A review of lanternfish otoliths (Myctophidae, Teleostei) of the early Badenian (Langhian, middle Miocene) from Bęczyn, southern Poland

Lanternfishes (Myctophidae) is one of the most common groups of fishes in the mesopelagic zone of the world ocean, and they have been so since at least Miocene times. Their otoliths are dominant in pelagic sediments since then. Many species have a wide geographic distribution, several of them circumglobal, making myctophid otoliths potentially useful for supraregional stratigraphic purposes. Such application first requires clear definitions and sound differential morphological diagnoses to recognise the species, which may occur across significantly wide geographic arrays. In respect to the middle Miocene, many otolith-based myctophid species have been initially established based on specimens from the Central Paratethys. Their taxonomy was chaotic until the substantial reviews of Brzobohatý & Nolf (1996, 2000), but some morphotypes have remained unresolved or unrecognised in comparison with species established in distant regions such as Japan or New Zealand. Here, we review an unusually diverse and well-preserved myctophid otolith assemblage from Bęczyn, a late early Badenian age locality in the northern Carpathian Foredeep of southern Poland. We identified 13 of the 18 myctophid species of that time interval known from the Paratethys and present differential diagnoses for most of them, particularly for the many species of the species-rich genus Diaphus Eigenmann & Eigenmann, 1890. Many widely and potentially circumglobal distributed species are recognised in comparison with previous studies from other European basins, Central America, West Africa, New Zealand and ongoing research in Japan. Two species groups within the genus Diaphus appear to be particularly typical for the early and middle Miocene and are termed here the Diaphus austriacus plexus and the Diaphus kokeni plexus. One new species is described: Lampanyctus beczynensis n. sp. Two other species remain in open nomenclature.