Disponible en ligne sur www.sciencedirect.com Annales de Paléontologie 98 (2012) 131–151 Original article The first known fossil record of pygmy pipehorses (Teleostei: Syngnathidae: Hippocampinae) from the Miocene Coprolitic Horizon, Tunjice Hills, Slovenia La première découverte de fossiles d’hippocampes « pygmy pipehorses » (Teleostei : Syngnathidae : Hippocampinae) de l’Horizon Coprolithique du Miocène des collines de Tunjice, Slovénie a,∗ b Jure Zaloharˇ , Tomazˇ Hitij a Department of Geology, Faculty of Natural Sciences and Engineering, University of Ljubljana, Aˇskerˇceva 12, SI-1000 Ljubljana, Slovenia b Dental School, Faculty of Medicine, University of Ljubljana, Hrvatski trg 6, SI-1000 Ljubljana, Slovenia Available online 27 March 2012 Abstract The first known fossil record of pygmy pipehorses is described. The fossils were collected in the Middle Miocene (Sarmatian) beds of the Coprolitic Horizon in the Tunjice Hills, Slovenia. They belong to a new genus and species Hippotropiscis frenki, which was similar to the extant representatives of Acentronura, Amphelikturus, Idiotropiscis, and Kyonemichthys genera. Hippotropiscis frenki lived among seagrasses and macroalgae and probably also on a mud and silt bottom in the temperate shallow coastal waters of the western part of the Central Paratethys Sea. The high coronet on the head, the ridge system and the high angle at which the head is angled ventrad indicate that Hippotropiscis is most related to Idiotropiscis and Hippocampus (seahorses) and probably separated from the main seahorse lineage later than Idiotropiscis. © 2012 Elsevier Masson SAS. All rights reserved. Keywords: Seahorses; Slovenia; Coprolitic Horizon; Sarmatian; Miocene Résumé L’article décrit la première découverte connue de fossiles d’hippocampes « pygmy pipehorses ». Les fos- siles ont été trouvés dans les plages du Miocène moyen (Sarmatien) de l’horizon coprolithique dans les collines de Tunjice, en Slovénie. Le fossile appartient au nouveau genre et à la nouvelle espèce Hippotropis- cis frenki, semblable aux représentants existants des genres Acentronura, Amphelikturus, Idiotropiscis et ∗ Corresponding author. E-mail address: [email protected] (J. Zalohar).ˇ 0753-3969/$ – see front matter © 2012 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.annpal.2012.02.003 ˇ 132 J. Zalohar, T. Hitij / Annales de Paléontologie 98 (2012) 131–151 Kyonemichthys. Hippotropiscis frenki vivait dans les herbiers marins, les macro-algues et probablement aussi dans la boue et le limon des eaux côtières peu profondes et tempérées de la partie occidentale de la Parathétys centrale. La haute couronne sur la tête, le système des crêtes et l’angle élevé sous lequel la tête est orientée vers le ventre indiquent que Hippotropiscis est étroitement apparenté à Idiotropiscis et Hippocampus et probablement séparé plus tard qu’Idiotropiscis de la lignée principale des hippocampes. © 2012 Elsevier Masson SAS. Tous droits réservés. Mots clés : Hippocampes ; Slovénie ; L’Horizon coprolithique ; Sarmatien ; Miocène 1. Introduction In 2009, the beds of the Coprolitic Horizon in the Tunjice Hills, Slovenia, became known worldwide for the oldest fossil record of seahorses (Zaloharˇ et al., 2009). Two seahorse species were described from these beds, Hippocampus sarmaticus Zaloharˇ et al., 2009, and Hippocam- pus slovenicus Zaloharˇ et al., 2009. In February, 2009, and June, 2011, new excavations were performed, yielding several fossils of seahorses and pipefishes. Among highly diverse syngnathid material, the pygmy pipehorses were discovered for the first time. Extant members of pygmy pipehorses refer to four genera Acentronura Kaup, 1853, Amphelik- turus Parr, 1930, Idiotropiscis Whitley, 1947, and Kyonemichthys Gomon, 2007 (Fraser-Brunner and Whitley, 1949; Dawson, 1984; Kuiter, 2004; Gomon, 2007) comprising only eight known species. Together with pygmy seahorses and seahorses they belong to the subfamily Hip- pocampinae Kaup, 1856, of the family Syngnathidae Rafinesque, 1810 (Kuiter, 2000; Teske and Beheregaray, 2009a). Pygmy pipehorses are morphologically very similar to seahorses but all lack the upright posture. This suggests that they could be a surviving evolutionary link between seahorses and remaining members of the family Syngnathidae, all of which have a horizon- tal posture (Teske and Beheregaray, 2009a). Just like seahorses, most pygmy pipehorses have a prehensile tail that they use to hold onto vegetation, a tough exoskeleton consisting of bony rings, and fused jaws used to suck in small prey items. Like in seahorses, their males have a brood pouch in which they fertilize the eggs which they collect from the females and brood their young. The only major difference is that they do not swim upright (Teske and