Key for the bulimulid snails from the Atacama Region, based on shell characters of adult shells.
1.	Shell very elongated or turrited.......	2
1a.	Shell obese-ovate to ovate-elongated or fusiform.......	6
2.	Shell medium sized (H > 12 mm, up to 28 mm), sculptured by fine growth lines.......	3
2a.	Shell elongate to turrited, very small (H up to 11 mm), white or corneous, with convex whorls sculptured only by growth lines, sutures deep, aperture small, oval.......	Bostryx pumilio (Rehder, 1945) (Figs. 7V–7Y)
3.	Shell corneous, elongate-turrited, slightly large (up to 27 mm), tapering from the middle of the shell to the apex, outer lip simple.......	4
3a.	Shell plain white, elongate-turrited, slightly large (up to 28 mm), and tapering in all length, outer lip acute anteriorly, slightly expanded or flared below, umbilical area defined by a sharp angle in last whorl.......	Bostryx ischnus (Pilsbry, 1902) (Figs. 6X–6AB)
4.	Protoconch and earlier whorls corneous or pale white, shell decorated with irregular white maculations or streaks, last whorl flattened, with an obtuse keel around the umbilicus, aperture narrowly ovate, slightly slanted, outer lip slightly expanded.......	Bostryx inaquosumBreure, 1978 (Figs. 6G–6N)
4a.	Protoconch and earlier whorls pale brown to reddish-brown .......	5
5.	Shell tapering posteriorly, cylindrical below, sculptured by fine growth marks, aperture ovate-elongate (about 0.25 H).......	Bostryx pupiformis (Broderip, 1832) (Figs. 8A–8I)
5a.	Shell with earlier whorls convex and darker, with a reddish-brown protoconch; last whorl large, with a slightly raised parietal callus, aperture ovate (about 0.27 H).......	Bostryx valdovinosi sp. nov. (Figs. 8W–8AF)
6.	Shell sculptured only by growth lines, spiral lines absent or very faint.......	7
6a.	Shell sculptured by strong growth lines and spiral lines which create minute axial pustules, whorls slightly plicated near the deep sutures, aperture ovate, lip simple, size small (H up to 17 mm).......	Bostryx pustulosus (Broderip, 1832) (Figs. 8J–8M)
7.	Shell small (H up to 14 mm), oblong-ovate, with a large last whorl (LW > 0.5 H).......	8
7a.	Shell large (H up to 32 mm), obese to fusiform, HA > 0.3 H, umbilicus deep.......	9
8.	Shell white or dull grayish, whorls slightly flattened, with an impressed and slightly crenulated suture, umbilicus very ample and deep, straight columellar lip, aperture oval, slightly narrow.......	Bostryx umbilicaris (Souleyet, 1842) (Figs. 8S–8V)
8a.	Shell corneous, thin, with a pink or reddish apex, shell decorated with sparse white and pink streaks or maculations, last whorl about 0.4 H.......	Bostryx rhodacme (Pfeiffer, 1843) (Figs. 8N–8R)
9.	Shell obese-ovate, solid, aperture white, pink or redish-brown, HA > 0.5 H, lip simple.......	10
9a.	Shell oblong-ovate to fusiform, thin.......	13
10.	Protoconch corneous, white or pinkish.......	11
10a.	Protoconch pink to crimson or brown.......	12
11.	Shell small (H up to 20 mm), shiny, with a white or pinkish protoconch, aperture slightly brownish, parietal callus a mere shiny glaze.......	Bostryx albicans (Broderip, 1832) (Figs. 2A–2K)
11a.	Shell of medium size (H up to 26 mm), with a dull or slightly shiny and sometimes malleated surface, HA about 0.6 H, protoconch white, corneous, aperture white, umbilicus shallow.......	Bostryx ancavilorum sp. nov. (Figs. 2L–2V)
12.	Corneous or pinkish protoconch, umbilicus deep almost reaching first whorls, sharp and broad columellar lip (much wider posteriorly), shiny and slightly raised parietal callus, HA/H ratio rather variable, aperture white to peach or pink, slightly angulated.......	Bostryx calderensis sp. nov. (Figs. 4A–4S)
12a.	Deep red or reddish protoconch, shell obese, large (H up to 32 mm), wider than longer, with a shiny surface; spire short, aperture pink to crimson or dark brown, larger than 0.5 H, umbilicus deep.......	Bostryx erythrostomus (Sowerby, 1833) (Figs. 5A–5P)
13.	Spire conic, convex to slightly concave, last whorl not compressed below.......	14
13a.	Spire conic, convex to slightly concave, last whorl compressed below.......	15
14.	Shell opaque white, spire conic, aperture less than 0.5 H, columella slightly concave, aperture very slightly slanted.......	Bostryx mejillonensis (Pfeiffer & Dunker, 1857) (Figs. 7A–7E)
14a.	Shell opaque white, solid, spire long, conic, apex pink or corneous, aperture yellowish-brown, about 0.5 H.......	Bostryx huascensis (Reeve, 1848) (Figs. 6A–6F)
15.	Shell thin but stout, with a shiny surface.......	16
15a.	Shell very fragile, white, surface sculptured by axial lines crossed by fine spiral lines, aperture large (HA/H ∼ 0.55), umbilicus shallow, partially covered by short columellar lip, lip simple, sharp.......	Bostryx breurei sp. nov. (Figs. 3A–3J)
16.	Shell small (H up to 15 mm), with a convex spire, first whorls reddish or pinkish, surface sculptured with irregular growth lines, LW about 0.7 H, columellar lip short, HA about 0.4 H.......	Bostryx pruinosus (Sowerby, 1833) (Figs. 7F–7P)
16a.	Shell fusiform to almost spindle shaped, corneous or yellowish, with a whitish protoconch and slightly concave spire, last whorl well compressed below, aperture oval elongate, slightly acute anteriorly.......	Bostryx ireneae sp. nov. (Figs. 6O–6W)