Pseudotachea Boettger, 1909 (Gastropoda: Pulmonata, Helicidae) from the non-marine Middle Pleistocene of the Valdelsa Basin (central Italy)

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117 Bollettino della Società Paleontologica Italiana, 44 (2), 2005, 117-125. Modena, 30 settembre 2005 Pseudotachea Boettger, 1909 (Gastropoda: Pulmonata, Helicidae) from the non-marine Middle Pleistocene of the Valdelsa Basin (central Italy) Giuseppe MANGANELLI, Andrea BENOCCI, Enrico CAPEZZUOLI & Folco GIUSTI G. Manganelli, Dipartimento di Scienze Ambientali, Università di Siena, Via Mattioli 4, I-53100 Siena, Italy. A. Benocci, Dipartimento di Scienze Ambientali, Università di Siena, Via Mattioli 4, I-53100 Siena, Italy. E. Capezzuoli, Dipartimento di Scienze della Terra, Università di Siena, Via Laterina 8, I-53100 Siena, Italy. F. Giusti, Dipartimento di Scienze Ambientali, Università di Siena, Via Mattioli 4, I-53100 Siena, Italy. KEY WORDS - Pseudotachea cf. splendida, Gastropoda, Middle Pleistocene, Italy. ABSTRACT - Fossil shells of helicid snails were collected in clayey and calcareous lithofacies of the Campiglia dei Foci Synthem, cropping out near Colle Val d Elsa and San Gimignano of early Middle Pleistocene age. The specimens, consisting of shells and internal casts of shells, are assigned to Pseudotachea cf. splendida (Draparnaud, 1801). Literature records of alleged Pseudotachea species dating back to the Tertiary and Quaternary are discussed: many belong to different taxa, and others require further revision. In conclusion, specimens from the Valdelsa Basin are the most ancient known members of Pseudotachea, and constitute the first record of this genus from Italy; they also provide valuable information about paleoenvironmental conditions where the limestones of the Valdelsa Basin were formed. RIASSUNTO - [Pseudotachea Boettger, 1909 (Gastropoda: Pulmonata, Helicidae) nel Pleistocene Medio del Bacino della Valdelsa (Italia centrale)] - Nel Bacino della Valdelsa affiorano estesi depositi continentali formati da sedimenti palustri e lacustri (Sintema di Campiglia dei Foci) e depositi fluviali terrazzati. I depositi palustri e lacustri risalgono al Pleistocene Medio inferiore, mentre quelli fluviali sono databili al tardo Pleistocene-Olocene. I primi hanno restituito numerosi reperti fossili di vegetali e animali, tra cui conchiglie e modelli interni di Pseudotachea, un genere mai prima segnalato in Italia. Tali reperti provengono da litofacies argillose e calcaree affioranti nei pressi di Colle di Val d Elsa e San Gimignano (Sintema di Campiglia dei Foci). La Pseudotachea del Pleistocene Medio della Valdelsa è molto simile a Pseudotachea splendida (Draparnaud, 1801), una specie attualmente diffusa lungo le coste francesi del Mediterraneo dalle Alpi Marittime meridionali alla Valle del Rodano e in parte della Penisola Iberica occidentale (dalle coste catalane ad Almerìa, nella valle dell Ebro, nelle regioni subpirenaiche e a Mallorca). Tuttavia, le dimensioni particolarmente ridotte e altri caratteri (come il profilo dell ultimo giro) suggeriscono una determinazione per confronto. Numerose specie fossili di Pseudotachea sono state segnalate per il Mediterraneo occidentale già a partire dal Miocene Superiore. Un analisi critica dimostra che molte di queste segnalazioni sono infondate (i materiali su cui sono state basate appartengono ad altri generi oppure necessitano di ulteriori indagini per poterne accertare l inquadramento generico). I materiali del Bacino della Valdelsa rappresentano, quindi, i più antichi reperti sicuramente attribuibili a questo genere a tutt oggi conosciuti. Essi rivestono anche una notevole importanza per la ricostruzione paleoambientale dell area in cui si sono formati i depositi continentali del Bacino della Valdelsa. INTRODUCTION The southern Valdelsa Basin has vast early Middle Pleistocene lacustrine/palustrine deposits characterized by rich fossil assemblages that include plant remains (stems and roots of grasses), oogons of charophytes, ostracod valves and shells of terrestrial and freshwater molluscs. Some outcrops of this sediment contain rich malacofaunas with several taxa of remarkable value from a palaeontological and biogeographical point of view. Analysis of this material began some years ago with a paper on parmacellids (Manganelli & Giusti, 1993), but was then unfortunately suspended. It now resumes with a short note on a Pseudotachea species (Gastropoda, Pulmonata), a group of helicid snails never previously reported from the Italian Peninsula. GEOLOGICAL SETTING The Valdelsa Basin is a segment of a tectonic depression extending NW-SE for over 300 km from the Serchio Valley to the north, to the upper Tiber Valley to the south (Fig. 1a). Its northern end is near Empoli where the basin is about 25 km wide. To the south, between Poggibonsi and Monteriggioni, its width reduces to only 15 km. The boundary between northern and southern parts coincides with a major transverse tectonic line of the Northern Apennines, the Piombino- Faenza Line (Costantini et al., 1980) (Fig. 1b). The basin is an extensional structure that developed in the Late Miocene (Bossio et al., 1995b), bordered to the west and south by the Middle Tuscan Ridge and to the east by the Chianti Ridge. The former is mainly represented by formations of the Tuscan Domain ISSN 0375-7633

118 Bollettino della Società Paleontologica Italiana, 44 (2), 2005 Fig. 1 - a) Structural setting of Southern Tuscany. b) Geological sketch of the southern Valdelsa Basin. c) Stratigraphic reconstruction of the Quaternary synthems in the southern Valdelsa sector (not to scale - from Capezzuoli & Sandrelli, 2004).

G. Manganelli, A. Benocci, F. Capezzuoli, F. Giusti - Pseudotachea from Tuscan Middle Pleistocene 119 (Triassic Verrucano metaconglomerates and Calcare cavernoso tectonic carbonate breccia derived from Late Triassic anhydrites). The tectonic units of the Ligurian Domain (Lower Cretaceous-Eocene flysch successions and Middle-Late Jurassic ophiolites) crop out in the Chianti Ridge. The basin is filled with a thick succession of terrigenous late Miocene continental (mainly clays and conglomerates) and Pliocene marine sediments (sands and clays). In the late Middle Pliocene, the Valdelsa Basin, like most of southern Tuscany, underwent a general uplift that led to emersion of the area (Bossio et al., 1995a). In the southern sector, particularly around Colle di Val d Elsa, Quaternary sediments including early Middle Pleistocene palustrine-lacustrine deposits (Campiglia dei Foci Synthem) and Late Pleistocene-Holocene fluvialpalustrine successions of terraced deposits (Abbadia Synthem, Calcinaia Synthem, Torrente Foci Synthem and Bellavista Synthem) crop out in the main river valleys. They consist mainly of calcareous tufa (sensu Ford & Pedley 1996) and detrital deposits (Capezzuoli & Sandrelli, 2004) (Fig. 1c). The valley floor is covered by Holocene alluvial deposits (Poggibonsi Synthem) consisting essentially of sands and sandy silts with associated pebbles or gravel lenses. Calcareous tufas are currently forming in localized areas. The Campiglia dei Foci Synthem crops out in different proportions and variable thickness (maximum about 30 m) in the various areas mainly in two subhorizontal plateaux on hilltops. It is composed of four lithofacies (Fig. 1c): - Calcareous lithofacies - compact, micritic limestone and marls, locally with vacuoles or bioturbation (roots). The stratification is locally enhanced by thin silty-marly beds. It is interpreted as a lacustrine environment with waters high in CaCO 3. - Clayey lithofacies - grey clay, clayey silt and marls (max 10 m thick) locally characterized by thin, plane laminations and carbonaceous plant remains. In the San Gimignano area, lignite layers in this lithofacies were completely mined in the early 20 th century. They contained fossils of early Middle Pleistocene (Berzi, 1972) or Galerian mammals (Ambrosetti et al., 1972). This lithofacies can be attributed to a palustrine environment. Shells of Pseudotachea were collected in this lithofacies near Campiglia dei Foci and San Gimignano (Fig. 1c; Tab. 1). - Sandy lithofacies - poorly cemented, fine-grained, quartz-carbonate sands in beds or lenticular layers (up to 50 cm thick), with a sometimes abundant silty matrix and locally scattered centimetric pebbles. In some outcrops, there are plant remains (grass stems and roots) encased in carbonate crusts. This lithofacies can be attributed to the marginal part of the lacustrine/ palustrine basin. - Conglomerate lithofacies - conglomerates and paraconglomerates in variable amounts in the different areas of the basin. They are characterized by a medium size, sandy matrix and usually massive fabric. This lithofacies is interpreted as alluvial fan deposits of small rivers. Relationships among the various lithofacies show vertical and lateral evolution of an endorheic