Leptacme cuongi
Encyclopedia
Leptacme cuongi is a species
of air-breathing land snail
, a terrestrial
gastropod mollusk in the family Clausiliidae
, the door snails.
This species is know to occur in a limestone
area in Thanh Hoa Province, Vietnam
. The shell
is high-spired
and slender with numerous whorls
, and is usually a little over 10 mm in length. When the species was described in 2007, as well as a detailed shell description, full accounts of the reproductive system
and the radula
of this species were also given.
The specific name cuongi is in honor of the biologist Duong Ngoc Cuong, who works at the Institute of Ecology and Biological Resources in Hanoi
, Vietnam, and who is a friend of the first author.
The type locality is Pu Luong Nature Reserve
, a limestone
hill near the native village Am, 20°27.39'N 105°13.65'E, in Thanh Hoa Province, Vietnam.
is dextral, not decollate, light corneous, fragile, glossy and rather translucent. It is very slender, with a nearly cylindrical, narrow, upper third and a spindle-shaped lower part. The shell has 12-15 moderately convex whorls
separated by an indented, relatively deep suture. Protoconch
is glossy, teleoconch whorls are with obtuse growth-lines, which are more rib-like on the more narrowly sculptured
, cervical part of the last whorl. Peristome is double; inner lip recognizable as a narrow ridge, contacting the body whorl and closing the umbilicus (visible in not fully grown specimens); outer lip very strongly thickened, with some prominent growth-ridges, tube-like protruding. Neck is with a more or less clearly developed basal crest. Aperture
is obliquely pear-shaped to narrowed elliptical, with a sinulus bordered by the lamella parietalis and a knob on the peristome, whitish inside. Peristome is continuous, white, broadly reflexed. In frontal view, the prominent lamella parietalis (= superior), and the more inconspicuous lamella columellaris (= inferior) and plica principalis are seen, whereas the frontal end of the lamella subcolumellaris is usually discernible as a blunt denticle. The lamella parietalis is connected with the spiralis, which reaches as far as the lamella subcolumellaris inside, i.e. hardly further than the columellaris; there is no lamella inserta. Ventro-laterally, next to the plica principalis, there are four short, nearly parallel plicae palatales. Clausilial
blade is rather broad, curvature of its outer border dictated by the position of the short palatal plicae.
The width of the shell is 2.0–2.6 mm, 2.2 mm on average. The height of the shell is 10.4 mm (12 whorls)–14.0 mm (15 whorls), 11.9 mm on average.
The conchologically most similar species, Leptacme eregia Szekeres, 1969, can be distinguished from Leptacme cuongi by its much larger shell (17.8 mm instead of 11.9 mm), its more rounded neck, i.e. without a basal crest, the lamella inferior which is situated more deeply inside, and the plica principalis, which ends less deep.
Reproductive system
: Vagina is more than twice the length of the oviduct. Oviduct about half as long as the proximal part of the pedunculus, which is longer than the distal part. Basally the pedunculus is much broader than the adjoining oviduct. The bursa of the bursa copulatrix is separate from the spermoviduct; it reaches hardly further than the diverticulum. Male part of the genitalia with a single retractor muscle, without flagellum or caecum. Penis is tripartite as far as can be judged on the basis of the transparent genital slides, forming a loop with a sharp curvature about halfway. Proximal half formed by (1) a short segment with a relatively simple luminal surface, followed by (2) a clearly broader and about three times longer part with some longitudinal ridges with zigzag borders. Distal half, with the insertion of the retractor muscle slightly distal from halfway, about as broad or little broader than the narrow part of the proximal half; penial segment (3) with a relatively simple luminal surface; epiphallus (4) with a vague pattern of small pustulae, most clearly seen at its distal end. Vas deferens, a short part of the penis and nearly as much as the proximal half of the vagina united by a common sheath.
The large main cusp of the central tooth of radula
is accompanied by prominent ectocones. The 7-8 adjoining lateral teeth in half a row have equally small ectocones. All these teeth have prominent basal plates with interrow support ridges. In the first marginal tooth, the main cusp is less symmetrical and the basal plate is less prominently developed. The following c.10 marginal teeth are increasingly more asymmetrical initially, with an endocone on the main cusp and ectones with two or three cusps in the teeth closer to the margin, which are irregularly comb-like when the main cusp with the endocone becomes relatively smaller.
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
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...
, 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 in the family Clausiliidae
Clausiliidae
Clausiliidae, common name door snails, are a taxonomic family of small, very elongate, mostly left-handed, air-breathing land snails, sinistral terrestrial pulmonate gastropod mollusks....
, the door snails.
This species is know to occur in a limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
area in Thanh Hoa Province, 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 –...
. The shell
Gastropod 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 high-spired
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...
and slender with numerous 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...
