''Orthalicus reses'', the Stock Island tree snail, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of large tropical air-breathing

tree snail Tree snail is a common name that is applied to various kinds of tropical air-breathing land snails, pulmonate gastropod mollusks that have shells, and that live in trees, in other words, are exclusively arboreal in habitat. Some other species of a ...

, a

terrestrial Terrestrial refers to things related to land or the planet Earth. Terrestrial may also refer to: * Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...

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

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the family

Orthalicidae Orthalicidae (orthalicid land snails) are a family of tropical air-breathing land snails, terrestrial pulmonate gastropod mollusks are classified in the subfamily Orthalicoidea of the order Stylommatophora. MolluscaBase eds. (2021). MolluscaBase ...

. It was first described in 1830 by the American naturalist

Thomas Say Thomas Say (June 27, 1787 – October 10, 1834) was an American entomologist, conchologist, and Herpetology, herpetologist. His studies of insects and shells, numerous contributions to scientific journals, and scientific expeditions to Florida, Ge ...

. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

, a specimen probably collected in

Key West Key West ( es, Cayo Hueso) is an island in the Straits of Florida, within the U.S. state of Florida. Together with all or parts of the separate islands of Dredgers Key, Fleming Key, Sunset Key, and the northern part of Stock Island, it cons ...

, was subsequently lost. Over a hundred years later, in 1946, the American

biologist A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual Cell (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...

Henry Augustus Pilsbry Henry Augustus Pilsbry (7 December 1862 – 26 October 1957) 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 centu ...

redescribed the species using a specimen from Stock Island, Florida. ''Orthalicus reses'' has two subspecies, ''O. reses reses'' and ''O. reses nosodryas''. The validity of these two

taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

is still being discussed, but some experts argue that considering them as independent units may be important for management purposes. The Stock Island tree snail has a large conical

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard ou ...

(45–55 mm in length) with variable thickness, generally lighter and more translucent than other species of ''Orthalicus''. It is colored white to buff, with weakly developed

spiral In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are:apical whorl,

columella Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire. His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the wo ...

, and

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 nominate subspecies ''Orthalicus reses reses'' is threatened; it lives on trees in hardwood hammocks habitat in Southern

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

, USA, specifically the

Florida Keys The Florida Keys are a coral cay archipelago located off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of Miami, and e ...

Taxonomy

''Orthalicus reses'' is a species within the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

''Orthalicus'', a group of large,

arboreal Arboreal locomotion is the Animal locomotion, locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. Th ...

pulmonate snails in the family

. The genus ''Orthalicus'' occurs primarily in Central and South America. Two species occur in North America, ''Orthalicus reses'' and ''

Orthalicus floridensis ''Orthalicus'' is a genus of land snails in the family Orthalicidae. MolluscaBase eds. (2021). MolluscaBase. Orthalicus H. Beck, 1837. Accessed through: World Register of Marine Species at: http://marinespecies.org/aphia.php?p=taxdetails&id=9954 ...

'' Pilsbry, both of which are restricted to South Florida. The Stock Island tree snail (''Orthalicus reses'') was first described by

in 1830, based on a snail which was probably collected in

. That specimen was lost, and the species was later redescribed by

in 1946 using a snail collected from Stock Island. ''Orthalicus reses'' has two subspecies: * ''Orthalicus reses reses'' (

Say Say may refer to: Music *''Say'' (album), 2008 album by J-pop singer Misono * "Say" (John Mayer song), 2007 *"Say (All I Need)", 2007 song by American pop rock band OneRepublic * "Say" (Method Man song), 2006 single by rapper Method Man * "Say" ( ...

, 1830) - Stock Island tree snail * '' Orthalicus reses nesodryas''

Pilsbry Henry Augustus Pilsbry (7 December 1862 – 26 October 1957) 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 centu ...

