Aclis pulchra sp. nov.

Figs 7, 8

Aclis hyalina auct. non Watson, 1881: Rios (2009: 197, Fig. 487).

Type material. Holotype. MNRJ 16825 [†]; R/ V Ocean Stalwart coll., 25/ii/2019. Paratypes. Brazil: Rio de Janeiro state: HAB16 sta. D5: MNRJ 17713 [1†]; HAB13 sta. H4: MNRJ 16323 [1†]; Campos Basin; 23°05′00″S, 40°58′00″W, 100 m; vi/2004: MNRJ 26601 [1†]; Campos Basin; 23°05′23″S, 40°58′56″W, 100 m; 16/ix/2004: MNRJ 30872 [1†]; Espírito Santo state: off Vitória; 50 m; 1994; R/V Victor Hensen col.: MORG 39469 [1†].

Type locality. Brazil: Rio de Janeiro state; Campos Basin, HAB11 sta. G3 (22°03′41″, 40°10′06″, 76 m).

Material examined. The types and: Brazil: Rio de Janeiro state: OP II sta. 49; MNRJ 26716 [1†]; Campos Basin; 22°42′34″S, 40°41′24″W, 110 m; 19/ix/2003; MNRJ 26588 [3†]; MNRJ 33252 [1†]; Campos Basin; 22°42′34″S, 40°41′24″W, 110m; 19/ix/2009; MNRJ 31892 [6†]; Campos Basin; 23°05′23″S, 40°58′56″W, 100 m; 16/ix/2004; MNRJ 33081 [13†]; HAB 11 sta. A5; MNRJ 33418 [1†].

Etymology. The epithet means beautiful, pretty, fine, lovely, a Latin singular adjective in the nominative case, and refers to the beauty of the shell.

Description. Shell tall, conical, reaching about 2.7 mm long, 1.2 mm wide, seven whorls. Protoconch globose, subcylindrical, nucleus elevated, about 2.0 whorls, 390 μm high, surface smooth. Teleoconch with strongly convex whorls, surface glossy presenting strong microscopical spiral striae and strong incremental scars with irregular intervals. Body whorl about half the total length, base strongly rounded; aperture broad, width about 80% of length, elliptical in shape, about 60% of body whorl length, strongly expanded laterally, rounded and slightly channeled anteriorly, acute posteriorly; outer lip thin, strongly opisthocline, gradually advancing forward, rectilinear; inner lip thin, reflected. Umbilicus wide.

Measurements. MNRJ 16825: 6 whorls; SL= 2.4 mm; BWL= 1.2 mm; AL= 0.7 mm; SW= 1.0 mm; AW= 0.6 mm. MNRJ 26601: 6 whorls; SL= 2.6 mm; BWL= 1.3 mm; AL= 0.8 mm; SW= 1.1 mm; AW= 0.6 mm. MNRJ 26601: 7 whorls; SL= 2.7 mm; BWL= 1.2 mm; AL= 0.8 mm; SW= 1.2 mm; AW= 0.6 mm.

Remarks. Aclis pulchra sp. nov was misidentified as “ Aclis hyalina ” by Rios (2009: 197). We could not reassess the specimen studied by Rios (2009), but the shell figured fits the specimens studied here. Rios (2009) did not cite a precise locality for that record, but the geographic distribution was limited to Northeast Brazil. During our revision, we did not find any other specimen from this area

Aclis pulchra sp. nov can be clearly distinguished from C. hyalina by the absence of axial sculpture, which is present in the latter species, and by having more convex teleoconch whorls and a wider umbilicus.

Most of the shells studied have no trace of spiral keels, but they show the characteristic microscopic striae, specially visible below suture (Fig. 7F–G). The shell of A. pulchra sp. nov has, in general, a rapid increase in diameter and may vary from less (Figs 7A, 8A, B, D) to more abrupt (Figs 7D, E, 8C).

Aclis pulchra sp. nov resembles A. sarissa (Figs 2–3), but differs in having more convex teleoconch whorls, a wider umbilicus, more profound and better demarcated incremental scars. Besides that, the false suture is not conspicuous as in A. sarissa, and A. pulchra sp. nov has a more advanced and straighter outer lip.

Aclis pulchra sp. nov resembles A. rushi Bartsch, 1911 (Fig. 17C–D) and A. tenuis Verrill, 1882 (Fig. 18A–B), however the former has a noticeably more conical shape with a faster increase in diameter, a wider umbilicus and an opisthocline outer lip, which is orthocline in A. rushi and prosocline in A. tenuis.

Aclis pulchra sp. nov differs from A. carolinensis (Fig. 2J–K) because the newly described species has a faster increase in diameter despite not so evident like in the species compared above, more convex teleoconch whorls, a wider umbilicus, and an aperture more expanded anteriorly.

Aclis pulchra sp. nov. differs from A. costai sp. nov. (Fig. 12) and Aclis georgiana Dall, 1927 (Fig. 19G–H) mainly by having a more conical shape, a teleoconch with more convex whorls and a wider umbilicus.

Geographic Distribution. Brazil: Espírito Santo, Rio de Janeiro. From 50 m to 720 m.