''Homalopoma indutum'', common name the two-faced dwarf turban, is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of small
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 ...
with
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an adje ...
opercula, 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
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...
in the
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Colloniidae
Colloniidae is a family of small sea snails with calcareous opercula, marine gastropod mollusks in the clade Vetigastropoda.MolluscaBase eds. (2020). MolluscaBase. Colloniidae Cossmann, 1917. Accessed through: World Register of Marine Species at ...
.
[Rosenberg, G. (2012). ''Homalopoma indutum'' (Watson, 1879). Accessed through: ]World Register of Marine Species
The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms.
Content
The content of the registry is edited and maintained by scientific specialist ...
at http://www.marinespecies.org/aphia.php?p=taxdetails&id=528069 on 2013-02-10
Description
The white-glossy shell grows to a height of 6.9 mm. The small shell has a conoidal shape. 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 tumid. The base is flattened. The whole surface is faintly marked with remote spiral threads, and very faintly scratched with closer microscopic striae. The whorls are bluntly angulated in the middle, and the last is so, besides, at the base below the periphery. This angulation meets the outer
lip. The second and third whorls have two or three strong spiral threads. There are very many close unequal oblique lines of growth. Of these, the strongest rise in close-set infra-sutural puckerings, which on the third whorl resemble small beads. There is a glossy, thin ivory-white calcareous coat over a brilliant pearly white layer. The
spire
A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires are ...
is high and fine-pointed. The
apex is blunt, the smooth rounded 1½ whorl is scarcely
projecting. There are six tumid whorls increasing rapidly. The penultimate whorl rises swollen out of the
suture. The base of the shell is a little flattened. The suture is linear, not impressed, a little coarse, slightly marginated by the overlap of the succeeding on the preceding whorl and the slight tumidity caused by the infra-sutural puckerings. The round
aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane.
An opt ...
is very oblique, with a soft pearly nacre all round. The outer lip is very slightly descending, thick, and bevelled outwards to a sharp edge. There is a broad thin hyaline pad spread over the body that connects the outer lip and the
columella, which is broad, thick, shallowly excavated, with a slight external median horizontal tooth or ridge. The edge is reverted and closely appressed. The thin, calcareous
operculum is small. It is flat, convex on the inside, where it shows 7½ whorls. 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 ...
begins suddenly to enlarge close to its end.
G.W. Tryon (1888), Manual of Conchology X; Academy of Natural Sciences, Philadelphia
(described as ''Leptothyra induta'')
Distribution
This species occurs in the Atlantic Ocean off North Carolina
North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...
, USA;, and Puerto Rico
Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...
.
References
* Dall, W. H. 1889. ''Reports on the results of dredgings, under the supervision of Alexander Agassiz, in the Gulf of Mexico (1877-78) and in the Caribbean Sea (1879-80), by the U. S. Coast Survey Steamer 'Blake,'.'' Bulletin of the Museum of Comparative Zoology 18: 1-492, pls. 10-40.
* Turgeon, D.; Quinn, J.F.; Bogan, A.E.; Coan, E.V.; Hochberg, F.G.; Lyons, W.G.; Mikkelsen, P.M.; Neves, R.J.; Roper, C.F.E.; Rosenberg, G.; Roth, B.; Scheltema, A.; Thompson, F.G.; Vecchione, M.; Williams, J.D. (1998). ''Common and scientific names of aquatic invertebrates from the United States and Canada: mollusks.'' 2nd ed. American Fisheries Society Special Publication, 26. American Fisheries Society: Bethesda, MD (USA). . IX, 526 + cd-rom pp. (look up in IMIS)
page(s): 59
External links
Biodiversity Heritage Library (1 publication)
Encyclopedia of Life
ITIS
World Register of Marine Species
{{Taxonbar, from=Q3732831
Colloniidae
Gastropods described in 1879