Amphidromus
Encyclopedia
Amphidromus is a genus
of air-breathing land snail
s, terrestrial
pulmonate gastropod mollusks in the family Camaenidae
.
Amphidromus is a genus of arboreal pulmonate land snails. The shells of Amphidromus are relatively large, from one to three inches high, and colorful.
, dextral or sinistral with one to three inches high with 5 to 8 whorls
which increase regularly in size. The aperture
is sublunate or auriform, without teeth or folds, height two-fifths to one-third that of shell. The peristome is expanded and reflected, sometimes thickened. Parietal callus
is weak to well-developed. The umbilicus is open or closed. Color pattern is monochrome to variegated. The jaw is thin and weak with low flat ribs. The radula
is with cusped teeth arranged in V-shaped rows and modified in typical arboreal pattern. The pallial region is sigmurethrous
with very long, narrow kidney. Genitalia
are camaenid, with long seminal receptacle, and short penis with low insertion of retractor muscle. The habitat is arboreal.
The shells of Amphidromus are relatively large and colorful and were among the first Indonesia
n land snails brought back to Europe; most specimens in collections were brought back by travelers or explorers during the 18th century. Comparatively little material has been gathered by malacologists. Several species and forms were described before 1800, generally with inadequate locality data. At least two kinds — Amphidromus laevus
(Müller, 1774) and the form Amphidromus perversus f. aureus Martyn, 1784 — still have not been reported from a precise locality.
19th century
Many species and varieties were named during the first half of the nineteenth century, again usually with poor locality data. Not until Eduard von Martens
' (1867) publication was there an effort to deal with the entire complex. This paper showed an amazing grasp of variation and problems of geographic distribution
, and many of von Martens' concepts are still utilized. Hugh Fulton (1896) organized 142 specific and varietal names into eighteen species groups with 64 species. When the monograph Manual of Conchology of Henry Augustus Pilsbry
(1900) appeared, the number of species had increased to 81, which were placed in nineteen groups. Pilsbry's study has remained the only illustrated monograph of the genus, and it is still indispensable for any serious study.
20th century
Since 1900, the major taxonomic studies on Amphidromus have been faunistic (a study of the fauna of some territory or area) in scope. The papers of Paul Bartsch
(1917, 1918, 1919) on the Philippine species, Bernhard Rensch
(1932) on the Lesser Sunda Islands
forms, and Tera van Benthem Jutting (1950, 1959) on Javan and Sumatran populations are especially comprehensive. Potentially the most valuable contribution is that of Curt Haniel (1921), who discussed the variation of Amphidromus contrarius and Amphidromus reflexilabris on Timor
. Variations in color and form were well illustrated in a series of color plates. Many of later conclusions by Frank Fortescue Laidlaw
& Alan Solem
(1961) concerning the relationships of color forms described as species were taken not as much from new collections as from the extent of variation found by Haniel (1921) in his pioneer study. Adolf Michael Zilch (1953) listed type specimens in the Senckenberg Museum
and illustrated many previously unfigured species. The literature contains many scattered descriptions of new color forms and subspecies that appeared after 1900. Of the 309 names in the nomenclatural list, 111 (35.9 %) were published after Pilsbry (1900). Frank Fortescue Laidlaw
& Alan Solem
(1961) recognized 74 species by name and considered that material from the Banda Islands
probably represents an undescribed species. There are eleven species recognized by them that were described after the appearance of Pilsbry's monograph. Several species recognized by Pilsbry we have subordinated to subspecific or varietal status, and a few names have been transferred to incertae sedis
, since they are based on hundred-year-old references that have not been substantiated by more recent collectors. Study by Frank Fortescue Laidlaw
& Alan Solem
(1961) forms a supplement to Pilsbry's monograph with his extensive plates.
Amphidromus is found from the Garo Hills
and Khasi Hills
of Meghalaya
in northeastern India, throughout Burma, Malay Peninsula
, Thailand
, Laos
, Cambodia
, Vietnam
, Indonesia
as far east as the Sulawesi
, Banda Islands
, Timor
and the Tenimber Islands (but not on Ceram, Buru, Halmahera, Batjan Island, the Obi Islands, the Aru and Kei Islands, or the Talaud Archipelago and some Celebesian satellite islands), in the southern Philippines
, notably Mindanao
and the Balabac, Palawan
, and in northern Australia.
from the Trinil Beds of Java. Neither record ante dates human occupancy, and thus yields no record on the early history of Amphidromus.
of Amphidromus are relatively large, from one to three inches high, and colorful. Amphidromus has an elongate conic or ovate conic helicoid shell of 5 to 8 whorls
. The shell may be thin and fragile or very heavy and solid with no known correlation of shell structure with distribution or habitats.
In some species the shell coils invariably to the right, and in many others just as invariably to the left. A significant number of species however are "amphidromine". That is to say, both left- and right-handed coiling are found in the same population (they are polymorphic
for direction of the shell coiling, but as there are only two possible types of shell coiling, they are known as dimorphic
in coiling), sometimes in approximately equal numbers, other times with a distinct predominance of one phase. In Amphidromus there is no information on the heredity of this character.
Most species of other amphidromine species such as Partula and Achatinella have became extinct, so the genus Amphidromus with its over 80 species is unique and useful for study of the evolution
of asymmetry
in animals. This is also the reason for urge of this genus conservation
.
The whorls of Amphidromus are moderately convex and, with few exceptions, smooth or with only a faint sculpture
of growth lines. At least four separate times, however, a sculpture of moderately heavy oblique radial ribs has appeared (Amphidromus costifer Smith from Binh Dinh Province
in Vietnam, Amphidromus begini Morlet from Cambodia, Amphidromus heccarii Tapparone-Canefri from Celebes, and the Amphidromus palaceus
-Amphidromus winteri complex from Java and Sumatra). Correlated with the ribbing is light, monochrome coloration, thin shell with large aperture
, and flaring lip. Many solid shells show a slight roughening of the surface, but this is quite different from the ribbed sculpture mentioned above.
