''Seguenzia formosa'' is a species of extremely small deep water

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

, a

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk in the family

Seguenziidae Seguenziidae is a family of very small deepwater sea snails, marine gastropod mollusks in the superfamily Seguenzioidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).Bouchet, P. (2012). Seguenziidae. Accessed through ...

.Intergovernmental Oceanographic Commission (IOC) of UNESCO. The Ocean Biogeographic Information System (OBIS) The epithet "formosa" means "beautiful". It resembles ''

Seguenzia monocingulata ''Seguenzia monocingulata'' is an extinct species of sea snail, a marine gastropod mollusk in the family Seguenziidae. It resembles '' Seguenzia formosa'' and has been regarded as a synonym of that (extant) species. However the two species are ...

'' and has been regarded as a synonym of that (extinct) species. However the two species are distinct, based on shell morphology.

Description

(Original description by J.G. Jeffreys) The rather thin, semitransparent,

nacreous Nacre ( , ), also known as mother of pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer; it is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is ...

and glossy shell has a globosely conical shape. The sculpture of the shell shows sharp keel-like spiral ribs or ridges, of which there are two on the middle of the

body whorl The body whorl is part of the morphology of the 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. In gastropods In gastropods, the b ...

(besides ten thread-like riblets on the base) and one on the middle of each of the other

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). Whorls in nature File:Photograph and axial plane floral ...

s. There is also a slighter rib immediately below the suture. Between the ribs the surface is covered with numerous and delicate curved striae, which turn alternately in different directions, so as to give a flexuous character to this part of the sculpture. The striae between the infrasutural and peripheral rib turn of the left, while those between the peripheral and the next rib (or in the upper whorls between the rib in the middle and the base) turn to the right. The same alternate order is to a great extent observable as to the direction of the striae on the base of the body whorl. These striae are crossed by fine close-set spiral lines, producing a reticulated appearance. All the whorls are similarly sculptured, except the top whorl or apex, which is smooth. The colour of the shell is pearly white. The suture is marked by the uppermost rib. The spire is turreted. The seven whorls are somewhat convex and gradually enlarging. The last takes up three fifths of the shell. The apex is globular. The large aperture is indented by the spiral ribs. The thin outer lip is prominent, and deeply scalloped. The inner lip is thick and folded back on the columella, which is short and incurved. At the bottom of the columella is a small but sharp tooth-like projection, below which is a short and abrupt notch. The groove or slit on the upper part of the body whorl, and the opening from the aperture (which characterizes the genus), is wide and deep, terminating in a curved indentation. The base of the shell is somewhat concave, but imperforate or without any umbilicus. There is no operculum.

Distribution

This species occurs in the Atlantic Ocean off the

Bay of Biscay The Bay of Biscay (), known in Spain as the Gulf of Biscay ( es, Golfo de Vizcaya, eu, Bizkaiko Golkoa), and in France and some border regions as the Gulf of Gascony (french: Golfe de Gascogne, oc, Golf de Gasconha, br, Pleg-mor Gwaskogn), ...

, off Spain and Portugal at depths between 1,300 m and 1,400 m; also off South-east Brazil.

References

External links

Jeffreys, J. G. (1876). Preliminary report of the biological results of a cruise in H.M.S. Valorous to Davis Straits in 1875. Proceedings of the Royal Society of London. 25: 177-237

Salvador, R. B.; Cavallari, D. C.; Simone, L. R. L. (2014). Seguenziidae (Gastropoda: Vetigastropoda) from SE Brazil collected by the Marion Dufresne (MD55) expedition. Zootaxa. 3878(6): 536

Serge GOFAS, Ángel A. LUQUE, Joan Daniel OLIVER,José TEMPLADO & Alberto SERRA (2021) - The Mollusca of Galicia Bank (NE Atlantic Ocean); European Journal of Taxonomy 785: 1–114

Biodiversity Heritage Library (29 publications)

USNM Invertebrate Zoology Mollusca Collection

ITIS
{{Taxonbar, from=Q3729550

formosa Taiwan, officially the Republic of China (ROC), is an island country located in East Asia. The main island of Taiwan, formerly known in the Western political circles, press and literature as Formosa, makes up 99% of the land area of the territorie ...

Gastropods described in 1876