Beheregaray, 2009b). Revision of the data on the fossil syngnathids (Wilson and Orr, 2001) shows that no fossil forms of the pygmy pipehorses were described to date. It appears that the fossil pygmy pipehorses found in the Middle Miocene beds of the Coprolitic Horizon in the Tunjice Hills, Slovenia, are the first known fossil record of this group. In this article we describe the new and the only known extinct genus and species of pygmy pipehorses, Hippotropiscis frenki, and discuss its possible relationship to other pygmy pipehorses and seahorses. Because a new genus and a (single) new species are described, the genus diagnosis corresponds to the species diagnosis. We have no argument to decipher which is a species feature or a generic one. In the “Systematic paleontology” section we first give the “Diagnosis” with the features that allow the recognition of the species. In the “Description” we describe additional characters. Finally, in the “Systematic discussion” we compare the new species with other pygmy pipehorses. A “Systematic discussion” is necessary to discuss the fact that we define a new genus, as well as to discuss its possible relationships among the subfamily. As most of the pygmy pipehorse genera are mono-specific, most of the characters might have a specific and/or a generic status. ˇ J. Zalohar, T. Hitij / Annales de Paléontologie 98 (2012) 131–151 133 Fig. 1. Index map showing main tectonic and geographic units of Alpine Foldbelt and Alpine-Carpathian-Dinaric Moun- tains. Tunjice Hills (as indicated by pentagon) are positioned in the westernmost part of the Pannonian basin. Carte montrant les principales unités tectoniques et géographiques des contreforts alpins, de l’arc Carpathique et des Dinarides. Les collines de Tunjice (flèche) sont situées dans la partie la plus occidentale du Bassin Pannonien. Modified from Horváth (1985), Horvat (2003b) and Dolton (2006). Modifié d’après Horváth (1985), Horvat (2003b) et Dolton (2006). 2. Geological setting Sarmatian deposits in the Tunjice Hills paleogeographically belong to the southwestern mar- gins of the Central Paratethys (Fig. 1) and geotectonically to the Pannonian Basin system (Vrabec, 2001; Horvat and Misiˇ c,ˇ 2004). The Coprolitic Horizon is best exposed in a ravine of a small stream about 500 m west of the Tunjice village. The exact geographical coordinates are: lati- tude = 46.2350N and longitude = 14.5740E. In the last 14 years, the beds of the Coprolitic Horizon have been extensively researched. Horvat (2003a,b) and Horvat and Misiˇ cˇ (2004) carried out detailed petrological, sedimentological and micropaleontological analyses. The macropaleon- tological records as well as the results of the stratigraphical research have been described by Zaloharˇ and Zevnik (1998, 2006), Zaloharˇ (2004), Kriznarˇ (2006), Zaloharˇ et al. (2006a,b), Hitij and Zaloharˇ (2007), Zessin et al. (2008), and Zaloharˇ et al. (2009). The Coprolitic Horizon consists of alternation of gray marly clay or marl and laminated diatomaceous carbonate siltstone. The age of the Coprolitic Horizon was determined based on the diatomaceous microflora (Horvat, 2003a). This consists of a typical Lower Sarmatian association. The Coprolitic Horizon is estimated to be about 12.5 Ma old (Fig. 2). The beds of the Coprolitic Horizon yielded abundant macrofossil content. The fossil assem- blage of diatomaceous carbonate siltstone is characterized by large coprolites, fishes, insects, and also by marine and terrestrial plants, however, it is almost barren of the mollusk macrofauna. Bivalves and gastropods are rarely found. In several laminas, numerous scyphozoan medusae appear. The most numerous are insects, and even multiple occurrences in a single bedding-plane can often be observed. Marine aquatic plants are represented by seagrasses and several macroalgae. Leaves, needles, and fragments of the branches of terrestrial plants are also common. The terres- trial flora suggests a more temperate Lower Sarmatian climate, since deciduous and mesothermic species predominate (Zessin et al., 2008; Zaloharˇ et al., 2009). The beds of the Coprolitic Horizon were deposited in a semi-enclosed depositional environ- ment, in which stratified waterbody, shallow depths, and a soft bottom represented all necessary ˇ 134 J. Zalohar, T. Hitij / Annales de Paléontologie 98 (2012) 131–151 Fig. 2. Stratigraphic correlation chart of standard scale in the Central Paratethys and the Eastern Paratethys. Tableau de corrélation stratigraphique entre les étages miocènes de la Méditerranée, de la Paratéthys centrale et de la Paratéthys orientale. Modified after Rögl (1998), Kowalke and Harzhauser (2004) and Harzhauser and Piller (2004). Modifié d’après Rögl (1998), Kowalke et Harzhauser (2004) et Harzhauser et Piller (2004).