Chilonopsis melanioides ( Wollaston, 1878 )

Chilonopsis melanioides ( Wollaston, 1878)

Figs 4h View Fig , 10e View Fig

Subulina melanioides Wollaston, 1878: 550 .

Bulimulus melanioides – Smith 1892: 267.

Pachyotus melanioides – Dall 1896: 416.

Chilonopsis melanoides – Pilsbry 1904: 177. — Crowley & Pain 1977: 557.

Chilonopsis (Chilonopsis) melanoides – Germain 1931: 170.

Diagnosis

The most elongate Chilonopsis (mean height/diameter 3.12 compared to 1.31–2.79) with the most whorls (7.5–9.0 compared to 4.5–7.0); sutures distinctively wavy. Low irregular sutural bosses present and teleoconch sculpture irregular and coarse.

Type material

Syntypes of Subulina melanioides

SAINT HELENA • 1 shell; Lowe-Wollaston collection; ANSP 97326 About ANSP ( Fig. 10e View Fig ) • 3 shells; NHMUK 1896.42.197 • 1 shell; RMNH. MOL.269649 .

Wollaston described the species based on all the specimens collected by Mrs Wollaston, himself and Mr P. Whitehead mid-way between Actaeon and Diana’s Peak.

Other material examined

SAINT HELENA • 2 radula slides (presumably extracted from ANSP 97326 ); ANSP 69937 • 2 shells; DMNH 184024 • 1 shell; FMNH 76902 • 1 shell ; Diana’s Peak ; 2000 feet; W.H. Turton leg.; NHMUK 1892.2.24.204-8 • Diana’s Peak; presented by G.T. Angas; NHMUK 1878.5.23.1 • 1 shell; J. Ponsonby, Suter collection; NMNZ M.209881 • 1 shell; Diana’s Peak ; elev. over 2000 feet; W.H. Turton leg.; Tomlin collection; NMW • 1 shell; P. Dupuis collection ex Fulton; RBINS: IG:8907-HIST.4 • 3 shells; Ponsonby collection; UMMZ 141295 • 3 shells; W.H. Turton leg.; USNM 197822 , 126269.

Description

A long species (height 23.8–24.8 mm; Table 1 View Table 1 ). Elongately conical. Shell moderately thick. Apex acute. 7.5–9 slightly convex whorls. Body whorl with a distinct, low carina just below the margin. Sutures deep, wavy. Protoconch of 1 whorl with faint traces of spiral striae. Teleoconch with fine spiral striae crossed by coarse radial ridges, forming a coarse scalloping pattern. Spirals clearest at middle and lower half of each whorl. Irregular very widely spaced low bosses present at the sutures. Aperture narrowly ovate, slightly oblique. Lip narrow, simple, margins joined by a very thin palatal callus. Columella vertical, with a prominent oblique fold, truncated at base. Umbilicus almost completely covered.

Most specimens are fresh with the periostracum intact: apical 1.5 whorls yellowish, rest dark red-brown to black, with irregular ochre streaks on the sutural bosses extending to near the margin of each whorl.

Distribution

Known only from Diana’s Peak ( Fig. 11 View Fig ) over 600 m above sea level (Turton in Smith 1892) and between Mt Actaeon and Diana’s Peak ( Wollaston 1878).

Remarks

A single live animal and fresh shells were recorded in 1878 ( Wollaston 1878). Reports of it being extant after this date ( Smith 1892; Germain 1931) are both in reference to the original description rather than evidence of continued survival.

Wollaston (1878: 551) described the habitat in which they found the specimens: “… though a single living example which was secured by Mr. P. Whitehead in an immediately adjoining locality sufficed abundantly to indicate the modus vivendi of the species, – it having been taken at the roots of one of the damp masses of intermingled moss and grass which pad the base of the perpendicular rocks formed by the excavation of what is known as the ‘Cabbage-Tree Road’. There can be little doubt, consequently, that the S. melanoides will be ascertained to occur in humid places generally along the northern slopes of the ridge below Diana’s Peak.”