Complete
This is an archived version of a Tree of Life page. For up-to-date information, please refer to the current version of this page.

Atlanta helicinoidea Gray 1850

Atlanta helicinoides Souleyet 1852

Roger R. Seapy
Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window
Containing group: Atlanta

Introduction

Atlanta helicinoidea is a small species, with a maximal shell diameter of 2 mm. The last whorl in adult shells is broadly oval to rounded. The keel is moderately tall and rounded in undamaged specimens, with a posteriorly-slanted corrugated texture. The spire is low conical, consisting of 4-1/2 to 4-3/4 whorls. The second through fourth whorls have spiral ridges that increase from two in the second whorl to four in the first half of the fifth whorl. Spire coloration is dimorphic; light purple or light yellowish tan, due to underlying tissue pigmentation. Eyes type c, with a black cup-shaped base (unique in the genus), operculum type c, and radula type I. The species is cosmopolitan in tropical to subtropical waters, and is limited to the upper 100 m of the water column in Hawaiian waters. The species shares many similarities with A. inflata, but is immediately distinguishable by its eye morphology.

Diagnosis

Characteristics

  1. Shell
    1. Small, with a maximal diameter of 2.0 mm
    2. Keel moderately tall and rounded in undamaged specimens (see especially the tilted view of the shell in first figure below)
    3. Keel corrugated, with corrugations angled posteriorly (see first figure below)
    4. Spire consists of about 4-1/2 to 4-3/4 whorls (see first two figures below)
    5. Spire whorls with rows of spiral ridges that are moderately to strongly expressed in Hawaiian waters. Minimally (see the first figure below), the number of ridges begin at the end of the second whorl with one or two ridges and end in the first half of the fifth whorl with five ridges in the fourth whorl. Maximally expressed (see the second figure below), two ridges appear at the beginning of the second whorl and increase to three ridges on the third whorl and up to five ridges on the fourth and first half of the fifth whorl.
      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Figure. Scanning electron micrographs of the shell of a 2.0 mm Atlanta helicinoidea, viewed from the right side (upper left), the right side tilted (lower left), and the spire from the right side (upper right) and right side tilted (lower right). Scale bar in upper left SEM = 0.5 mm. ©

      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Figure. Scanning electron micrographs of the shell of a 1.4 mm diameter Atlanta helicinoidea, viewed from the right side (upper left), the right side tilted (lower left), and the spire from the right side (upper right) and right side tilted (lower right). Scale bars = 0.5 mm (upper and lower left) and 0.1 mm (upper and lower righti. © Roger R. Seapy

  2. Coloration
    1. Keel base coloration variable, ranging from clear to brown or yellowish brown.
    2. Spire either light purple or light yellow to yellow-tan, due to pigmentation of underlying tissues.
      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Figure. Atlanta helicinoidea, viewed from right side, with the body fully extended from the shell (left), and with the spire region magnfied (right) to illustrate the light purple coloration due to the underlying tissues. © Roger R. Seapy

      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window


      Figure. Juvenile (left) and young adult (right) examples of Atlanta helicinoidea that illustrate the yellow to yellow-tan coloration of the spire. ©
  3. Eyes type c, with a black, cup-shaped base (see title illustration). This eye morphology is unique in the genus Atlanta, although it is also seen in Oxygyrus keraudreni.
  4. Operculum type c
  5. Radula type I

Comments

The spiral ridge sculpture on the shell spire described above applies to shells from Hawaiian waters and the North Atlantic, as reported by Richter (1987). However, among his specimens from the Arabian Sea of the Indian Ocean, Richter also found shells with reduced spiral sculpture, having a single ridge beginning at whorl 1-1/2 and two additional ridges on the fourth whorl (see left image below).
Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window

Figure. Spires of two shells from the Arabian Sea in the Indian Ocean, illustrating the range in expression of spiral ridge sculpture. © 1987 G. Richter


Other Names for Atlanta helicinoidea Gray 1850

References

Richter, G. 1987. Zur Kenntnis der Gattung Atlanta (III): Atlanta inflata, A. helicinoides, A. echinogyra und A. plana (Prosobranchia: Heteropoda). Archiv fur Mollusken-Kunde 117: 177-201.

Seapy, R. R. 1990a. The pelagic family Atlantidae (Gastropoda: Heteropoda) from Hawaiian waters: a taxonomic survey. Malacologia 32: 107-130.

Seapy, R. R. 1990b. Patterns of vertical distribution in epipelagic heteropod molluscs off Hawaii. Marine Ecology Progress Series 60: 235-246.

Title Illustrations
Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window
Scientific Name Atlanta helicinoidea
Location Hawaiian waters
Specimen Condition Live Specimen
Sex Female
Life Cycle Stage adult
View right side
Image Use creative commons This media file is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0.
Copyright ©
About This Page


California State University, Fullerton, California, USA

Correspondence regarding this page should be directed to Roger R. Seapy at

Page: Tree of Life Atlanta helicinoidea Gray 1850. Atlanta helicinoides Souleyet 1852. Authored by Roger R. Seapy. The TEXT of this page is licensed under the Creative Commons Attribution License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.

Citing this page:

Seapy, Roger R. 2009. Atlanta helicinoidea Gray 1850. Atlanta helicinoides Souleyet 1852. Version 07 October 2009. http://tolweb.org/Atlanta_helicinoidea/28762/2009.10.07 in The Tree of Life Web Project, http://tolweb.org/

edit this page
close box

This page is a Tree of Life Leaf Page.

Each ToL leaf page provides a synopsis of the characteristics of a group of organisms representing a leaf at the tip of the Tree of Life. The major distinction between a leaf and a branch of the Tree of Life is that a leaf cannot generally be further subdivided into subgroups representing distinct genetic lineages.

For a more detailed explanation of the different ToL page types, have a look at the Structure of the Tree of Life page.

close box

Atlanta helicinoidea

Page Content

articles & notes

collections

people

Explore Other Groups

random page

  go to the Tree of Life home page
top