Atlanta echinogyra is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae.[3]
Atlanta echinogyra was described in 1972 by Dr. Gotthard Richter (from Senckenberg Museum, Frankfurt am Main, Germany) based on specimens collected during the Meteor Expedition to the northern Indian Ocean.[4] Richter named the species after the unique structure of the opercular gyre, with its raised spiral row of spines.[4]
Atlanta echinogyra is a small species (to 2.5 mm shell diameter).[4] The shell is colorless, although the tissues underlying the shell spire give it a red-violet to red-brown color.[4] The spire is low conical and consists of 3-3.25 whorls.[1][4] The spire whorls have incised sutures and bear low spiral ridges on the second through most of the fourth whorls.[4] The outer edge of the third and fourth whorls have a raised ridge (seen best in the larval shell).[4] The fourth whorl (first teleoconch whorl) increases rapidly in width and bears a flange-like keel.[1] The keel is moderately elevated with a slightly truncate leading edge.[4] The keel does not insert between the last two shell whorls.[4] The keel base is either clear or brown.[4] The early whorls are covered with a distinct and relatively coarse ornament consisting of four spirals.[1] This ornament is also visible on the base of the shell, where it is present in the umbilicus, on the last part of the protoconch.[1]
Eyes are type a.[4] Operculum is type c, with a gyre that bears a raised spiral row of strong, distally-tapering spines (hence the specific epithet, "echinogyra").[4] Radula is type I, with unlimited numbers of tooth rows and lacking sexual dimorphism.[4]
Description overview:
Geographic distribution of Atlanta echinogyra is Indo-Pacific.[4]
In the plankton samples from the Meteor Expedition studied by Richter (1974), Atlanta echinogyra was the fourth most abundant species of heteropod (accounting for 9.1% of the total).[4] By contrast, the species was uncommon off northeastern Australia (ranking ninth, accounting for 1.5% of the total number of heteropods collected) in a study by Seapy et al. (2003).[4] In Hawaiian waters Atlanta echinogyra was variable in its presence and numbers among different collections, ranking eleventh out of thirteen species of atlantids (Seapy, 1990a); from five different sampling periods between 1984 and 1986, it was not collected twice, was represented by a single individual once, and by 27 and 19 individuals in two collections.[4] In eastern Australian waters, Newman (1990) recorded Atlanta echinogyra as rare in northern and central Great Barrier Reef waters.[4] Thus, it would appear that in the Pacific and Indian Oceans, Atlanta echinogyra is only abundant in the northern Indian Ocean.[4]
Atlanta cf. echinogyra is known from the Pliocene of Anda, Pangasinan, Luzon, Philippines.[1]
Vertical distribution limited to the upper 100 m in Hawaiian waters.[4]
This article incorporates CC-BY-3.0 text from references.[1][4]
Atlanta echinogyra is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae.
