Page 24 - Land Snails of New Mexico

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Matureshellwithperistomethin,andnotcalloused .................................Valloniacyclophorella(p.34)
Mature shell with peristome thickly calloused except for the short parietal wall, a species mainly of
northeasternNew Mexico ...........................................................Valloniaparvula(p.34)
Mature shell with peristomethin and not calloused, a species of Upper Sonoran and Transition Life Zones intheSouthernhalfofthestate .................................................... Valloniaperspectiva(p.34)
Urocoptidae
Body whorl twisted so as tobecome necklike behind aperture, which isin sinistralposition
(on lower left side of shell as viewed); a strong, fold-like tooth within right margin of peristome,
shellnotribbed .................................................................Metastomaroemeri(p.35)
Body whorl not twisted; aperture in dextral position (on lower right side of shell); no tooth on right side ofaperture,shellsribbedtovariousdegrees ...............................................................2
Whorls in upper 1/3 of shell reduced in size so as to produce an apical point, entire shell strongly ribbed, foundonlyonBishopsCapMountain,DoñaAnaCo. ..............................Coelostemmapyrgonasta(p.63)
Shell elongate-conic; upper part not markedly sharp pointed, variously ribbed, found in various mountain ranges insouthernNewMexico,asfollows:
(1) Eastern foothills of Black Range, including Cuchillo Mountains. ...................... Holospira cockerelli (p. 36) (2) Big Hatchet Mountains and associated, lower mountains, Hidalgo Co. .................... Holospira crossei (p. 36) (3)HowellsRidge,GrantCo. ...................................................... Holospirametcalfi(p.37) (4)GuadalupeMountains,EddyCo. ..............................................Holospiramontivaga(p.36)
Bulimulidae
Shellrelativelylarge,being>20mm inheightwithfullymatureshellsnearing30mm •**************************************************************** Rabdotusdealbatusneomexicanus(p.38)
Shellrelativelysmall,<20mm inheight,withfullymatureshellsabout16mm inheightoronly abouthalftheheightoftheabove(1a)taxon .......................................Rabdotusdurangoanus(p.38)
Punctidae and Charopidae
Shell<2mm inwidth,withoutwell-developedribs,periostracumlightbrownandsmooth
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Punctumminutissimum(p.39)
Shell2mm ormoreinwidth,withwell-developedribs ..................................................... 2
Ribsalmostverticalonwhorls,closeset,butclearlydefinedwithsharpedges ..........Radiodiscusmillecostatus(p.39)
Ribs oblique and sinuous on whorls, appearing to be enlarged growth lines, without sharp edges
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Paralaomacaputspinulae(p.39)
Helicodiscidae
Matureshell>3.5mm inwidth,withwell-developedspiralliraeencirclingshell........Helicodiscuseigenmanni(p.40)
Matureshell<3.5mm inwidth,smooth,withnospirallirae ........................Helicodiscussingleyanus(p.40)
There is no difficulty in separating shells of the above 2 species, but problems often are encountered in trying to separate H. s i n g l e y a n u s f r o m H a w a i i a m i n u s c u l a . F r e s h s h e l l s o f b o t h s p e c i e s a r e t r a n s l u c e n t w i t h p a l e t a n n i s h tint. H o w e v e r , m a n y s h e l l s f o u n d are old,weathered, orfossils,and may be bleached and opaque. Growth lines are more evident in H. minuscula, being numerous, closely
set, a n d p r o d u c i n g a n e f f e c t t h a t h a s b e e n c o m p a r e d t o w o v e n s i l k t h r e a d s . G r o w t h l i n e s i n H s i n g l e y a n u s a r e m o r e o b s c u r e , a n d o f t e n