Otoliths in situ from Sarmatian (Middle Miocene) fishes of the Paratethys. Part III: tales from the cradle of the Ponto-Caspian gobies

Abstract

Articulated fossil fish skeletons with otoliths in situ provide a unique opportunity to link these two, otherwise independent data sets of skeletons and otoliths. They provide calibration points for otoliths also adding important information for the evolutionary interpretation of fishes. Here, we review nine articulated skeletons of gobies from the early Sarmatian of Dolje, Croatia, and Belgrade, Serbia, which were previously regarded as members of a single gobiid and a callionymid species. We found them to represent five different gobiid species belonging to five different genera, four of which are related to extant endemic Ponto-Caspian gobiid lineages. The species are: Aphia macrophthalma n.sp., Proneogobius n.gen. pullus (the only previously recognized species), Protobenthophilus n.gen. squamatus n.sp., Economidichthys triangularis (a species first described based on otoliths) and Hesperichthys n.gen. reductus n.sp. Five specimens contained otoliths in situ and a sixth shows imprints of otoliths which unfortunately must have been lost in the past, probably during preparation of the fossil. Together, they represent all five species recognized by skeletons, and three are linked to otolith-based species. Isolated otoliths have been reviewed from a variety of collections from Sarmatian strata in Austria, Bulgaria, Czechia, Romania and Slovakia resulting in the description of five new otolith-based species: Benthophilus? ovisulcus n.sp., Benthophilus styriacus n.sp., Protobenthophilus strashimirovi n.sp., Economidichthys altidorsalis n.sp. and Knipowitschia bulgarica n.sp. Our review demonstrates that all major endemic Ponto-Caspian gobiid lineages were already present during Sarmatian times, thereby pushing back their origin by approximately 5-10 myr in comparison to previously published dates for dichotomies. In our assessment, the origination of these lineages is linked to the early stage of separation of the Paratethys from the world oceans and the ecological changes that occurred during that time. These geological events parallel a dramatic increase in gobiid radiation and speciation, giving rise to many lineages, not all of which have persisted until today.Editorial handling:

Bessarabian (Tortonian, Late Miocene) fish otoliths from a transitional freshwater-brackish environment of Mykhailivka, Southern Ukraine

“…Other coeval otolith associations stem from marine or restricted marine environments, e.g., Weiler (1943), Pobedina (1954), Strashimirov (1984Strashimirov ( , 1985, and Djafarova (2006). The same is true for fish faunas based on articulated skeletons, sometimes with otoliths in situ, e.g., Carnevale et al (2006), Bannikov (2010), Bannikov and Kotlyar (2015), Schwarzhans et al (2017aSchwarzhans et al ( , 2017bSchwarzhans et al ( , 2017c.…”

“…Neogobius bettinae differs from N. rhachis by the low anterodorsal angle and curved dorsal rim (vs. rather flat). Both species occur together in Mykhailivka, indicating an already advanced speciation of the genus in the Ponto-Caspian Basin, possibly including extinct lineages (see also Schwarzhans et al, 2017c). Rückert-Ülkümen, 1993in Rückert-Ülkümen et al, 1993Figure 4.10-19 1993 Neogobius rhachis n.…”

“…It is interpreted as related to the extant N. fluviatilis, which is a fresh-to brackish water species of the tributaries of the Ponto-Caspian Basin. All three gobiid species at Mykhailivka thus represent the endemic Ponto-Caspian goby group, which has adapted so successfully to the changing environments and water salinities of the basin since the Sarmatian times of the Paratethys (Schwarzhans et al, , 2017c. None of these species has been recorded from the rich stenohaline marine gobiid faunas of the Sarmatian of the Paratethys.…”

Revision of so-called Pomatoschistus (Gobiiformes, Teleostei) from the late Eocene and early Oligocene

“…The only reliable records of 'sand goby' skeletons seem to be Pomatoschistus sp. (with otoliths in situ) from the upper Miocene of the North Caucasus (Russia) described in Carnevale et al (2006) and the species described in Schwarzhans et al (2017) from the middle Miocene (Sarmatian) of the Central Paratethys (Croatia). Besides, there are some otolith-based species of the 'sand gobies' from the middle Miocene (see Weiler, 1943;Wienrich et al, 2009;Schwarzhans, 2010Schwarzhans, , 2014Bratishko et al, 2015;Schwarzhans et al, 2015;Schwarzhans et al, 2017).…”

Morphometric convergence among European sand gobies in freshwater (Gobiiformes: Gobionellidae)

“…We constructed a 50% majority‐rule consensus tree, trimmed the hypothesis to two exemplars of each species (three for widespread P. marmoratus ), and then calibrated the phylogeny using BEAST 1.7.5 (Drummond, Suchard, Xie, & Rambaut, ). We used three fossil calibrations from Schwarzhans et al () for the origins of Economidichthys (15.0 Mya), Pomatoschistus (excluding P. quagga , in accordance with the Bayesian results; 16.0 Mya), and Knipowitschia (13.0 Mya), applied as exponential priors, and a legacy calibration from the phylogeny of Thacker () for the origin of Gobionellidae at 48.7 Mya, assigned as a normal prior. We then trimmed the phylogeny to single exemplars of species for which we had shape data using Mesquite version 3.1.0 (Maddison & Maddison, ) for use in the comparative analyses.…”