, 1946 - Florida Keys treesnail It is generally thought that the two subspecies of ''Orthalicus reses'' do not

interbreed In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in ...

due to

anatomical Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...

incompatibility. However, Emmel and Perry (2004) recommended that if the two ''Orthalicus reses'' subspecies prove to be as genetically invariant as was observed in their study, the groups should be considered a single

taxon In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

or taxonomic unit. In that case, the nominate form, ''Orthalicus reses reses'', would prevail, and ''Orthalicus reses nesodryas'' would be demoted to a

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

instead of a valid subspecies. Emmel and Perry (2004) however asserted that the taxa "should continue to be considered as independent units for management purposes".

Description

''Orthalicus reses'' is a snail with a large, conical

that is approximately 45 to 55 mm in length. The thickness of the shell varies, but is usually more lightweight and translucent than other species of '' Orthalicus''. Pilsbry, H.A. (1946). ''Land Mollusca of North America (north of Mexico)''. Monograph Academy of Natural Science, Philadelphia 3 (1) 1-520. The external ground color of the shell is white to buff, with three poorly developed spiral bands and several flame-like purple-brown axial stripes that stop at the lower of the spiral bands. The axial stripes are typically narrower than their whitish interspaces and do not fork near the upper suture. There are two to three white apical

whorls A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

. The

last whorl The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the b ...

contains two to four darker brown growth-rest

varices A varix (pl. varices) is an abnormally dilated vessel with a tortuous course. Varices usually occur in the venous system, but may also occur in arterial or lymphatic vessels. Examples of varices include: * Varicose veins, large tortuous veins usua ...

. The

and

are white or faint chestnut brown. The nominate subspecies ''Orthalicus reses reses'' is distinguished from the supposed subspecies ''Orthalicus reses nesodryas'' by the lighter color pattern of the apical whorl, columella, and parietal callus. These characteristics are chestnut-brown or darker in ''Orthalicus reses nesodryas''.

Distribution

Henry Augustus Pilsbry suggested, in 1946, that ''Orthalicus reses reses'' arrived in

from

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

and the

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...

shortly after the emergence of the Florida peninsula in the

late Pleistocene The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...

. Snails that were sealed in place on floating tropical trees may have been cast ashore on the Florida peninsula by high winds and

hurricane A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...

s. This form of dispersal has been suggested for both ''Orthalicus'' and '' Liguus'', but the exact origin of these species is still in question. In 1972, Craig suggested that populations of ''Orthalicus'' arrived directly across the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...

from Central America, but the mode of transportation and whether dispersal occurred as a single event or multiple events was not known. No one knows when ''Orthalicus reses reses'' arrived in the Lower Keys. Historically, the Stock Island tree snail was believed to have a very limited distribution, being found only in tropical hardwood hammocks on Stock Island and

; although it may have been found in other hammock areas in the Lower Keys. The distribution has since been artificially extended by collectors, who have introduced them to

Key Largo Key Largo ( es, Cayo Largo) is an island in the upper Florida Keys archipelago and is the largest section of the keys, at long. It is one of the northernmost of the Florida Keys in Monroe County, and the northernmost of the keys connected b ...

and the southernmost parts of mainland Florida. ''Orthalicus reses nesodryas'' has a broader range, occurring throughout the Florida Keys from

Sugarloaf Key Sugarloaf Key is a single island in the lower Florida Keys that forms a loop on the Atlantic Ocean side giving the illusion of separate islands. Although frequently referred to simply and with technical accuracy as "Sugarloaf Key", this island c ...

north. ''

'' is the only ''Orthalicus'' species to occur naturally on the mainland, and is also found in the Keys. This species is known to occur in the

National Key Deer Refuge The National Key Deer Refuge is a National Wildlife Refuge located on Big Pine Key and No Name Key in the Florida Keys in Monroe County, Florida. The refuge is home to the endangered Key deer, a subspecies of the white-tailed deer that is ende ...

Behavior

''Orthalicus reses reses'' snails are active mainly during the wet season, i.e. May through November, during which time breeding, feeding, and dispersal takes place. Dry periods (December through April) are spent in

aestivation Aestivation ( la, aestas (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and ...

