Aporrhais siberica Wieneke & Trubin 2024, sp. nov.

Aporrhais siberica Wieneke & Trubin sp. nov. Plate 1: figs 1–12 Synonymy. 1959. Aporrhais cornutus Alexeiev – Turbina, pp. 30–31, pl. 2, figs. 13, 14 [non Aporrhais cornuta Korobkov, 1949]. 1962. Aporrhais cornutus Alexeiev, 1945 – Turbina, p. 312, pl. 10, figs. 10, 11 [non Aporrhais cornuta Korobkov, 1949]. 2019 Aporrhais sp. – Popov et al., pl. 3, fig. 5. Types. Holotype: Museum of the Tyumen Industrial University MTIU K 6 (Plate 1: figs 1, 2); paratypes: Museum of the Tyumen Industrial University MTIU K 7, MTIU K 8, MTIU K 45, Slovtsov Museum Complex of Tyumen SMCT MF 33788, MF 33789. Etymology. The species is named after Siberia, where Anton Maslennikov collected the holotype. Diagnosis. A medium-sized, heavily callused Aporrhais with long digitations and no digitation adnate to the spire. Description. High conical shell of medium size [~ 43 mm], conical spire with about eight whorls, aperture bears two digitations. Protoconch unknown. First three teleoconch whorls rounded, with numerous opisthocyrt growth lines. Fourth teleoconch whorl with opisthocyrt axial ribs, 11 on the abapertural part of the whorl. On the penultimate whorl, ribs strengthened, 6 on abapertural part. Last whorl with three keels, adapical keel most prominent, with about 5–6 ribs on the abapertural side, apertural side covered with callus, middle keel small with no ribs, abapical keel strongly reduced. Height of last whorl is almost half of the total height. Outer lip formed by two aperturally canaliculated digitations. Lateral adapical digitation is a spearhead-like elongation of adapical keel, long, adapically curved. Middle keel runs into the lateral abapical digitation, short, abapically directed. Abapical keel ends without building a digitation. Inner and outer lip of aperture thickly callused, columella heavily callused, callus covers the last whorl aperturally completely, adapical part of aperture also callused. Rostrum triangular, channeled. Material. Six specimens: Four shells, MTIU K 6, K 7, K 8, and K 45. The shell MTIU K 6 is fully preserved, K 7 and K 8 have a broken apertural extension, and K 45 is a fragment. Two shells, MF 33788 and MF 33789, are stored in the STMC. The specimen with the number MF 33788 is fully preserved. These six specimens are figured in plate 1. In the specimen with the number MF 33789, the early whorls are broken off. Measurements. fully preserved specimens: MTIU 6 (holotype), height: 43 mm; SMCT MF 33788 (paratype), height: 46 mm. Locus typicus. Northeastern wall of Kyshtyrla quarry (55 ° 55 ' 15 " N, 65 ° 49 ' 26 " E), Western Siberia, Trans-Ural region, Russia. Stratum typicum. Upper part of Tavda Formation, Priabonian, Eocene, Paleogene. Distribution. Trans-Ural region, including the type locality (Turbina 1959; this paper) and the southern part of Western Siberia near Omsk (Turbina 1962). Discussion. Aporrhais siberica sp. nov. differs from A. cornuta by an adspiral digitation, that is absent in A. siberica (Plate 2: fig. 1 b). The lateral adapical digitation is slightly curved in A. cornuta (Plate 2: fig. 2 a) but more strongly curved in A. siberica (Plate 2: fig. 1 a). A thick callus covers the apertural part of the last whorl of Aporrhais siberica (Plate 2: fig. 1 c), while A. cornuta only has a thin callus restricted to the columella (Plate 2: fig. 2 c) (see also Table 1). Turbina (1959, 1962) considered the Trans-Ural morph as a subadult of Aporrhais cornuta. The thick apertural callus, which occurs only in an adult stage, is an argument to reject this assumption.