Aclis pulchra, 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 : 465-468

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.

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 12. Aclis costai sp. nov. A, B. Holotype, MNRJ 23776. C. Paratype, MNRJ 22634. E, F, H, I, K. Paratypes, MNRJ 26730. D, G, J. Paratype, MNRJ 33559. A, C–E. Shell in frontal view. B, F. Shell in lateral view. G, H. Detail of body whorl in frontal and lateral views, respectively. I. Detail of the teleoconch surface, arrows indicate microscopical spiral striae. J. Protoconch in apical view; arrow indicates transition protoconch-teleoconch.. K. Detail of apical whorls. Scale bars: A–F. 1 mm; G–H. 500 μm; I. 50 μm; J–K. 200 μm.

FIGURE 17. A, B. Aclis marguerita (Bartsch, 1947): Holotype, USNM 108019. A. Shell in frontal view; the two fragments in A belongs to the broken holotype. B. Detail of body whorl in lateral view. C–E. Aclis rushi Bartsch, 1911: Holotype, USNM 82973. C. Shell in frontal view. D. Shell in lateral view. E. Detail of apical whorls. Scale bars: A, C–D. 1 mm; B. 500 μm; E. 200 μm.

FIGURE 18. A, B. Aclis tenuis Verrill, 1882: Holotype, USNM 44821. A. Shell in frontal view. B. Shell in lateral view. C, D. Aclis fernandinae Dall, 1927: Holotype, USNM 108047. C. Shell in frontal view. D. Protoconch in apical view. E–I. Aclis verrilli Bartsch, 1911: E–G. Holotype, USNM 44811; H–I. Holotype of Aclis tanneri (Bartsch, 1947), USNM 417444. E, I. Shell in frontal view. F, H. Shell in lateral view. G. Detail of apical whorls. Scale bars: A–C, E–F, H–I. 1 mm; D, G. 200 μm. Credits: C–D. USNM

FIGURE 19. A–D. Aclis eolis Bartsch, 1947: Holotype, USNM 573617. A. Shell in frontal view. B. Shell in lateral view. C. Detail of apical whorls. D. Detail of the body whorl in frontal view. E–F. Aclis hendersoni Dall, 1927: E, F. Holotype, USNM 333465; E. Shell in frontal view. F. Protoconch in apical view. G–H. Aclis georgiana Dall, 1927: Holotype, USNM 108020. G. Shell in frontal view. H. Protoconch in apical view. Scale bars: A, B, E, G. 1 mm; C, F, H. 200 μm, D. 500 μm. Credits: E–H. USNM.