''Fossarina reedi'', common name Reed top shell, is a
species of very 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 ...
, 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 ...
mollusc
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 esti ...
or
micromollusk
A micromollusk is a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also ...
in the
family Trochidae, the top snails.
[MolluscaBase eds. (2020). MolluscaBase. Fossarina reedi (Verco, 1907). Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=719230 on 2020-11-25]
Description
The shell grows to a height of 3 mm, its diameter 6 mm.
The solid shell has a depressed conoid shape. The four
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 smooth, flatly convex, slightly hollowed just below the
suture. The
apex is blunt. The suture is impressed. The periphery is round and barely angulate. The base of the shell is convex. The
umbilicus is moderate. The oblique
aperture is roundly elliptical. The outer
lip is simple and bevelled inside. A short
thin glaze can be found on the base of the whorl. The arcuate
columella is everted posteriorly, with a tiny notch where it joins the round basal lip at the end of the bordering lira of the umbilicus. The throat is smooth and iridescent.
Sculpture: the dorsum looks as though it were spirally lirate, but is really quite smooth except for very fine microscopic curved retrocurrent accremental scratchings. On the base are about a dozen fine spiral incisions, with radial scratch-marks more valid and distant than on the dorsum. These are still stouter and wrinkling within and near the perforation. An inconspicuous lira borders the umbilicus, which has a shallow groove just above it.
Colour: chestnut-brown, with dark-brown spiral hair-lines of varying width; dotted with tiny white spots, which, below the suture, are aggregated into small pyramidal blotches with their apex upward, six in 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 ...
. A white band, scalloped on both edges of these aggregated dots, encircles the periphery. An articulated white-and-brown spiral ornaments the lira bordering the umbilicus, a second lies just outside this, and another with more distant double white spots beyond. The rest of the base, which is of a lighter tint than the dorsum, has scattered tiny white dots. The umbilicus is white. Over all is a transparent glaze, with a bronze reflex.
There may be a faint gutter where the labrum joins the body whorl. The colour may be dark-brown. The peripheral white band may fade out toward the aperture. The white blotches beneath the suture and the articulated bands around the perforation seem the most constant ornament.
Verco, J.C. 1907. Notes on South Australian marine Mollusca with descriptions of new species. Part VII. Transactions of the Royal Society of South Australia 31: 305-315
(described as ''Gibbula reedi'')
Distribution
This marine species is endemic to Australia and occurs off South Australia.
References
* Cotton, B.C. 1959. ''South Australian Mollusca. Archaeogastropoda''. Handbook of the Flora and Fauna of South Australia. Adelaide : South Australian Government Printer 449 pp.
* Wilson, B. 1993. ''Australian Marine Shells. Prosobranch Gastropods''. Kallaroo, Western Australia : Odyssey Publishing Vol. 1 408 pp.
External links
Verco, J.C. 1907. ''Notes on South Australian marine Mollusca with descriptions of new species. Part VII''. Transactions of the Royal Society of South Australia 31: 305-315
{{Taxonbar, from=Q13637263
reedi
Gastropods of Australia
Gastropods described in 1907