''Radiodiscus patagonicus'' is a minute
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 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 gastropod mollusks that have shells (those without shells are known as ...
, a
terrestrial
Terrestrial refers to things related to land or the planet Earth.
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 or near the ground, as opposed to ...
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 ...
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
Charopidae
Charopidae is a taxonomic family of small air-breathing land snails (and semi-slugs such as ''Otoconcha dimidiata''), terrestrial pulmonate gastropod mollusks in the superfamily Punctoidea.MolluscaBase eds. (2021). MolluscaBase. Charopidae Hutt ...
.
Distribution
This species occurs in countries including:
*
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
[ (in Portuguese with English abstract)]
*
Patagonia
Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...
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
** Thin-shell structure
Science Biology
* Seashell, a hard ou ...
is openly umbilicate (the
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. Spires are ...
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).
Whorls in nature
File:Photograph and axial plane floral d ...
, 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, 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 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
A creative work is a manifestation of creative effort including fine artwork (sculpture, paintings, drawing, sketching, performance art), dance, writing (literature), filmmaking, ...
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