Gradiconus

Gradiconus
Aperatural view of shell of Gradiconus regularis (G.B. Sowerby I, 1833)
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
(unranked): clade Caenogastropoda
clade Hypsogastropoda
clade Neogastropoda
Superfamily: Conoidea
Family: Conidae
Subfamily: Puncticuliinae
Genus: Conus
Subgenus: Gradiconus
da Motta, 1991
Synonyms

Conus (Dauciconus) Cotton, 1945

Gradiconus is a synonym of a subgenus of sea snails, marine gastropod mollusks in the genus Conus, family Conidae, the cone snails and their allies.[1] T

In the new classification of the family Conidae by Puillandre N., Duda T.F., Meyer C., Olivera B.M. & Bouchet P. (2015), Gradiconus has become a subgenus of Conus: Conus (Dauciconus) Cotton, 1945 (type species: Conus gradatus W. Wood, 1828) represented as Conus Thiele, 1929 [2]

Distinguishing characteristics

The Tucker & Tenorio 2009 taxonomy distinguishes Gradiconus from Conus in the following ways:[3]

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.[3]
Shell characters (living and fossil species)
The shell is turbinate in shape. The protoconch is paucispiral, cords are either absent or disappear in the early postnuclear whorls. The anal notch is deep. The shell may be ornamented with hemispherical nodules undulating along the shoulder angle in the early postnuclear whorls, and ridges may persist or die out on the body whorl. The color pattern consists of dots or dashes in spiral lines and/or longitudinal markings. The periostracum is tufted or has a fringe along the shoulder angle, and the operculum is small to minute.
Radular tooth (not known for fossil species)
The anterior section of the radular tooth is roughly equal to the length of the posterior section, and the blade is more than half the length of the anterior section. A basal spur is present, the barb is short, and there is an internal terminating cusp. The radular tooth is serrated.
Geographical distribution
The species in this genus occur in the West Atlantic and Eastern Pacific regions.
Feeding habits
These cone snails are vermivorous, meaning that the cones prey on polychaete worms.[3]

Species list

This list of species is based on the information in the World Register of Marine Species (WoRMS) list.

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]

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.[3] Published accounts of genera within the Conidae that include the genus Gradiconus include J.K. Tucker & M.J. Tenorio (2009), and Bouchet et al. (2011).[6]

Testing in order to try to understand the molecular phylogeny of the Conidae was initially begun by Christopher Meyer and Alan Kohn,[7] 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." [8] 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.[3][9][10][11][12][13][14][15][16][17]

In 2015, in the Journal of Molluscan Studies, Puillandre, Duda, Meyer, Olivera & Bouchet presented a new classification for the old genus Conus. Using 329 species, the authors carried out molecular phylogenetic analyses. The results suggested that the authors should place all cone snails in a single family, Conidae, containing four genera: Conus, Conasprella, Profundiconus and Californiconus. The authors group 85% of all known cone snail species under Conus, They recognize 57 subgenera within Conus, and 11 subgenera within the genus Conasprella.[2]

References

  1. 1 2 Gradiconus da Motta, 1991.  Retrieved through: World Register of Marine Species on 05/10/11.
  2. 1 2 Puillandre N., Duda T.F., Meyer C., Olivera B.M. & Bouchet P. (2015). One, four or 100 genera? A new classification of the cone snails. Journal of Molluscan Studies. 81: 1-23
  3. 1 2 3 4 5 Tucker J.K. & Tenorio M.J. (2009), Systematic Classification of Recent and Fossil Conoidean Gastropods, ConchBooks, Hankenheim, Germany, 295 pp.
  4. 1 2 Petuch E.J. & Sargent D.M. (2011) New species of Conidae and Conilithidae (Gastropoda) from the tropical Americas and Philippines. With notes on some poorly-known Floridian species. Visaya 3(3): 37-58. [August 2011] page(s): 42
  5. ↑ Tucker J.K. & Tenorio M.J. (2011) New species of Gradiconus and Kohniconus from the western Atlantic (Gastropoda: Conoidea: Conidae, Conilithidae). Miscellanea Malacologica 5(1): 1-16. [Published 14 April 2011]
  6. ↑ Bouchet P., Kantor Yu.I., Sysoev A. & Puillandre N. (2011). "A new operational classification of the Conoidea". Journal of Molluscan Studies 77: 273-308.
  7. ↑ Interview of Professor Alan Kohn, Professor Emeritus, Zoology http://www.seashell-collector.com/articles/interviews/2009-kohn.html
  8. ↑ 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]
  9. ↑ 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
  10. ↑ 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.
  11. ↑ 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.
  12. ↑ 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. Molecular Phylogenetics and Evolution 46: 215-223.
  13. ↑ S.T. Williams & T.F. Duda, Jr. (2008), Did tectonic activity stimulate Oligo-Miocene speciation in the Indo-West Pacific? Evolution 62:1618-1634.
  14. ↑ R.L. Cunha, R. Castilho, L. 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.
  15. ↑ 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.
  16. ↑ T.F. Duda, Jr. & E. Rolan (2005), Explosive radiation of Cape Verde Conus, a marine species flock, Molecular Ecology 14:267-272.
  17. ↑ 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

External identifiers for Gradiconus
NCBI 6489
WoRMS 571641
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