basin from a palustrine environment with mainly terrigenous sedimentation (clayey lithofacies), to a lacustrine environment characterized by sedimentation of calcareous muds (calcareous lithofacies) in the central areas of the basin and deposition of coarser materials in the marginal areas, especially near the mouths of small tributaries (sandy and conglomerate lithofacies) (Capezzuoli & Sandrelli, 2004). PSEUDOTACHEA FROM THE MIDDLE PLEISTOCENE OF THE VALDELSA BASIN Our material from Campiglia dei Foci Synthem (Tab. 1; Pl. 1, figs. 1-4) is assigned to Pseudotachea because its characters perfectly match those of the genus: small size, eccentric shape (due to accentuated dilation of the last whorl in its final quarter), peristome delicate and slightly reflexed and umbilicus absent. Similarly Locality Geological setting Materials 1 - Campiglia dei Foci (Colle di Val d Elsa, Siena) 2 - Podere Sovestro (San Gimignano, Siena) The outcrop, about 3 metres thick, is characterized by non-marine clays and silty-marly clays in the lower part, that gradually merge into marly limestone with traces of roots and evidence of dessication (mud-cracks and soil) in the upper part (clayey and calcareous lithofacies of the Campiglia dei Foci Synthem). The fossils were collected in slumped non-marine clay and marly clay (clayey lithofacies of the Campiglia dei Foci Synthem) at the base of a high cliff of Pliocene marine sands, topped by a small outcrop of the Campiglia dei Foci Synthem. Numerous internal casts (Pl. 1, figs. 3-4). Two shells (Pl. 1, figs. 1-2). Tab. 1 - Pseudotachea cf. splendida (Draparnaud, 1801): material examined.

120 Bollettino della Società Paleontologica Italiana, 44 (2), 2005 sized helicids, such as species of Theba, Marmorana, Chilostoma s.l., Tyrrheniberus and Macularia have very different shells, never so eccentric (the last whorl is only slightly dilated in its final quarter). The colour pattern is also consistent with Pseudotachea. Pseudotachea includes two species, P. splendida (Draparnaud, 1801) and P. litturata (Pfeiffer, 1851) (Hesse, 1919; Sacchi, 1956; Aparicio & Ramos, 1988), distinguished by conchological and anatomical characters (more depressed and eccentric shell with white peristome; section of dart anchor-like in P. splendida; more globose and less eccentric shell with pinkish peristome; section of dart cross-like in P. litturata) (Pl. 2, figs. 1-4). P. splendida is found in some areas of France and Spain: its range includes the southern Alpes-Maritimes, the French Mediterranean seaboard, part of the Rhone Valley and part of the eastern Iberian Peninsula. In France it has been reported from the following departments: Pyrénées-Orientales, Aude, Hérault, Aveyron, Gard, Ardèche (far N to Viviers and le Teil), Drôme (NE to Donzère and Grignan), Vaucluse, Bouches-du-Rhône, Var and Alpes-Maritimes (eastern limit the right bank of the Var) (Germain, 1928, 1930). In Spain it is widespread in sub-pyrenean regions, in the middle Ebro Valley (as far as the southern Province of Alava), along the Mediterranean shores from Catalonia to Almería and on Mallorca (Balearic Islands), where it may have been introduced (Altonaga et al., 1994). P. splendida has also been reported from Bonifacio and Saint-Florent in Corsica (Payraudeau, 1827), the French Pyrénées (Mermet, 1843), Ibiza in the Baleares (Hidalgo, 1878), Gibraltar (von Frauenfeld, 1869) and Estepona (Frank, 1987). However, these reports are regarded as unfounded. The species is confirmed absent in these sites (Caziot, 1903; Germain, 1928; Puente, 1994) or replaced by the congeneric P. litturata (in which case, the reports may have been based on misidentification; Puente, 1994) (Fig. 2). Fossil records are reported from the tufs quaternaires of Saint-Pons-Géménos (Bouches-du- Rhône) (Germain, 1928) and the Cuaternario of La Nucía, Rojales, Arenales del Sol and Tibi (Alicante, Comunidad Valenciana) and Cartagena (Murcia, Region de Murcia) (Gasull, 1975). Madurga (1973) cited P. cossoni (Letourneux, 1877) (a junior synonym of P. Fig. 2 - Distribution of Pseudotachea species and fossil records of P. splendida/p. cf. splendida. Distribution (uncertain reports of P. splendida from southern Spain see text omitted) according to Sacchi (1956), Altonaga et al. (1994) and Puente (1994) (vertical lines, P. litturata; oblique lines, P. splendida; asterisks, fossil records). Fossil records according to Germain (1930), Gasull (1975) and this paper.

