Gradiconus

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

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

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]

• Genus Conus sensu stricto Linnaeus, 1758

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]

• Subgenus Gradiconus da Motta, 1991

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]

• Gradiconus anabathrum (Crosse, 1865): synonym of Conus anabathrum Crosse, 1865
• Gradiconus aureopunctatus (Petuch, 1987) : synonym of Conus aureopunctatus Petuch, 1987
• Gradiconus bayeri (Petuch, 1987): synonym of Conus bayeri Petuch, 1987
• Gradiconus brunneofilaris (Petuch, 1990): synonym of Conus brunneofilaris Petuch, 1990
• Gradiconus burryae (Clench, 1942): synonym of Conus burryae Clench, 1942
• Gradiconus castaneus (Kiener, 1848): synonym of Conus castaneus Kiener, 1848
• Gradiconus ceruttii (Cargile, 1997): synonym of Conus ceruttii Cargile, 1997
• Gradiconus cingulatus (Lamarck, 1810): synonym of Conus cingulatus Lamarck, 1810
• Gradiconus dispar (G.B. Sowerby I, 1833): synonym of Conus dispar G.B. Sowerby I, 1833
• Gradiconus ernesti (Petuch, 1990): synonym of Conus ernesti Petuch, 1990
• Gradiconus flamingo (Petuch, 1980): synonym of Conus flamingo Petuch, 1980
• Gradiconus flavescens (G.B. Sowerby I, 1834): synonym of Conus flavescens G.B. Sowerby I, 1834
• Gradiconus garciai (da Motta, 1982): synonym of Conus garciai da Motta, 1982
• Gradiconus gibsonsmithorum (Petuch, 1986): synonym of Conus gibsonsmithorum Petuch, 1986
• Gradiconus gradatus (Wood, 1828): synonym of Conus gradatus Wood, 1828
• Gradiconus honkerorum Petuch & R. F. Myers, 2014: synonym of Conus honkerorum (Petuch & R. F. Myers, 2014)
• Gradiconus largilliertii (Kiener, 1847): synonym of Conus largilliertii Kiener, 1847
• Gradiconus maya Petuch & Sargent, 2011:^[4] synonym of Conus maya (Petuch & Sargent, 2011)
• Gradiconus mazzolii Petuch & Sargent, 2011: synonym of Conus burryae Clench, 1942
• Gradiconus monilifer (Broderip, 1833): synonym of Conus monilifer Broderip, 1833
• Gradiconus nybakkeni Tenorio, Tucker & Chaney, 2012: synonym of Conus nybakkeni (Tenorio, Tucker & Chaney, 2012)
• Gradiconus ostrinus Tucker & Tenorio, 2011:^[5] synonym of Conus ostrinus (Tucker & Tenorio, 2011)
• Gradiconus parascalaris (Petuch, 1987): synonym of Conus parascalaris Petuch, 1987
• Gradiconus paschalli (Petuch, 1998): synonym of Conus paschalli Petuch, 1998
• Gradiconus patglicksteinae (Petuch, 1987): synonym of Conus patglicksteinae Petuch, 1987
• Gradiconus paulae (Petuch, 1988): synonym of Conus paulae Petuch, 1988
• Gradiconus philippii (Kiener, 1845): synonym of Conus philippii Kiener, 1845
• Gradiconus portobeloensis (Petuch, 1990): synonym of Conus portobeloensis Petuch, 1990
• Gradiconus recurvus (Broderip, 1833): synonym of Conus recurvus Broderip, 1833
• Gradiconus regularis (G.B. Sowerby I, 1833): synonym of Conus regularis G.B. Sowerby I, 1833
• Gradiconus rosemaryae (Petuch, 1990): synonym of Conus rosemaryae Petuch, 1990
• Gradiconus scalaris (Valenciennes, 1832): synonym of Conus scalaris Valenciennes, 1832
• Gradiconus scalarissimus (da Motta, 1988): synonym of Conus scalarissimus da Motta, 1988
• Gradiconus sennottorum (Rehder & Abbott, 1951): synonym of Conus sennottorum Rehder & Abbott, 1951
• Gradiconus skoglundae Tenorio, Tucker & Chaney, 2012: synonym of Conus skoglundae (Tenorio, Tucker & Chaney, 2012)
• Gradiconus sunderlandi (Petuch, 1987): synonym of Conus sunderlandi Petuch, 1987
• Gradiconus tortuganus Petuch & Sargent, 2011:^[4] synonym of Conus burryae Clench, 1942
• Gradiconus tristensis (Petuch, 1987): synonym of Conus tristensis Petuch, 1987

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]