Notobranchaea macdonaldi Pelseneer, 1886b morpha macdonaldi Pelseneer, 1886b
This is a small naked pelagic snail, up to 1 cm long, with an opaque body, the visceral organs may be seen through the body wall. The anterior tentacles are small. There are two pairs of buccal cones. The posterior gill has three crests. It is a good swimmer that hunts zooplankton, and it lives in the all ocean (Notobranchaea m. macdonaldi 2).
Head is rounded, the neck is contracted. The body is brown/yellow to grayish (Notobranchaea m. macdonaldi). The fins are large (Notobranchaea m. macdonaldi 3). The footlobes are well developed; the posterior one is long and pointed, the lateral ones are triangular and are fixed to the body for 1/3 of their base. A median tubercle is present. The penial sucker is absent. The lateral gills are only simple protrusions of the skin. The posterior gill has three crests, these may be very broad in living specimens, the dorsal one has 8 to 10 fringes at each side. The penis is extremely large with unarmed chitinous plates. When invaginated, it is coiled spirally in the head parts; it emerges through the penial aperture at the right of the lateral footlobe. At the base of the evaginated penis a long and flexible flagellum is found, above its attachment the penis broadens and its walls are lined with transverse thickenings in pairs. The end of the penis has a long flagellum with a longitudinal groove. The Notobranchaea m. macdonaldi radula formula is 8-1-8, the median plate is unicuspoid. The jaw is composed of one line of cusps 13 to 14 in number. The hook sacs are shallow with about 20 short hooks. Two pairs of buccal cones.
Maximum body length 10 mm.
A special description is not available.
This species is a protandric hermaphrodite.
This species is carnivorous and is sometimes infected with Pteroxena papillifera Stock and Van der Spoel, 1976.
It is discontinuously distributed between 40°N and 40°S in all the oceans and does not show differences in dispersal with species like Pneumoderma atlanticum though it differs from most Pneumodermopsis species being more stenothermic. It is found in the Atlantic, Mediterranean, Caribbean, Indian Ocean, Tasman Sea and Panama area, see the Notobranchaea m. macdonaldi map. Future research may show a more continuous dispersal for this species, like for many others. The morph pelseneeri is found in central waters of the North Atlantic Ocean, Indo-Malayan waters and Tasman Sea, which shows that it is sympatric with the type form of the species.
Notobranchaea macdonaldi Pelseneer, 1886: 225.
Types not preserved in BMNH.
Type locality: off Carolina, 38°10'N 74°15'W. Coll.: CALE.