Page 34 - Land Snails of New Mexico

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General Distribution—East of the Rocky Mountains: southwestern South Dakota, eastern Wyoming, western Nebraska, eastern Colorado, and northeastern N e w Mexico.
New Mexico Distribution-Wehavetakenthisspeciesin the high plains of northeastern N e w Mexico, from near Las Vegas, to the northeastern corner of the state.
Habitat-Our collections are from areas of rocky outcrop,
includingCretaceouslimestoneandthecaprockoftheMiocene
Pliocene Ogallala Formation. Specimens also were found
associatedwithoutcropsofQuaternarybasalts. Remarks--We have found Pleistocene fossils of P.
inornatus from the Pecos River Valley in Chaves Co. and from the eastern slopes of the Sacramento Mountains, indicating that thespeciesrangedfarthertothesouthintimespast.Thesefossil occurrencessupportrecognitionofitasafullspecies,distinct from P. hordaceus as discussed above.
Genus Gastrocopta Subgenus Albinula
Gastrocopta armifera armifera (T. Say, 1821, as Pupa). Journal of the Academy of Natural Sciences of Philadelphia, 2:162. T.L.: Germantown, Pennsylvania. (T.L. selectedby Pilsbry, 1948.875). (armed snaggletooth)
Gastrocopta armifera ruidosensis (T.D.A. Cockerell, 1899, as Bifidaria). The Nautilus, 13:36. T.L.: Ruidoso,
Lincoln Co., N e w Mexico. (Ruidoso snaggletooth)
This species is a giant among the members of its genus, reaching heights of 4.5 mm. In the typical subspecies, the angulo-parietal isrelatively small and exhibits a furrow along thelineoffusionoftheangularandparietal,thetipsofwhich areunfusedanddivergentfromeachother.InG.a ruidosensis, the angulo-parietal is more massive, its two elements show a more intimate fusion, and there are no divergent tips.
A s noted by Hubricht (1972:74–76), the columellar denticle
isdistinctivelydifferentinthetwo subspecies--inG. a.armifera
resembling "an inverted 'Y', being branched below" while in G. a ruidosensisit"lackstheforwardandverticallobesandthe
backwardlobeisexpandedintoabroadplate." Hubrichtalso notedthattheshellofG.a ruidosensisisslightlysmallerand lessovoidthaninthetypicalsubspecies.
Hubricht (1972:75,76) has treated G. a. ruidosensis as a full species, noting: "G. ruidosensis is found living in a small area incentralNew Mexico,butoccursasaPleistocenefossilfrom westernKansastocentralTexas." Hubrichthassomapped r u i d o s e n s i s i n h i s w o r k o f 1 9 8 5 ( M a p 5 1 ) , s h o w i n g it o n l y a s a fossilinWestTexas.On theotherhand,he maps G. armifera as a living species in West Texas (Map 44), although of very scatteredoccurrence.We pointoutthissituationinWestTexas because itisthereverseofthatprevailingintheSacramento Mountains of N e w Mexico, where the living form is ruidosensis. All Pleistocene fossils from a number of localities in N e w
Mexico, including the Sacramento Mountains, are ascribable to the typical armifera form.
We followPilsbry(1948,877)intreatingruidosensisasonly a subspecies of G. armifera.
GeneralDistribution--Thespeciesisfoundinmostofthe easternUnitedStates,westwardtoNew MexicoandColorado, and in southern Canada, westward to Alberta.
New Mexico Distribution--Thetypicalsubspecies,G. a. armifera, isfound in northeastern N e w Mexico. W e have found it at various places along the eastern foothills and along the Pecos River Valley in the southern foothills of the Sangre de Cristo Mountains. Specimens collected by T. D. A. Cockerell along“RockyledgesalongtheGallinasRivernearLasVegas” (ANSP79647)in1900stillhadintactepiphragmsin1977. It occurs southward along the Pecos Valley to near Puerto de Luna and along the Cimarron River Valley in the extreme northeastern part of the state.
ThesubspeciesG. a.ruidosensisoccursintheSacramento Mountains, where the type specimen was obtained from an anthill at Ruidoso. Apparently, the subspecies is restricted to this mountain range at present, although, as noted above, Hubricht (1985)mappedfossilrecordsinstateseastofNew Mexico.
Habitat--InnortheasternNewMexico,wehavefoundG. armifera armifera on brushy hillsides and low scarps bordering river valleys. It has been found in riparian brushy woodland along the Pecos River Valley from near Villanueva to near Puerto de Luna. In the Sacramento Mountains, G. a. ruidosensis hasbeentakenatanumber ofplacesintheTransitionLifeZone along canyons inforested areas. Most of our specimens are from TularosaandPeñascoCanyons,wherewe haveconcentratedour collecting in this range.
Remarks--Gastrocopta armifera is one of several species
of land snails of more eastern distribution, which extended its
range in the Pleistocene (or early Holocene) as far west as Arizona. There are Pleistocene records from central and western
New Mexico also. ThemostabundantassemblageoffossilG.a.armiferathat
wehaveseenfromNewMexicowascollectedbyDr.John Appelgarth from an archaeological excavation in the Pecos River Valley, 9 miles N N W of Santa Rosa, Guadalupe Co. These and other fossil specimens indicate that the species must have been especially c o m m o n along the Pecos Valley in the past.
Gastrocopta contracta (T. Say, 1822, as Pupa). Journal of the Academy of Natural Sciences of Philadelphia, 2:374. T.L.: Occoquan, Virginia. (bottleneck snaggletooth)
General Distribution—Gastrocopta contracta is distributed generally over the eastern half of the United States, westward to the Plains states. Hubricht (1985:Map 42) mapped it as occurring in Texas, west to Val Verde Co. Ithas been recorded also from southern Canada and México.
N e w Mexico Distribution--In N e w Mexico, this snail is known onlyfromtheGuadalupeandSacramentoMountains. These populations are separated widely from the nearest ones in central Texas and northeastern México.
Gastrocopta contracta has been taken as a Quaternary fossil in southeastern N e w Mexico (Leonard, Frye, and Glass, 1975) and in Pleistocene deposits in the Guadalupe Mountains of Texas, a few miles from N e w Mexico. This indicates that the speciesisnotanewcomertosoutheasternNew Mexico.