Sarmatigobius cavatus, Schwarzhans & Klots & Kovalchuk & Dubikovska & Ryabokon & Kovalenko, 2024

Sarmatigobius cavatus n. sp.

Figure 4 View FIGURE 4 J-Q

zoobank.org/ DF3FE8DE-5B66-4B6C-9AB0-CA3C5F7EE751

Holotype. NMNHU-P PI 2650 ( Figure 4 View FIGURE 4 O-Q), Novyi Pliazh , western Ukraine, late Badenian.

Paratypes. 2 otoliths, SMF PO 101.348 , same data as holotype .

Etymology. From cavatus (Latin) = excavated, referring to a concave dorsal rim observed in the holotype.

Diagnosis. OL:OH 0.87–0.97. Ventral rim curved; dorsal rim high, expanded, with flat or concave central portion. OL:SuL = 1.8–2.1; sulcus inclination 5–12°. Cauda narrow; subcaudal iugum distinct.

Description. Thick, high-bodied otoliths up to 1.8 mm in length (holotype 1.4 mm). OL:OH = 0.87– 0.97; OH:OT = 2.5–3.0. The anterior rim is nearly vertical, smooth; the posterior rim is nearly vertical or slightly inclined, with a slight concavity at the level of the caudal tip. The dorsal rim is high, with a well-developed postdorsal angle and slightly lower predorsal angle; the middorsal rim is slightly inclined, straight, or concave. All rims are smooth. The inner face is flat, smooth, with a centrally positioned, deepened, sole-shaped sulcus. The latter is relatively short (OL:SuL = 1.8–2.1), with a low inclination (5–12°), with a narrow cauda and a distinct and large subcaudal iugum. The dorsal depression is deep but with indistinct margins, open to the dorsal rim of otolith. The ventral furrow is relatively weak, close to the ventral rim of the otolith, not connected to the dorsal depression around the sulcus. The outer face is smooth and distinctly convex.

Discussion. Reichenbacher and Bannikov (2023) found otoliths in situ and described Sarmatigobius compactus from the Sarmatian of Moldova. They also placed Hesperichthys iugosus Schwarzhans, Brzobohatý and Radwańska, 2020 into Sarmatigobius . Thus, otoliths of Sarmatigobius differ from those of Hesperichthys in the presence of a large subcaudal iugum (vs. no subcaudal iugum) (see also Schwarzhans et al., 2017a). Sarmatigobius cavatus differs from its two congeners in the more compressed shape (OL:OH = 0.87–0.97 vs. 1.0– 1.1) and the overall shape of the dorsal rim. It shares with its congeners the deep dorsal depression that reaches close to the dorsal margin of the sulcus and opens to the dorsal margin of the otolith, and the large subcaudal iugum. The specimens show a certain degree of variability in the overall shape, but the curved ventral otolith rim, the convex to flat dorsal rim and the compressed shape remain characteristical.

POMATOSCHISTUS Lineage sensu Agorreta et al., 2013

Genus BUENIA Iljin, 1930

Buenia gibba n. sp.

Figure 5 View FIGURE 5 K-S

zoobank.org/ 9A08D560-36E1-4834-AC6B-E2165E533862

Holotype. NMNHU-P PI 2677 ( Figure 5 View FIGURE 5 K-M), Novyi Pliazh , western Ukraine, late Badenian.

Paratypes. 3 specimens, SMF PO 101.349 , Stary Zavod , western Ukraine, late Badenian .

Additional material. 17 otoliths: 2 specimens, NMNHU-P 2678 , Lisohirka ; 15 specimens, NMNHU-P PI 2679 , Staryi Zavod .

Etymology. From gibbus (Latin) = bent, referring to the convex inner face, the main distinguishing to juvenile otoliths of Deltentosteus telleri .

Diagnosis. Nearly quadratic otolith shape; OL:OH = 0.95–1.05. Predorsal angle slightly protruding; dorsal rim highest middorsally. Inner face distinctly convex, smooth. Sulcus steeply inclined, with broad ostium and narrow, tapering cauda; sulcus inclination angle 23–28°. OL:SuL = 1.75–2.2.

