Turbonilla gracilior
Drawing of the shell and the protoconch of Turbonilla gracilior
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Heterobranchia
Family: Pyramidellidae
Genus: Turbonilla
Species:
T. gracilior
Binomial name
Turbonilla gracilior
(C.B. Adams, 1852)
Synonyms

Chemnitzia gracilior C. B. Adams [1] p. 391.

Turbonilla gracilior is a species of sea snail, a marine gastropod mollusk in the family Pyramidellidae, the pyrams and their allies.[2][3]

Description

The milk-white shell has an elongate-conic shape. Its length measures 6.1 mm. (The whorls of the protoconch are decollated). The eleven whorls of the teleoconch are well-rounded. They are moderately shouldered at the summit; later ones are slightly exserted at it. They are marked by slender, curved, slightly protractive axial ribs, of which 16 occur upon the first and second, 18 upon the third, 20 upon the fourth to seventh, 22 upon the eighth, 26 upon the ninth, and 32 upon the penultimate turn. The intercostal spaces are about twice as wide as the ribs. A double series of pits mark them, the first at the periphery, the second a little posterior to the middle between the sutures. In addition to these pits, they are marked by fine, equal, and equally spaced spiral striations, of which thirty-one probably occur between the peripheral and median pits and twenty between that and the summit. The sutures are well-marked. The periphery and the base of the body whorl are well-rounded. The continuations of the axial ribs and numerous fine, well-incised, wavy spiral striations mark them. The aperture is rather long and rhomboidal. The outer lip is fractured. The columella is moderately strong, slightly curved and somewhat reflected. It is provided with a weak oblique fold at its insertion.[4]

Description

The type specimen of this marine species was found off Panama.

References

  1. ↑ C.B. Adams, Ann. Lyc. of Nat. Hist. N. Y., vol. 5, 1852
  2. ↑ WoRMS (2011). Turbonilla gracilior. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=576024 on 2012-03-01
  3. ↑ Keen M. (1971). Sea shells of Tropical West America. Marine mollusks from Baja California to Perú. (2nd edit.). Stanford University Press pp. 1064
  4. ↑ Dall & Bartsch (1909), A Monograph of West American Pyramidellid Mollusks, United States National Museum, bulletin 68
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