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Description

“SYSTEMATICS

 

 

Class Gastropoda Cuvier, 1791

 

Subclass Ortogastropoda Ponder and Lindberg, 1996

 

Superorder Caenogastropoda Cox, 1959

 

Order Sorbeoconcha Ponder and Lindberg, 1996

 

Infraorder Neogastropoda Wenz, 1938

 

Family Muricidae da Costa, 1776

 

Subfamily Trophoninae Cossmann, 1903

 

Genus Trophon Montfort, 1810

 

 

Type Species: Murex magellanicus Gmelin, 1791 (=Buccinum geversianus Pallas, 1774) by original des­ignation. Polyplex Perry, 1811 (type species Polyplex bul­bosa Perry, 1811 = Buccinum geversianum Pallas, 1774) and Muricidea Swainson, 1840 (type species Murex ma­gellanicus Chemnitz, 1780 (nomen nudum) =Murex magellanicus Gmelin, 1791 =Buccinum geversianum Pallas, 1774) are synonyms.

 

 

Description: Shells variable in size, ranging from about 1 to more than 10 centimeters high, fusiform, su­bquadrate to elongate. Protoconch paucispiral, with 2 to 2½ asymmetrical, smooth, slightly globose, and regularly convex whorls. Spire of about 4 whorls, equal or slightly shorter than aperture height, never higher. Subsutural ramp generally present, variously developed and slightly inclined posteriorly, defining a conspicuous keel. Axial sculpture variable, from weak growth lines to strong la­mellae—in some instances even growing over the subsutural ramp; axial sculpture generally better developed than spiral sculpture. Lamellae along keel sometimes growing into fairly strong, always open, spines, which may even curve backwards. Spiral ornamentation vari­ably developed; sometimes missing, but generally con­sisting of slightly rounded and equally developed cords, wider than interspaces and sometimes accompanied by weaker secondary intercalated ones. Spiral ornamenta­tion usually restricted to surface abapical to keel, while missing along subsutural ramp and in some cases only present in the earliest whorls. Aperture subovoid; outer lip sharp, sometimes slightly reflected, but always smooth throughout. Siphonal canal always present and open, although variably developed in length, sometimes curved. Umbilicus variable, usually open, wide, although in some species totally absent or represented by a chink.

 

Shell ultrastructure arranged invariably in 2 layers: in­nermost layer of crossed lamellar aragonite, outer layer of amorphous calcite. Relative thickness of both layers variable according to species or—within a given spe­cies—latitude at which the population lives.

 

Radulae rachiglossate, rachidian teeth with 3 median cusps, the central one the larger and the lateral ones with a denticle, sometimes obsolete but always present, attached to the interior margin (never free). Rachidian base always sinuous and with the base offset under the proximal tooth. Marginal cusps always single, never bifid. Lateral teeth always thin, with the attachment area also thin. Operculum circular or suboval tear-shaped, attach­ment area with horseshoe shaped scars.

 

Accessory salivary glands always developed, tubular, single or coiled and unfilled. Esophagus with a loop run­ning along the left side of the gland of Leiblein; esoph­ageal glands externally invisible.

 

Egg-capsules always erect, never lenticular, usually with nurse eggs.”

 

 

(Pastorino, 2005: 56)

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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