, during which time the snail forms a tight sealed barrier between the

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

and a tree trunk or branch. Snails secrete this

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

seal (an

epiphragm An epiphragm (from the Ancient Greek ἐπί, '' epi '' " upon, on, over " and φράγμα, '' -phrágma '' "fence") is a temporary structure which can be created by many species of shelled, air-breathing land snails, terrestrial pulmonate gast ...

) that cements their shell to a tree in order to protect them from

desiccation Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...

during the dry period. Snails may come out of aestivation briefly to feed during dry-season rains, and also may go into aestivation during summer dry spells.

Ecology

Habitat

Originally, ''Orthalicus reses'' occurred exclusively in hardwood hammocks of the

Keys Key or The Key may refer to: Common meanings * Key (cryptography), a piece of information that controls the operation of a cryptography algorithm * Key (lock), device used to control access to places or facilities restricted by a lock * Key (map ...

. ''Orthalicus reses'' survives best in hammocks with smooth-barked native trees that support relatively large amounts of

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

. In the Florida Keys, ''Orthalicus'' is limited to the higher portions of the islands that support hammock forests (minimum elevations of 5 to 11 feet). Lower Keys hammocks consist of thick forests of tropical trees and shrubs which grow in

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...

, and calcareous sand soils. Canopy trees include black ironwood (''

Krugiodendron ferreum ''Krugiodendron ferreum'', commonly known as the black ironwood or leadwood, is a species of tree in the family Rhamnaceae. It is found in southern Florida, throughout the Caribbean and from southern Mexico to Honduras. Originally described by M ...

''), gumbo limbo (''

Bursera simaruba ''Bursera simaruba'', commonly known as gumbo-limbo, copperwood, chaca, West Indian birch, naked Indian, and turpentine tree, is a tree species in the family Burseraceae, native to the Neotropics, from South Florida to Mexico and the Caribbean ...

''), Jamaican dogwood (''

Piscidia piscipula ''Piscidia piscipula'', commonly named Florida fishpoison tree, Jamaican dogwood, or fishfuddle, is a medium-sized, deciduous, tropical tree in the Fabaceae family. It is native to the Greater Antilles (except Puerto Rico), extreme southern Flori ...

''), mahogany (''

Swietenia mahagoni ''Swietenia mahagoni'', commonly known as American mahogany, Cuban mahogany, small-leaved mahogany, and West Indian mahogany, is a species of ''Swietenia'' native to South Florida in the United States and islands in the Caribbean including the Ba ...

''), pigeon plum (''

Coccoloba diversifolia ''Coccoloba diversifolia'', known as pigeonplum or tietongue, is a species of the genus ''Coccoloba'' native to coastal areas of the Caribbean, Central America (Belize, Guatemala), southern Mexico, southern Florida (coastal regions from Cape Can ...

''), poisonwood (''

Metopium toxiferum ''Metopium toxiferum'', the poisonwood, Florida poisontree, or hog gum, is a species of flowering tree in the cashew or sumac family, Anacardiaceae, that is native to the American Neotropics. It produces the irritant urushiol much like its close ...

''), and strangler fig (''

Ficus aurea ''Ficus aurea'', commonly known as the Florida strangler fig (or simply strangler fig), golden fig, or ''higuerón'', is a tree in the family Moraceae that is native to the U.S. state of Florida, the northern and western Caribbean, southern Me ...

''). Hammock understory contains torchwood (''

Amyris elemifera ''Amyris elemifera'' is a species of flowering plant in the citrus family, Rutaceae. Its common names include sea torchwood, smooth torchwood,Drypetes diversifolia''), wild coffee (''

Psychotria nervosa ''Psychotria nervosa'', also known as Seminole balsamo or wild coffee, is a shade tolerant medium-sized shrub native to Florida as well as the West Indies and Central and South America. It produces a "small, red, ellipsoid fruit" that resembles " ...

''), marlberry ('' Ardisia escallonioides''), stoppers (''

Eugenia ''Eugenia'' is a genus of flowering plants in the myrtle family Myrtaceae. It has a worldwide, although highly uneven, distribution in tropical and subtropical regions. The bulk of the approximately 1,100 species occur in the New World tropics, ...

