Page 9 - Land Snails of New Mexico

The snailscollectedby Cockerell and Ashmun were coming to the attention of Henry A. Pilsbry of the Academy of Natural SciencesofPhiladelphia,andthismay havestimulatedhiswish to visit the Southwest. However, Pilsbry himself (1926), in a eulogy and short biography for James H. Ferriss, credits Ferriss with inspiring him to undertake investigations in the Southwest. Ferriss had traveled in Arizona and N e w Mexico in 1904, and collected some new species. In 1906, Ferriss and Pilsbry made their firstjoint expedition to the Southwest, crossing through,
andcollectingin,northernNew MexicoonthewaytoArizona. In 1910, Pilsbry and party collected at several N e w Mexico localities, concentrating on the Big Hatchet Mountains, where Mearns had collected 18 years earlier. The most extensive and intensive Pilsbry-Ferriss expedition was to the Black Range in
1915. The party secured a pack train of horses, skillfully managed by Teodoro Solis, w h o m Ferriss (1917:99) described as "the best packer and camper alive." Pilsbry was with the group for about a month as they proceeded leisurely up the crest oftheBlack Range, with numerous side excursions. Pilsbry left the party in mid-September, and Ferriss continued to explore the northern Black Range and the area over to the southern San Mateo Mountains (Pilsbry and Ferriss, 1917) for about a month.
In1922,PilsbryandFerrisstraveledfromSantaFetothe Big Bend area in Texas, collecting en route in the Organ, San Andres, and Guadalupe Mountains and in some western canyons of the Sacramento and Sierra Blanca ranges. Several localities in southern N e w Mexico were visited in 1934 and 1935, in connection with collecting trips that Pilsbry m a d e into México. Field notes from some of the above expeditions were published by Metcalf(1970). -
J. H . F e r r i s s , a n e w s p a p e r e d i t o r , p u b l i s h e d s e v e r a l a c c o u n t s about land snails of N e w Mexico, including interesting and jocular accounts of the expedition to the Black Range (Ferriss,
1917) and of an extended excursion into the Mogollon Mountains of western N e w Mexico and adjacent Arizona in 1914 (Ferriss, 1915). The Mogollons excursion was made by a party offour in a farm wagon over a period of three months with
some 335 miles being covered in an unhurried fashion.
The above summary would seem to include the major collectors of N e w Mexico land snails in the period 1874-1935, althoughnumeroussmallercollectionsweremade andreported in publications by various authors. Deserving mention are the papersofW. H.Dall(paleontologist,U.S.GeologicalSurvey from 1884 to 1927) and of Junius Henderson of Colorado.
Henderson wrote extensively on molluscs of the western states, including a few reports concerning N e w Mexican species. In a short paper, "The Mollusca of N e w Mexico and Arizona," Henderson (1939) summarized some general aspects of the land-snail faunas of the two states, and listed the genera of molluscs that had been reported from the states.
Alexander G. Ruthven collected snails atseveral localitites while studying the herpetofauna in a transect from Cloudcroft to Alamogordo, Otero Co., in 1906 (Ruthven, 1907). His collections are at the University of Michigan Museum of Zoology(UMMZ). CollectinginthesameareaasRuthven were: 1) the entomologists James A. G. Rehn and Henry L. Viereck (in 1902; collections at the Academy of Natural
SciencesofPhiladelphia[ANSP]); 2)Bohumil Shimek (in 1903
and1906),and3)C.R.Orcutt(in1926). Thecollectionsof Shimek(forwhomDiscusshimekiiwasnamed)andofOrcutt are at the National Museum of Natural History (USNM). Collections were made by the paleontologist Ermine C. Case in the years immediately prior to 1915 at eight localities in north centralNew Mexico. Thesewereshellspickedoutofstream drift,aswasoftenthecaseinearlysouthwesterncollections. A list of localities and of species, by locality, from the Case collection(nowatUMMZ) waspublishedbyBryantWalker (1915). InreferencetoCase’scollectionsinthearidlandsofthe west,Walker suggested,nottopresciently,that“...manyofthe localities have never been visited by conchologists and are not likely to b e o n account of the local conditions.”
We have studied earlier collections, mainly in USNM,
UMMZ, the Museum of Comparative Zoology, Harvard
University (MCZ), and, most importantly, A N S P , which houses
the extensive collections of the Pilsbry and Ferriss expeditions to the Southwest. These earlier collections and associated
literatureprovide a basis for understanding the land-snail fauna of the state.
The present survey is based on collections made between 1966 and 1996 and housed in the Laboratory of Environmental BiologyattheUniversityofTexasatElPasoandtheNew Mexico Museum ofNatural History and Science, Albuquerque. Itis anticipated that, in the future, both these collections will be
housedatthelatterinstitution.
ECOSYSTEMS AND NICHES
Collections were made during the period when contours on U.S. topographic maps were indicatedinfeet and this system has been used rather than the metric system in the following discussion, and in the species accounts, hereafter.
To describe separately the various aspects of the New Mexico environment that impinge on land snails, even in summary fashion, would be unduly complicated. By using the concept of ecosystems, many aspects may be brought together. Raymond L. Lindeman (1942:399) provided an early and basic definition of an ecosystem by characterizing it as a "system
composed of physical-chemical-biological processes active within a space-time unit of any magnitude, i.e., the biotic community plus itsabiotic environment." The phrase "ofany magnitude" indicates that an ecosystem could be as small as an ephemeral desert pool or laboratory terrarium, or as large as the central North American prairies, or even larger. This allows ecologists great latitude in the ways they use this concept. The definition also stresses that an ecosystem comprises both the biotic (living organisms) and abiotic (physical) features of the environment. These are further interrelated, through the decay of dead organisms, which returns them to the dust of the abiotic, includingthecalcareousdustofdisintegratingsnailshells.
A snail,apopulation,oraspeciesmayoccupyanecological niche (often simply termed niche) within its ecosystem. In fact, its niche is rather like a personalized ecosystem, including its ownroleandthatoftheabioticandbioticfeatureswithwhichit
interacts.Much ofthemoredetailedworkexploringaspectsof the niches of land snails has been done in Europe. Helix aspersa--a common, introduced snail in New Mexico--has
3