''Callogaza watsoni'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

, a marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Margaritidae.

Description

The slightly nacreous shell reaches a length of 15 mm. It contains 6¼

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). In nature File:Photograph and axial plane floral diagra ...

s having the same general form as in '' Gaza fischeri'', but with a more prominent nucleus. This nucleus is small, bulbous, and dark brown. The first 2½ whorls are glassy, brown spotted, smooth. Subsequently, the exterior two-thirds of the upper surface of the whorls are sculptured with four or five strong revolving threads. The space between them and the suture above contains strong, even, flexuously radiating, shining, rounded plications (about eight to a millimeter) which pass obliquely over the revolving threads and appear again on the base as strong regular plications in the umbilical region, extending from the umbilical carina one-third of the way toward the periphery. The base of the shell is covered with numerous revolving threads flattened until their interspaces appear like grooves. The umbilicus is similarly formed to '' Gaza fischeri'', but somewhat more turreted internally. The

body whorl The body whorl is part of the morphology (biology), morphology of the gastropod shell, shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk ...

is less contracted behind the

lip The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

, which is not produced forward above. The umbilical callus is not nacreous. It has a granular surface, white and covering less than half the umbilicus. The lip and the aperture oare only slightly nacreous. The base of the shell is waxy white. The top is the same, with cloudy radiating brown blotches near the suture and on the periphery. Some of the revolving threads are also continuously brown.Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia
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Distribution

This species occurs in the

Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...

and in the Atlantic Ocean off

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

References

Luiz Ricardo L. Simone & Carlo M. Cunha, ''Revision of genera Gaza and Callogaza (Vetigastropoda, Trochidae), with description of a new Brazilian species''; Zootaxa1318: 1–40 (2006)
* Rosenberg, G., F. Moretzsohn, and E. F. García. 2009. ''Gastropoda (Mollusca) of the Gulf of Mexico,'' Pp. 579–699 in Felder, D.L. and D.K. Camp (eds.), Gulf of Mexico–Origins, Waters, and Biota. Biodiversity. Texas A&M Press, College Station, Texas {{DEFAULTSORT:Callogaza Watsoni watsoni Gastropods described in 1881