'' sp.), soldierwood (''

Colubrina elliptica ''Colubrina elliptica'', also known as mabi or soldierwood, is a species of flowering tree in the family Rhamnaceae, that is native to the Florida Keys, the Caribbean, Central America, Mexico, and Venezuela. It produces fruit the size of pepperco ...

''), crabwood (''

Gymnanthes lucida ''Gymnanthes lucida'', commonly known as shiny oysterwood or crabwood, is a species of flowering plant in the spurge family, Euphorbiaceae, that is native to southern Florida in the United States, the Bahamas, the Caribbean, Mexico, and Central A ...

''), and velvetseed ('' Guettarda scabra''). Larger trees are more likely to support more ''Orthalicus reses reses'' snails than smaller trees, probably because they provide the snails with an increased surface area for foraging. Deisler, J.E. (1987). The ecology of the Stock Island tree snail, ''Orthalicus reses reses'' (Say)". ''Bulletin Florida State Museum Biological Science'' 31(3): 107-145. It is not known if ''Orthalicus reses reses'' prefer certain tree types or species; however, Voss (1976) Voss, R. S. (1976). "Observations on the ecology of the Florida tree snail ''Liguus fasciatus'' (Muller)". ''Nautilus'' 90
65
69. suggested tree snails generally prefer trees with smooth bark rather than trees with rough bark, because it would require less energy to crawl over smooth bark. Voss also believed ''Orthalicus reses reses'' would prefer smooth bark because it would make it easier for them to form a secure

mucous Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...

seal when they were aestivating, resulting in lower mortalities from

dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...

or accidental dislodgement. ''Orthalicus reses reses'' snails are entirely

except when they move to the forest floor for nesting or traveling. Hammocks that contain well-developed soils or

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that have fallen to the ground. This detritus or dead organic material and its constituent ...

are important for nesting activity and dispersal. Essential factors affecting food availability are the light intensity and moisture content of the hammock habitat. No data are available on minimal hammock size needed to support a viable population of tree snails. Suitable habitat would have to include an area large enough to provide for foraging and nesting requirements, as well as provide for the

microclimate A microclimate (or micro-climate) is a local set of atmospheric conditions that differ from those in the surrounding areas, often with a slight difference but sometimes with a substantial one. The term may refer to areas as small as a few squ ...

(air temperature and humidity) needed by the ''Orthalicus reses reses''. Preferences for edge or interior hammock have been observed in '' Liguus'' populations on Lignumvitae Key.Tuskes, P.M. (1981). "Population structure and biology of ''Liguus'' tree snails on Lignumvitae Key, Florida". ''Nautilus'' 95(4)
162
169. Age-class differences were seen where older individuals were found in the central mature hammock, while younger individuals were found more often along the edges of the hammock. Tuskes (1981) suggested this may be an

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...

of younger snails to move to the edge to escape

competition Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

from older snails. It is not known whether ''Orthalicus reses reses'' prefer interior or edge hammock areas. Recent surveys of snails in the

populations have shown higher numbers of snails along the edge of the hammock than in the interior, but this result may be affected by the differences in visibility during surveying.

Feeding habits

Little is known about the feeding habits or food preferences of ''Orthalicus reses reses''. They feed on

epiphytic An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phoroph ...

growth on hardwood tree trunks, branches, and leaves. Likely food items include a variety of

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

, and

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.Mixobacteria'' and some small

mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evid ...

s may serve as a secondary food source. The rate at which individuals of ''Orthalicus reses reses'' grow is dependent upon the availability of food, and how quickly their food is replenished after being grazed. Regrowth of the epiphytes is affected by the light intensity and moisture (canopy density and climate) of the hammock habitat. Feeding can occur at any time during the day or night, with peak feeding activity occurring from late afternoon through the night to mid-morning and during or immediately after rainfall. When they are active, ''Orthalicus reses reses'' often follow a random twisting path that covers the entire bark surface, but they will move in a straight line if the surface moisture is abundant.

Life cycle

''Orthalicus reses reses'' snails are

hermaphroditic In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have separ ...

