Odostomia dux
Encyclopedia
Odostomia dux is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
are moderately large, obliquely deeply immersed in the first post-nuclear whorl, the peripheral portion only of the last volution projects above the edge. The four post-nuclear whorls are moderately rounded, and strongly crenulately shouldered. They are marked between the sutures by four spiral keels. The posterior two of these keels are a little more closely spaced than the res. They are also marked by twenty axial ribs which do not extend entirely across the whorl but terminate at the sulcus which separates the third from the fourth keel. Each junction of an axial rib and a spiral keel is marked by a tubercle The tubercles of the first and second keel belonging to the same axial rib are somewhat fused, there being a less prominent constriction between them than between the second and third. The complete effect is that of an exclamation point. The fourth spiral keel is strong and rounded and decidedly elevated, a very slender extension of the axial rib reaches across the deep spiral sulcus, which like the sulci of the base is crossed by fine, subequally spaced, raised axial threads. The base of the shell is moderately well rounded, attenuated, and ornamented with five subequal and subequally spaced, somewhat flattened, spiral keels. The suboval aperture
is rather large, and effuse at the junction of the outer lip
and the columella. The posterior angle is acute. The outer lip is wavy, thin,and shows the external sculpture
within. The columella is strong, curved, re-enforced by the attenuated base and provided with a strong fold at its insertion. The parietal wall is covered by a thin callus.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of sea snail
Sea snail
Sea snail is a common name for those snails that normally live in saltwater, marine gastropod molluscs....
, a marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
gastropod mollusk in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Pyramidellidae
Pyramidellidae
Pyramidellidae, common name the pyram family, or pyramid shells, is a voluminous taxonomic family of mostly small and minute ectoparasitic sea snails, marine heterobranch gastropod molluscs or micromolluscs....
, the pyrams and their allies.
Description
The white, ovate-conic shell measures 1.8 mm. The nuclear whorlsWhorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...
are moderately large, obliquely deeply immersed in the first post-nuclear whorl, the peripheral portion only of the last volution projects above the edge. The four post-nuclear whorls are moderately rounded, and strongly crenulately shouldered. They are marked between the sutures by four spiral keels. The posterior two of these keels are a little more closely spaced than the res. They are also marked by twenty axial ribs which do not extend entirely across the whorl but terminate at the sulcus which separates the third from the fourth keel. Each junction of an axial rib and a spiral keel is marked by a tubercle The tubercles of the first and second keel belonging to the same axial rib are somewhat fused, there being a less prominent constriction between them than between the second and third. The complete effect is that of an exclamation point. The fourth spiral keel is strong and rounded and decidedly elevated, a very slender extension of the axial rib reaches across the deep spiral sulcus, which like the sulci of the base is crossed by fine, subequally spaced, raised axial threads. The base of the shell is moderately well rounded, attenuated, and ornamented with five subequal and subequally spaced, somewhat flattened, spiral keels. The suboval aperture
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
is rather large, and effuse at the junction of the outer lip
Lip (gastropod)
In the shell of a gastropod mollusk , the margin of the aperture is called the lip or the peristome. In other words, this is a term used to describe part of gastropod shell anatomy....
and the columella. The posterior angle is acute. The outer lip is wavy, thin,and shows the external sculpture
Sculpture (mollusc)
The sculpture of a mollusc shell is the three-dimensional ornamentation on the outer surface, as distinct from the basic shape of the shell itself or colouration. Sculpture may be concave as well as convex. Sometimes it has microscopic detail. Sculpture refers to the calcareous outer layer, not the...
within. The columella is strong, curved, re-enforced by the attenuated base and provided with a strong fold at its insertion. The parietal wall is covered by a thin callus.
Distribution
This species occurs in the following locations:- Pacific Ocean : off JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
- Northwest Atlantic (not valid - see remarks)