Under Construction

Atlanta meteori Richter 1972

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 meteori attains a maximal shell diameter of 4 mm. The shell is transparent and colorless, and the walls are thin and fragile. The surface of the shell is smooth, without any sculpture. The keel is tall, with a truncate leading edge. The keel inserts between the penultimate and last shell whorls in shells larger than about 2 mm. The shell spire is comprised of about 5-1/2 to 5-3/4 whorls, and is strongly tilted relative to the shell plane. The spire is conical, with a rounded apex and an apical angle of 60-70°. The spire sutures are very shallow, with the result that the whorls are difficult to distinguish when the shell is viewed from the side. The umbilicus is very small and narrow. Eyes type b; lens conspicuously large in adults. Operculum type b; very thin and fragile. Radula type II and narrow, with a growth angle of 12-14°. Radulae not sexually dimorphic. Lateral teeth with accessory cusps. Marginal teeth with long, straight shafts and sharply bent hooks. Rachidian teeth broad and with a long median cusp. Atlanta meteori was previously considered to be an Indo-Pacific species in tropical to subtropical waters, but with its identification off northwestern Africa, it must now be regarded as cosmopolitan.

Diagnosis

Characteristics

  1. Shell
    1. Shell of moderate size (to 4 mm diameter)
    2. Shell transparent and colorless
    3. Shell fragile, with thin walls
    4. Keel tall, with a truncate leading edge that begins nearly 1/4 whorl from  the shell aperture (see title illustration)
    5. Keel penetrates between penultimate and last whorls in shells larger than about 2 mm (see first SEM below)
    6. Spire strongly tilted relative to shell plane (see third SEM 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. Shell of Atlanta meteori; views of the right side (left) and spire (right). Scale bars = 0.5 mm and 0.1 mm, respectively. © 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

      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. Shell of a 3.7 mm Atlanta meteori; views of the right side, tilted (left) and the spire, tilted (right). Scale bars = 0.5 mm and 0.1 mm, respectively. ©

    7. Spire of about 5-1/2 to 5-3/4 whorls
    8. Spire conical in side view, with an apical angle of 60-70°. Richter (1990) characterized the apical angle as 70°, and this value is in agreement with the apical angles of the adult shells shown above and in the spire photograph below. However, Richter's photographs of larval shells (see fourth SEM above and transmitted light photograph below) have apical angles of about 60°. Without pursuing an explanation for this discrepancy, the apical angle is given here as 60-70°
      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. Shell spire in Atlanta meteori; photograph taken with shell positioned about 45° above the shell plane. Image cropped from the original in de Vera, et al. (2006, fig. 4b). © 2006 A. de Vera

      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. Larval shell of Atlanta meteori, in apertural view. Image from G. Richter (1990, fig. 12), modified by addition of scale bar (=0.5 mm). © 1990 G. Richter

    9. 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
      Spire sutures very shallow, with the result that when the spire is viewed from the side, the sutures are difficult to distinguish (see SEMs of adult and larval shells above)
    10. Internal walls of spire intact (see transmitted light photograph below); not decalcified as in A. inclinata and A. tokiokai
      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. Larval shell of Atlanta meteori, in side view using transmitted light. Photograph from Richter (1990, fig. 24), modified by addition of scale bar (=0.5 mm). © 1990 G. Richter

    11. Left side of shell with a very small and narrow umbilicus
      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. Shell of Atlanta meteori; views of left side of shell (left) and umbilical region (right). Scanning electron micrographs from G. Richter (1990, figs. 8 and 20), modified by 180° rotation of second photograph and addition of scale bars (= 1.0 mm and 250 µm, respectively). © 1990 G. Richter

  2. Eyes type b
    1. Lens conspicuously large in adults, suggesting that the species prefers deeper daytime depths (Richter, 1974)
  3. Operculum type b
    1. Operculum thin and fragile
  4. Radula type II
    1. Radula with a growth angle of 12-14°; slightly narrower than in A. gibbosa
    2. Radulae of males and females show no sexual dimorphism
    3. Lateral teeth with accessory cusp (see label on SEM 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. Section of the radula from Atlanta meteori. Image from Richter (1990, fig. 33), modified by addition of scale bar (= 100 um). © 1990 G. Richter