, and

cross-fertilization Out-crossing or out-breeding is the technique of crossing between different breeds. This is the practice of introducing distantly related genetic material into a breeding line, thereby increasing genetic diversity. Outcrossing can be a useful ...

is common. '' Liguus'' individuals are able to locate each other by following mucus trails, and ''Orthalicus reses reses'' likely do the same. They mate and nest in late summer and early fall during the wettest part of the rainy season. They lay approximately 15 eggs per clutch in a cavity that is dug into the soil

humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Lati ...

layer, usually at the base of a tree, and take anywhere from 24 to 105 hours to deposit their eggs.McNeese, P. L. (1989). "A proposal for the study of the Stock Island tree snail, ''Orthalicus reses reses'', at its type locality". Monroe County Environmental Resources Department, Marathon, Florida. The presence of this humus layer is essential for egg laying. The eggs hatch during the onset of the rains the following spring. Upon hatching, the juvenile snails immediately proceed to climb adjacent trees. Most nesting snails appear to be approximately 2 to 3 years old and are estimated to live for up to 6 years, with 2.11 years being the mean age for the Stock Island population at the time of Deisler's study (1987). Tree snail age can be estimated by counting the number of dark "suture-like" lines resulting from pigment deposition during long dry spells (the dry season).

Interaction with other snails in the genus

Emmel and Perry (2004)Emmel, T. C. & Perry M. W. (2004). Evaluation of the genetic and systematic distinction of the Stock Island tree snail and its relatives. Final report to U.S. Fish and Wildlife Service, South Florida Ecological Services Office, for Grant Agreement 1448-40181-00-G-133. University of Florida, Gainesville, Florida. believed there to be shifts in the relative abundances of the three ''Orthalicus'' taxa in the Keys. In the past, ''

'' was the most common and widespread of the three, whereas subsequent to 2000, Emmel and Perry (2004) considered the ''Orthalicus floridensis'' to be the rarest. This situation results partly from the translocations that bolstered ''Orthalicus reses reses'' distribution and allowed them to avoid extinction, but probably also reflects actual declines in ''Orthalicus floridensis'' populations over time. ''Orthalicus reses reses'' now occur in sympatry with their congeners in several locations. The observations of Emmel and Perry (2004) suggested that translocated ''Orthalicus reses reses'', all of which are outside the historic range, perform as well or better than congeners in those places where they overlap.

Population biology

The abundance and range of ''Orthalicus reses reses'' declined throughout the 20th century. Rigorous estimates of ''Orthalicus reses reses'' numbers are not known for any population. ''Orthalicus reses reses'' status is currently assessed by the numbers of discrete populations that are known. Accordingly, potential trend information only includes observations of whether various populations continue to persist. However, for most populations, even the area occupied is poorly defined. As of 2006, a tabulation of all well-known and poorly documented sites indicated that ''Orthalicus reses reses'' occupied approximately 25 sites in the Florida Keys (Monroe County) and two sites on the mainland (Miami-Dade County).U.S. Fish and Wildlife Service. 2006. Biological opinion on the Federal Emergency Management Agency’s National Flood Insurance Program’s actions in the Florida Keys. U.S. Fish and Wildlife Service, Atlanta, Georgia. However, for many of those sites, even confirmation as to whether ''Orthalicus reses reses'' persists in recent years is lacking. Survey and monitoring efforts have been limited and highly variable, and methodologies are usually not reported in detail. Whereas ''Orthalicus reses reses'' occupies more sites at present than in the recorded past, the total area occupied remains unknown, as are trends in abundance and demographics. Overall, however, the ''Orthalicus reses reses'' population status appears to be more secure than when it was listed, due to the widespread translocations that occurred subsequently. ''Orthalicus reses reses'' no longer occupies the Key West Botanical Forest and Garden. In contrast, many populations exist on

, well beyond ''Orthalicus reses reses'' historic range, as a result of relocations by shell collectors. The majority of relocations had occurred by the late 1990s. These were largely carried out by private hobbyists, who sought to thwart extinction. However, these actions were poorly documented, and were subsequently poorly monitored. One clear trend is that Key Largo has accumulated more populations than the Lower Keys.

