| Summary: | Neoliothyrina nakremi Bitner sp. nov. Figs. 2, 3. ?1927 Terebratulina sp.; Gripp 1927: 30, pl. 6: 13–14. 2016 Pliothyrina ? sp.; Hryniewicz et al. 2016, table 2. ZooBank LSID : urn:lsid:zoobank.org:act: C889EAF7-1909-4819-9B0E-9709A1EBA6ED Etymology : In honour of Norwegian palaeontologist Hans Arne Nakrem, in recognition of his studies on fossil chemosynthesis-based faunas from Spitsbergen. Type material : Holotype: ZPAL V.48/9-1, decorticated specimen with broken beak (Fig. 3A). Paratypes: ZPAL V.48/9-2–4, decorticated specimens with broken beak (ZPAL V.48/9-2) and anterior part (ZPAL V.48/9-2–3); a set of acetate peels (ZPAL V.48/9-4) (Figs. 2, 3B, C). Type locality : Fossildalen, Spitsbergen, Svalbard. Type horizon : Cold seep carbonates from the Basilika Formation, upper Paleocene. Material. — 13 specimens (ZPAL V.48/9-1–13), complete specimens, apart from the holotype all with broken anterior part, all from the type locality and horizon. Measurements .— Holotype (ZPAL V.48/9-1): L, 25.6 mm; W, 19.9 mm; H, 12.9 mm; other specimens inappropriate for measurements. Diagnosis. —Small Neoliothyrina with rectimarginate anterior commissure. Outer hinge plates relatively wide, ventrally concave, inner hinge plates narrow and short, not contacting each other. Crural processes short, bluntly pointed. Loop short. Description. —Shell of medium size, subpentagonal to elongate oval in outline, biconvex with ventral valve deeper. Shell surface smooth with numerous growth lines. Lateral commissure slightly ventrally convex, anterior commissure rectimarginate. Beak suberect with rounded beak ridges. Foramen large, circular, mesothyrid. Symphytium small, only partially visible. Internal characters investigated in transverse serial sections. Cardinal process distinct, flat, surface with numerous grooves. Inner socket ridges thick, parallel to valve margin. Dental sockets moderately deep. Outer hinge plates relatively wide, ventrally concave, separated from inner hinge plates by distinct crural bases. Inner hinge plates short, ...
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