''Pseudodaphnella alternans'' 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 ...

Raphitomidae Raphitomidae is a Family (biology), family of small to medium-sized sea snails, marine (ocean), marine gastropod mollusks in the superfamily Conoidea.Bouchet P. & Rocroi J.-P. (Ed.) (2005). "Classification and nomenclator of gastropod families" ...

.MolluscaBase (2019). MolluscaBase. Pseudodaphnella alternans (E. A. Smith, 1882). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=596309 on 2019-11-11

Description

The length of the shell attains 6 mm, its diameter 2.5 mm. The ovate shell contains probably 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

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics) A-Bomb Abomination Absorbing Man Abraxas Abyss Abyss is the name of two characters appearing in Ameri ...

is missing). The 5 remaining whorls are slightly convex and contain 12 longitudinal ribs (continuing to the base of the body whorl). The spiral lirae form small nodules when crossing the ribs (4 in the penultimate whorl, 10 in the body whorl) and are very cancellate. 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 very narrow and measures about 3/7 of the total length. 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 incrassate with about 6 denticules within and is somewhat sinuate at the top. The

siphonal canal The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water i ...

is narrow, short and truncate. The colouring of this species is very remarkable. In the upper whorls the ribs are alternately brown and white, and the lowest liration, which is in conjunction with the suture and encircles the middle 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 ...

, is wholly white. The fifth and sixth lirations on the last, reckoning from the suture, are rather far apart, and the longitudinal ribs between them are uniformly brown. Smith E.A. (1882). Diagnoses of new species of Pleurotomidae in the British Museum. Annals and Magazine of Natural History. ser. 5, 10: 296-306
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References

External links

*
Kilburn, R. N. (2009). Genus Kermia (Mollusca: Gastropoda: Conoidea: Conidae: Raphitominae) in South African Waters, with Observations on the Identities of Related Extralimital Species. African Invertebrates. 50(2): 217-236

Li B.-Q. [Baoquan] & Li X.-Z. [Xinzheng] (2014) Report on the Raphitomidae Bellardi, 1875 (Mollusca: Gastropoda: Conoidea) from the China Seas. Journal of Natural History 48(17-18): 999-1025
{{DEFAULTSORT:Pseudodaphnella alternans alternans Gastropods described in 1882