Overview

Brief Summary

Introduction

Atlanta inclinata attains a large maximal size (to 6-7 mm), and the adult shell is clear to light yellow. The keel is moderately elevated, with a rounded to slightly truncated leading edge. The spire consists of about 5 whorls and is globose (or beehive shaped). The internal walls of the spire are decalcified. The spire surface bears small, low tubercles (or punctae) that are usually scattered but sometimes can form irregular spiral lines. The inner surface of the spire has radially-arranged lines (as in A. tokiokai). The innermost whorl adjacent to the umbilicus is rounded and has a low and wide, but nearly indistinct, ridge. Eyes type b, operculum type c, and radula type II. The radula is large, with a growth angle of about 16°, and the number of tooth rows are limited to about 60. The lateral teeth are monocuspid, and the rachidian teeth are about 20% wider than in A. tokoikai. The species has a cosmopolitan distribution in tropical to subtropical waters.

Diagnosis

  • Shell diameter to 6-7 mm
  • Adult shell clear to light yellow
  • Keel moderately elevated with a rounded to slightly truncate leading edge
  • Spire tilted relative to shell plane and consists of about 5 whorls
  • Spire shape globose or beehive shaped
  • Internal spire walls decalcified
  • Outer surface of spire whorls with small, low punctae that are scattered or form irregular spiral lines
  • Inner surface of spire with radially-arranged lines
  • Innermost whorl adjacent to umbilicus rounded, with wide and low ridge
  • Eyes type b
  • Operculum type c
  • Radula type II
  • Radula large, with a growth angle of about 16°
  • Number of tooth rows in radula limited to about 60
  • Lateral teeth monocuspid
  • Rachidian teeth about 20% wider than in A. tokiokai

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Comprehensive Description

Characteristics

  1. Shell
    1. Maximal shell diameter large (to 6-7 mm)
    2. Shell clear to light yellow in color
    3. Spire inclined relative to the shell plane

      Figure. Shell of a 3.6 mm Atlanta inclinata; views of the right side (left) and the spire (right). Images from Richter (1990, figs. 3 and 15), modified by addition of scale bars (= 1.0 mm and 0.1 mm, respectively). © 1990 G. Richter

    4. Spire consists of about 5 whorls (see image below of juvenile shell with a total number of whorls of about 5-1/3)

      Figure. Juvenile shell of Atlanta inclinata, viewed from the right side. Image from Richter (1990, fig. 26), modified by addition of scale bar (= 0.5 mm). © 1990 G. Richter

    5. Spire shape globose (beehive shaped), with shallow but distinct sutures (when spire is viewed from the side; as in the larval shell below)

      Figure. Larval shell of Atlanta inclinata in side view. Image modified from Richter (1990, fig. 10) by addition of scale bar (= 0.5 mm). © 1990 G. Richter

    6. Spire surface with small, low tubercles (or punctae) that are usually scattered, but can form irregular spiral lines. Tubercles occasionally continue on to first teleoconch whorl

      Figure. Shell spire of Atlanta inclinata. Image from Leslie Newman (pers. comm.). Scale bar = 100 µm. © 1990 L. J. Newman

    7. Inner walls of spire with radially-arranged lines, which can only be seen using transmitted light (click on image below to resolve the radial lines, which are seen most clearly in the upper portion of the outermost whorl)

      Figure. Shell spire of Atlanta inclinata, viewed using transmitted light. Image from Richter (1990, fig. 30). © 1990 G. Richter

    8. Internal walls of spire whorls decalcified (only seen using transmitted light)

      Figure. Larval shell of Atlanta inclinata in side view, photographed using transmitted light. Image from Richter (1990, fig. 22), modified by addition of scale bar (= 0.5 mm). © 1990 G. Richter

    9. A low and wide spiral ridge, that is nearly indisinct (see second image below), is present on the rounded whorl adjacent to the umbilicus

      Figure. Shell of Atlanta inclinata, viewed from the left side (left) and enlarged to show umbilical region (right). Images from Richter (1990, figs. 4 and 16), modiefied by addition of scale bars (= 1.0 mm and 100µm, respectively). © 1990 G. Richter