The aperture is generally large and varies from about two-fifths to one-third the height of the shell, often in the same population. Usually the lip is at least somewhat expanded, and in forms such as Amphidromus reflexilahris Schepman and Amphidromus winteri (Pfeiffer) var. inauris Fulton, the lip can only be called flaring. In Amphidromus perversus
(Linnaeus) and most other thick-shelled species, the lip is internally thickened, forms a "roll" in its expansion, and has a very heavy parietal callus
. In thin-shelled species, the lip is usually a simple reflected edge. The umbilical area may be partially open, nearly closed or sealed. This sometimes provides a handy criterion for specific identification. The angle of the parietal wall varies, but no precise information on this has been compiled.
Generally the whorls increase rather regularly in size, but probably related species such as Amphidromus sinistralis (Reeve) and Amphidromus heccarii Tapparone-Canefri can have quite different degrees of whorl increment. No attempt has been made to express these differences meristically, since most of the available material was inadequate for statistical treatment (but see Haniel, 1921). Actual dimensions vary greatly both within and between species. Minimum adult size is about 21 mm high, the observed maximum about 75 mm. Only a few species, notably Amphidromus maculiferus, Amphidromus sinensis and Amphidromus entobaptus, seem to have a range in adult size of more than seven or eight millimeters.
The major shell variation is found in the color pattern. Most arboreal snails are brightly colored, the bulimulid genera Drymaeus
and Liguus
, cepolid Polymita
, and the camaenid Papuina being obvious examples. Polymita
, Liguus
and Amphidromus are noted for their color variations.
The basic ground color of Amphidromus seems to be yellow and is usually (except for Amphidromus entobaptus) confined to the surface layers
of the shell, since worn specimens appear to be nearly devoid of color. Many species are whitish, and a few have dark ground colors. The apical
whorls are pale, purple, brown, or black; they sometimes vary within a population (Amphidromus quadrasi). A few species, for example, Amphidromus schomburgki
, have a deciduous green periostracum
. Continuous zonal patterns can take the form of whitish subsutural bands (Amphidromus similis
), heavy subperipheral pigmentation (Amphidromus perversus
var. infraviridis), subsutural color lines (Amphidromus columellaris), broad spiral color bands (Amphidromus metabletus, Amphidromus webbi), or narrow spiral bands (Amphidromus laevus
). Interrupted zonation can be the interruption of bands into spots (Amphidromus maculatus), highly irregular splitting of zones (Amphidromus perversus
vars. sultanus and interruptus), formation of oblique radial streaks which can parallel (Amphidromus inversus
) or cross (Amphidromus latestrigatus) the incremental growth lines, or almost every conceivable combination and variation of these factors. Often the pattern will change radically from the apex
to the body whorl
(Amphidromus quadrasi vars.). Aperture, parietal callus
, columella, lip, and umbilical region are variously marked with pink, brown, purple, white, or black. Haniel (1921) has several color plates which show effectively the extent of color variation within two species of the Syndromus type. Amphidromus perversus
and Amphidromus maculiferus of the Amphidromus subgenus are equally variable, while species such as Amphidromus inversus
and Amphidromus similis
are almost uniform in coloration.
Most of the Amphidromus subgenus show resting stages by the deposition of a brown or black radial band called a varix
. This is apparently rare in the Syndromus subgenus, although Amphidromus laevus
shows evidence of interruption of the spiral banding after a resting phase.
Species recognition is based on combinations of minor structural variations in the shape, aperture, whorl contour, umbilical region, and color pattern. Apparently, many species have a stable color pattern, while others seem to vary tremendously. Adequate unselected field samples will enable a better understanding of the relative stability or variability of particular species in single localities.
, Natuna Islands
and Djemadja, Anamba Islands. Unfortunately, although anatomical differences between the two species existed, we have no idea which forms he was dissecting, since, of the two names he used in his paper, Amphidromus chloris is found only in the Philippine Islands and the interruptus phase of Amphidromus perversus
is not known from the Natuna Islands. Carl Arend Friedrich Wiegmann (1893, 1898) discussed portions of the anatomy of Amphidromus adamsii
, Amphidromus porcellanus
, Amphidromus contrarius, and Amphidromus sinistralis; Walter Edward Collinge (1901, 1902) briefly noted features of Amphidromus palaceus
and Amphidromus perakensis (reported as Amphidromus perversus); Haniel (1921) dissected Amphidromus contrarius and Amphidromus reflexilabris; and Bernhard Rensch
published a few scattered notes in his various faunistic surveys. A few earlier notes are mentioned in Pilsbry (1900).
The long, narrow kidney with reflexed ureter and closed secondary ureter, the penial complex with distinct penis, epiphallus, vas deferens and flagellum, and the basic condition of the nervous and retractor muscle systems all serve to place Amphidromus in the Camaenidae. Apparently, specific differences exist in the penial complex, but present data are insufficient to allow any recognition of species groups through anatomical characters. Laidlaw
& Solem
(1961) provided no more additional details on anatomy.
. The dissections made by Wiegmann and Jacobi clearly showed that the anatomical features were those of the Asian-Indonesian Camaenidae
and that the shell resemblance to bulimulids was a parallelism.
Subgenera and species
Laidlaw and Solem (1961) recognized 75 species in the genus Amphidromus and another seven names placed under incertae sedis
.
In 2010, there are 87 species in the genus Amphidromus.
Species within the genus Amphidromus are divided into two subgenera and they include:
Amphidromus perversus
(Linnaeus, 1758) is the type species
of the genus Amphidromus, by the subsequent designation of Eduard von Martens
(1860). Species in the subgenus Amphidromus are amphidromine (left-handed and right-handed snails occur in the population) with exceptions: four dextral taxa are: Amphidromus givenchyi
, Amphidromus protania, Amphidromus schomburgki
dextrochlorus and Amphidromus inversus
annamiticus; and one sinistral Amphidromus atricallosus
classiaris.
