Clio chaptali (ms. Eydoux and Souleyet) Gray, 1850
Overview
This is a shelled, uncoiled, very broad pyramidally shaped, pelagic snail, up to 2 cm long. The shell is transparent, broadly triangular and oval in cross-section. The dark purple-brown body and visceral mass shines through the transparent shell. Growth lines are not prominent, the lateral sides are rounded in cross section. It is a good swimmer that feeds on phytoplankton and protozoa. It lives in the deep waters of all oceans (Clio chaptali).
Taxonomic Description
The shell is triangular in ventral view. The shell curves regularly dorsally. The sharp lateral ridges are concave. A wavy transverse striation is found on the ventral and dorsal shell sides. Three dorsal ribs are present, the ventral side does not have a rib or swelling. The medio-dorsal rib is the broadest. The width near the shell aperture is about 3/4 of the total shell length. The outline of the shell, in ventral view, is more triangular and the lateral ribs are sharper, never flattened, than in Clio recurva. The blunt ending, obtuse embryonic shell with transverse and longitudinal striae, is anteriorly no sharply marked off. The animal is very large in relation to its shell and is not capable of retracting completely into its shell. The body and wings are entirely dark reddish brown, only the posterior footlobe and the rim of the wings is white. The Clio chaptali radula formula is 1-1-1 (Clio chaptali median radula).
Shell measurements are: 19 mm long, maximum width near the aperture 16 mm.
Morphology and Structure
The wings are extremely well developed, fleshy and thick, the posterior footlobe is enormous and rises above the fins. All parts visible in the shell aperture are purple to dark-brown. The pallial gland turns to the right side of the body so the B, C, II and III band extend beyond the dorsal side. Band I is reduced to a thin strip of fibrous tissue. The well-developed cephalic lobe is triangular and the right tentacle is enclosed in a distinct sheath. In dorsal view a double loop of the intestine is seen through the thin membrane enveloping the body at this side. The other organs are visible where they lie outside the large liver. At the ventral side the intestine forms a long sweeping flexure, then passes over to the back, ending in the anus, quite near the medio-ventral line of the body on a small papilla. The kidney and heart are in normal position and are clearly visible. In female stage the penis, within a distinct sac, is reduced and shrunken after producing eggs. The gonad is composed of radiating sections the follicle walls. The gonoduct protrudes outside the liver and runs straight towards the accessory sexual gland, crossing the throat region ventrally. This gland is extremely reduced in females when the embryos are present. The ovoviviparous strategy is typical for deep-sea species, a second character typical for the deep-sea forms is the ivory-coloured tentacle tips.
Juveniles
It is composed of a globular to oval protoconch with irregular longitudinal lines. An incision between protoconch I and II is absent. Above protoconch I the shell directly widens.
Reproduction
The species is a protandric, ovoviviparous, hermaphrodite with broad protection. The larvae of this species are kept in the anterior part of the pallial cavity at the end of the sexual development of the mother when the gonad and the accessory gland are reduced. In their first stage the larvae show only a conglomeration of cells with three lobes at one pole. The larvae adhere to the membraneous part of the mantle cavity opposite the gizzard. The oval larvae are surrounded by similarly shaped capsula arranged in clusters.
Ecology
The species is phytophagous and bathypelagic.
Distribution
This rare species is found in all oceans. An exceptional record between Greenland and Iceland is, in all probability, not due to the influence of the Gulf Stream, see the Clio chaptali map. This species is bathypelagic. Its rare occurrence together with the great depth at which it lives accounts for the small number of records.
Types
Clio chaptalii Gray, 1850: 14.
Holotype: MHNP (dry collection) u.s.
Type locality: Near Cape of Good Hope. Coll.: CBOE, Eydoux and Souleyet, 1838.