Notobranchaea longicollis (Bonnevie, 1913)
Overview
This is a small naked pelagic snail, up to 0.7 cm long, with an opaque body; the visceral organs may be seen through the body wall. The anterior tentacles are small. The footlobes are placed far posterior of the wing base. It is a good swimmer that hunts zooplankton, living in the N-Atlantic Ocean (Notobranchaea longicollis type, a paratype).
Taxonomic Description
Body spindle-shaped with a narrow neck region. The skin is smooth, unpigmented. No lateral gill. The posterior gill is composed of four radiating crests meeting at the posterior body tip. Wings narrow at the base and tapering towards the distal end. Lateral footlobes normal, posterior lobe narrow and pointed. There are no buccal cones. The Notobranchaea longicollis radula formula is 10-1-10. Median teeth not sickle-shaped as originally described, but unicuspoid and not saw-like as dentation is lacking. The radula teeth in general are small (Notobranchaea longicollis radula after Pruvot-Fol). The jaw is composed of a median row of 8 to 9 double pointed spines with five single denticles on each side. The hook sacs are shallow with about 17 hooks. There is a group of "clear cells" forming a large and conspicuous cushion dorsally to each hook sac. The hooks are short triangular with curved tops. A structure, like a median foot tubercle, is present in the form of a triangular elevation between the lateral footlobes. More research is necessary to prove the absence or presence of a real median tubercle in comparison with the other species of this genus.
Body length 7 mm.
Juveniles
A special description is not available.
Reproduction
This species is a protandric hermaphrodite.
Ecology
This species is a carnivore.
Distribution
Microdonta longicollis occurs in the Atlantic Ocean, where it is only known from its type locality.
Types
Microdonta longicollis Bonnevie, 1913 (1933): 65, pl. 9, figs. 69-78.
Lectotype: ZMVB 39491 (alcohol collection). Paralectotypes: ZMVB 14988, 2 spec. (alcohol collection) and 1 spec. enclosed on a slide and 2 slides with buccal organs.
Type locality: 37°37'N 29°25'W. Coll.: CMSE, stat. 58.