All species of the subgenus Syndromus are sinistral with two exceptions: amphidromine Amphidromus glaucolarynx
and dextral Amphidromus kruehni
. The type species of the subgenus Syndromus is Amphidromus contrarius Müller, 1774, by the subsequent designation of Adolf Michael Zilch (1960).
There have been also used subgenus Goniodromus Bülow, 1905 with type Amphidromus büllowi Fruhstorfer, 1905, but its subgeneric status is doubtful.
Cladogram
Genetic analyses confirmed that the genus Amphidromus is monophyletic. A (simplified) cladogram
showing phylogenic relations of (18 analyzed) species of Amphidromus based on partial sequences of 16S rDNA:
perakensis probably feeds on microscopic Fungi, lichens or terrestrial algae
.
His observations were made on Amphidromus palaceus
var. pura at Palimanan, West Java
, in October, 1920. Natives brought in two nests with the snails depositing eggs. One snail had folded the exterior leaves of a young bamboo
shoot and gummed them together into a pointed cornet. The shoot hung vertically with the narrow end pointed upward and the wide opening below. The upper part of the sack was filled with eggs when collected. The snail descended slowly, rotating around its longitudinal axis, and deposited eggs until the entire cavity was filled. If a crack in the basket exposed eggs to the air, they quickly dried up. Two days after capture, egg-laying was finished and the snail closed the opening by folding over more leaves. Probably four days were spent in egg-laying, since the cavity was half filled at the start of observations. A second nest of similarly folded mango
leaves contained 234 eggs.
The volume of eggs in each case greatly exceeded the size of the snail, indicating that the eggs must be encapsulated just before deposition. The capsules were very thin and dried quickly upon any exposure to the air. October marked the start of the rainy season and probably this is the normal breeding period. Eggs of Amphidromus porcellanus
were reported by van Benthem Jutting (1950, p. 493) to have started hatching only ten days after being laid. Similar nest-building habits have been reported for other species, but no complete study of a life cycle has been published.
No information were not available on the cycle of activity, longevity, rate of growth, etc. up to 1961, but more information appeared since 1961:
Schilthuizen et al. (2005) described spatial structure
of a population of Amphidromus inversus
in Malaysia.
Schilthuizen et al. (2007) found, that there is sexual selection
in mating with snails of opposite chirality. This means that left-handed snail are mating more often with right-handed snails, than with snails of the same coiling. Additionally there are anatomical adaptations of the spermatophore
and of the female part of the reproductive system
for these matings success.
s.
Many shells of Amphidromus were found in the den of a rat
in Malaysia.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of air-breathing land snail
Land snail
A land snail is any of the many species of snail that live on land, as opposed to those that live in salt water and fresh water. Land snails are terrestrial gastropod mollusks that have shells, It is not always an easy matter to say which species are terrestrial, because some are more or less...
s, 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...
pulmonate gastropod mollusks in the family Camaenidae
Camaenidae
Camaenidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Helicoidea.This is one of the most diverse families in the clade Stylommatophora....
.
Amphidromus is a genus of arboreal pulmonate land snails. The shells of Amphidromus are relatively large, from one to three inches high, and colorful.
Definition of Amphidromus
The genus may be characterized as follows: It has brightly colored, elongate conic shellsGastropod 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...
, dextral or sinistral with one to three inches high with 5 to 8 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...
which increase regularly in size. 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 sublunate or auriform, without teeth or folds, height two-fifths to one-third that of shell. The peristome is expanded and reflected, sometimes thickened. Parietal callus
Parietal callus
A parietal callus is a feature of the shell anatomy of some groups of snails, i.e. gastropods. It is a thickened calcareous deposit which may be present on the parietal wall of the aperture of the adult shell. The parietal wall is the margin of the aperture and part of the wall of the body whorl...
is weak to well-developed. The umbilicus is open or closed. Color pattern is monochrome to variegated. The jaw is thin and weak with low flat ribs. 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...
is with cusped teeth arranged in V-shaped rows and modified in typical arboreal pattern. The pallial region is sigmurethrous
Sigmurethra
Sigmurethra is a taxonomic category of air-breathing land snails and slugs, terrestrial pulmonate gastropod molluscs. This is an Informal Group which includes the majority of land snails and slugs....
with very long, narrow kidney. Genitalia
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...
are camaenid, with long seminal receptacle, and short penis with low insertion of retractor muscle. The habitat is arboreal.
History
18th centuryThe shells of Amphidromus are relatively large and colorful and were among the first Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
n land snails brought back to Europe; most specimens in collections were brought back by travelers or explorers during the 18th century. Comparatively little material has been gathered by malacologists. Several species and forms were described before 1800, generally with inadequate locality data. At least two kinds — Amphidromus laevus
Amphidromus laevus
Amphidromus laevus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
(Müller, 1774) and the form Amphidromus perversus f. aureus Martyn, 1784 — still have not been reported from a precise locality.
19th century
Many species and varieties were named during the first half of the nineteenth century, again usually with poor locality data. Not until Eduard von Martens
Eduard von Martens
Eduard von Martens sometimes known as Carl or Karl Eduard von Martens, was a German zoologist.Born in Stuttgart in 1831, von Martens attended universities in Tübingen, Stuttgart and Munich, graduating from the University of Tübingen in 1855. In 1860, he set off as part of an expedition to the Far...
' (1867) publication was there an effort to deal with the entire complex. This paper showed an amazing grasp of variation and problems of geographic distribution
Zoogeography
Zoogeography is the branch of the science of biogeography that is concerned with the geographic distribution of animal species.-External links:*: A course outline and collection of Web resources by Dr. Taylor, UBC...
