Family Littorinidae Key

Key: Family Littorinidae

Phylum Mollusca
Class Gastropoda
Subclass Prosobranchia
Order Mesogastropoda
Suborder Taenioglossa

Note: Since the writing of Kozloff's key, Family Lacunidae has been included in Family Littorinidae as Subfamily Lacuninae

Jump to:

Lower taxonomic level Main Page Alphabetic Index Systematic Index Glossary

1a Diameter almost equal to the height; often with rather prominent spiral ridges (height up to about 2 cm; common, but mostly north of Oregon; primarily on rocky shores, but also on rocks, wood, and debris in bays and salt marshes Littorina sitkana

1b Height of shell decidedly greater than the diameter; without obvious spiral ridges 2

2a Spire generally consisting of 3 whorls; usually with a white band inside the lower portion of the aperture, near the columella (color, except when the shell is eroded, usually brown or nearly olive, with irregular lighter mottling; not likely to be found north of Oregon) Littorina keenae

2b Spire generally consisting of 4 whorls; without a white band inside the aperture 3

3a Shell thick (typical for Littorina); without an umbilicus; height to 1.5 cm; color usually dark brown, purple, or black, often with a checkerboard pattern of whitish areas or white streaks. Common on rocky shores and also found on rocks in bays. [Littorina plena, known to occur in Oregon and California, cannot be distinguished from L. scutulata based on these characters] Littorina scutulata

3b Shell thinner than typical for Littorina; with an umbilicus that is partly covered by the flangelike inner lip of the aperture; height to 8 mm; color brown (there are generally 2 or 3 wide, spiral bands of dark brown separated by narrow bands of lighter brown); restricted to salt marshes, where it is found on vegetation Algamorda subrotundata

Taxonomic Levels Represented in This Key:

Littorina scutulata
Littorina sitkana

Page created by Dave Cowles, 2004
Edited by: Dave Cowles 2005, 2006

Jump to:
Lower taxonomic level	Main Page	Alphabetic Index	Systematic Index	Glossary

1a	Diameter almost equal to the height; often with rather prominent spiral ridges (height up to about 2 cm; common, but mostly north of Oregon; primarily on rocky shores, but also on rocks, wood, and debris in bays and salt marshes	Littorina sitkana
1b	Height of shell decidedly greater than the diameter; without obvious spiral ridges	2
2a	Spire generally consisting of 3 whorls; usually with a white band inside the lower portion of the aperture, near the columella (color, except when the shell is eroded, usually brown or nearly olive, with irregular lighter mottling; not likely to be found north of Oregon)	Littorina keenae
2b	Spire generally consisting of 4 whorls; without a white band inside the aperture	3
3a	Shell thick (typical for Littorina); without an umbilicus; height to 1.5 cm; color usually dark brown, purple, or black, often with a checkerboard pattern of whitish areas or white streaks. Common on rocky shores and also found on rocks in bays. [Littorina plena, known to occur in Oregon and California, cannot be distinguished from L. scutulata based on these characters]	Littorina scutulata
3b	Shell thinner than typical for Littorina; with an umbilicus that is partly covered by the flangelike inner lip of the aperture; height to 8 mm; color brown (there are generally 2 or 3 wide, spiral bands of dark brown separated by narrow bands of lighter brown); restricted to salt marshes, where it is found on vegetation	Algamorda subrotundata