Helicina rhodostoma
Encyclopedia
Helicina rhodostoma is a species
of tropical land snail
with an operculum
, a terrestrial
gastropod mollusk in the family Helicinidae
.
(1868) noted that this species is not found above 1000 m altitude. Three names have been used for this species, but material by Robinson et al. (2009) shows that the forms intergrade, illustrating the variability of the species. In general, populations from higher altitudes have a more pronounced columellar spine, and are more likely to have a red to reddish-orange aperture
, as seen in typical Helicina rhodostoma. Populations from drier, coastal areas tend to lack a columellar spine, and the aperture may be white or yellow. Juvenile specimens of this species often have a hairy periostracum
, which is gradually worn off as the snail reaches sexual maturity.
Despite the fact that Helicina rhodostoma was originally errorneously described from Guadeloupe – and in subsequent reports from that island the error has been perpetuated – this species is undoubtedly a Dominican endemic. It has not been found during subsequent surveys of Guadeloupe
and Marie-Galante
. The fact that no museum material exists labelled “Guadeloupe”, not even in the Muséum national d'histoire naturelle
in Paris, indicates that the species has never been collected on that island. The synonymy of Helicina goldfussi and Helicina rhodostoma inermis is confirmed by morphometrics
and anatomical studies.
s, and also between rocks and gravel.
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 tropical 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...
with an operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
, 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 Helicinidae
Helicinidae
Helicinidae is a family of small tropical land snails which have an operculum. They are terrestrial operculate gastropod mollusks in the superfamily Helicinoidea....
.
Shell description
Robert John Lechmere GuppyRobert John Lechmere Guppy
Robert John Lechmere Guppy was a British-born naturalist after whom the guppy is named...
(1868) noted that this species is not found above 1000 m altitude. Three names have been used for this species, but material by Robinson et al. (2009) shows that the forms intergrade, illustrating the variability of the species. In general, populations from higher altitudes have a more pronounced columellar spine, and are more likely to have a red to reddish-orange 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....
, as seen in typical Helicina rhodostoma. Populations from drier, coastal areas tend to lack a columellar spine, and the aperture may be white or yellow. Juvenile specimens of this species often have a hairy 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...
, which is gradually worn off as the snail reaches sexual maturity.
Distribution
Helicina rhodostoma is endemic to the West Indian island of Dominica.Despite the fact that Helicina rhodostoma was originally errorneously described from Guadeloupe – and in subsequent reports from that island the error has been perpetuated – this species is undoubtedly a Dominican endemic. It has not been found during subsequent surveys of Guadeloupe
Guadeloupe
Guadeloupe is an archipelago located in the Leeward Islands, in the Lesser Antilles, with a land area of 1,628 square kilometres and a population of 400,000. It is the first overseas region of France, consisting of a single overseas department. As with the other overseas departments, Guadeloupe...
and Marie-Galante
Marie-Galante
Marie-Galante is an island of the Caribbean Sea located at the south of Guadeloupe and at north of Dominica. Marie-Galante is a dependence of Guadeloupe which is a french overseas department....
. The fact that no museum material exists labelled “Guadeloupe”, not even in the Muséum national d'histoire naturelle
Muséum national d'histoire naturelle
The Muséum national d'Histoire naturelle is the National Museum of Natural History in Paris, France.- History :The museum was formally founded on 10 June 1793, during the French Revolution...
in Paris, indicates that the species has never been collected on that island. The synonymy of Helicina goldfussi and Helicina rhodostoma inermis is confirmed by morphometrics
Morphometrics
Morphometrics refers to the quantitative analysis of form, a concept that encompasses size and shape. Morphometric analyses are commonly performed on organisms, and are useful in analyzing their fossil record, the impact of mutations on shape, developmental changes in form, covariances between...
and anatomical studies.
Ecology
Helicina rhodostoma can be found living on trees, on fernFern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
s, and also between rocks and gravel.
External links
- Richling I. The Land Snail Family Helicinidae. www.helicina.de