, and many of von Martens' concepts are still utilized. Hugh Fulton (1896) organized 142 specific and varietal names into eighteen species groups with 64 species. When the monograph Manual of Conchology of Henry Augustus Pilsbry
Henry Augustus Pilsbry
Henry Augustus Pilsbry was an American biologist, malacologist and carcinologist, among other areas of study. He was a dominant presence in many fields of invertebrate taxonomy for the better part of a century...
(1900) appeared, the number of species had increased to 81, which were placed in nineteen groups. Pilsbry's study has remained the only illustrated monograph of the genus, and it is still indispensable for any serious study.
20th century
Since 1900, the major taxonomic studies on Amphidromus have been faunistic (a study of the fauna of some territory or area) in scope. The papers of Paul Bartsch
Paul Bartsch
Paul Bartsch was an American malacologist and carcinologist.Paul Bartsch emigrated to the U.S.A in 1880. He graduated from the University of Iowa with a B.S. in 1896, and M.S. in 1899, and PhD in 1905...
(1917, 1918, 1919) on the Philippine species, Bernhard Rensch
Bernhard Rensch
Bernhard Rensch was a German evolutionary biologist, and ornithologist who did field work in Indonesia and India. He is probably best known as one of the architects of the modern evolutionary synthesis, which he popularised in Germany...
(1932) on the Lesser Sunda Islands
Lesser Sunda Islands
The Lesser Sunda Islands or Nusa Tenggara are a group of islands in the southern Maritime Southeast Asia, north of Australia. Together with the Greater Sunda Islands to the west they make up the Sunda Islands...
forms, and Tera van Benthem Jutting (1950, 1959) on Javan and Sumatran populations are especially comprehensive. Potentially the most valuable contribution is that of Curt Haniel (1921), who discussed the variation of Amphidromus contrarius and Amphidromus reflexilabris on Timor
Timor
Timor is an island at the southern end of Maritime Southeast Asia, north of the Timor Sea. It is divided between the independent state of East Timor, and West Timor, belonging to the Indonesian province of East Nusa Tenggara. The island's surface is 30,777 square kilometres...
. Variations in color and form were well illustrated in a series of color plates. Many of later conclusions by Frank Fortescue Laidlaw
Frank Fortescue Laidlaw
Frank Fortescue Laidlaw was a British biologist who studied molluscs, a malacologist.He named a number of species of snails, including:* The land snail genus Colparion- Bibliography :...
& Alan Solem
Alan Solem
Alan Solem, full name George Alan Solem was an American malacologist, a biologist who studied mollusks.He was one of the most renown land snail experts of his time and had earned a reputation for his comprehensive revisions of mainly terrestrial pulmonates...
(1961) concerning the relationships of color forms described as species were taken not as much from new collections as from the extent of variation found by Haniel (1921) in his pioneer study. Adolf Michael Zilch (1953) listed type specimens in the Senckenberg Museum
Senckenberg Museum
The Naturmuseum Senckenberg in Frankfurt is the second largest museum of natural history in Germany. It is particularly popular with children, who enjoy the extensive collection of dinosaur skeletons: Senckenberg boasts the largest exhibition of large dinosaurs in Europe. One particular treasure is...
and illustrated many previously unfigured species. The literature contains many scattered descriptions of new color forms and subspecies that appeared after 1900. Of the 309 names in the nomenclatural list, 111 (35.9 %) were published after Pilsbry (1900). Frank Fortescue Laidlaw
Frank Fortescue Laidlaw
Frank Fortescue Laidlaw was a British biologist who studied molluscs, a malacologist.He named a number of species of snails, including:* The land snail genus Colparion- Bibliography :...
& Alan Solem
Alan Solem
Alan Solem, full name George Alan Solem was an American malacologist, a biologist who studied mollusks.He was one of the most renown land snail experts of his time and had earned a reputation for his comprehensive revisions of mainly terrestrial pulmonates...
(1961) recognized 74 species by name and considered that material from the Banda Islands
Banda Islands
The Banda Islands are a volcanic group of ten small volcanic islands in the Banda Sea, about south of Seram Island and about east of Java, and are part of the Indonesian province of Maluku. The main town and administrative centre is Bandanaira, located on the island of the same name. They rise...
probably represents an undescribed species. There are eleven species recognized by them that were described after the appearance of Pilsbry's monograph. Several species recognized by Pilsbry we have subordinated to subspecific or varietal status, and a few names have been transferred to incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
, since they are based on hundred-year-old references that have not been substantiated by more recent collectors. Study by Frank Fortescue Laidlaw
Frank Fortescue Laidlaw
Frank Fortescue Laidlaw was a British biologist who studied molluscs, a malacologist.He named a number of species of snails, including:* The land snail genus Colparion- Bibliography :...
& Alan Solem
Alan Solem
Alan Solem, full name George Alan Solem was an American malacologist, a biologist who studied mollusks.He was one of the most renown land snail experts of his time and had earned a reputation for his comprehensive revisions of mainly terrestrial pulmonates...
(1961) forms a supplement to Pilsbry's monograph with his extensive plates.
Distribution
Distribution of the genus Amphidromus include from eastern India in south-western Asia to northern Australia.Amphidromus is found from the Garo Hills
Garo Hills
The Garo Hills are part of the Garo-Khasi range in Meghalaya, India. They are inhabited mainly by tribal dwellers. Shillong, the capital of Meghalaya, is located in this range. It is one of the wettest places in the world. The range is part of the Meghalaya subtropical forests ecoregion.Garo Hills...
and Khasi Hills
Khasi Hills
The Khasi Hills are part of the Garo-Khasi range in the Indian state of Meghalaya, and is part of the Patkai range and of the Meghalaya subtropical forests ecoregion...
of Meghalaya
Meghalaya
Meghalaya is a state in north-eastern India. The word "Meghalaya" literally means the Abode of Clouds in Sanskrit and other Indic languages. Meghalaya is a hilly strip in the eastern part of the country about 300 km long and 100 km wide, with a total area of about 8,700 sq mi . The...
in northeastern India, throughout Burma, Malay Peninsula
Malay Peninsula
The Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...
, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
, Laos
Laos
Laos Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ Sathalanalat Paxathipatai Paxaxon Lao, officially the Lao People's Democratic Republic, is a landlocked country in Southeast Asia, bordered by Burma and China to the northwest, Vietnam to the east, Cambodia to the south and Thailand to the west...
, Cambodia
Cambodia
Cambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...
, Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
as far east as the Sulawesi
Sulawesi
Sulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...
, Banda Islands
Banda Islands
The Banda Islands are a volcanic group of ten small volcanic islands in the Banda Sea, about south of Seram Island and about east of Java, and are part of the Indonesian province of Maluku. The main town and administrative centre is Bandanaira, located on the island of the same name. They rise...
, Timor
Timor
Timor is an island at the southern end of Maritime Southeast Asia, north of the Timor Sea. It is divided between the independent state of East Timor, and West Timor, belonging to the Indonesian province of East Nusa Tenggara. The island's surface is 30,777 square kilometres...
and the Tenimber Islands (but not on Ceram, Buru, Halmahera, Batjan Island, the Obi Islands, the Aru and Kei Islands, or the Talaud Archipelago and some Celebesian satellite islands), in the southern Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, notably Mindanao
Mindanao
Mindanao is the second largest and easternmost island in the Philippines. It is also the name of one of the three island groups in the country, which consists of the island of Mindanao and smaller surrounding islands. The other two are Luzon and the Visayas. The island of Mindanao is called The...
and the Balabac, Palawan
Balabac, Palawan
Balabac is a 3rd class municipality in the province of Palawan, Philippines, off the southern end of Palawan Island. According to the 2000 census, it has a population of 25,257 people in 4,723 households...
, and in northern Australia.
Fossil distribution
No pre-human fossil occurrences have been recorded. Tera van Benthem Jutting (1932) reported several specimens of Amphidromus filozonatus that had been eaten by natives from Sampoeng Cave, central Java, and later (van Benthem Jutting, 1937, pp. 92–94) a single specimen of Amphidromus palaceusAmphidromus palaceus
Amphidromus palaceus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
from the Trinil Beds of Java. Neither record ante dates human occupancy, and thus yields no record on the early history of Amphidromus.
Shell description
The shellsGastropod 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...
of Amphidromus are relatively large, from one to three inches high, and colorful. Amphidromus has an elongate conic or ovate conic helicoid shell of 5 to 8 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 shell may be thin and fragile or very heavy and solid with no known correlation of shell structure with distribution or habitats.
In some species the shell coils invariably to the right, and in many others just as invariably to the left. A significant number of species however are "amphidromine". That is to say, both left- and right-handed coiling are found in the same population (they are polymorphic
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...
for direction of the shell coiling, but as there are only two possible types of shell coiling, they are known as dimorphic
Polymorphism (biology)
Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...
in coiling), sometimes in approximately equal numbers, other times with a distinct predominance of one phase. In Amphidromus there is no information on the heredity of this character.
Most species of other amphidromine species such as Partula and Achatinella have became extinct, so the genus Amphidromus with its over 80 species is unique and useful for study of the evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
of asymmetry
Asymmetry
Asymmetry is the absence of, or a violation of, symmetry.-In organisms:Due to how cells divide in organisms, asymmetry in organisms is fairly usual in at least one dimension, with biological symmetry also being common in at least one dimension....
in animals. This is also the reason for urge of this genus conservation
Conservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
.
The whorls of Amphidromus are moderately convex and, with few exceptions, smooth or with only a faint sculpture
Sculpture (mollusc)
The sculpture of a mollusc shell is the three-dimensional ornamentation on the outer surface, as distinct from the basic shape of the shell itself or colouration. Sculpture may be concave as well as convex. Sometimes it has microscopic detail. Sculpture refers to the calcareous outer layer, not the...
of growth lines. At least four separate times, however, a sculpture of moderately heavy oblique radial ribs has appeared (Amphidromus costifer Smith from Binh Dinh Province
Binh Dinh Province
Bình Định is a province of Vietnam. It is located in Vietnam's South Central Coast region.-Administration:Binh Dinh is divided into one city and 10 districts:*An Lão*An Nhơn*Hoài Ân*Hoài Nhơn*Phù Cát*Phù Mỹ*Tuy Phước*Tây Sơn*Vân Canh...
in Vietnam, Amphidromus begini Morlet from Cambodia, Amphidromus heccarii Tapparone-Canefri from Celebes, and the Amphidromus palaceus
Amphidromus palaceus
Amphidromus palaceus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
-Amphidromus winteri complex from Java and Sumatra). Correlated with the ribbing is light, monochrome coloration, thin shell with large 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....
, and flaring lip. Many solid shells show a slight roughening of the surface, but this is quite different from the ribbed sculpture mentioned above.
The aperture is generally large and varies from about two-fifths to one-third the height of the shell, often in the same population. Usually the lip is at least somewhat expanded, and in forms such as Amphidromus reflexilahris Schepman and Amphidromus winteri (Pfeiffer) var. inauris Fulton, the lip can only be called flaring. In Amphidromus perversus
Amphidromus perversus
Amphidromus perversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.Amphidromus perversus is the type species of the genus Amphidromus, by the subsequent designation of Eduard von Martens .- Subspecies :There are six subspecies of...
(Linnaeus) and most other thick-shelled species, the lip is internally thickened, forms a "roll" in its expansion, and has a very heavy parietal callus
Parietal callus
A parietal callus is a feature of the shell anatomy of some groups of snails, i.e. gastropods. It is a thickened calcareous deposit which may be present on the parietal wall of the aperture of the adult shell. The parietal wall is the margin of the aperture and part of the wall of the body whorl...
