Chilonopsis exulatus ( Reeve, 1849 )

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 : 197-199

Chilonopsis exulatus ( Reeve, 1849)

Figs 4e , 10a

Achatina exulata Benson MS in Reeve, 1849: pl. 78 fig. 77 (in text for pl. 21).

Achatina exulata – Melliss 1875: 123.

Bulimus exulatus – Wollaston 1878: 542. — Smith 1892: 266.

Bulimus (Cleostyla) exulatus – Dall 1896: 419.

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

Chilonopsis exulatus – Crowley & Pain 1977: 559.

Cleostyla exulata – Schileyko 1999: 531.

Diagnosis

Smallest of the two ovately elongate Chilonopsis (17.2–21.5 mm compared to 29.0– 31.5 mm); differs from C. subtruncatus in having a less flared aperture and, well developed sculpture. The wrinkled radial striae on the teleoconch are unique and give an irregular scalloping effect.

Type material

Possible holotype of Chlionopsis exulatus

SAINT HELENA • UMZC I.105095 ( Fig. 10a ).

Remarks

Reeve (1849) states it was collected by Lieut. Lefroy. Reeve’s description of a specimen in the Benson collection does not enable any particular specimen to be identified. The figure ( Reeve 1849: pl. 78 fig. 572) appears to show a more striped shell than the UMZC specimen, but this may have faded. It is impossible to be certain that this is the holotype, although it is the only specimen known to be associated with Benson.

Other material examined

SAINT HELENA • 1 shell; ANSP 69979 • 1 shell; Sugarloaf Ridge , N coast facing E; A. Loveridge leg.; FMNH 173183 • 4 shells; W.H. Turton leg.; NHMUK 1893.2.24.171-5 • 1 shell; Trechmann collection; NHMUK 2176 • 1 shell; W.H. Turton leg.; Tomlin collection; NMW • 5 shells; W.H. Turton leg.; USNM 126267 .

Description

A small species (height 17.2–21.5 mm; Table 1 ). Shell elongately ovate, thin. Apex rounded, projecting. 6.5–7 convex whorls, first 4 slowly widening, the rest very rapidly widening and less convex. Whorls very narrowly shouldered, sutures impressed. Protoconch of 1.5–2 whorls, ornamented with 6–8 very fine spiral striae, usually indistinct at apex. Teleoconch with irregular growth-lines and wrinkled radial ridges, crossed by spiral striae. Aperture ovate. Lip thin, very narrowly expanded, flaring at base. Columella short, with a prominent internal fold, truncate at base. Umbilicus closed.

Fresh shells glossy, off-white to pale grey with white markings. Apical 3 whorls yellowish. Surface very glossy.

Distribution

Restricted to the north of the island ( Fig. 11 ); recorded from Sugarloaf Ridge ( Smith 1892) and Side Path ( Melliss 1875). Melliss had them only from surface-soil (1875) but some of Turton’s 1884– 86 specimens appear to be fresh, being shiny and pigmented.

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.