''Megasurcula stearnsiana'' 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 Pseudomelatomidae
Pseudomelatomidae is a family of predatory sea snails, marine gastropods included in the superfamily Conoidea (previously Conacea) and part of the Neogastropoda ( Bouchet & Rocroi, 2005).
In 1995 Kantor elevated the subfamily Pseudomelatominae ...
, the turrids and allies.
[MolluscaBase (2018). Megasurcula stearnsiana (Raymond, 1904). Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=723947 on 2018-12-06]
Description
The length of the shell attains 40 mm, its diameter 13 mm.
(Original description) The shell is broadly fusiform with an acute
spire. The outline of the spire is moderately convex. The shell contains 8½
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 flo ...
s, convex anteriorly, slightly concave near the suture, the margin at the suture strongly appressed. The suture is distinct. The
aperture is longer than the spire. The color of the shell is orange to cream with a broad, spiral, brown band below the suture and nine or ten narrow, clearly defined bands on 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 ...
, one or two of these also visible on the spire, bands nearly as wide as the lighter interspaces. The interior of the aperture is yellowish, lighter within and spotted with brown on the outer
lip by the external bands. The first two whorls are smooth, the later whorls show numerous revolving threads, closely beaded on the spire by incremental lines which follow the outline of the lip. The threads are not beaded below the periphery of the body whorl, but roughened by the growth lines and somewhat coarser anteriorly. The aperture is rather narrow. The posterior sinus is shallow and rounded. The outer lip is acute, produced below the sinus. 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 wide. The
columella is solid, somewhat curved, obliquely truncate below. The
operculum is normal.
Raymond W.J. 1904. ''Two new species of Pleurotoma from California''. The Nautilus, 18: 1–3
/ref>
Distribution
This marine species occurs off California in the United States.
References
External links
*
Gastropods.com: ''Megasurcula stearnsiana''
{{DEFAULTSORT:Megasurcula Stearnsiana
stearnsiana
Gastropods described in 1904