Turbonilla gracilior

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

Turbonilla gracilior
Drawing of the shell and the protoconch of Turbonilla gracilior
Scientific classification
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.

Description

The milk-white shell has an elongate-conic shape. Its length measures 6.1 mm. (The whorls of the protoconch aredecollated). The eleven whorls of the teleoconch are well rounded. They are moderately shouldered at the summit; later ones slightly exserted at the summit. They are marked by slender, sinuous, 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. They are marked by a double series of pits, the first of which is 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 pit and twenty between that and the summit. The sutures are well marked. The periphery and the base of the body whorl are well rounded. They are marked by the continuations of the axial ribs and numerous fine, well-incised, wavy spiral striations. 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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