Sinezona cingulata, Sin.

Nolt, Jaya M., 2008, A new species of Scissurella from the Azores with discussions on Sinezona semicostata Burnay & Rolán, 1990 and Sinezona cingulata (O. G. Costa, 1861) (Gastropoda: Vetigastropoda: Scissurellidae), Zootaxa 1678, pp. 51-62 : 58-59

Comparisons of Sinezona cingulata, Sin. fayalensis, Sin. depressa and Sin. crossei

Sinezona cingulata is applied to a Mediterranean species with type locality Sardinia Island, Italy. The whereabouts of the holotype is unknown. Burnay & Rolán (1990) argued that Costa’s (1861) description did not match the cited figure (here shown in Fig. 5A ) and that Thiele (1912: figs. 6, 7; here shown in Fig. 5 B) noted a different figure in Costa referring to Sin. cingulata . They concluded that Sin. cingulata is a nomen dubium and should be referred to by the first available name to which it is usually applied, Sin. crossei (Folin, 1896) with designated neotype ( Burnay & Rolán 1990), type locality São Vincente, Cape Verde Islands. However taking into account the microscope technology of that time, the original description matches the figure; with 11–12 strong axial cords on the teleoconch, open umbilicus and semi oval aperture ( Fig. 5A ). The shorter teleoconch II and open slit in the original figure are characteristic of a juvenile specimen. That the figure in Thiele (1912) was an error and did not contain the strong axial cords of Costa’s original description has no relevance to the identity of Costa’s species. Costa’s original figure of Sin. cingulata corresponds with the Mediterranean species to which that name has usually been applied. Sinezona crossei as its neotype illustrated by Burnay & Rolán (1990: pl. 1, figs 3–5) compared to Sin. cingulata ( Fig. 2 B) from Spain show differences in numbers of axial cords (protoconch 18 vs. 17, teleoconch I 14 vs. 12, teleoconch II 16 vs. 13) and spiral lines (7 vs. 5). These differences in amounts are insignificant and can be accounted for by intraspecific variation.

Three syntypes of Sin. depressa (BMNH 1911.17.21–23, one shown here in Fig. 2 C), type locality Madeira, and seven specimens of Sin. fayalensis (MNHN, one is shown in Fig. 4 C) from Santa Maria Island, Azores where examined. The neotype of Sin. crossei could not be located in the MNHN collections (Geiger pers. obs. 4/2005), but was adequately illustrated by Burnay & Rolán (1990: pl. 1, figs 3–5). One type specimen of Sin. fayalensis is in Koninklijk Belgisch Instituut voor Natuurwetenschappen in Brussels (T. Backeljau pers. comm.10/2006), but was not available for examination, hence near topotypical specimens were used in this study. Specimens of Sin. fayalensis from the Azores tended to display fewer axial ribs and have a smoother sculpture than specimens from the Mediterranean. One syntype of Sin. depressa was smoother due to erosion. Comparisons of these species with Sin. cingulata are given in Table 2 .

Sculpture and shape are the same. All the specimens have no apertural varix and an open umbilicus. The nominal taxa differ in the number of axial cords (protoconch 16–17 and teleoconch I 12–17) and axial lines (teleoconch II 15–16 and base 12–16). These differences are not sufficient to justify recognition as separate species and can be accounted for by intraspecific variations. A radula of Sin. cingulata from Spain in Figure 6 shows features typically seen in members of Scissurellidae s.s., including serrated rachidian, with 5 serrated laterals, lateral 5 enlarged and serrated marginals ( Geiger 2003). In Figure 6 B the rachidian is triangular with 5 denticles the central on being the largest. The first three laterals have three denticles on the outer margin, the innermost is largest. The fourth lateral tooth is hook shaped. The fifth is broad with about 10 denticles.

Figures

FIGURE 2. SEM-micrographs of shells in frontal, umbilical, apical and detail on protoconch (apical view). A. Scissurella azorensis n. sp., paratype MCZ 356976. B. Sinezona cingulata AMS C. 380708. Benzu, Spain 35.91 ° N, 5.40 ° W. C. Sinezona depressa syntype BMNH 1911.7. 17.21. Madeira Islands 32.66 ° N, 16.75 ° W. Scale bars: shell 200 µm, protoconch 100 µm.

FIGURE 4. SEM-micrographs of shells in frontal, umbilical, apical and detail on protoconch (apical view). A. Sinezona semicostata paratype MNHN Moll 5280. Cape Verde Archipelago, Boavista Island 15 ° N, 23 ° W. B. Sinezona confusa paratype BMNH 1994094 Playa Baracoa, Cuba 23 ° 03 ’ N, 82 ° 34 ’ W. C. Sinezona fayalensis MNHN. Santa Maria Island, Azores 36.95 ° N, 25.11 ° W. Scale bars: shell 200 µm, protoconch 100 µm.

FIGURE 6. Sinezona cingulata radula AMS 380705. Ceuta, Anse Sachel, Caseme del Reine, Spain 35.88 º N, 5.30 ºW. A. Central section, scale bar = 20 µm. B. Close up of rachidian, lateral teeth and marginals, scale bar = 10 µm. C. Full radula, scale bar = 250 µm.

FIGURE 5. A. Original illustration of Sinezona cingulata Costa (1861: pl. 12, figs 9 A – B). B. Sinezona cingulata as figured in Thiele (1912: pl. 3, figs 6 – 7).

Tables

TABLE 2. Comparisons of Sin. cingulata, Sin. fayalensis and Sin. depressa.

Species	Shell Shape	Protoconch	Teleoconch I	Teleoconch II	Base
Sinezona cingulata Spain (Fig. 3A)	trochid, slightly depressed	1.5 whorls, 17 strong axial cords	approx. 1 whorl, 12 strong axial cords	0.25 whorls, 16 axial lines, 5 weak spiral lines, irregular lamellae	16 axial lines
Sinezona fayalen- sis topotypical, Azores (Fig. 3D)	trochid, slightly depressed	1.5 whorls, 16 strong axial cords	1 whorl, 14 strong axial cords	0.25 whorls, 15 axial lines, 8 weak spiral lines, irregular lamellae	14 axial lines
Sinezona depressa syntype, Azores (Fig. 2D)	trochid, slightly depressed	1.5 whorls, 16 strong axial cords	approx. 1 whorl, 17 strong axial cords	0.25 whorls, 16 axial lines, 4 weak spiral lines, irregular lamellae	12 axial lines