Molecular Biology and Genetics

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Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records: 14
Specimens with Sequences: 17
Specimens with Barcodes: 17
Species: 2
Species With Barcodes: 2
Public Records: 7
Public Species: 1
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Gastridium

Gastridium is a small genus of grasses. It contains two species, Gastridium ventricosum, and Gastridium phleoides, although the latter is sometimes grouped with the former, making it a monotypic genus in some treatments. These grasses are sometimes called nit grass.

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Gastridium (gastropod)

Gastridium is a proposed genus of sea snails, marine gastropod mollusks in the family Conidae, the cone snails and their allies.[1] This genus currently (November 2011) is still treated by some experts as an "alternative representation" of this group of species.

When the "alternative representations" are not used, this group of species is instead still placed in the Linnaean genus Conus.

Contents

Distinguishing characteristics

The Tucker & Tenorio 2009 taxonomy distinguishes Gastridium from Conus in the following ways:[2]

Shell characters (living and fossil species)
The basic shell shape is conical to elongated conical, has a deep anal notch on the shoulder, a smooth periostracum and a small operculum. The shoulder of the shell is usually nodulose and the protoconch is usually multispiral. Markings often include the presence of tents except for black or white color variants, with the absence of spiral lines of minute tents and textile bars.
Radular tooth (not known for fossil species)
The radula has an elongated anterior section with serrations and a large exposed terminating cusp, a non-obvious waist, blade is either small or absent and has a short barb, and lacks a basal spur.
Geographical distribution
These species are found in the Indo-Pacific region.
Feeding habits
These species eat other gastropods including cones.[2]
Shell characters (living and fossil species)
The shell is cylindrical to ovately cylindrical in shape. The protoconch is multispiral. The shell has bulging body whorl creating a very wide aperture . The anal notch is shallow. The shell is ornamented with tents, as well as spiral lines of minute tents. Textile bars are absent. The periostracum is tufted or ridged, and the operculum is small.
Radular tooth (not known for fossil species)
The anterior section of the radular tooth is greatly elongated compared to the posterior section. The waist is not obvious. The basal spur is absent, and the barb and blade are short. Serrations are present. The radular morphology of this genus is unique as it has no terminating cusp or accessory process.
Geographical distribution
These species are found in the Indo-Pacific region.
Feeding habits
These species are piscivorous, meaning that these cone snails prey on fish.[2]

Species list

This list of species is based on the information in the World Register of Marine Species (WoRMS) list. Species within the genus Gastridium include:[1]

The following species names are recognized as "alternate representations" (see full explanation below) in contrast to the traditional system, which uses the genus Conus for all species in the family:[1]

  • Gastridium cuvieri (Crosse, 1858) is equivalent to Conus cuvieri Crosse, 1858
  • Gastridium eldredi (Morrison, 1955) is equivalent to Conus eldredi Morrison, 1955
  • Gastridium fragilissimum (Petuch, 1979) is equivalent to Conus fragilissimus Petuch, 1979
  • Gastridium geographus (Linnaeus, 1758) is equivalent to Conus geographus Linnaeus, 1758
  • Gastridium tulipa (Linnaeus, 1758) is equivalent to Conus tulipa Linnaeus, 1758

Significance of "alternative representation"

Prior to 2009, all species within the family Conidae were placed in one genus, Conus. In 2009 however, J.K. Tucker and M.J. Tenorio proposed a classification system for the over 600 recognized species that were in the family. Their classification proposed 3 distinct families and 82 genera for the living species of cone snails. This classification was based upon shell morphology, radular differences, anatomy, physiology, cladistics, with comparisons to molecular (DNA) studies.[2] Published accounts of genera within the Conidae that include the genus Gastridium include J.K. Tucker & M.J. Tenorio (2009), and Bouchet et al. (2011).[3]

Testing in order to try to understand the molecular phylogeny of the Conidae was initially begun by Christopher Meyer and Alan Kohn,[4] and is continuing, particularly with the advent of nuclear DNA testing in addition to mDNA testing.

