Chilonopsis turtoni (E.A. Smith, 1892 )

Gerlach, Justin, Griffiths, Owen, Hume, Julian P., Louchart, Antoine, Sorrel, Philippe & Cairns-Wicks, Rebecca, 2025, Diversity of the extinct land snail genus Chilonopsis of St Helena (Mollusca: Gastropoda: Achatinidae), European Journal of Taxonomy 1007, pp. 176-210 : 203-204

Chilonopsis turtoni (E.A. Smith, 1892)

Figs 4i , 10f–i

Bulimulus turtoni E.A. Smith, 1892: 255 .

Chilonopsis turtoni – Pilsbry 1904: 181. — Crowley & Pain 1977: 560.

Chilonopsis (Cleostyla) Turtoni – Pilsbry 1904: 181 . — Germain 1931: 170.

Diagnosis

The only conical Chilonopsis ; shell thinner than in other species; sutures very shallowly impressed; sculpture very weakly developed.

Type material

Syntypes of Bulimulus turtoni

SAINT HELENA • 1 juv. shell; ex Museum of Economic Geology; NHMUK 1860.1 .23.50 • 1 adult shell; ex Museum of Economic Geology; NHMUK 1860.1 .23.49 • 10 adult, 2 juv. shells; near High Peak; Capt. Turton R.E. leg.; NHMUK 1892.2.24.209-218 ( Fig. 10f –h ) .

The main syntype series were collected by Turton but Smith’s description also includes the specimens then in the Museum of Economic Geology ( NHMUK 1860.1.23.49–50), collected by E. Alexander and donated by Forbes, this collection later became part of NHMUK.

Forbes (1852: 3) referred to these specimens as “an existing undescribed species found by Mr. Alexander feeding on the cabbage-trees only on the highest points of the island.”

Other material examined

SAINT HELENA • 2 shells; ANSP MAL 69936 • 4 shells; W.H. Turton leg.; Melvill-Tomlin collection; NMW. 1955.158.27975 • 1 shell; W.H. Turton leg.; Pain collection; NMW. 1981.118.04853 • 1 shell; Géret 1919; P. Dupuy collection; RBINS: IG:8907-HIST.7 • 3 shells; Ponsonby collection; UMMZ 141298 • 5 shells; W.H. Turton leg.; USNM 126268 .

Description

A relatively small species (height 14.7–18.4 mm; Table 1 ). Shell conical, thin, glossy. Apex rounded, produced. 7 slightly convex whorls, body whorl evenly rounded. Sutures very shallowly impressed. Protoconch of 2 whorls with faint spiral striae. Teleoconch with oblique growth-lines and low ridges, crossed by low, indistinct spiral ridges. Aperture ovate, acuminate above. Lip not expanded; margins united by a thin, shiny callus. Columella truncate, upper margin narrowly reflexed, with a small fold or nodule on the middle. Umbilicus open, narrow.

All specimens are fresh with periostracum intact: dark to mid-brown, with irregular oblique white streaks and spots, often interrupted. Streaks may be fine or broad, some deflected into a zig-zag pattern. One specimen ochre with indistinct darker streaking and a dark brown columella ( Fig. 10i ).

Distribution

High Peak (Turton in Smith 1892) ( Fig. 11 ). Last recorded alive in 1884–86 when Turton reported it as living in native vegetation ( Smith 1892), and his specimens are mostly recent.

Figures

Fig. 4. Species of Chilonopsis. a. C. aurisvulpina (Holten, 1802) (NHMD-172594). b. C. helena (Quoy & Gaimard, 1832) (NHMUK 20240185). c. C. blofeldi (Forbes, 1852) (NHMUK). d. C. lanceoloideus sp. nov., holotype (NHMUK 20240171). e. C. exulatus (Reeve, 1849) (UMZC I.105095). f. C. subtruncatus (E.A. Smith, 1892) (NHMUK 92.2.24.224-8). g. C. turtoni (E.A. Smith, 1892) (NHMUK 1892.2.24.209-218). h. C. subplicatus (G.B. Sowerby I, 1844) (MSH). i. C. melanioides (Wollaston, 1878) (ANSP 97326). Scale bar = 25 mm.

Fig. 10. Elongate species of Chilonopsis. a. C. exulatus (Reeve, 1849), possible holotype (UMZC I.105095). b. C. subtruncatus (E.A. Smith, 1892), lectotype (NMHUK 92.2.24.224-8). c–d. C. subplicatus (G.B. Sowerby I, 1844). c. Cochlicopa terebellum G.B. Sowerby I, 1844 figure (Forbes 1892). d. Typical C. subplicatus specimen (NHMUK 20240182). e. Chilonopsis melanioides (Wollaston, 1878), syntype (ANSP 97326). f–i. Chilonopsis turtoni (E.A. Smith, 1892), syntypes. f–h. NHMUK 1892.2.24.209-218. i. NHMUK 1860.1.23.49. Scale bar = 20 mm.

Fig. 11. Distributions of species of Chilonopsis Fischer von Waldheim, 1848.