Radiodiscus patagonicus
Encyclopedia
Radiodiscus patagonicus is a minute species
of air-breathing land snail
, a terrestrial
gastropod mollusk or micromollusk
in the family Charopidae
.
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).
is openly umbilicate (the umbilicus about one-fourth the total diameter), of a uniform pale brown tint, discoidal. The spire
is convex but low. Suture is deeply impressed. The shell has 3 ½ whorls
, 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
. 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
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.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of air-breathing land snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
, a terrestrial
Terrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...
gastropod mollusk or micromollusk
Micromollusk
A micromollusk is a descriptive term for 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 reach adult size at very small...
in the family Charopidae
Charopidae
Charopidae is a taxonomic family of small air-breathing land snails , terrestrial pulmonate gastropod mollusks in the superfamily Punctoidea .- Subfamilies and genera :The family Charopidae consists of the following subfamilies:* Charopinae Hutton, 1884 - synonyms:...
.
Distribution
This species occurs in countries including:- Brazil
- PatagoniaPatagoniaPatagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...
The type locality is Santa Cruz near Mt. of Observation on the Rio Chico
Río Chico
Río Chico is a city in the state of Miranda, Venezuela. It is the capital of Páez Municipality....
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 shellGastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...
is openly umbilicate (the umbilicus about one-fourth the total diameter), of a uniform pale brown tint, discoidal. The spire
Spire (mollusc)
A spire is a descriptive term for part of the coiled shell of mollusks. The word is a convenient aid in describing shells, but it does not refer to a very precise part of shell anatomy: the spire consists of all of the whorls except for the body whorl...
is convex but low. Suture is deeply impressed. The shell has 3 ½ whorls
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...
, 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
Body whorl
Body whorl is part of the morphology of a coiled gastropod mollusk.- In gastropods :In gastropods, the body whorl, or last whorl, is the most recently-formed and largest whorl of a spiral or helical shell, terminating in the aperture...
. 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
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
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.