''Anisancylus obliquus'' 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,

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

, air-breathing

limpet Limpets are a group of aquatic snails that exhibit a conical shell shape (patelliform) and a strong, muscular foot. Limpets are members of the class Gastropoda, but are polyphyletic, meaning the various groups called "limpets" descended indep ...

, an aquatic

pulmonate Pulmonata or pulmonates, is an informal group (previously an order, and before that a subclass) of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includ ...

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 ...

in the family Planorbidae, the ram's horn snails and their allies.

Distribution

''A. obliquus'' is native to

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 ...

, where it occurs in the southern part of the country,

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

and

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. Its occurrence in

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

, in the city of

Callao Callao () is a Peruvian seaside city and Regions of Peru, region on the Pacific Ocean in the Lima metropolitan area. Callao is Peru's chief seaport and home to its main airport, Jorge Chávez International Airport. Callao municipality consists o ...

, needs to be confirmed.

Description

''A. obliquus'' has a high shell, reaching in length. The apex is prominent but not sharp, dorsally flattened, curved to the back and slightly to the right, with the tip usually facing down. The

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called ...

shows a deep apical depression, from which clear radial lines depart, and rounded, irregularly arranged punctuations. The

teleoconch The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage. Some ...

shows prominent radial lines, more salient in the anterior-medial region of the shell. The

mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...

is strongly pigmented and can be totally black; pigmentation is also present in the areas of muscle insertion (foot and tentacles). The anterior right muscle impression is elongated, extending to the middle region of the body. The left impression is elliptical and transversely arranged while the posterior impression is rounded. The rachidian tooth has two long main cusps and might have a denticle between them, with one to two cusps to the side of the left main cusp and one to the side of the right one. The lateral teeth are tricuspid, with the mesocone largest and two to five minor cusps to the side of the endocone and the ectocone. The marginal teeth have up to ten cusps. The

ovotestis An ovotestis is a gonad with both testicular and ovarian aspects. In humans, ovotestes are an infrequent anatomical variation associated with gonadal dysgenesis. The only mammals where ovotestes are not symptomatic of an intersex variation are mole ...

has 30 follicles on average. The prostate has 3 to 5 follicles.

References

{{Taxonbar, from=Q17183745 Planorbidae Molluscs of Argentina Molluscs of Brazil Molluscs of Chile Molluscs of Uruguay Gastropods described in 1832 Taxa named by William Broderip