Biomphalaria tenagophila
Encyclopedia
Biomphalaria tenagophila is a species
of air-breathing freshwater snail
, an aquatic
pulmonate gastropod mollusk in the family
Planorbidae, the ram's horn snails.
This species is medically important pest, because of transferring the disease intestinal schistosomiasis. (Intestinal schistosomiasis is the most widespread of all types of schistosomiasis
).
The parasite Schistosoma mansoni
, which Biomphalaria
snails carry, infects about 83.31 million people worldwide.
The shell of this species, like all planorbids is sinistral in coiling, but is carried upside down and thus appears to be dextral.
in 1935. Orbigny (1935) referred its distribution to Corrientes Province
, Argentina and to Santa Cruz Department
, Bolivia (referred as "Santa-Cruz et Chiquitos"). But Orbigny himself later limited its distribution to Ensenada, Buenos Aires Province, Argentina in 1937.
Subspecies recognized in this species include:
There are also three "old-style" proposals of subspecies, based on shell characteristics:
History of discoveries summarized Paraense (2001).
showing phylogenic relations of species in the genus Biomphalaria:
This species has recently expanded its native range.
The non-indigenous distribution of Biomphalaria tenagophila includes a hypothermal spring near Răbăgani
, Romania
(46°45´1.3´´N, 22°12´44.8´´E).
is sinistrally coiled (has left-handed coiling). The flat shells are yellow-brown, discoidal, deeply and symmetrically biconcave, and consist of 5 or 6 slowly increasing whorls
. The last whorl
is rounded; the intermediate whorls are slightly angled on the left side. The aperture
is circular or slightly ovate and angled toward the left side of the shell (i.e., toward the upper surface on the bottom right shell). Fine, parallel, rib-like transverse lines can be seen on the outer surface of the whorls.
The width of the shell is usually from 11 to 13 mm, but in the largest individuals, the shell can reach 21 mm in width, 6.5 mm in height and have 6.5 whorls.
The body length varies from 56 mm to 64 mm.
The radula
has from 125 to 168 rows of denticles (tiny teeth). The number of lateral teeth varying from 28 to 36. The mode radula formula is 31-0-31.
The specific characteristics of the reproductive system
of Biomphalaria tenagophila are: more than 200 diverticulae of the ovotestis; 7–11 main lobes of the prostate; and presence of vaginal pouch.
Biomphalaria tenagophila is an intermediate host
for Schistosoma mansoni
and a vector of schistosomiasis
. Schistosoma mansoni came to Neotropics from Africa in context of the slave trade. Schistosoma mansoni was not able to infect Biomphalaria tenagophila in 1916 and it have adapted to this host since 1916.
Experimental parasites include:
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 freshwater snail
Freshwater snail
A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine habitat. The majority of freshwater gastropods have a shell, with very few exceptions....
, an aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
pulmonate gastropod mollusk in the family
Family
In human context, a family is a group of people affiliated by consanguinity, affinity, or co-residence. In most societies it is the principal institution for the socialization of children...
Planorbidae, the ram's horn snails.
This species is medically important pest, because of transferring the disease intestinal schistosomiasis. (Intestinal schistosomiasis is the most widespread of all types of schistosomiasis
Schistosomiasis
Schistosomiasis is a parasitic disease caused by several species of trematodes , a parasitic worm of the genus Schistosoma. Snails often act as an intermediary agent for the infectious diseases until a new human host is found...
).
The parasite Schistosoma mansoni
Schistosoma mansoni
Schistosoma mansoni is a significant parasite of humans, a trematode that is one of the major agents of the disease schistosomiasis. The schistosomiasis caused by Schistosoma mansoni is intestinal schistosomiasis....
, which Biomphalaria
Biomphalaria
Biomphalaria is a genus of air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails and their allies.Biomphalaria is the type genus of the tribe Biomphalariini....
snails carry, infects about 83.31 million people worldwide.
The shell of this species, like all planorbids is sinistral in coiling, but is carried upside down and thus appears to be dextral.
Taxonomy
Biomphalaria tenagophila was originally discovered and described under the name Planorbis tenagophilus by the French naturalist Alcide d'OrbignyAlcide d'Orbigny
Alcide Charles Victor Marie Dessalines d'Orbigny was a French naturalist who made major contributions in many areas, including zoology , palaeontology, geology, archaeology and anthropology....
in 1935. Orbigny (1935) referred its distribution to Corrientes Province
Corrientes Province
Corrientes is a province in northeast Argentina, in the Mesopotamia region. It is surrounded by : Paraguay, the province of Misiones, Brazil, Uruguay, and the provinces of Entre Rios, Santa Fe and Chaco.-History:...
, Argentina and to Santa Cruz Department
Santa Cruz Department
Santa Cruz, with an area of 370,621 km², is the largest of the nine constituent departments of Bolivia. In the 2001 census, it reported a population of 2,029,471. The capital is the city of Santa Cruz de la Sierra. The state is one of the wealthiest states in Bolivia with huge reserves of...
