Jsowerbya Merle, Pacaud, Ledon & Goret, 2024, n. gen.

Informal group Jsowerbya, Beyregrex Merle, n. gen, Pseudotrophonopsis Merle, n. gen. DIAGNOSIS. — Shell medium sized for family, biconic. P6 not atrophied. IP, ADP, MP and ABP present. Poorly developed axial sculpture formed by slightly lamellose varices. Posterior sinus of sutural ramp shallow. Shoulder sinus of P1 reduced or missing. ID missing, D1 to D6 present. Columellar lip occasionally ornamented by 1-3 tubercles. Microstructure of three aragonite layers. INCLUDED GENERA. — Jsowerbya Merle, 2005b, Beyregrex Merle, n. gen. and Pseudotrophonopsis Merle, n. gen. DISCUSSION This informal group includes basal taxa often erroneously attributed to the Muricopsinae (synonym of Aspellinae) because of their biconic shape and the presence of 1-3 columellar tubercles or attributed to the Trophoninae, because of the more or less lamellose varices. In the phylogenetic analysis, they represent basal taxa (Clades G, H, I, J, L of Winclada [Fig. 1; Appendix 3] and Clades 44, 43, 42, 41, 40 of PAUP [Appendix 5]). They essentially differ from members from the other subfamilies by having a combination of characters including a posterior sinus, a D6 denticle, occasional columellar tubercles, and by lacking the ID denticle. The primary cords appear late in ontogeny and IP is missing in the most basal species of this group (e.g., Beyregrex sarroniensis (Carez, 1879), n. comb.) from the Thanetian, whereas in the derived members (e.g., members of Jsowerbya Merle, 2005b) they appear earlier, and the primary cord IP is often present. From an evolutionary point of view, members of this group are diversified from the late Paleocene to the middle Eocene with Beyregrex Merle, n. gen. and Jsowerbya. The decline of the group begins at the Priabonian in which only Beyregrex Merle, n. gen. and Pseudotrophonopsis Merle, n. gen. are recorded. Beyregrex Merle, n. gen. survives after the Eocene/ Oligocene climatic crisis and is known in the Early Miocene (Burdigalian) with Beyregrex cedillatus (Cossmann & Peyrot, 1924), n. comb ..