Paedoclione doliiformis Danforth, 1907
Overview
This is a very small naked pelagic snail, up to 0.15 cm long, with a mainly transparent body and visceral mass is seen through the body wall. It is a neotenous species and the three larval cilia bands are always present. The shape is elongate oval to cylindrical. The lateral footlobes and posterior footlobe are small. It hunts shelled pteropods as food, and lives in the N-Atlantic in the upper water layers where it can occur in mass blooms (Paedoclione doliiformis).
Taxonomic Description
The integument is unpigmented, transparent, but unicellular glands are present as in Pneumoderma. The body is barrel-shaped, the head is elliptical in outline, when expanded. The wings are, flat, elongate oval shaped. The posterior footlobe is rather long. In the oral hood the buccal cones are asymmetrically placed, one at the left and two at the right. Recent findings showed a second but strongly reduced buccal cone present at left side. The buccal cones are of the same structure as in Clione. The ventral right cone, the asymmetrical one, shows more glandular activity than the other cones. Three ciliary bands are always present around the body, cilia are also found on the wing borders, on the osphradium and lateral footlobes. The lateral footlobes are small and retractile. The radula formula is 5-1-5 (Paedoclione doliiformis radula), the lateral teeth are falcate shaped with a slightly widened base. The median plate bears one cusp. There are about 8 hooks in each hook sac.
Body length up to 1.5 mm.
Juveniles
The larval shell shows, in lateral view, a rounded protoconch I, the cross section is irregularly rounded and blunt at the top. A small incision separates protoconch I and II. Protoconch II has many growth lines and is rather straight (cf. Lalli and Gilmer, 1989). Protoconch II does not grow much and is smaller then protoconch I.
Reproduction
This species is a protandric hermaphrodite.
Ecology
This species is a carnivore.
Distribution
This species is only recorded from the NW-Atlantic, see the Paedoclione doliiformis map. In the opinion of Dr. Lalli (personal comm.) this species is probably more common and more widely distributed than indicated and may be easily confused with juvenile Clione limacina.
Other
The protoconch described for P. doliiformis by Grecchi and Bertolotti (1988) does not belong to this species as it is much too oval in cross-section. The subfossils identified by Grecchi (1987) as belonging to this species are Gymnosomata larvae but they do not belong this species since the protoconch I is perfectly round, and the protoconch II is strongly dorso-laterally compressed.
Types
Paedoclione doliiformis Danforth, 1907:2, pl. 1-4, figs. A + B.
Type locality: Casco Bay, Main. Coll.: Danforth.