^epidochitona, Ischnochiton, Chiton, Acanthochitona, Cryptoplax DULAI, A.: Badenian (Middle Miocene) Polyplacophora from the Central Paratethys (Bánd and Devecser, Bakony Mountains, Hungary). — Fragmenta Palaeontologica Hungarica, 23: 29—50. Introduction The Badenian (Middle Miocene) marine fauna is very abundant and diverse in Hungary but polyplacophorans are rare elements of these fossil assemblages. However, disregarding this scarcity', chitons are even so under-represented in Hungarian palaeontological literature. Chiton lepidus (RbUSS) and Chiton denudatus (REUSS) were mentioned without any illustrations from Hidas (Mecsek Mts, South Hungary) by PETERS (1861) and CSEPREGHY-MEZNERICS (1950). JAKUBOWSKI & MUSIAL (1977), as well as STUDENCKA & STUDBNCKI (1988) gave further short information, mentioning Ljpidochitona (Ijpidochitond) subgranosa BALUK and Acanthochitona faluniensis (ROCHEBRUNE) from Várpalota (Bakony Mts, Transdanubian Central Range) on the basis of an occasional collection by G. JAKUBOWSKI. The only paper illustrating Miocene chitons from Hungary was published by DULAI (2001): four species (including a new one) were described and figured by SEM pictures from Szokolya (Börzsöny Mountains, North Hungary): I^epidochitona lepida (REUSS), Acanthochitona faluniensis (ROCHEBRUNE), Cryptoplax weinlandi SULC and Cryptoplax margitae DULAI. At the same time, polyplacophorans are much better known in the other areas of the Central Paratethys. The most diverse fauna was published from Poland (BALUK 1965, 1971, 1984; STUDENCKA & STUDENCKI 1988; MACIOSZCZYK 1988). The world-famous Korytnica clays yielded not less than 18 species. The chiton fauna of the Vienna Basin was also studied by several palaeontologists (e. g. REUSS 1860; SULC 1934; KROH 2002, 2003). The polyplacophorans of the famous Transylvanian localities, Läpugiu and Costei were studied by BOETTGER (1896), ZILCH (1934) and recently by DELLANGELO et al. (2005). The taxonomic composition of these faunas is very similar within the Central Paratethys, only the Polish region is exceptional with its very high diversity but this species richness is unambiguously due to the exceedingly intensive collecting works. Both fossil and Recent Mediterranean chiton faunas are also similar to the Central Paratethyan one and their knowledge offer useful help in the identification of the Hungarian Miocene material. Fossil Mediterranean polyplacophorans are especially thoroughly studied in Italy, from the Middle Miocene through the Pliocene to the Pleistocene (e. g. Miocene: SACCO 1897; LAGHI 1977; DELL'ANGELO et al. 1999; Pliocene: CHIRLI 2004; Pleistocene: SABFLLI & TAVLVNI 1979; BELLOMO & SABELLI 1995). Localities and material The studied chitons are derived from two localities of the Bakony Mountains (Transdanubian Central Range). Most of them were collected from Bánd, while Devecser yielded only some polyplacophoran specimens (Figure 1). Bánd is a well-known Middle Miocene locality at the middle part of the Bakony Mts. After some papers, mentioning the Neogene formations and fossils of this area, KÓKAY (1966) published an important monograph on the mollusc fauna of the Miocene coal-bearing sections and boreholes around the villages of Szentgál, Herend, Bánd and Márkó. Altogether 166 Gastropoda, 4 Scaphopoda and 64 Bivalvia species were described in this monograph but without mentioning any Polyplacophora. One of KÓKAY's best localities was Bánd, where 126 Early Badenian mollusc