  2. Eyes type b
  3. Operculum type c
  4. Radula type II
    1. Radula large, with a growth angle of about 16°

      Figure. Radula of Atlanta inclinata in dorsal view. Image from Richter (1990, fig. 37), modified by addition of scale bar (= 100 µm). © 1990 G. Richter

    2. Number of tooth rows limited to about 60
    3. Lateral teeth monocuspid (click on image below to enhance photograph)

      Figure. Section of radula in Atlanta inclinata. Rachidian and lateral teeth labeled. Image from Richter (1990, fig. 32), modified by addition of labels and scale bar (= 100 µm). © 1990 G. Richter

    4. Rachidian teeth in the adult portion of the radula about 20% wider than in A. tokiokai, but about 30% narrower than in A. gibbosa and A. meteori (see the respective species pages)

      Figure. Rachidian tooth from adult portion of radula in Atlanta inclinata. Image from Richter (1990, fig. 39), modified by addition of scale bar (= 10 µm). © 1990 G. Richter

    Comments

    Historically, the species of Atlanta with inclined spires (i.e., tilted strongly relative to the shell plane) have been treated together in a single A. inclinata species group (van der Spoel, 1976). In his 1990 paper, however, Richter characterized four species of Atlanta with inclined spires, and concluded that they belonged to two distinctively different species groups. He placed two of the species, A. inclinata and A. tokiokai, in the A. inclinata species group and the other two, A. gibbosa and A. meteori, in an A. gibbosa species group.

    The two species in the Atlanta inclinata species group are very similar and Richter (1990) regarded them as closely related. Features shared by A. inclinata and A. tokiokai (summarized in Richter and Seapy, 1999) include: (1) spire large and globose, (2) internal spire whorls decalcified, (3) internal wall of spire whorls with radially-arranged lines, (4) external surface of spire whorls with sculpture of small punctae that continue on to the first whorl of the adult shell, (5) eyes type b, and (6) operculum type c. The main differences between the two species are: (1) the punctae on the spire are smaller and scattered or form irregular spiral lines in A. inclinata, while in A. tokiokai the punctae are larger and are arranged in distinct spiral lines, (2) when the spire is viewed from the side, the sutures are shallow but clearly separate the spire whorls in the former species, while they are shallower and difficult to distinguish in the latter species, (3) a low, nearly indistinct ridge is present on the whorl adjacent to the umbilicus on the left side of the shell in the former species, while this ridge is strongly developed in the latter species, (4) the area between the aforementioned ridge and the umbilicus is rounded in the former species but is flattened in the latter species, (5) the radula is large, with a growth angle of about 16° in the former species, and is small and ribbon-like, with a growth angle of about 9° in the latter species, (6) the lateral teeth are moncuspid in the former species, and have an accessory cusp in the latter species, and (7) the rachidian teeth in the adult portion of the radula are about 20% wider in the former compared with the latter species.

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Ecology

Habitat

Depth range based on 1 specimen in 1 taxon.
Water temperature and chemistry ranges based on 1 sample.

Environmental ranges
  Depth range (m): 201 - 201
  Temperature range (°C): 12.684 - 12.684
  Nitrate (umol/L): 26.308 - 26.308
  Salinity (PPS): 34.870 - 34.870
  Oxygen (ml/l): 1.392 - 1.392
  Phosphate (umol/l): 2.068 - 2.068
  Silicate (umol/l): 24.469 - 24.469
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Wikipedia

Atlanta inclinata

Atlanta inclinata is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae.[1]

Contents

Distribution

Description

The maximum recorded shell length is 7 mm.[2]

Habitat

Minimum recorded depth is 0 m.[2] Maximum recorded depth is 150 m.[2]

References

  1. ^ a b Atlanta inclinata J. E. Gray, 1850. WoRMS (2009). Atlanta inclinata J. E. Gray, 1850. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=430422 on 14 August 2010.
  2. ^ a b c Welch J. J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". PLoS ONE 5(1): e8776. doi:10.1371/journal.pone.0008776.
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