, Bolivia (referred as "Santa-Cruz et Chiquitos"). But Orbigny himself later limited its distribution to Ensenada, Buenos Aires Province, Argentina in 1937.
Subspecies recognized in this species include:
- Biomphalaria tenagophila tenagophila (d’Orbigny, 1835)
- Biomphalaria tenagophila guaibensis Paraense, 1984 - Biomphalaria tenagophila guaibensis can be distinguished from the nominal subspecies according to the details on the reproductive systemReproductive system of gastropodsThe reproductive system of gastropods varies greatly from one group to another within this very large and diverse taxonomic class of animals...
only.
There are also three "old-style" proposals of subspecies, based on shell characteristics:
- Planorbis tenagophilus chemnitziana Beck, 1837 - this name is based on the catalog for the shell in Museum of Copenhagen, but without description.
- Planorbis tenagophilus orbignyana Beck, 1837 - the same situation as in P. t. chemnitziana
- Australorbis bahiensis megas Pilsbry, 1951
History of discoveries summarized Paraense (2001).
Phylogeny
A cladogramCladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
showing phylogenic relations of species in the genus Biomphalaria:
Distribution
Biomphalaria tenagophila is a Neotropical species and its native distribution include Peru, Brazil, Uruguay and Argentina.This species has recently expanded its native range.
The non-indigenous distribution of Biomphalaria tenagophila includes a hypothermal spring near Răbăgani
Rabagani
Răbăgani is a commune in Bihor County, Romania. It is composed of six villages: Albeşti, Brăteşti, Răbăgani, Sălişte de Pomezeu, Săucani and Vărăşeni. It is located about 50 km south of Oradea. It was mosly Hungarian until 1955, when it became equally split 50/50 with the Romanian community....
, Romania
Romania
Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...
(46°45´1.3´´N, 22°12´44.8´´E).
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 sinistrally coiled (has left-handed coiling). The flat shells are yellow-brown, discoidal, deeply and symmetrically biconcave, and consist of 5 or 6 slowly increasing 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...
. 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...
is rounded; the intermediate whorls are slightly angled on the left side. The 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 circular or slightly ovate and angled toward the left side of the shell (i.e., toward the upper surface on the bottom right shell). Fine, parallel, rib-like transverse lines can be seen on the outer surface of the whorls.
The width of the shell is usually from 11 to 13 mm, but in the largest individuals, the shell can reach 21 mm in width, 6.5 mm in height and have 6.5 whorls.
Anatomy
The anatomy of this species was firstly published under the synonym Australorbis nigricans in 1955.The body length varies from 56 mm to 64 mm.
The radula
Radula
The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...
has from 125 to 168 rows of denticles (tiny teeth). The number of lateral teeth varying from 28 to 36. The mode radula formula is 31-0-31.
The specific characteristics of the reproductive system
Reproductive system of gastropods
The reproductive system of gastropods varies greatly from one group to another within this very large and diverse taxonomic class of animals...
of Biomphalaria tenagophila are: more than 200 diverticulae of the ovotestis; 7–11 main lobes of the prostate; and presence of vaginal pouch.
Ecology
Habitat of Biomphalaria tenagophila is tropical standing water or freshwater.Biomphalaria tenagophila is an intermediate host
Intermediate host
A secondary host or intermediate host is a host that harbors the parasite only for a short transition period, during which some developmental stage is completed. For trypanosomes, the cause of sleeping sickness, humans are the primary host, while the tsetse fly is the secondary host...
for Schistosoma mansoni
Schistosoma mansoni
Schistosoma mansoni is a significant parasite of humans, a trematode that is one of the major agents of the disease schistosomiasis. The schistosomiasis caused by Schistosoma mansoni is intestinal schistosomiasis....
and a vector of schistosomiasis
Schistosomiasis
Schistosomiasis is a parasitic disease caused by several species of trematodes , a parasitic worm of the genus Schistosoma. Snails often act as an intermediary agent for the infectious diseases until a new human host is found...
. Schistosoma mansoni came to Neotropics from Africa in context of the slave trade. Schistosoma mansoni was not able to infect Biomphalaria tenagophila in 1916 and it have adapted to this host since 1916.
Experimental parasites include:
- Angiostrongylus vasorumAngiostrongylus vasorumAngiostrongylus vasorum, also known as French heartworm, is a species of parasitic nematode in the family Metastrongylidae. It causes the disease canine angiostrongylosis in dogs.Not much is known about the biology of this species.- Description :...
- (experimental)
External links
- Barracco, Margherita Anna, Steil, Ana Angélica and Gargioni, Rogério (March 1993) "Morphological characterization of the hemocytes of the pulmonate snail Biomphalaria tenagophila". Mem. Inst. Oswaldo Cruz 88(1): 73-83. abstract