Aclis multicarinata Souza & Araújo & Pimenta 2024, sp. nov.

Aclis multicarinata sp. nov.

Fig. 15

Type material. Holotype: MNRJ 28215 [†]; R/ V Professor Wladimir Besnard coll., xi/1997 - i/1998. Paratypes: Brazil: Paraná state: Revizee Sul sta. 6699: MNRJ 2821 7 [1†]; PADCT sta. 6641 (23°35′49″, 41°42′25″, 143 m): MNRJ 28216 [1†]. off Itajaí; 26°38′45″S, 46°51′54″W, 150 m; ii/2004: MNRJ 36004 [1†].

Type locality. Brazil: Santa Catarina state: PADCT sta. 6635; 27°10′23″S, 47°27′33″W, 129 m.

Etymology. From the Latin adjective multus, meaning many, and carinatus, meaning keeled; referring to the plethora of spiral keels.

Description. Shell tall, conical, spire angle 14°, reaching about 4.2 mm long, 1.2 mm wide, eight whorls, whitish. Protoconch globose, apex dome-shaped, about 3.0 whorls, 315 μm high, surface smooth. Teleoconch with moderately convex whorls, moderately convex outline, crenulated; suture slightly deep; presence of microscopic spiral striae near suture; presence of sharp, pronounced spiral keels, first teleoconch whorl smooth, two spiral keels emerging at second whorl, remaining whorls with a progressive number of keels, reaching seven at the body whorl; incremental scars strongly demarcated, appearing at irregular intervals. Body whorl about 40% of the total length, base crenulated; aperture high, about 55% of body whorl length, rounded anteriorly, acute posteriorly; outer lip thin, sinuous, slightly advanced close to distal area; inner lip thin, reflected. Umbilical fissure present.

Measurements. Holotype, MNRJ 28215: 8 whorls; SL= 4.2 mm; BWL= 1.6 mm; AL= 0.9 mm; SW= 1.2 mm; AW= 0.7 mm.

Remarks. Aclis multicarinata sp. nov. is conspicuous by the late development of the spiral keels that starts around the third teleoconch whorl as faint elevations (Fig. 15E). In the last whorls the spiral keels are more numerous and more pronounced (Fig. 15 A−B). The body whorl of the largest specimen has six spiral keels and one beginning at the basal region (Fig. 15C, H).

In addition to the features cited above, A. multicarinata sp. nov. can be distinguished from A. marplatensis comb. nov. by having a higher number of microscopic spiral striae, a more circular aperture, and a more advanced outer lip in the distal region; from A. anaglyptica sp. nov., by having a smaller interval between the spiral cords, a more rounded outline of the teleoconch whorls and a less expanded aperture anteriorly.

Aclis multicarinata sp. nov. resembles A. maestratii Poppe & Tagaro, 2016, from the Philippines, but it differs by the late development of the spiral keels, which starts consistently since the beginning of the teleoconch in A. maestratii. Besides that, A. multicarinata sp. nov. has less pronounced spiral keels and a wider interval between the suture and the first spiral keel.

Geographic Distribution. Brazil: Santa Catarina, Paraná. From 129 m to 150 m.