    4. Rachidian teeth with a tall median cusp; in contrast with the short median cusp in A. gibbosa
      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. Rachidian tooth from adult portion of radula in Atlanta meteori. Image from Richter (1990, fig. 41), modified by addition of scale bar (= 10 µm). © 1990 G. Richter

Comments

Atlanta meteori shares a number of features with A. gibbosa. Both species have: (1) the same maximal shell size, (2) a transparent, colorless shell with thin, fragile walls, (3) a tall keel with a truncate leading edge, (4) a keel that penetrates between the last two whorls in shells larger than about 2 mm, (5) intact internal spire walls; not decalcified as in A. inclinata and A. tokiokai, and (6) the same eye, operculum and radular types. They differ, however, in several ways: (1) the apical angle of the shell spire is much narrower in A. meteori (60-70°) than in A. gibbosa (85°), (2) the spire is more steeply inclined relative to the shell plane in the former than in the latter species, (3) the spire sutures are very shallow in A. meteori and moderately incised in A. gibbosa, (4) the umbilicus is very small and narrow in A. meteori and very wide and deep in A. gibbosa, (5) there is no sexual dimorphism in the radulae of the former species , while the radular shape and tooth morphologies show strong sexual differences in the latter one , (6) the rachidian teeth have a notably longer median cusp in the former than in the latter species.

Historically, Atlanta meteori has been reported only from the Indian and Pacific Oceans. However, in a survey of the heteropod fauna of waters around the Selvagens Islands in the eastern North Atlantic, it was recorded by de Vera et al. (2006). Thus, the species must now be regarded as cosmopolitan, although possibly rare in the Atlantic Ocean.

In Hawaiian waters, the abundances and diel vertical distribution of Atlanta meteori were studied by Seapy (1990, 2008). In the first paper it was found to range downward during the day from a depth interval of 45-90 m to the maximal depth interval sampled (200-300 m) in low abundances (less than 1.5 individuals per 1,000 m3). At night there was a strong upward migration into the upper 140 m, with most individuals (85%) between the surface and 90 m and with the highest abundance (5 individuals per 1,000 m3) between the surface and 45 m. In the latter paper, A. meteori also occurred in low abundances (less than 4 individuals per 1,000 m3) at stations located 1, 5, and 15 nmi offshore. At all three stations there was evidence of strong nocturnal vertical migration, as found in the previous paper.

References

de Vera, A., R. R. Seapy, and F. Hernandez. 2006. Heteropod molluscs from waters around the Selvagens Islands (Gastropoda: Carinarioidea). Vieraea 34:33-43.

Richter, G. 1972. Zur Kenntnis der Gattung Atlanta (Heteropoda: Atlantidae). Archiv für Molluskenkunde 102(1/3): 85-91.

Richter, G. 1974. Die Heteropoden der "Meteor" Expedition in den Indischen Ozean 1964/65. "Meteor" Forschungs-Ergibnisse Ser. D, No. 17, pp. 55-78.

Richter, G. 1990. Zur Kenntnis der Gattung Atlanta (IV). Die Atlanta inclinata-Gruppe (Prosobranchia: Heteropoda). Archiv für Molluskenkunde 119: 239-275.

Richter, G. and R. R. Seapy. 1999. Heteropoda, pp. 621-647. In: D. Boltovskoy (ed.), South Atlantic Zooplankton. Backhuys Publishers, Leiden.

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

Seapy, R. R. 2008. Offshore-inshore and vertical distributional patterns of heteropod mollusks off leeward Oahu, Hawaii. Marine Biology 154: 985-995.

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 meteori
Location Indian Ocean
Life Cycle Stage adult
Body Part shell of holotype specimen
View right side
Size 3.7 mm diameter
Copyright © 1972 G. Richter
Scientific Name Atlanta meteori
Location Indian Ocean
Life Cycle Stage adult
Body Part shell of holotype specimen
View left side
Size 3.7 mm diameter
Copyright © 1972 G. Richter
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 meteori Richter 1972. 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. 2011. Atlanta meteori Richter 1972. Version 23 July 2011 (under construction). http://tolweb.org/Atlanta_meteori/28766/2011.07.23 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 meteori

Page Content

articles & notes

collections

people

Explore Other Groups

random page

  go to the Tree of Life home page
top