However, in 2011, some experts still prefer to use the traditional classification, where all species are placed in Conus within the single family Conidae: for example, according to the current November 2011 version of the World Register of Marine Species, all species within the family Conidae are in the genus Conus. The binomial names of species in the 82 cone snail genera listed in Tucker & Tenorio 2009 are recognized by the World Register of Marine Species as "alternative representations." [5] Debate within the scientific community regarding this issue continues, and additional molecular phylogeny studies are being carried out in an attempt to clarify the issue.[2][6][7][8][9][10][11][12][13][14]

References

  1. ^ a b c Gastridium Modeer, 1793.  Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=428955 on 06/24/11.
  2. ^ a b c d e Tucker J.K. & Tenorio M.J. (2009), Systematic Classification of Recent and Fossil Conoidean Gastropods, ConchBooks, Hankenheim, Germany, 295 pp.
  3. ^ Bouchet P., Kantor Yu.I., Sysoev A. & Puillandre N. (2011). "A new operational classification of the Conoidea". Journal of Molluscan Studies 77: 273-308.
  4. ^ Interview of Professor Alan Kohn, Professor Emeritus, Zoology http://www.seashell-collector.com/articles/interviews/2009-kohn.html
  5. ^ http://www.marinespecies.org/aphia.php?p=taxdetails&id=14107 Classification: Traditionally, all cone shells have been included in the Linnaean genus Conus. Tucker & Tenorio (2009) have recently proposed an alternative shell- and radula-based classification that recognizes 4 families and 80 genera of cones. In WoRMS, we currently still recognize a single family Conidae (following Puillandre et al. 2011), but Tucker & Tenorio's 80 genera classification is presented as "alternative representation". [P. Bouchet, 14 Aug. 2011]
  6. ^ C.M.L. Afonso & M.J. Tenorio (August 2011), A new, distinct endemic Africonus species (Gastropoda, Conidae) from Sao Vicente Island, Cape Verde Archipelago, West Africa, Gloria Maris 50(5): 124-135
  7. ^ P. Bouchet, Yu I. Kantor, A. Sysoev, and N. Puillandre (March 2011), A New Operational Classification of the Conoidea, Journal of Molluscan Studies 77:273-308, at p. 275.
  8. ^ N. Puillandre, E. Strong, P. Bouchet, M. Boisselier, V. Couloux, & S. Samadi (2009), Identifying gastropod spawn from DNA barcodes: possible but not yet practicable, Molecular Ecology Resources 9:1311-1321.
  9. ^ P.K. Bandyopadhyay, B.J. Stevenson, J.P. Ownby, M.T. Cady, M. Watkins, & B. Olivera (2008), The mitochondrial genome of Conus textile, coxI-conII intergenic sequences and conoidean evolution. Mollecular Phylogenetics and Evolution 46: 215-223.
  10. ^ S.T. Williams & T.F. Duda, Jr. (2008), Did tectonic activity stimulate Oligo-Miocene speciation in the Indo-West Pacific? Evolution 62:1618-1634.
  11. ^ R.L. Cunha, R. Castilho, Ruber, & R. Zardoya (2005), Patterns of cladogenesis in the venomous marine gastropod genus Conus from the Cape Verde Islands Systematic Biology 54(4):634-650.
  12. ^ T.F. Duda, Jr. & A.J. Kohn (2005), Species-level phylogeography and evolutionary history of the hyperdiverse marine gastropod genus Conus, Molecular Phylogenetics and Evolution 34:257-272.
  13. ^ T.F. Duda, Jr. & E. Rolan (2005), Explosive radiation of Cape Verde Conus, a marine species flock, Molecular Ecology 14:267-272.
  14. ^ B. Vallejo, Jr. (2005), Inferring the mode of speciation in the Indo-West Pacific Conus (Gastropoda: Conidae), Journal of Biogeography 32:1429-1439.

Further reading

  • Kohn A. A. (1992). Chronological Taxonomy of Conus, 1758-1840". Smithsonian Institution Press, Washington and London.
  • Monteiro A. (ed.) (2007). The Cone Collector 1: 1-28.
  • Berschauer D. (2010). Technology and the Fall of the Mono-Generic Family The Cone Collector 15: pp. 51-54
  • Puillandre N., Meyer C.P., Bouchet P., and Olivera B.M. (2011), Genetic divergence and geographical variation in the deep-water Conus orbignyi complex (Mollusca: Conoidea), Zoologica Scripta 40(4) 350-363.
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