Conservation

''Orthalicus reses reses'' is listed as threatened on the

United States Fish and Wildlife Service list of endangered species This is a list of the bird and mammal species and subspecies described as endangered by the United States Fish and Wildlife Service. It contains species and subspecies not only in the U.S. and its territories, but also those only found in other par ...

, since 2 August 1978. It was originally listed as ''Orthalicus reses''. However, ''Othalicus reses'' comprises two recognized taxa, and only ''Orthalicus reses reses'' is threatened. In the time of listing, the Florida Game and Fresh Water Fish Commission favored listing, since intensive development has reduced the range to Stock Island.

Leslie Hubricht Leslie Hubricht (born 11 January 1908 in Los Angeles, California, died 16 September 2005 in Meridian, Mississippi) was an American biologist and malacologist.Alan Solem George Alan Solem (21 June 1931 – 26 March 1990),Coan E. V., Kabat A. R. & Petit R. E. (2009). ''2,400 years of malacology, 6th ed.'', February 15, 2009, 830 pp. + 32 pp. nnex of Collations American Malacological Society: http://www.malacologi ...

supported listing. Solem believed that collecting or expansion of tourist facilities could have drastic effects. The primary threat to ''Orthalicus reses reses'' at the time of listing was habitat loss due to development. Additional threats include pesticides, hurricanes, vegetation trimming along utility corridors, over-utilization of the habitat areas, and non-native predators. Trends in those threats are continuing at the same level, except for predation, the threat level for which is unknown. The population trend is unknown in 2009. The recovery criteria largely pertain to habitat, in particular a minimum number of sites (four) and habitat stability for those sites in the Lower Keys. However, only one Lower Keys site is currently occupied by a persistent population, whereas more populations and larger numbers of ''Orthalicus reses reses'' occur at various sites in the Upper Keys. In the Lower Keys, the

No Name Key No Name Key is an island in the lower Florida Keys in the United States. It is from US 1 and sparsely populated, with only 43 homes. It is only about in comparison to its larger neighbor, Big Pine Key, which lies about half a mile (800 m ...

population is the only one that persists in natural surroundings and generally appears to be viable. Accordingly, the criteria do not reflect the best available and most up-to-date information on the biology of the species because they treat the Lower Keys as the only area to conduct reintroductions and otherwise achieve recovery for ''Orthalicus reses reses''. Moreover, significant threats in addition to habitat loss have emerged, and these are not adequately addressed in the recovery criteria.

References

This article incorporates public domain

work of the United States Government A work of the United States government, is defined by the United States copyright law, as "a work prepared by an officer or employee of the United States Government as part of that person's official duties." "A 'work of the United States Governmen ...

from references.U.S. Fish and Wildlife Service. (18 May 1999)
''South Florida multi-species recovery plan''
U.S. Fish and Wildlife Service, Atlanta, Georgia. 2172 pp. Caption ''Stock Island Tree Snail Orthalicus reses''
767-786
U.S. Fish & Wildlife Service (2009
Stock Island tree snail (''Orthalicus reses'' (not including ''nesodryas'')) 5-Year Review: Summary and Evaluation
U.S. Fish & Wildlife Service. 26 pp.(3 July 1978) "Final Determination that Seven Eastern U.S. Land Snails are Endangered or Threatened Species". ''

Federal Register The ''Federal Register'' (FR or sometimes Fed. Reg.) is the official journal of the federal government of the United States that contains government agency rules, proposed rules, and public notices. It is published every weekday, except on feder ...

'' 43(128)
28932-28935

External links

Species Profile of Stock Island Tree snail (''Orthalicus reses'') at U.S. Fish & Wildlife Service webpage

* at NatureServe Explorer: *
''Orthalicus reses''
*
''Orthalicus reses reses''
*
''Orthalicus reses nesodryas''
{{DEFAULTSORT:Orthalicus Reses Orthalicidae Gastropods described in 1830

Taxonomy

Description

Distribution

Behavior

Ecology

Habitat

Feeding habits

Life cycle

Interaction with other snails in the genus

Population biology

Conservation

References

Further reading

External links