. In thin-shelled species, the lip is usually a simple reflected edge. The umbilical area may be partially open, nearly closed or sealed. This sometimes provides a handy criterion for specific identification. The angle of the parietal wall varies, but no precise information on this has been compiled.
Generally the whorls increase rather regularly in size, but probably related species such as Amphidromus sinistralis (Reeve) and Amphidromus heccarii Tapparone-Canefri can have quite different degrees of whorl increment. No attempt has been made to express these differences meristically, since most of the available material was inadequate for statistical treatment (but see Haniel, 1921). Actual dimensions vary greatly both within and between species. Minimum adult size is about 21 mm high, the observed maximum about 75 mm. Only a few species, notably Amphidromus maculiferus, Amphidromus sinensis and Amphidromus entobaptus, seem to have a range in adult size of more than seven or eight millimeters.
The major shell variation is found in the color pattern. Most arboreal snails are brightly colored, the bulimulid genera Drymaeus
Drymaeus
Drymaeus is a genus of medium-sized air-breathing, tropical land snails, terrestrial pulmonate gastropod molluscs in the subfamily Bulimulinae and the family Orthalicidae, according to the taxonomy of the Gastropoda ....
and Liguus
Liguus
Liguus is a genus of large tropical air-breathing land snails, more specifically arboreal or tree snails, terrestrial pulmonate gastropod mollusks in the family Orthalicidae....
, cepolid Polymita
Polymita
Polymita, is a genus of large, air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Helminthoglyptidae.The shell of this species is large, brightly colored, and has numerous color varieties....
, and the camaenid Papuina being obvious examples. Polymita
Polymita
Polymita, is a genus of large, air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Helminthoglyptidae.The shell of this species is large, brightly colored, and has numerous color varieties....
, Liguus
Liguus
Liguus is a genus of large tropical air-breathing land snails, more specifically arboreal or tree snails, terrestrial pulmonate gastropod mollusks in the family Orthalicidae....
and Amphidromus are noted for their color variations.
The basic ground color of Amphidromus seems to be yellow and is usually (except for Amphidromus entobaptus) confined to the surface layers
of the shell, since worn specimens appear to be nearly devoid of color. Many species are whitish, and a few have dark ground colors. The apical
Apex (mollusc)
Apex is an anatomical term for the tip of the mollusc shell of a gastropod, scaphopod, or cephalopod mollusc.-Gastropods:The word "apex" is most often used to mean the tip of the spire of the shell of a gastropod...
whorls are pale, purple, brown, or black; they sometimes vary within a population (Amphidromus quadrasi). A few species, for example, Amphidromus schomburgki
Amphidromus schomburgki
Amphidromus schomburgki is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
, have a deciduous green periostracum
Periostracum
The periostracum is a thin organic coating or "skin" which is the outermost layer of the shell of many shelled animals, including mollusks and brachiopods. Among mollusks it is primarily seen in snails and clams, i.e. in bivalves and gastropods, but it is also found in cephalopods such as the...
. Continuous zonal patterns can take the form of whitish subsutural bands (Amphidromus similis
Amphidromus similis
Amphidromus similis is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
), heavy subperipheral pigmentation (Amphidromus perversus
Amphidromus perversus
Amphidromus perversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.Amphidromus perversus is the type species of the genus Amphidromus, by the subsequent designation of Eduard von Martens .- Subspecies :There are six subspecies of...
var. infraviridis), subsutural color lines (Amphidromus columellaris), broad spiral color bands (Amphidromus metabletus, Amphidromus webbi), or narrow spiral bands (Amphidromus laevus
Amphidromus laevus
Amphidromus laevus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
). Interrupted zonation can be the interruption of bands into spots (Amphidromus maculatus), highly irregular splitting of zones (Amphidromus perversus
Amphidromus perversus
Amphidromus perversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.Amphidromus perversus is the type species of the genus Amphidromus, by the subsequent designation of Eduard von Martens .- Subspecies :There are six subspecies of...
vars. sultanus and interruptus), formation of oblique radial streaks which can parallel (Amphidromus inversus
Amphidromus inversus
Amphidromus inversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.- Ecology :Schilthuizen et al. described spatial structure of population of Amphidromus inversus in Malaysia....
) or cross (Amphidromus latestrigatus) the incremental growth lines, or almost every conceivable combination and variation of these factors. Often the pattern will change radically from the apex
Apex (mollusc)
Apex is an anatomical term for the tip of the mollusc shell of a gastropod, scaphopod, or cephalopod mollusc.-Gastropods:The word "apex" is most often used to mean the tip of the spire of the shell of a gastropod...
to the body 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...
(Amphidromus quadrasi vars.). Aperture, parietal callus
Parietal callus
A parietal callus is a feature of the shell anatomy of some groups of snails, i.e. gastropods. It is a thickened calcareous deposit which may be present on the parietal wall of the aperture of the adult shell. The parietal wall is the margin of the aperture and part of the wall of the body whorl...
, columella, lip, and umbilical region are variously marked with pink, brown, purple, white, or black. Haniel (1921) has several color plates which show effectively the extent of color variation within two species of the Syndromus type. Amphidromus perversus
Amphidromus perversus
Amphidromus perversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.Amphidromus perversus is the type species of the genus Amphidromus, by the subsequent designation of Eduard von Martens .- Subspecies :There are six subspecies of...
and Amphidromus maculiferus of the Amphidromus subgenus are equally variable, while species such as Amphidromus inversus
Amphidromus inversus
Amphidromus inversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.- Ecology :Schilthuizen et al. described spatial structure of population of Amphidromus inversus in Malaysia....
and Amphidromus similis
Amphidromus similis
Amphidromus similis is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
are almost uniform in coloration.
