Atlanta echinogyra Richter, 1972b
Overview
This is a medium sized dextrally shelled, pelagic snail, 0.3 cm in diameter with very large eyes, a single swimming fin. It is strongly flattened and keeled. The spire is violet, turrate with spiral lines, the rest of the shell is colourless. The operculum has a very small spire and a spiral line with hooks. It is a carnivore predating on relatively large zooplankton. This species occurs in warm waters of the Indian Ocean (Atlanta echinogyra 1, Atlanta echinogyra oral).
Taxonomic Description [after Richter, 1987]
Small, solid shell, the spire is moderately large, turrate with clear spiral sculpture. The suture is deep and clearly visible The spire is deep red-violet. The body whorl is inflated with a widening aperture. The inside of the aperture is darker in colour (Atlanta echinogyra). The inner whorls of the spire are not decalcified. The Atlanta echinogyra operculum (type C) is broad oval, monogyre, the nucleus has 15 to 20 strong hooks-shaped spines in spiral arrangement (Atlanta echinogyra operculum 1). The eyes (type A) have a cylindrical pigment mantle with triangular dorsal window. The radula is moderately large, ribbon-shaped. The median tooth is broad rectangular with a strong median cusp and side flaps. There is no sexual dimorphism in the radula.
Shell up to 2.5 mm in diameter.
Juveniles
The Atlanta echinogyra juvenile has a small dextrally coiled shell, with a smooth protoconch I and and three spiral lines composed of irregular crests and dots on the first three whorls of the spire (Atlanta echinogyra protoconch, Atlanta echinogyra protoc). Veliger with 3.5 whorls shows the beginning of the dorsal shell slit and flattened whorls.
Reproduction
In this species the sexes are separate.
Ecology
This species is carnivorous and epipelagic.
Distribution
This species occurs in the W-Indian and Pacific Oceans, see the Atlanta echinogyra map.
Types
Atlanta echinogyra Richter, 1972: 90, fig 3. 3, 5, 7.
Holotype: SMFM 223052. Paratypes: SMFM 223053.
Type locality: Indian Ocean. Coll.: CMEE.