''Drilliola difficilis'' is a species of

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

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

Borsoniidae Borsoniidae is a monophyletic family of small to medium-sized sea snails, marine gastropod mollusks in the superfamily Conoidea.Bouchet, P. (2011). Borsoniidae. Accessed through: World Register of Marine Species at http://www.marinespecies.or ...

.MolluscaBase eds. (2022). MolluscaBase. Drilliola difficilis (E. A. Smith, 1879). Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=1557980 on 2022-12-15

Description

The length of the shell attains 7 mm; its width 2 mm.. The shell contains about ten rather coarse spiral lirae on the body whorl. The sinus is situated above the submedian liration. The shell has a brownish horn-color. (Original description) The shell has a shortly fusiform shape and has a brownish horn-colour. The

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 are nearly flat, strongly keeled a little below the middle, and above at the suture, with one or two thread-like spiral lirae in the spaces between these two carinae and between the subcentral one and the suture below it. The lines of growth are moderately distinct, raised, flexuous, and more or less oblique. The nucleus (or the three apical whorls) is smooth, glassy, shining, convex. The fourth whorl is also convex and coarsely obliquely costate. 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 ...

is encircled by about ten coarsish lirae, whereof the three uppermost are equal in size to the submedian carina of the upper whorls, which falls just above them on this volution. The interstices between them are coarsely striated by the lines of growth. The aperture is small, occupying three-sevenths of the entire length. The columella is brown, coated with a smooth enamel, oblique below the middle. It is slit above the submedian liration. 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 is ...

is short, very little recurved. The operculum is ovate, pointed at the base. Its nucleus is apical.Smith, Edgar A. "11. On a Collection of Mollusca from Japan." Proceedings of the Zoological Society of London. Vol. 47. No. 1. Blackwell Publishing Ltd, 1879.
(described as ''Pleurotoma difficilis'')

Distribution

This marine species occurs off

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

References

* Poppe, G.T. & Tagaro, S.P. (2021). New Borsoniidae from the Central Philippines. Gloria Maris. 60(4): 188-207.

External links

Bouchet P., Kantor Yu.I., Sysoev A. & Puillandre N. (2011) A new operational classification of the Conoidea. Journal of Molluscan Studies 77: 273–308
* {{DEFAULTSORT:Drilliola Difficilis difficilis Gastropods described in 1879