G. Manganelli, A. Benocci, F. Capezzuoli, F. Giusti - Pseudotachea from Tuscan Middle Pleistocene 1211 Pl. EXPLANATION OF PLATE 1 Figs. 1-4 - Pseudotachea cf. splendida (Draparnaud, 1801) (G. Manganelli collection, Dipartimento di Scienze Ambientali, Università di Siena). 1 - shell from Podere Sovestro (San Gimignano, Siena). 2 - shell from Podere Sovestro (San Gimignano, Siena). 3 - internal cast from Campiglia dei Foci (Colle di Val d Elsa, Siena). 4 - internal cast from Campiglia dei Foci (Colle di Val d Elsa, Siena). Sometimes the fifth colour band (arrow) is also evident in internal casts (fig. 4).

122 Bollettino della Società Paleontologica Italiana, 44 (2), 2005 splendida; Prieto, 1986) from the Cuaternario of Padul (Granada, Andalucia) but this report was questioned by Puente (1994). P. litturata is characterized by a more globose and less eccentric shell shape and its systematic relationships have been the subject of a long controversy. In fact, it has long been believed a species of Cepaea (Morelet, 1854; Kobelt, 1880; Perrot, 1938; Zilch, 1987). Only recently has it been definitively assigned to Pseudotachea (Aparicio & Ramos, 1988). P. litturata is widespread in northern Morocco (mainly Tetouan region) (Germain, 1928; Perrot & Perrot, 1938; Sacchi, 1956; Puente, 1994) and is also present in certain localities in southern Spain (Cádiz, Gibraltar and Estepona) where it was probably introduced (Sacchi, 1956) (Fig. 2). Our specimens are more similar to P. splendida than to P. litturata. However their dimensions (14-? 17 mm in maximum diameter) are at the lower end of the size range of P. splendida (15-24 mm, Moquin-Tandon, 1855-1856; 16-22 mm, Kerney et al., 1983; 17-21 mm, Prieto, 1986), the last whorl is slightly angled and the final quarter of the last whorl is slightly more dilated. We therefore assign our material to this species by comparison. The finding of a species of Pseudotachea from the Middle Pleistocene of the Italian Peninsula is very interesting. Fossil species of Pseudotachea have been reported from the Neogene of France, Spain, Portugal and Morocco (Wenz, 1923; Jodot, 1953, 1955, 1958), but never from Italy. Wenz (1923) listed two fossil Pseudotachea species, P. ogerieni (Delafond & Depéret, 1893) and P. tersannensis (Locard, 1879), and two more species of uncertain validity, P. cotteri (Roman, 1907) and P. torresi (Roman, 1907). The systematics and relationships of alleged Neogene Pseudotachea species were subsequently investigated by Jodot (1953, 1955, 1958). Jodot (1953, 1955) described two new taxa of Pseudotachea, Helix (P.) tersannensis var. minor Jodot, 1953, from Sierra de Baza (province of Granada, southern Spain), and H. (P.) tersannensis var. elata Jodot, 1955, from Aïn Lorma à l W de Meknès (Morocco), and extensively discussed the biogeography of this group of helicids. He initially regarded H. (P.) tersannensis as the most ancient form of the genus and traced its origins to Spain, where small-sized specimens ( forme minor ) had first appeared. From there, this form was thought to have spread to North Africa (before opening of the Straits of Gibraltar) and to the Rhone Valley, in France, evolving later into the typical form. H. (P.) tersannensis was thought to have inhabited shrublands and arid lowlands and would have survived until the Upper Pliocene, at least in Spain and Morocco. Jodot (1958) subsequently reported two more species from the Spanish Neogene, H. (P.) concudensis nov. sp. and H. (P.) cf. ogierini [sic] Delafond & Depéret, 1893, and revised the histoire phylétique of H. (P.) tersannensis, beginning with a stratigraphic redefinition of the French localities where the species had previously been reported (Bas-Neyron, Combesse, Sermenaz, Tersannes and Villereversure): some were still assigned to the Early Pliocene (Bas-Neyron, Sermenaz and Tersannes), while others were assigned to the Late Miocene (Villereversure). H. (P.) concudensis from the Late Miocene ( Méotien ) of Concud (a species similar to P. splendida but apparently unrelated to H. (P.) tersannensis), was then identified as the most ancient species of the genus. H. (P.) tersannensis var. minor was no longer considered to be the ancestral form of this species, but rather a forme régionale that evolved under unfavourable ecological conditions: its small size was supposedly the result of adverse environmental