Apletodon conwayi, Schwarzhans & Klots & Kovalchuk & Dubikovska & Ryabokon & Kovalenko, 2024

Apletodon conwayi n. sp.

Figure 6 View FIGURE 6 S-X

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Holotype. NMNHU-P PI 2713 ( Figure 6 View FIGURE 6 S-U), Mlyntsi , western Ukraine, late Badenian.

Paratype. SMF PO 101.352 , Staryi Zavod .

Etymology. Named in honour of Kevin Conway (College Station, Texas, USA) for his many contributions to the understanding of gobiesocid fishes.

Diagnosis. Otolith not exceeding 0.7 mm in length; OL:OH = 1.40–1.45. Rostrum slightly longer than antirostrum. OL:SuL = 1.5; OsL:CaL = 0.95–1.25.

Description. Tiny otoliths maximally reaching 0.7 mm in length (holotype). OL:OH = 1.40–1.45; OH:OT = 2.2–2.3. The dorsal and ventral rims are regularly curved, continuous with a well-rounded posterior rim. The rostrum is distinct with a rounded tip, 8–15% OL, longer than antirostrum; excisura is distinct, variably deep, and sharp. All rims are smooth and thick. The inner face is completely flat in ventral view ( Figure 6T, 6W View FIGURE 6 ), concave in anterior view because of a broad, depressed sulcus ( Figure 6U, 6X View FIGURE 6 ). The latter is deepened, anteriorly open, relatively short (OL:SuL = 1.5) divided into about equally long and wide ostium and cauda (OsL:CaL = 0.95–1.25). The sulcus is marked by a narrow, crest-like, and distinct crista superior and inferior along sulcus. Dorsal and ventral depressions are fading away from the sulcus. The outer face is convex and smooth.

Discussion. Gobiesocid fishes or clingfishes are small, cryptic fishes clinging to rocks or sea grass in shallow and littoral water with wave activity. Their otoliths are extremely small, regularly smaller than 1 mm in length and perhaps therefore not described from the fossil record except for a find made in situ (Schwarzhans et al., 2017b) in specimens tentatively attributed to the genus Apletodon from the Sarmatian of the Central Paratethys. These in situ otoliths were up to 0.5 mm in length. Gobiesocid otoliths are characterised by the broad and deepened sulcus with equally wide ostium and cauda and distinct, crest-like cristae surrounding the sulcus (for extant gobiesocid otoliths see Charmpila et al., 2021). Apletodon conwayi represents the first otolith-based species in this group. It differs from Apletodon ? sp. found in situ in the Sarmatian (Schwarzhans et al., 2017b) in the more elongate shape (OL:OH = 1.40–1.45 vs. 1.15– 1.30) and the relatively wide sulcus.