Creseis bulgia Sakthivel, 1974
Overview
This is a shelled pelagic snail, up to 0.2 cm long, with a transparent, uncoiled shell. The cross-section is round. The surface is smooth. The shell is short and narrow, tube shaped and not curved. The visceral mass is seen through the shell. It is a clumsy swimmer that feeds on phytoplankton and protozoa. It lives in the warmer waters of the Indian Ocean in the upper water layers (Creseis bulgia).
Taxonomic Description
The shell is smooth, nearly straight, conical and circular in cross section. A wavy transversal striation is present in some specimens but it never is as prominent as in Creseis chierchiae. Length of the shell is 4 times the maximum diameter. The protoconch has a distinct bulge at the anterior end which separates the adult and juvenile shell.
Shell length 2.2 mm, width 0.5 mm, protoconch length 0.45 mm width 0.12 mm.
Juveniles
The slender conical juvenile with its blunt tip and clear incision between embryonic and adult shell resembles the juveniles of C. a. clava although it is slightly broader.
Reproduction
This form is a protandric hermaphrodite.
Ecology
This form is phytophagous.
Distribution
This species is found in the Indian Ocean between 19°N-29°S and 73°E-109°E, see the Creseis bulgia map.
Types
Creseis bulgia Sakthivel, 1974: 619, fig. 1-2.
Holotype and paratypes in the Indian Ocean Biological, Centre Cochin, India.
Type locality: off Kalpeni Island of the Laccadive Sea, 10°04'N 73°36'E, paratypes were collected at 19°04'N 73°36'E, 20°19'N 38°21'E, 12°41'S 98°25'E, 29°25'S 109°29'E.