''Radiodiscus patagonicus'' is a minute

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of air-breathing

land snail A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial molluscs, terrestrial gastropod mollusks that have gastropod shell, shel ...

, a

terrestrial Terrestrial refers to things related to land or the planet Earth, as opposed to extraterrestrial. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on o ...

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

micromollusk A micromollusc is a shelled mollusc which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine molluscs, although in addition, numerous species of land snails and freshwater molluscs also ...

in the family

Charopidae Charopidae is a Taxonomy (biology), taxonomic family (biology), family of small air-breathing land snails (and semi-slugs such as ''Otoconcha dimidiata''), terrestrial molluscs, terrestrial pulmonate gastropod mollusks in the superfamily Punctoi ...

Distribution

This species occurs in countries including: *

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

(in Portuguese with English abstract) *

Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...

The type locality is Santa Cruz near Mt. of Observation on the Rio Chico 50 miles above Sierra Oveja, on a dry stone near the water (according to F. von Ihering). Spring near base of the Andes, 65 miles north of the Rio Chico, elevation 2400 ft. Banks of a small stream 10 miles from Ushe Lake (according to the J. B. Hatcher).

Shell description

The

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

is openly umbilicate (the

umbilicus Umbilicus may refer to: *The navel or belly button *Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy *Umbilicus (plant), ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants *Umbilicus ...

about one-fourth the total diameter), of a uniform pale brown tint, discoidal. 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. Spire ...

is convex but low. Suture is deeply impressed. The shell has 3 ½

whorls 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). In nature File:Photograph and axial plane floral diagram ...

, that are convex, slowly increasing, the embryonic 1 ½ densely striate spirally, the rest radially costellate. The riblets are about as wide as their intervals, about 25 ribblets in 1 mm. on the last half of the

last 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 ...

. Under the microscope some very minute striations may be seen upon the ribs, and in places an extremely minute and very faint spiral striation. The rotund-lunate

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

is slightly oblique. The width of the adult shell is about 1.7-1.8 mm, the height is 0.9-1.2 mm. The above description and the figures are from a shell collected alive 50 miles above the Sierra Oveja. The original description, in Portuguese, was based upon fossil specimens, which had lost the color and part of the finer sculpture. The original lot of ''Radiodiscus patagonicus'' was from Santa Cruz, on the coast, in a modern deposit. Specimen from original lot are a little larger than the living shell described, with the whorls slightly deeper.

References

This article incorporates

public domain The public domain (PD) consists of all the creative work to which no Exclusive exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly Waiver, waived, or may be inapplicable. Because no one holds ...

text from the reference. Pilsbry H. A. 1911
''Non-marine mollusca of Patagonia''
Princeton: The University
pages 517
��518.

External links

Image of the holotype specimen held at Museum of New Zealand Te Papa Tongarewa
{{DEFAULTSORT:Radiodiscus Patagonicus Radiodiscus Gastropods described in 1900