Most of the Amphidromus subgenus show resting stages by the deposition of a brown or black radial band called a varix
Varix (mollusc)
A varix is an anatomical feature of the shell of certain sea snails, marine gastropod molluscs.It is a thickened axial ridge in the shell of some families of gastropods. A varix is located at intervals around the whorl, and is formed by considerable thickening of the outer lip at a resting stage...
. This is apparently rare in the Syndromus subgenus, although Amphidromus laevus
Amphidromus laevus
Amphidromus laevus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
shows evidence of interruption of the spiral banding after a resting phase.
Species recognition is based on combinations of minor structural variations in the shape, aperture, whorl contour, umbilical region, and color pattern. Apparently, many species have a stable color pattern, while others seem to vary tremendously. Adequate unselected field samples will enable a better understanding of the relative stability or variability of particular species in single localities.
Anatomy
Information concerning the soft anatomy of Amphidromus is widely scattered and fragmentary. The most complete account is that of Arnold Jacobi (1895) on specimens from BunguranBunguran
Bunguran is a small archipelago of Indonesia, located in the South China Sea....
, Natuna Islands
Natuna Islands
The Natuna Islands archipelago is located in the Natuna Sea in the larger Tudjuh Archipelago, off the northwest coast of Borneo. The islands are administratively part of the Riau Islands province of Indonesia and are the northernmost non-disputed island group of Indonesia...
and Djemadja, Anamba Islands. Unfortunately, although anatomical differences between the two species existed, we have no idea which forms he was dissecting, since, of the two names he used in his paper, Amphidromus chloris is found only in the Philippine Islands and the interruptus phase of Amphidromus perversus
Amphidromus perversus
Amphidromus perversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.Amphidromus perversus is the type species of the genus Amphidromus, by the subsequent designation of Eduard von Martens .- Subspecies :There are six subspecies of...
is not known from the Natuna Islands. Carl Arend Friedrich Wiegmann (1893, 1898) discussed portions of the anatomy of Amphidromus adamsii
Amphidromus adamsii
Amphidromus adamsii is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
, Amphidromus porcellanus
Amphidromus porcellanus
Amphidromus porcellanus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.The anatomy of this species was described by Carl Arend Friedrich Wiegmann in 1898....
, Amphidromus contrarius, and Amphidromus sinistralis; Walter Edward Collinge (1901, 1902) briefly noted features of Amphidromus palaceus
Amphidromus palaceus
Amphidromus palaceus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
and Amphidromus perakensis (reported as Amphidromus perversus); Haniel (1921) dissected Amphidromus contrarius and Amphidromus reflexilabris; and Bernhard Rensch
Bernhard Rensch
Bernhard Rensch was a German evolutionary biologist, and ornithologist who did field work in Indonesia and India. He is probably best known as one of the architects of the modern evolutionary synthesis, which he popularised in Germany...
published a few scattered notes in his various faunistic surveys. A few earlier notes are mentioned in Pilsbry (1900).
The long, narrow kidney with reflexed ureter and closed secondary ureter, the penial complex with distinct penis, epiphallus, vas deferens and flagellum, and the basic condition of the nervous and retractor muscle systems all serve to place Amphidromus in the Camaenidae. Apparently, specific differences exist in the penial complex, but present data are insufficient to allow any recognition of species groups through anatomical characters. Laidlaw
Frank Fortescue Laidlaw
Frank Fortescue Laidlaw was a British biologist who studied molluscs, a malacologist.He named a number of species of snails, including:* The land snail genus Colparion- Bibliography :...
& Solem
Alan Solem
Alan Solem, full name George Alan Solem was an American malacologist, a biologist who studied mollusks.He was one of the most renown land snail experts of his time and had earned a reputation for his comprehensive revisions of mainly terrestrial pulmonates...
(1961) provided no more additional details on anatomy.
Taxonomy
Prior to 1900 the similarity in shape to the South American tree snails had led people to associate Amphidromus with the BulimulidaeBulimulidae
Bulimulinae is a taxonomic subfamily of medium-sized to large, air-breathing, tropical and sub-tropical land snails, terrestrial pulmonate gastropod molluscs in the family Orthalicidae, according to the taxonomy of the Gastropoda ....
. The dissections made by Wiegmann and Jacobi clearly showed that the anatomical features were those of the Asian-Indonesian Camaenidae
Camaenidae
Camaenidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Helicoidea.This is one of the most diverse families in the clade Stylommatophora....
and that the shell resemblance to bulimulids was a parallelism.
Subgenera and species
Laidlaw and Solem (1961) recognized 75 species in the genus Amphidromus and another seven names placed under incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
.
In 2010, there are 87 species in the genus Amphidromus.
Species within the genus Amphidromus are divided into two subgenera and they include:
- subgenus Amphidromus Albers, 1850
Amphidromus perversus
Amphidromus perversus
Amphidromus perversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.Amphidromus perversus is the type species of the genus Amphidromus, by the subsequent designation of Eduard von Martens .- Subspecies :There are six subspecies of...
(Linnaeus, 1758) is the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus Amphidromus, by the subsequent designation of Eduard von Martens
Eduard von Martens
Eduard von Martens sometimes known as Carl or Karl Eduard von Martens, was a German zoologist.Born in Stuttgart in 1831, von Martens attended universities in Tübingen, Stuttgart and Munich, graduating from the University of Tübingen in 1855. In 1860, he set off as part of an expedition to the Far...
(1860). Species in the subgenus Amphidromus are amphidromine (left-handed and right-handed snails occur in the population) with exceptions: four dextral taxa are: Amphidromus givenchyi
Amphidromus givenchyi
Amphidromus givenchyi is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
, Amphidromus protania, Amphidromus schomburgki
Amphidromus schomburgki
Amphidromus schomburgki is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
dextrochlorus and Amphidromus inversus
Amphidromus inversus
Amphidromus inversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.- Ecology :Schilthuizen et al. described spatial structure of population of Amphidromus inversus in Malaysia....
annamiticus; and one sinistral Amphidromus atricallosus
Amphidromus atricallosus
Amphidromus atricallosus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.- Subspecies :* Amphidromus atricallosus atricallosus...
classiaris.
