Emarginula salebrosa explained

Emarginula salebrosa is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets and slit limpets.

Description

(Original description)

• Dimensions: Holotype, base 7.0 × 5.4 mm, height 4.4 mm; largest specimen, base 8.4 × 6.0 mm, height 4.7 mm.
• Shell Characteristics
  • Size & Thickness: Small, with a basal length up to 8.4 mm, and notably thick.
  • Shape & Profile:
    • Apex

Strongly recurved, extending slightly beyond the posterior margin of the base in some specimens, though not reaching it in others.

• • • Dorsal Profile: Strongly convex.
    • Basal Outline: Broadly ovate, with a length-to-width ratio (L/W) of 1.3–1.4, appearing flat or slightly concave in side view.
    • Height: Moderate, with a height-to-length ratio (H/L) between 0.56 and 0.63.
    • Slope & Face:
      • Anterior Slope: Humped in side view; anterior face slightly flattened on either side of the slit.
      • Posterior Slope: Almost straight and steeply inclined in larger specimens, less so in smaller ones.
• Protoconch

Generally tucked beneath the apex but often missing; somewhat eroded in available specimens, typically emarginuliform with traces of irregular granulation and a diameter of about 140 μm.

• Sculpture & Texture:
  • Anterior Slit: Narrow and moderately deep, extending roughly one-third down the anterior slope.
  • Selenizone

Initially forms a low mid-line rib with coarse lunulae, diminishing in prominence with growth and becoming weaker than neighboring primary ribs.

• • Radial Sculpture: Coarsely cancellate, with 14–16 primary radial ribs, narrower secondary ribs between them, and occasional tertiary ribs near the basal margin.
  • Concentric Ridges: Cross the radial ribs, equal in strength to secondary ribs, creating strong nodules at intersections.
  • Interstices: Rounded, quadrate depressions with single or paired intritacalx pits.
  • Basal Margin: Coarsely crenulated by the ends of the radial ribs.
  • Interior: Features a broad, thickened ridge underlying the selenizone; the apex is visible from the interior.
• Coloration: Juvenile specimens are uniformly white, while larger shells tend to appear dirty white.

^[1]

Distribution

This marine species occurs on the Walters Shoals, a group of submerged mountains off the coast of Madagascar.

Notes and References

1. Herbert . D.G. . The Vetigastropoda (Mollusca) of Walters Shoal, with descriptions of two new genera and thirty new species . European Journal of Taxonomy . 2024 . 923 . 4 . 10.5852/ejt.2024.923.2445 . 2 November 2024.