Chilonopsis subtruncatus (E.A. Smith, 1892 )

Chilonopsis subtruncatus (E.A. Smith, 1892) View in CoL

Figs 4f View Fig , 10b View Fig

Bulimulus subtruncatus E.A. Smith, 1892: 266 .

Bulimus (Cleostyla) subtruncatus – Dall 1896: 419.

Chilonopsis (Cleostyla) subtruncatus View in CoL – Pilsbry 1904: 180. — Germain 1931: 170.

Chilonopsis subtruncatus View in CoL — Crowley & Pain 1977: 556.

Diagnosis

The larger of two elongately ovate species of Chilonopsis (29.0– 31.5 mm compared to 17.2–21.5 mm). Sculpture reduced; aperture distinctly flared at base.

Type material

Lectotype (here designated)

SAINT HELENA • shell; Side Path; W.H. Turton leg.; NHMUK 1892.2.24.224-8 ( Fig. 10b View Fig ). One of the syntypes marked as a holotype, corresponding to the specimen measured by Smith (1892) although no holotype was designated. We designate this specimen as the lectotype.

Paralectotypes (here designated)

SAINT HELENA • 4 shells; same data as for lectotype; NHMUK 1892.2.24.224-8 .

Other material examined

SAINT HELENA • 1 shell; ANSP 69868 • 2 shells; Sugarloaf Point; ex Jackson 10856; DMNH 148893 • 1 shell; Géret 1919; P. Dupuis collection; RBINS: IG:8907-HIST.6 • 1 shell (broken subadult); Castle Rock Plain (GB 882 SH); 1995; P. and M. Ashmole leg.; MSH • 1 shell; Tomlin collection; NMW. 1955.158 • 1 shell; Side Path; W.H. Turton leg.; Pain collection; NMW. 1981.118.04854 • 2 shells; USNM 126264 .

Description

A large species (height 29.0– 31.5 mm; Table 1 View Table 1 ). Elongately ovate. Apex conical, slightly projecting. 7 slightly convex whorls, suture deep. Protoconch of 2 whorls with fine spiral striae, usually very faint. Teleoconch with fine growth-lines and very shallow radial striae, crossed by sparse, shallow spiral striae. Aperture ovate to slightly auricular. Lip thin, very slightly expanded, distinctly flaring slightly toward base, margins united by a thin callus. Columella oblique with a vertical ridge. Last whorl obliquely sloping, but slightly ascending to the lip. Lip thin, slightly spreading or expanded in front. Umbilicus closed.

All specimens bleached white, mostly heavily worn. Oblique white streaks very faintly visible around the middle of each whorl and just above the sutures.

Distribution

All but one specimen from the north of the island ( Fig. 11 View Fig ): Side Path ( Smith 1892) and Sugarloaf Point (DMNH). One shell from Castle Rock Plain in the south (MSH). Shells were common in 1884–86 but already extinct ( Smith 1892).

Remarks

Very similar to C. exulatus but larger, more fusiform, columella less truncate, similar oblique intersecting opaque-white markings.