A rare window into a back-reef fish community from the middle Miocene (late Badenian) Medobory Hills barrier reef in western Ukraine, reconstructed mostly by means of otoliths Author Schwarzhans, Werner Natural History Museum of Denmark, Zoological Museum, Universitetsparken 15, 2100 Copenhagen, Denmark Author Klots, Oleksandr Author Ryabokon, Tamara Author Kovalchuk, Oleksandr text Swiss Journal of Palaeontology 2022 18 2022-11-17 141 1 1 35 http://dx.doi.org/10.1186/s13358-022-00261-3 journal article 10.1186/s13358-022-00261-3 1664-2384 11999827 Coris medoboryensis n. sp. Figure 8c, d Holotype NMNHU-P PI 2551 , Kozatskyi Yar , western Ukraine , late Badenian , Fig. 8c . Paratype 1 otolith, Mlyntsi, NMB P1208. Etymology Named after the Medobory Reef in western Ukraine . Diagnosis OL:OH = 1.6–1.7. Rostrum short, blunt, 15% or OL; excisura wide, shallow; antirostrum shorter than rostrum, 4–7% of OL. Dorsal and ventral rim gently curved; posterior tip pointed, expanded. Cauda terminating distant from posterior tip of otolith; OL:SuL= 1.35– 1.45. Outer face flat except rostral section being bent outward. Description Tin, delicate otoliths up to 2.0 mm in length ( holotype ). OH:OT = 2.5–2.8. Rostrum short, blunt, with rounded tip, about 15% of OL and about twice as long or more of antirostrum. Excisura very wide, relatively shallow. Dorsal rim gently and regularly curved, highest anteriorly above collum, without angles. Ventral rim regularly curved, deepest at about its middle, slightly behind highest point of dorsal rim. Posterior tip pointed, expanded, positioned higher than rostrum. All rims smooth or slightly undulating. Inner face convex, with deep, distinctly supramedian positioned and relatively short sulcus terminating far from posterior tip of otolith. Ostium slightly wider than cauda and distinctly shorter; CaL:OsL = 1.6–1.7. Collum/ anterior section of cauda slightly narrowed and shallower than remainder of sulcus. Rear part of cauda slightly widened, but not extent of ostium, deepened and terminating distant from posterior rim of otolith and not connected by postcaudal depression. Ventral furrow indistinct, discernable only at central part of ventral field and distant from ventral rim of otolith. Dorsal depression small but distinct with distinct crista superior toward sulcus, best seen in anterior view ( Fig. 8c 3 ). Outer face flat except outward bent rostral section ( Fig. 8c 2, d2 ), smooth. Discussion Te blunt anterior tip of the otoliths of Coris medoboryensis in combination with the gently curved dorsal rim, the expanded and pointed posterior tip, and the posteriorly closed cauda are characteristic traits of Coris otoliths among the many extant labrid genera. Te genus Coris contains 27 extant species, most of which are from the Indo-Pacific region, with only two stemming from the eastern Atlantic ( Parenti & Randall, 2000 , 2018 ), namely, C. atlantica Günther, 1862 , and C. julis (Linnaeus, 1758) . Coris medoboryensis clearly differs from otoliths of the extant C. julis (see Nolf, 2018 for figures) in the shorter sulcus terminating further away from the posterior tip of the otolith and the unusual outwardbending rostral region of the otolith. Labrid otoliths have rarely been recorded in the fossil record. Two cases of otoliths in situ are known from Sarmatian s.s. rocks of Croatia and Moldova : Symphodus woodwardi ( Kramberger, 1891 ; in Schwarzhans et al., 2017 ) and Symphodus salvus Bannikov, 1986 , both of which are clearly different from C. medoboryensis in otolith shape and the length and proportions of the sulcus. Stinton (1984) described a unique otolith from the Eocene of England as Coris tenellus Stinton, 1984 , which indeed represents a labrid but likely not of the genus Coris . Hence, we consider Coris medoboryensis as the first valid otolith-based fossil record of the genus.