Description. Small, thick, compact otoliths with nearly quadrangular shape up to 1.5 mm in length (holotype). OL:OH = 0.95–1.05; OH:OT = 2.6– 2.85. The anterior rim is usually inclined upward toward a rounded, slightly protruding predorsal angle. The dorsal rim is curved, highest at or slightly behind the middorsal point. The posterior rim vertical, without a distinct postdorsal projection, usually with a slight concavity at the level of the caudal tip. The ventral rim is flat horizontal. All rims are smooth except dorsal and anterior rims sometimes undulate slightly. The inner face is distinctly convex, increasing in convexity with size, and smooth with a relatively large, shallow, steeply inclined and pronounced asymmetrical otolith. OL:SuL = 1.75–2.2; sulcus inclination angle 23– 28°, ostium more steeply inclined than cauda. The ostium is strongly widened with a rounded ostial lobe, the cauda is narrow and tapering. Subcaudal iugum is indistinct and narrow. The dorsal depression is indistinct; the ventral furrow is narrow, relatively faint but long and joining up to a dorsal field around the sulcus. The outer face about as convex as the inner face.

Discussion. Several species occur in parallel with similar looking otoliths such as Deltentosteus telleri (Schubert, 1906) , particularly its juvenile specimens ( Figure 5 View FIGURE 5 W-AA), Hellenigobius bunyatovi (Bratishko, Schwarzhans and Reichenbacher, 2015) ( Figure 5 View FIGURE 5 AJ-AK) and Pomatoschistus elegans (Procházka, 1900) ( Figure 5 View FIGURE 5 AL-AN). Buenia gibba differs from all of them in the distinctly convex inner face that is as convex as the outer face (vs. flat or slightly convex, less than outer face). From the juveniles of D. telleri it differs additionally in the rectangular angle at the joint of the posterior and ventral rims (vs. projecting), while larger otoliths of D. telleri are distinctly more elongate ( Figure 5T View FIGURE 5 ). Buenia gibba differs additionally from Hellenigobius bunyatovi in the vertical posterior rim (vs. dorsally inclined) and the stronger ostial lobe and from Pomatoschistus elegans additionally in being less high bodied (OL:OH 0.95–1.05 vs. 0.9– 0.98) and the inclined anterior rim (vs. vertical).

Several Buenia species have recently been recognised or described from the Neogene of the Paratethys and the Mediterranean: B. rudolticensis (Procházka, 1900) from the late Badenian and Sarmatian of the Central Paratethys, Buenia rueckertae (Schwarzhans, 2014) from the Serravallian of the Mediterranean, the extant Buenia affinis Iljin, 1930 , from the Messinian and Zanclean of the Mediterranean, Buenia pisiformis Schwarzhans, Agiadi and Carnevale, 2020 , from the Tortonian and Messinian of the Mediterranean, and Buenia pulvinus van Hinsbergh and Hoedemakers, 2022 , from the Pliocene of the Mediterranean and adjacent NE Atlantic. The otoliths of Buenia pulvinus are mostly more elongate than those in B. gibba (OL:OH = 1.07–1.12 vs. 0.95–1.05) and show regularly curved and not projecting angles. Buenia rudolticensis is usually more highly bodied than B. gibba (OL:OH mostly 0.92–0.95, rarely 1.0 vs. 0.95–1.05) and shows a relatively narrow sulcus (vs. wide ostium and tapering cauda) and a vertical anterior rim (vs. inclined). Buenia rueckertae is similar in otolith shape to B. gibba but more slender (OL:OH = 1.05–1.15 vs. 0.95–1.05), and its cauda is normally wide and not tapering. The otoliths of Buenia pisiformis are more high bodied than those of B. gibba (OL:OH = 0.89–0.97 vs. 0.95–1.05) and show an extremely small sulcus (OL:SuL = 2.6–2.9 vs. 1.75–2.2). The most closely resembling species is the extant B. affinis with a similar index OL:OH of 0.95–1.1, but with a more gently curved dorsal rim and rounded pre- and postdorsal angles compared to B. gibba and normally a wide and not tapering cauda. We consider B. gibba to represent a species adapted to the environment of the Medobory backreef. It likely represents a short-lived endemism in the late Badenian.