Page 7 - Land Snails of New Mexico

Metcalf.A.L.,andSmartt,R.A.,eds.,1997,LandsnailsofNew Mexico. New MexicoMuseum ofNaturalHistoryandScienceBulletinNo. 10.
LAND SNAILS OF N E W MEXICO: A SYSTEMATIC REVIEW
A R T I E L. M E T C A L F and R I C H A R D A. S M A R T T
University of Texas at El Paso, Department of Biological Sciences, El Paso, Texas 79968-0519, NewMexicoMuseumofNaturalHistoryandScience,1801MountainRoadNW,Albuquerque,NewMexico87104
ABSTRACT: Summarizedinanintroductorysectionareseveraltopicsofageneralnature, including information about early collections, classification of land snails, and structure of their shells.A key,basedonshellfeaturesforfamiliesandformostgeneraandspecies,isprovidedto assist in identification. Included is a discussion of some aspects of ecosystems and ecological niches, which seem pertinent to the species surveyed. There are species accounts of the 114 native landsnails(allpulmonates)knownfromNew Mexico.Itislikelythatatleastthreeofthese species have gone extinct during the last century, some probably because of habitat loss or degradation. There are additional accounts for some subspecies. In the accounts, general, N e w Mexico,andaltitudinaldistributionsarediscussed,aswellashabitat.Insome accountstaxonomic andpaleontologicalaspectsarediscussed.Followingthespeciesaccountsthereisasummary of species or subspecies that seem to be of restricted occurrence in N e w Mexico. Finally, accounts aregivenforeightspeciesoflandsnailsorslugsconsiderednotnativetoNew Mexico,butwhich have become established, mainly in urban areas.
I N T R O D U C T I O N
between obligate levels--for example, inserting subclass and superorder between class and order. The Class Gastropoda is divided into several subclasses. A small group of land snails, togetherwithagreatnumberofaquaticspecies,areplacedinthe Subclass Prosobranchia. N o n e of these prosobranch land snails occursinNewMexicoatthistime,althoughsomeoccurin T e x a s a n d M é x i c o . T h e r e is, h o w e v e r , a f a m i l y o f p r o s o b r a n c h aquaticsnails(Hydrobiidae)representedinsome springhabitats inNewMexico.AllNewMexicolandsnailsbelongtothe Subclass Pulmonata, a name that refers to the lung-like, air breathing apparatus employed by these snails. All pulmonate land snails in N e w Mexico, save one minute, rare species (see species account of Carychium exiguum), belong to the Stylommatophora, considered as either an order or a superorder by various malacologists. Snails in the Stylommatophora have two pairs of tentacles arising from the head, with eyes borne at the outer tips of the upper pair.
Three interrelated papers concerning land snails of N e w Mexico areinthisBulletin.The firstand presentpaper(Metcalf and Smartt) surveys species of land snails occurring in the state. In this paper, patterns of present geographic, altitudinal, and habitat distribution are stressed. The second paper (Metcalf) discusses historical zoogeographic aspects of the fauna of N e w Mexicolandsnails.Thethirdpaper(DillonandMetcalf) describes altitudinal surveys of some mountains in different sections of the state.
CLASSIFYING SNAILS
A vastnumberofdifferentorganismsmaybecomparedtoa vast number of different library books. To be useful, productively, both require some form of classification system.
Intheclassificationsystem used by zoologists, itisrequired thatlandsnails,likeallanimals,beassignedtoahierarchyof. obligate categories: Kingdom, Phylum, Class, Order, Family, Genus, and Species. Snails are in the Kingdom Animalia. They belongtothePhylum Mollusca, which, innumber ofspecies,is surpassedonlybythePhylumArthropoda, containingthe insects and crustaceans. The Phylum Mollusca is apportioned amongsevenoreightclasses,andthemajorityofmolluscsin these classes inhabitmarine waters, likely the original molluscan home. However, some groups in the Class Bivalvia, to which clams, oysters, mussels, and others belong, have invaded the freshwaterenvironmentsuccessfully.Some groupsintheClass Gastropoda, to which snails and slugs belong, have established themselves not only in freshwater, but also in terrestrial environments.Gastropodaisthelargestclassofmolluscs, numbering more than 50,000 kinds. In addition to the basic (obligate) units of classification, zoologists often feel the n e e d to squeeze additional classification levels (called non-obligate) in
The Order (orSuperorder) Stylommatophora isdivided into numerousfamiliesoflandsnails,ofwhich 19arenativetoNew Mexico. A key to these families is provided, hereafter. (The n a m e s o f all f a m i l i e s i n t h e A n i m a l K i n g d o m t e r m i n a t e i n - i d a e ) .
Families are, in turn, divided into genera, and genera are comprisedofspecies.ExamplesarethegenusHomoandspecies sapiens for a human being, or genus Pupilla and species
muscorumforaNewMexicolandsnail.Thiscombinationofa
genericandaspecificname makesup,then,ascientificname
for the species. This name is in Latin, as in the examples, or
latinized as in the species name blandi, applied to another
m e m b e r of the genus Pupilla. In this name, the Latin genitive
ending -i is added to the surname Bland, thus coining a name
calledapatronym,whichhonorsthezoologistThomasBland. GenericnamesareoftenLatinversionsofclassicalGreekwords.
A patronymshouldnotbeconfusedwiththenameoftheperson (author) who named (described) a species. Often the author's name may beseenimmediatelyafterthespecies'name,asin