Pneumoderma degraaffi Van der Spoel and Pafort-van Iersel, 1982
Overview
This is a small naked pelagic snail, about 1 cm long. It is oval, with a slightly transparent, usually purple or violet-blue coloured skin. The wings are well developed as are the posterior and lateral footlobes. The buccal mass has two lateral arms, each with up to 6 suckers. It lives in the Atlantic in the upper water layers although it is never abundant (Pneumoderma degraaffi drawing).
Taxonomic Description
The living specimen is ovoid, with a large swollen, transparent lateral gill and whitish posterior gill. The lateral gill is fringed as are the four radiating branches around the central ring of the posterior gill (Pneumoderma degraaffi). These fringed structures are caused by shrinking due to fixation. The integument is transparent beset with numerous purple chromatophores. The wings are fleshy-yellowish in living specimens. The posterior footlobe, of moderate length, is thick and whitish. The lateral footlobes are large, fixed over half their length, and beset with large purple chromatophores. Between the lateral footlobes a prominent median tubercle is present. The hood over the buccal organs is dark purple and well separated from the body. The visceral mass fills the entire body and is seen through the body wall as yellow/grayish. The buccal appendages consist of six suckers implanted on the buccal wall. They are equal in shape and size. The hook-sacs are slender, half as long as the body, there are about 200 hooks in each sac. The jaw consists of irregular plates. The radula formula is 3-0-3, and consists of 24 rows. The lateral plates have large square basal plates.
Body length 11.8 mm, max. width 9.6 mm
Juveniles
A special description is not available.
Reproduction
This species is a protandric hermaphrodite.
Ecology
This species is a carnivore.
Distribution
So far this species has only been recorded from the N-Atlantic Ocean.
Types
Pneumoderma degraaffi Van der Spoel, 1982; 18, fig. 1.
Holotype: Preserved in ZMAN, collected by AMNAPE stat. 25 haul 7.
Type locality: depth 40-100 m, 21.2°C.
Etymology: the name is given in honour of the commander Kltz. G.J.H. de Graaff of the research vessel 'Tydeman'.