- subgenus Syndromus Pilsbry, 1900
All species of the subgenus Syndromus are sinistral with two exceptions: amphidromine Amphidromus glaucolarynx
Amphidromus glaucolarynx
Amphidromus glaucolarynx is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.This is the only one amphidromine species in the subgenus Syndromus....
and dextral Amphidromus kruehni
Amphidromus kruehni
Amphidromus kruehni is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.This is the only dextral species in the subgenus Syndromus....
. The type species of the subgenus Syndromus is Amphidromus contrarius Müller, 1774, by the subsequent designation of Adolf Michael Zilch (1960).
There have been also used subgenus Goniodromus Bülow, 1905 with type Amphidromus büllowi Fruhstorfer, 1905, but its subgeneric status is doubtful.
Cladogram
Genetic analyses confirmed that the genus Amphidromus is monophyletic. A (simplified) cladogram
Cladogram
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 (18 analyzed) species of Amphidromus based on partial sequences of 16S rDNA:
Habitat
Amphidromus is a genus of arboreal pulmonate land snails. Information concerning the habits and mode of life of the species of Amphidromus is almost non-existent. They have generally been collected crawling on trees or shrubs.Feeding habits
The diet of Amphidromus is not known, but Amphidromus atricallosusAmphidromus atricallosus
Amphidromus atricallosus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.- Subspecies :* Amphidromus atricallosus atricallosus...
perakensis probably feeds on microscopic Fungi, lichens or terrestrial algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
.
Life cycle
No life history studies have been published and only a few random observations are scattered through the literature. The most important is that of Eugen Paravicini (1921) on egg-laying.His observations were made on Amphidromus palaceus
Amphidromus palaceus
Amphidromus palaceus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae....
var. pura at Palimanan, West Java
West Java
West Java , with a population of over 43 million, is the most populous and most densely populated province of Indonesia. Located on the island of Java, it is slightly smaller in area than densely populated Taiwan, but with nearly double the population...
, in October, 1920. Natives brought in two nests with the snails depositing eggs. One snail had folded the exterior leaves of a young bamboo
Bamboo
Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....
shoot and gummed them together into a pointed cornet. The shoot hung vertically with the narrow end pointed upward and the wide opening below. The upper part of the sack was filled with eggs when collected. The snail descended slowly, rotating around its longitudinal axis, and deposited eggs until the entire cavity was filled. If a crack in the basket exposed eggs to the air, they quickly dried up. Two days after capture, egg-laying was finished and the snail closed the opening by folding over more leaves. Probably four days were spent in egg-laying, since the cavity was half filled at the start of observations. A second nest of similarly folded mango
Mango
The mango is a fleshy stone fruit belonging to the genus Mangifera, consisting of numerous tropical fruiting trees in the flowering plant family Anacardiaceae. The mango is native to India from where it spread all over the world. It is also the most cultivated fruit of the tropical world. While...
leaves contained 234 eggs.
The volume of eggs in each case greatly exceeded the size of the snail, indicating that the eggs must be encapsulated just before deposition. The capsules were very thin and dried quickly upon any exposure to the air. October marked the start of the rainy season and probably this is the normal breeding period. Eggs of Amphidromus porcellanus
Amphidromus porcellanus
Amphidromus porcellanus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.The anatomy of this species was described by Carl Arend Friedrich Wiegmann in 1898....
were reported by van Benthem Jutting (1950, p. 493) to have started hatching only ten days after being laid. Similar nest-building habits have been reported for other species, but no complete study of a life cycle has been published.
No information were not available on the cycle of activity, longevity, rate of growth, etc. up to 1961, but more information appeared since 1961:
Schilthuizen et al. (2005) described spatial structure
Spatial ecology
Spatial ecology is a specialization of ecologyand geography that is concerned with the identification of spatial patterns and their relationships to ecological events. In spatial ecology, ecological events can be explained through the detection of patterns at a given spatial scale; local,...
of a population of Amphidromus inversus
Amphidromus inversus
Amphidromus inversus is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Camaenidae.- Ecology :Schilthuizen et al. described spatial structure of population of Amphidromus inversus in Malaysia....
in Malaysia.
Schilthuizen et al. (2007) found, that there is sexual selection
Sexual selection
Sexual selection, a concept introduced by Charles Darwin in his 1859 book On the Origin of Species, is a significant element of his theory of natural selection...
in mating with snails of opposite chirality. This means that left-handed snail are mating more often with right-handed snails, than with snails of the same coiling. Additionally there are anatomical adaptations of the spermatophore
Spermatophore
A spermatophore or sperm ampulla is a capsule or mass created by males of various animal species, containing spermatozoa and transferred in entirety to the female's ovipore during copulation...
and of the female part 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...
for these matings success.
Predators
Predators of Amphidromus sp. include Red-crowned Barbet Megalaima rafflesii. and probably other birdBird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s.
Many shells of Amphidromus were found in the den of a rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
in Malaysia.
Further reading
- Dumrongrojwattana P., Mutchacheep S. & Senapin R. (2006). "Identification of 7 Thai arboreal snails genus Amphidromus Alber, 1850 by using morphometrics technique (Pulmonata: Camaenidae)". The Proceeding of 44th Kasetsart University Annual Conference, 30 Jan - 2 Feb 2006, Subject Science: 7 pp. Kasetsart UniversityKasetsart UniversityKasetsart University is a public university in Thailand and a top-ranked Public University in Thailand. It is ranked No.401-500 in the world by QS. It was also the first agricultural university and the third oldest university in Thailand...
, Bangkok.