Page 22 - Land Snails of New Mexico

16
11b
12a
12b
13a
13b
14a
14b
15a
15b
Shellpalegraytotan,cylindrical,basalandpalatalteethdeeplysetbackfromapertureinsteadof
onanaperturalcallus ................................................................................15
Shellreaching3.5-4.5mm inheight,thus,thelargestofNorthAmericanGastrocoptas.........Gastrocoptaarmifera 13
Shell<3.0mm inheight ...................................... 14
Combined angulo-parietal tooth complex descending to about 1/3 of aperture height ******************************************************************** Gastrocoptaarmiferaarmifera(p.28)
Combined angulo-parietaltoothcomplexmassive,descendingtoabout2/3ofapertureheight,fillingmuch
of the aperture, a subspecies of the Sacramento Mountains. .................. Gastrocopta armifera ruidosensis (p. 28)
Shell2.0-2.5mm inheight;massiveangulo-parietaltoothcomplexdescendingtoabout2/3ofaperturalheight, andfillingmuchofaperture ....................................................Gastrocoptacontracta(p.28)
Shell<2mm inheight,angulo-parietalcomplexdescendingabouthalfwayofaperturalheight,andresembling anupside-downletterY whenobservedfrombelow.................................Gastrocoptaholzingeri(p.29)
Angular and parietal teeth united behind (away from) aperture, but diverging forward, when viewed from below. Otherteetharelocatedfarbackintheaperture,somenot,orbarely,visibleinaperturalview ...SubgenusImmersidens 16
Angular and parietal not divergent from each other, joined to produce a bifid appearance, other teeth
located behind peristomial callus, but not so deeply as in Immersidens (15a), so that they are clearly seen inaperturalview(Fig.2H) .........................................................SubgenusGastrocopta19
ThemostdistinctiveofthespeciesofImmersidensisthemostcommon andmostwidespreadspecies--ashmuni.Inotherspecies it i s n e c e s s a r y t o t i l t s h e l l s s o t h a t o n e c a n o b s e r v e t h e p a t t e r n o f t h e a n g u l o - p a r i e t a l c o m p l e x f r o m b e l o w a n d n o t e w h e t h e r t h e b a c k p a r t of the parietal part of the complex is straight or curved strongly towards the outer (palatal) lip of the aperture.
16a
16b
17a
17b
18a
18b
|9a
19b
20a
20b
I n n e r e n d (i.e., t h e e n d a w a y f r o m t h e a p e r t u r e ) o f t h e p a r i e t a l l a m e l l a p o r t i o n o f t h e a n g u l o - p a r i e t a l c o m p l e x , sharplycurvedtowardstheouter(palatal)lipsideoftheperistome ............................................17
Inner end of parietal portion of angulo-parietal complex rather straight, and not sharply curved outward, as in 16a ....... 1 8
Inaperturalview,amassiveangulo-parietalcomplexfillsmuch oftheaperture,descendingabout3/4
of the height of the aperture, other teeth not, or barely, observable, parietal peristome is separated from
w h o r l b e h i n d it, p r o d u c i n g a n e c k - l i k e s t r u c t u r e a n d s l i g h t l y f l a r e d p e r i s t o m e . . . . . . . . . . . . . . G a s t r o c o p t a a s h m u n i ( p . 3 0 )
Angulo-parietalcomplex descendingtoabouthalftheheightoftheaperture,otherteethalsoobservable
in apertural view, parietal peristome firmly attached to surface of whorl behind it. ........ Gastrocopta cochisensis (p. 30)
Shell>2.0mm inheight,oftenreaching2.5mm,angularbranchofangulo-parietalcomplexmuchsmaller thanparietalbranchanddivergingmainlyaboveitontoparietalwall ..................Gastrocoptaprototypus(p.30)
Shell<2.0mm inheight,angularandparietalbranchesaboutthesamesize...............Gastrocoptadalliana(p.31)
Shellusually2.5mm ormoreinheight,peristomethicklycallousedwithin,shellbrownish.........................20
Shell usually <2.5 m m , often <2.0 m m , in height, peristome thin, not calloused within; shell whitish tolighttan.................................................................. Gastrocoptapellucida(p.31)
Angular and parietal components diverging from each other at tip of the angulo-parietal complex, producing anX-shapedeffect;upperpartofpalatalcallusthinned ................................Gastrocoptaprocera(p.31)
Angulo-parietal complex appearing as one sinuous denticle, not divergent at the lower tip; upper part
of palatal wall callus not noticeably thinned .......................................... Gastrocopta cristata (p. 31)
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