Sticteulima canopusensis, Souza & Pimenta & Barros, 2021

Souza, Leonardo Santos De, Pimenta, Alexandre Dias & Barros, José Carlos Nascimento De, 2021, Revision of the deep-sea Eulimidae (Gastropoda, Caenogastropoda) from off Northeast Brazil, Zootaxa 4927 (4), pp. 451-504 : 489-491

Sticteulima canopusensis sp. nov.

urn:lsid:zoobank.org:act:6EAC026F-FCE5-4A14-BB94-BE39BB9C7A41

( Figure 21 A–J)

Type material. Holotype MZSP 70328 a ( Figure 21A ) . Paratypes: MNRJ 26724 [5 dd] ( Figure 21D, E, I, J ), MZSP 65317 [2 dd] ( Figure 21B, C, G, H ), MZSP 70328 b [3 dd], MZSP 72027 [1 lv] ; MZSP 94231 [1 dd].

Type locality. Brazil: Ceará, Canopus Bank (02°14′25″S 38°22′50″W, 260 m), coll. vii/2005 .

Etymology. Named after the type locality.

Description (Holotype). Shell conical, straight, reaching about 6.0 mm long, 2.1 mm wide. Larval shell dark to light brownish, almost cylindrical, 2.0 slightly convex whorls, 360 µm wide, smooth, transition to teleoconch marked by a distinct incremental scar. Teleoconch about 8.0 whorls, slightly convex outline; suture distinct, sloping; subsutural zone about 20% of the whorl; surface smooth; incremental scars slightly demarcated, appearing at irregular intervals. Last whorl about 40% of the shell length; base rounded. Aperture short, pear shaped, acute posteriorly and rounded anteriorly; outer lip thin, opisthocline, sinuous, slightly retracted near the suture and projecting in the uppermost third; inner lip sinuous, sloping, reflected and well demarcated. Umbilical fissure present. Shell yellowish to brownish, with dark brownish spiral bands close to suture.

Measurements. Holotype MZSP 70328a, 10 whorls, SL= 6.0 mm; BWL= 2.6 mm; AL= 1.6 mm; SW= 2.1 mm; AW= 1.1 mm. Paratype MZSP 65317, 10 whorls, SL= 5.7 mm; BWL= 2.4 mm; AL= 1.5 mm; SW= 1.9 mm; AW= 1.0 mm. Paratype MZSP 65317, 10 whorls, SL= 5.5 mm; BWL= 2.5 mm; AL= 1.5 mm; SW= 2.0 mm; AW= 1.1 mm. Paratype MNRJ 26724, 9 whorls, SL= 4.4 mm; BWL= 2.1 mm; AL= 1.3 mm; SW= 1.7 mm; AW= 0.9 mm.

Remarks. Sticteulima canopusensis sp. nov. ( Figure 21 A–J) is known only from the type locality, but a large number of specimens were collected, including one specimen with soft parts (MZSP 72027), empty shells and shells inhabited by hermit crabs ( Figure 21F ).

Sticteulima canopusensis sp. nov. differs from Atlantic congeners by presenting a more cylindrical appearance, with a tapered shell ( Figure 21A, B ), while most Sticteulima present a more conical shell. However, the color pattern combined with the smooth teleoconch, broad tip, dimensions and depth of occurrence are similar to other Sticteulima species. The generic classification of this species is provisional. Sticteulima canopusensis sp. nov. is similar to members of Fusceulima by the subcylindrical shell with a dome shaped apex. However, species of Fusceulima usually reach 6.0 whorls and the last whorl usually comprises half of the total length. Sticteulima canopusensis sp. nov. reaches around 11 whorls and the last whorl represents 40% of the total shell length. Another possible placement would be in Eulimostraca Bartsch, 1917 by the color pattern and relatively low aperture of the newly described species. However, Eulimostraca is restricted to the continental shelf and the type species ( Eulimostraca galapagensis Bartsch, 1917 ) has a conical, sharp outline, a multispiral protoconch, slightly convex teleoconch whorls and no umbilical chink (Warén 1992: figures 12, 33, 35), but the genus also has been used to group species with a more cylindrical shape (Warén 1992).

Sticteulima canopusensis sp. nov. resembles S. jeffreysiana ( Brusina, 1869) , but differs by having a wider aperture, by the presence of an umbilical fissure ( Figure 21G ), which is absent in S. jeffreysiana , and by the different color pattern. Sticteulima canopusensis sp. nov. has a more homogeneous brownish color, sometimes appearing as a wide spiral band at the teleoconch ( Figure 21A ), while S. jeffreysiana has random brownish patches over the whole shell.

Geographical distribution. Only known from the type locality.

Bathymetric distribution. 260 m.

Figures

FIGURE 21. A–J. Sticteulima canopusensis sp. nov. A. Holotype, MZSP 70328. B, C, G, H. MZSP 65317. D, E, I, J. MNRJ 26724. I. Detail of protoconch, frontal view. J. Detail of protoconch, apical view. Scale bars: A–E= 1.0 mm; F–H= 500 µm; I, J= 100 µm.