factors. The form was presumed to have spread from Spain, where it had evolved, to North Africa, colonising part of Morocco. The systematics and relationships of some taxa previously attributed to Pseudotachea (H. tersannensis and H. ogerieni) were revised again by Truc (1971) who established that the specimens described by Locard had not been collected from the Pliocene site of Hauterives, but from the Miocene outcrop of Combesse (in the municipality of Hauterives), where the species is found in marls with Nassa michaudi and in the overbedding marls and sands. Truc therefore completely revised Jodot s statements on the phylogeny and biogeography of H. tersannensis, since they were based on incorrect stratigraphical and taxonomic assumptions. He regarded Locard s species as EXPLANATION OF PLATE 2 Shells of extant Pseudotachea species. Fig. 1 - P. litturata (Pfeiffer, 1851) from Gibraltar (Museo Zoologico La Specola, Sezione del Museo di Storia Naturale dell Università di Firenze, no. 13060). Fig. 2 - P. splendida (Draparnaud, 1801) from Montpellier (F. Giusti collection, Dipartimento di Scienze Ambientali, Università di Siena, no. 27234). Fig. 3 - P. splendida (Draparnaud, 1801) from Barcelona (Museo Zoologico La Specola, Sezione del Museo di Storia Naturale dell Università di Firenze, no. 13061). Fig. 4 - P. splendida (Draparnaud, 1801) from Palma de Mallorca (F. Giusti collection, Dipartimento di Scienze Ambientali, Università di Siena, no. 27235).

G. Manganelli, A. Benocci, F. Capezzuoli, F. Giusti - Pseudotachea from Tuscan Middle Pleistocene 1232 Pl.

124 Bollettino della Società Paleontologica Italiana, 44 (2), 2005 morphotype of Megalotachea delphinensis (Fontannes, 1876), noting that all forms intermediate between the typical form of this species and H. tersannensis were found in Tersannes (the main differences being spire height and the shape of the last whorl). Delafond & Depéret (1893) had already suspected a relation between H. tersannensis and H. delphinensis, suggesting the former to be a Pliocene mutation of the latter. Truc (1971, 1977) also suggested that other species, previously classified as Pseudotachea, were unrelated to this genus. He considered that H. ogerieni more properly belonged to the genus Frechenia, though the specimen depicted by Delafond & Depéret (1893) appeared more similar to Megalotachea gualinoi (Michaud, 1855). He also suggested that H. cotteri belonged to the genus Megalotachea. Analysis of the relevant literature shows that small helicids regarded as related to Pseudotachea have been reported from the western Mediterranean (Morocco, Spain and France) since the Upper Miocene (Wenz, 1923; Jodot, 1953, 1955, 1958). Although some have been revised and assigned to other helicid genera, it is impossible to exclude that others are really related to Pseudotachea. Only the re-examination of the material will make this clear. Our specimens turned out to represent the most ancient members of the genus; they widen the known distribution of Pseudotachea and provide valuable information about paleoenvironmental conditions where the limestones of the Upper Valdelsa Basin were formed. Extant Pseudotachea species are confined to parts of the western Mediterranean, where they inhabit garrigues and arid lowlands. The fossil specimens presumably lived in similar environments. This seems confirmed by the presence of Parmacella slugs and calcareous lithofacies in the same outcrops. Indeed, today, Parmacella slugs live in western Mediterranean areas characterized by warm conditions and moderate aridity (Manganelli & Giusti, 1993) and deposition of limestone is favoured by progressive concentration and evaporation of palustrine/lacustrine water high in CaCO 3 in an endorheic setting (Capezzuoli & Sandrelli, 2004). ACKNOWLEDGEMENTS We thank Antonella Daviddi for technical assistance, Viviana Fiorentino for helping prepare plates 1 and 2, Anna Gandin and Massimo Zatini for providing material they collected and Helen Ampt for revising the English. We also thank Daniela Esu (Rome, Italy) and Giovanni Zanchetta (Pisa, Italy) for comments that enabled us to improve the paper. Research financed by Siena University (PAR 2003, project I molluschi non marini della fauna italiana: filogenesi, sistematica, faunistica, zoogeografia, conservazione ). 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