Emarginula aff. souverbiana Pilsbry, 1890

Helwerda, Renate A. & Wesselingh, Frank P., 2014, Revision of Scissurellidae, Anatomidae and Fissurellidae (Gastropoda: Vetigastropoda) from the Plio-Pleistocene of the Philippines, Zootaxa 3838 (2), pp. 183-194 : 189-191

Emarginula aff. souverbiana Pilsbry, 1890

( Figure 11 )

1872 Emarginula maculata nov. spec.—Souverbie: p. 55, pl. 1, fig. 6.

1890 Emarginula souverbiana nom. nov.—Pilsbry: p. 262–263, pl. 64, fig. 28. 1966 Emarginula souverbiana Pilsbry, 1890 —Ladd: p. 28, pl. 2, figs. 17–18. 1999 Emarginula souverbiana Pilsbry, 1891 in 1888–1896 —Higo et al.: p. 39.

Material. Anda6 (1) RGM 961.723.

Characterization. Shell patelliform; L 9.45 mm; H 3.77 mm; W 6.36 mm; apex at 0.85 of shell length, not strongly involute; sculpture of about 23 regularly spaced primary radial ribs, primary and secondary ribs easily distinguished, commarginal ribs forming moderately dense knobs on radial ribs; selenizone filled with sediment, demarcated by strong keels; slit well-developed; posterior slope slightly convex.

Distribution. Emarginula souverbiana Pilsbry, 1890 is known from the type locality Art Island, New Caledonia, Recent ( Souverbie 1872), from Enitewok Atoll, Marshall Islands, Recent ( Ladd 1966) and from Amami and Okinawa Islands, Japan ( Higo et al. 1999).

Remarks. The original name of Emarginula souverbiana Pilsbry, 1890 was preoccupied by E. maculata Adams, 1863 from Japan. The studied material resembles E. souverbiana Pilsbry, 1890 , especially the material figured and described by Ladd (1966), in its general shape and sculpture, but the holotype of E. souverbiana Pilsbry, 1890 ( Figure 13 ) is relatively taller (L 5.9 mm; H 3.3 mm) and it has more primary radial ribs, about 32, which are less regularly spaced and less easily distinguished from secondary radial ribs. Therefore, it is doubtful that the studied material, as well as the material figured and described by Ladd (1966), belong to E. souverbiana Pilsbry, 1890 . Yet, it is difficult to assign them to a different species, because little is known about the intraspecific variation within E. souverbiana Pilsbry, 1890 . Furthermore, none of the other Emarginula species compared to the material, represent a better match. The studied material is very similar to E. patula Cotton, 1930 from Southern Australia with respect to its shape and size, but this species has a much less involute and slightly more centered apex and its commarginal ribs are spaced farther apart and its radial ribs closer together. Emarginula dubia Schepman, 1908 and E. sibogae Schepman, 1908 from Indonesia are also similar with respect to their general shape, size and sculpture, but E. dubia has a finer sculpture with more ribs and E. sibogae has a centered apex.

Figures

FIGURE 13. Emarginula souverbiana Pilsbry, 1890 (= Emarginula maculata Souverbie, 1872), holotype. MHNBx (Muséum d’Histoire Naturelle de Bordeaux) 2004. TY. 131. Locality Art Island, New Caledonia, Recent. Length 5.9 mm; width 4.1 mm; height 3.3 mm. (a) left view, (b) apical view. Photographs courtesy of L. Charles of MHNBx.

FIGURES 10 – 12. 10. Emarginula tosaensis Habe, 1953. RGM 961.722. Locality Anda 3. (a) left view, (b) right view, (c) basal view, (d) apical view. 11. Emarginula aff. souverbiana Pilsbry, 1890. RGM 961.723. Locality Anda 6. (a) left view, (b) right view, (c) basal view, (d) apical view. 12. Zeidora geigeri nov. spec. RGM 961.724. Locality Anda 2. (a) left view, (b) right view, (c) basal view, (d) apical view, (e) SEM apical view, (f) SEM detail of protoconch.