, and is usually a little over 10 mm in length. When the species was described in 2007, as well as a detailed shell description, full accounts 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...
and 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...
of this species were also given.
The specific name cuongi is in honor of the biologist Duong Ngoc Cuong, who works at the Institute of Ecology and Biological Resources in Hanoi
Hanoi
Hanoi , is the capital of Vietnam and the country's second largest city. Its population in 2009 was estimated at 2.6 million for urban districts, 6.5 million for the metropolitan jurisdiction. From 1010 until 1802, it was the most important political centre of Vietnam...
, Vietnam, and who is a friend of the first author.
Distribution
This species occurs in:The type locality is Pu Luong Nature Reserve
Pu Luong Nature Reserve
Pù Luông Nature Reserve is a nature reserve in northern Vietnam. This nature reserve is situated in Quan Hoa and Ba Thuoc districts of Thanh Hoa Province, North Central Coast region of Vietnam. Pu Luong Nature Reserve is bordered by Mai Chau, Tan Lac and Lac Son districts of Hoa Binh Province...
, a limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
hill near the native village Am, 20°27.39'N 105°13.65'E, in Thanh Hoa Province, Vietnam.
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 dextral, not decollate, light corneous, fragile, glossy and rather translucent. It is very slender, with a nearly cylindrical, narrow, upper third and a spindle-shaped lower part. The shell has 12-15 moderately convex 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...
separated by an indented, relatively deep suture. Protoconch
Protoconch
A protoconch is an embryonic or larval shell of some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod...
is glossy, teleoconch whorls are with obtuse growth-lines, which are more rib-like on the more narrowly sculptured
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...
, cervical part of the last whorl. Peristome is double; inner lip recognizable as a narrow ridge, contacting the body whorl and closing the umbilicus (visible in not fully grown specimens); outer lip very strongly thickened, with some prominent growth-ridges, tube-like protruding. Neck is with a more or less clearly developed basal crest. 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 obliquely pear-shaped to narrowed elliptical, with a sinulus bordered by the lamella parietalis and a knob on the peristome, whitish inside. Peristome is continuous, white, broadly reflexed. In frontal view, the prominent lamella parietalis (= superior), and the more inconspicuous lamella columellaris (= inferior) and plica principalis are seen, whereas the frontal end of the lamella subcolumellaris is usually discernible as a blunt denticle. The lamella parietalis is connected with the spiralis, which reaches as far as the lamella subcolumellaris inside, i.e. hardly further than the columellaris; there is no lamella inserta. Ventro-laterally, next to the plica principalis, there are four short, nearly parallel plicae palatales. Clausilial
Clausilium
The clausilium is a calcareous anatomical structure which is found in one group of air-breathing land snails: terrestrial pulmonate gastropod mollusks in the family Clausiliidae, the door snails...
blade is rather broad, curvature of its outer border dictated by the position of the short palatal plicae.
The width of the shell is 2.0–2.6 mm, 2.2 mm on average. The height of the shell is 10.4 mm (12 whorls)–14.0 mm (15 whorls), 11.9 mm on average.
The conchologically most similar species, Leptacme eregia Szekeres, 1969, can be distinguished from Leptacme cuongi by its much larger shell (17.8 mm instead of 11.9 mm), its more rounded neck, i.e. without a basal crest, the lamella inferior which is situated more deeply inside, and the plica principalis, which ends less deep.
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...
: Vagina is more than twice the length of the oviduct. Oviduct about half as long as the proximal part of the pedunculus, which is longer than the distal part. Basally the pedunculus is much broader than the adjoining oviduct. The bursa of the bursa copulatrix is separate from the spermoviduct; it reaches hardly further than the diverticulum. Male part of the genitalia with a single retractor muscle, without flagellum or caecum. Penis is tripartite as far as can be judged on the basis of the transparent genital slides, forming a loop with a sharp curvature about halfway. Proximal half formed by (1) a short segment with a relatively simple luminal surface, followed by (2) a clearly broader and about three times longer part with some longitudinal ridges with zigzag borders. Distal half, with the insertion of the retractor muscle slightly distal from halfway, about as broad or little broader than the narrow part of the proximal half; penial segment (3) with a relatively simple luminal surface; epiphallus (4) with a vague pattern of small pustulae, most clearly seen at its distal end. Vas deferens, a short part of the penis and nearly as much as the proximal half of the vagina united by a common sheath.
The large main cusp of the central tooth of 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 accompanied by prominent ectocones. The 7-8 adjoining lateral teeth in half a row have equally small ectocones. All these teeth have prominent basal plates with interrow support ridges. In the first marginal tooth, the main cusp is less symmetrical and the basal plate is less prominently developed. The following c.10 marginal teeth are increasingly more asymmetrical initially, with an endocone on the main cusp and ectones with two or three cusps in the teeth closer to the margin, which are irregularly comb-like when the main cusp with the endocone becomes relatively smaller.