New species, misidentifications and problematic taxonomy of some Atlantic South American marine mollusks: a review Author Simone, Luiz Ricardo L. text Papéis Avulsos de Zoologia 2024 2024-08-09 64 1 104 https://doi.org/10.11606/1807-0205/2024.64.031 journal article 10.11606/1807-0205/2024.64.031 1807-0205 14705562 Genus Ennucula Iredale, 1931 Ennucula ipepa , new species ( Fig. 39 ) https://zoobank.org/ D91C55F5-3B23-4C4A-B4A5-AD0A130D1826 Types: Holotype MZSP 166732 , shell . Paratypes : MZSP 166733, 1 shell, MZSP 166629, 12 shells, 58 valves, MNRJ, 2 shells + 3 valves, MNHN-IM-2000-39810, 1 shell + 9 valves, all from type locality. Type locality: BRAZIL . Espírito Santo ; ItaÚnas, off, Abrolhos slope, 19°40.6′S 37°48.1′W , 790-940 m [ MD55 sta. CB77 , 27.v.1987 ] . Diagnosis: Species from off SE Brazil of ~ 5 mm , with almost central umbo. Ligament almost perpendicular. Hinge with 11-12 anterior and 8-9 posterior teeth. Description: Shell of ~ 5 mm ; outline rounded; ~1.2 times longer than heigh; walls slightly thin. Umbo relatively blunt, slightly prominent; almost central slightly dislocated anteriorly, with umbonal angulation of ~110°. Anterior and posterior umbonal edges almost symmetrical, both convex, flattened in edges, almost wing-like; posterior edge slightly shorter and more vertical; anterior edge longer and slightly more convex; ventral edge widely rounded ( Fig. 39 A-B, D-G, J-M) with weak, blunt posterior beak. Very weak, oblique anterior carina. Maximum inflation ~50% of length ( Fig. 39C ). outer surface glossy, shining; sculpture commarginal, narrow, uniform cords,from umbo up to edges ( Fig.39A,B,D,E );interspaces equivalent to each cord width. Periostracum heavy, brown ( Fig. 39 A-E); when absent, color white ( Fig. 39J, L ). Ligament with inner portion thick, guttiform, restricted to sub-umbonal region, angulation ~30° in relation to dorso-ventral axis ( Fig. 39F , G-I, K, M). Hinge occupying entire dorsal edge ( Fig. 39F, G, K, M ), thicker regions occupying ~15% of shell height; teeth reaching ligamental area; from this region both anterior and posterior series of teeth gradually growing towards edges, becoming wider in subterminal region in both sides, mainly in anterior set, with very broad subterminal stretch; 11-12 teeth in slightly curved, longer anterior set; 8-9 teeth in slightly shorter, also weakly curved posterior set. Both set of teeth with very tall, triangular, pointed teeth ( Fig. 39H, I ). Both adductor muscle scars rounded, located ventrally to both ends of hinge, anterior scar slightly larger ( Fig. 39G ); pallial line weakly visible parallel to ventral edge ( Fig. 39G, K ). Figure 39. Ennucula ipepa shell of types: (A-C) holotype MZSP 166732 (L 4.3 mm), left, right and dorsal views; (D) paratype MZSP 166733 (L 5.1 mm), left valve, outer view; (E) same,right valve,outer view;(F) same,right valve,inner view;(G) same,left valve, inner view; (H) same,right valve,detail of hinge,inner-slightly ventral view(some teeth are broken);(I) same for left valve,scales:=1 mm;(J-K)paratype MZSP166629#1(L 5.0mm),left valve,outer and inner views;(L-M) paratype MZSP 166629#2 (L 4.9 mm),left valve,outer and inner views. Etymology: The specific epithet is based on the Guarani language word ipepo, meaning wing, an allusion to the expansions in both sides of the umbo. Distribution: Off Espírito Santo , continental slope of Abrolhos.