''Lioglyphostoma rusum'' is an extinct

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 ...

Pseudomelatomidae Pseudomelatomidae is a family (biology), family of predatory sea snails, marine gastropods included in the superfamily Conoidea (previously Conacea) and part of the Neogastropoda (Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), Bouchet & Ro ...

, the turrids and allies.

Description

The length of the shell attains 14.7 mm, its diameter 6 mm. (Original description) The hell is of moderate size for the group. The

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spire ...

is elevated and turreted. The body is rather sharply constricted into the long and slender

columella Lucius Junius Moderatus Columella (, Arabic: ) was a prominent Roman writer on agriculture in the Roman Empire. His in twelve volumes has been completely preserved and forms an important source on Roman agriculture and ancient Roman cuisin ...

. The

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

is about half the entire altitude, maximum diameter a little less. The shell contains 7

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. The

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called " ...

is rather slender but elevated, thrice coiled. The initial whorl is tumid, tilted, and immersed at the tip. The second whorl is convex at its beginning, becoming increasingly angulated toward its close. The area behind the periphery is broadly and steeply sloping, the much narrower portion in front of it undercut. The periphery is a little less strongly anterior on the final turn and crowned with a flattened spiral. A second similar liration is intercalated directly behind the anterior suture. The dividing line between the

and the protoconch is indicated by the introduction of the axial

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

. The axials are sharply rounded and persist with diminished strength upon the early whorls to the posterior suture, broader but abruptly elevated and strongly rounded upon the later, 10 upon the penultimate whorl, irregular upon the last half of 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 ...

, a little more elevated medially than anteriorly, and more or less completely evanescent posteriorly and upon the base of the body. The intercostal areas are strongly concave and of approximately the same width as the costals. The spiral sculpture is equally developed upon the axial and interaxial areas, the primaries carried across from the protoconch, 2 on the earliest whorl, increasing to 3 on the second or third volutions, and to 4 on the penultimate whorl. Secondaries commonly are intercalated. There are 14 additional primaries without intercalated secondaries upon the

and the

, the lirae a little more sharply defined and less closely spaced anteriorly. The anterior

fasciole A fasciole in mollusks refers to a band or ribbon-like structure that is often seen as a flattened, slightly depressed area on the shell, formed by the successive growth lines on the edges of a canal. It is typically found on the surface of the s ...

is closely threaded with about a dozen rounded lirae. The posterior fasciole is lineated with sharp filaments, 8 in the type. The fasciole is defined by the constriction of the whorl, the abruptly diminished axials, and the equally abrupt change in the character of the spirals. Incrementals are strongly arcuate upon the fasciole and commonly rather vigorous. The posterior margin is very closely appressed against the preceding whorl and creeping up a little upon it, undulated in harmony with the axials of the preceding volution. The suture line is distinct, impressed and undulatory. The

is obliquely lenticular, open at both extremities. The outer

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 ...

is arcuate, varicated a little behind the margin, the edge thin, sharp, and finely crenulated. The inner surface of the outer lip is thickened directly in front of the posterior sinus, irregularly lirated, normal to the margin in the anterior third, feebly reinforced parallel to the anterior canal. The posterior sinus is very broad and deep, slightly constricted at the entrance, symmetrically disposed between the suture and the outer margin of the fasciole. The inner margin of the aperture is excavated at the base of the body. The parietal glaze is for the most part so thin that the spiral sculpture may be traced through it but very heavy near the entrance to the sinus. The columella is also rather heavily reinforced and rudely denticulated. The anterior canal is moderately long for the group and rather narrow, flaring at its extremity. The anterior fasciole is wide and deeply emarginate.Gardner J.A. (1937). The molluscan fauna of the Alum Bluff Group of Florida. Part VI. Pteropoda, Opisthobranchia and Ctenobranchia (in part). United States Geological Survey Professional Paper. 142-F: 251-435, pls 37-48
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Distribution

Fossils have been found in

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

strata of the Alum Bluff Formation in

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

References

{{DEFAULTSORT:Lioglyphostoma Rusum rusum Gastropods described in 1937 Extinct molluscs