Aclis corniculata, Souza & Araújo & Pimenta, 2024

Souza, Leonardo Santos De, Araújo, Tarciso Almeida De & Pimenta, Alexandre Dias, 2024, Taxonomic review of Aclis Lóven, 1846 (Gastropoda, Eulimidae) from Brazil with notes on other congeners from the western Atlantic and Saint Helena, Zootaxa 5433 (4), pp. 451-499 : 469

Aclis corniculata sp. nov.

Fig. 10

Type material: Holotype. MNRJ 33425 [†]; R/ V Ocean Stalwart coll., 17/vii/2009.

Paratypes. Brazil: Rio de Janeiro state: HAB 17 sta. E2. MNRJ 34073 [1†].

Type locality. Brazil: Rio de Janeiro state; Campos Basin , HAB11 sta. E2 (22°06′52″, 40°39′06″, 53 m).

Material examined. The types and: Brazil: Rio de Janeiro state: HAB 11 sta. E2; MNRJ 16934 [1†]; São Paulo state: off São Sebastião Island ; 24°12′45″S, 44°59 ″W, 79 m; R/ V Professor Wladimir Besnard col., xi/1997; MNRJ 36009 [2†]; MZSP 89179 [1†].

Etymology. The epithet means horn-shaped, a Latin singular adjective in the nominative case and refers to the shell shape.

Description. Shell tall, subcylindrical, reaching about 2.9 mm long, 0.9 mm wide, eight whorls. Protoconch globose, subcylindrical, nucleus elevated, about 1.75 whorls, surface smooth. Teleoconch with convex whorls, surface glossy presenting faint microscopical spiral striae and strong incremental scars with irregular intervals. Body whorl about half the total length, base rounded; aperture short, elliptical in shape, about 65% of body whorl length, slightly expanded laterally, rounded anteriorly, acute posteriorly; outer lip thin, almost orthocline, slightly advanced at distal area; inner lip thin, reflected. Umbilicus lacking.

Measurements. Holotype, MNRJ 33425: 7 whorls; SL= 2.9 mm; BWL= 1.3 mm; AL= 0.7 mm; SW= 0.9 mm; AW= 0.5 mm. Paratype, MNRJ 34073: 7 whorls; SL= 2.9 mm; BWL= 1.5 mm; AL= 0.6 mm; SW= 0.7 mm; AW= 0.4 mm. MNRJ 36009: 7 whorls; SL= 2.6 mm; BWL= 1.1 mm; AL= 0.6 mm; SW= 0.8 mm; AW= 0.4 mm.

Remarks. Aclis corniculata sp. nov. is noticeably different from most of his congeners because this newly described species has a subcylindrical shape, lack of spiral keels, a small aperture and straight outer lip. Other specific features can be mentioned to distinguish the present species.

Aclis corniculata sp. nov. differs from A. sarissa ( Figs 2–3 ) by the more acute spire angle, narrower and shorter aperture, narrower umbilical fissure, straighter outer lip and by having no trace of spiral keels.

Aclis corniculata sp. nov. differs from A. pulchra sp. nov. ( Figs 7–8 ) by having a narrower aperture anteriorly, lacking a flattened expansion, and an orthocline or slightly prosocline outer lip, which is strongly opisthocline in A. pulchra sp. nov. Moreover, A. corniculata has a small umbilical fissure while A. pulchra sp. nov. has a broader umbilicus.

Geographic Distribution. Brazil: Rio de Janeiro, São Paulo. From 53 m to 79 m.

Figures

FIGURE 2. Aclis sarissa Watson, 1881. A–C, E. Lectotype, NHMUK 1887.2.9.1576, herein designated; D. Paralectotype, NHMUK 1887.2.9.1576; F–I. Paralectotype, NMW 1955.158.26255; J–K. Holotype of Aclis carolinensis, USNM 83743. A, D, F, J. Shell in frontal view; B, G, K. Shell in lateral view. C, H. Shell in dorsal view. E, I. Body whorl in frontal view. Scale bars: A–D, F–H, I–J. 1 mm; E, I. 500 μm. Credits: A–E. NHMUK photographic unit; F–I. NMW.

FIGURE 3. Aclis sarissa Watson, 1881. A–B, H–K. MORG 49199. C–D. CZUFS GAS-00102. E–G. CZUFS GAS-00104. A, C, E. Shell in frontal view; square in A indicates detail in I. B, D, F. Shell in lateral view. G–H. Detail of the body whorl in frontal view. I–J. Detail of teleoconch surface; rectangle in I indicates detail in J. K. Detail of apical whorls; arrow indicates the transition protoconch–teleoconch. Scale bars: A–F. 1 mm; G–H. 500 μm; I–J. 50 μm; K. 200 μm.

FIGURE 7. Aclis pulchra sp. nov. A–C, F–I. Holotype, MNRJ 16825. D–E, J. paratype, MNRJ 26601. A, C–D. Shell in frontal view. B, E. Shell in lateral view. F–G. Detail of teleoconch surface; square in F indicates detail in G. H. Detail of body whorl in frontal view. I. Detail of apical whorls. J. Protoconch in apical view. Scale bars: A–E. 1 mm; F–G. 50 μm; H. 500 μm; I–J. 200 μm.

FIGURE 8. Aclis pulchra sp. nov. A. Paratype, MNRJ 16323. B, F, H. Paratype, MNRJ 17713. C. Paratype, MNRJ 30872. D, G, I. paratype, MORG 39469. E. Paratype, MNRJ 26601. A–D. Shell in frontal view. E–G. Detail of apical whorls. H–I. Detail of body whorl in frontal view. Scale bars: A–D. 1 mm; E–G. 200 μm; H–I. 500 μm.

FIGURE 10. Aclis corniculata sp. nov. A–C, I, J. Holotype, MNRJ 33425. D–H, K, L. Paratype, MNRJ 34073. A, C–E. Shell in frontal view; rectangle in E indicates detail in G. B, F. Shell in lateral view. G, H. Detail of teleoconch surface; square in G indicates detail in H. I. Detail of body whorl in frontal view. J, K. Detail of apical whorls. L. Protoconch in apical view; arrow indicates transition protoconch-teleoconch. Scale bars: A–F. 1 mm; G–H. 50 μm; I. 500 μm; J–L. 200 μm.