Key to Family Lottiidae

Phylum Mollusca
 Class Gastropoda
  Subclass Prosobranchia
   Order Patellogastropoda
    Family Lotiidae
 

Taken primarily from  Kozloff, 1987, 1996 p. 206  (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)
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1a  Apex (located near the end of the first one-eighth) decidedly lower than the highest part of the shell, which is near the middle; length up to 10 cm (not often found north of California) (picture) Lottia gigantea
1b Apex the highest point of the shell; length rarely more than 5 cm 2
2a Interior of the shell uniformly white, without an apical blotch or marginal markings (apex at the end of the first one-third; shell with prominent, flat radial ribs; length not exceeding 2 cm; associated with encrusting coralline algae and often coated by a bryozoan of the genus Rynchozoon; subtidal, rare)  [Note:  the anterior end of the shell can be determined by the location of the head, if the animal is still inside.  For an empty shell the anterior end is the end toward which the open end of the C-shaped mantle scar on the inside of the shell points] Niveotectura funiculata
2b Interior of shell not uniformly white (it may be uniformly dark or have markings, such as an apical blotch, marginal band, or marginal streaks or spots) 3
3a Right and left margins of the shell nearly parallel for much of their length (photo), the outline of the aperture thus somewhat elongated 4
3b Right and left margins of the shell curving outward, the outline of the shell thus oval (a form of Lottia pelta that lives on the kelp Egregia, and forms of  L. pelta and L. ochracea that live on stipes of laminarians, may also have nearly parallel margins; see choices 4a and 7a) 8
4a Right and left margins lower than the anterior and posterior margins (photo), so the shell can be rocked when it is on a flat surface (on stipes of laminarian kelps, such as Pterygophora, to which it clings after the fashion of a saddle; length up to about 2 (3.5) cm; shell brown).   Caution:  forms of Lottia pelta and L. ochracea also occur on the stipes of laminarians, and the shape of their shells may resemble that of this species; as a rule, however, they are not predominantly brown) Lottia instabilis
4b Right and left margins at essentially the same horizontal level as the anterior and posterior margins, so the shell has little tendency to rock when on a flat surface 5
5a Length about 4 times the width; apex near the end of the first quarter (restricted to the leaves of Phyllospadix; shell brown; lenth up to about 8 mm) Tectura paleacea
5b Length not more than 3 times the width; apex near the end of the first third or closer to the middle 6
6a Length about 3 times the width (exterior of shell mostly whitish, but with brown radial markings and sometimes witha brown spot at the apex; on coralline red algae; length up to about 8 mm; rare) Lottia triangularis
6b Length not more than twice the width 7
7a Exterior and interior of shell dark brown; length up to 2 cm; on the kep Egregia (picture), whose stipes it erodes (height about three-fourths the width) Discurria insessa
7b Exterior of shell mostly dark brown, but with light markings (these are more or less radial or contribute to a checkerboard pattern), interior bluish, with a brown apical stain and with external markings showing through; length up to 1.2 cm; on leaves of eelgrass, Zostera marina (not likely to be found south of Washington) Lottia alveus
8a Exterior of shell mostly pink, with white and/or light brown markings (length up to about 8 mm; on coralline red algae; subtidal, rare) Tectura rosacea
8b Exterior of shell not mostly pink, unless overgrown by coralline red algae 9
9a Exterior of shell mostly whitish, but with brown radial markings and a brown spot at the apex; apex nearly in the middle; on coralline red algae; length up to about 8 mm (rare) Lottia triangularis
9b Exterior of shell not mostly whitish (unless encrusted by a coralline alga that becomes white), with or without markings, but not typically with a brown spot at the apex; apex usually decidely anterior to the middle; except for Lottia painei and a form of L. ochracea, not generally on coralline red algae; length commonly more that 1 cm, except in Lottia asmi (includes most of the interidal and shallow subtidal limpets) 10
10a Shell grayish or brownish black externally, uniformly black internally; length not often more than 1 cm; mostly on Tegula funebralis, sometimes on Mytilus californianus, rarely on rock Lottia asmi
10b Color not uniformly black internally, although the exterior may be mostly dark; length commonly more that 1 cm, except in Lottia ochracea; except for some small L. pelta, not likely to be found on Tegula funebralis (large L. pelta, however, occur on Mytilus californianus) 11
11a Shell with prominent ribs radiating from the apex to the margin 12
11b Shell without prominent ribs radiating from the apex to the margin (if there are ribs, they are delicate and closely spaced) 15
12a Apex anterior to the end of the first quarter, and sometimes nearly level with the anterior margin; radial ribs more prominent posterior to the apex than anterior to it (common high intertidal species) Lottia digitalis
12b Apex at about the end of the first quarter or first third; ribs anterior to the apex about as well developed as those posterior to it 13
13a Height generally about one-fourth of the length (but sometimes more than one-fourth); margins prominently scalloped (the places where the radial ribs meet the margin may project as points) (length up to 3 cm; animal white, with dark spots on the sides of the foot; generally in depressions in rock, to which the animals return after foraging; not likely to be found north of Oregon) Family Nacellidae: 
Macclintockia scabra
13b Height generally more than one-fourth of the length ; margins not prominently scalloped (the places where radial ribs meet the margin are rounded and do not project as points) 14
14a Ribs with overlapping scales, thus rough to the touch Lottia limatula
14b Ribs without overlapping scales, not rough to the touch Lottia pelta
15a Length usually not more than 1.3 times the width 16
15b Length usually at least slightly more than 1.3 times the width 17
16a Height usually not more than one-third the width; exterior usually with a pattern of light and dark streaks or blotches; length sometimes exceeding 5 cm (common mid- and low intertidal and shallow subtidal species) Tectura scutum
16b Height usually more than one-third the width, exterior mostly uniformly brown, olive, or gray, but sometimes with a few white spots; length not often exceeding 3 cm (mostly on smooth boulders and rocks in the mid- and low intertidal) Tectura fenestrata
17a Shell thin, translucent; coloration of exterior resembling a checkerboard of white and dark (usually brownish or reddish) markings (these show through to the interior) (length up to about 1 cm) Lottia ochracea
17b Not generally thin or translucent except in young specimens; coloration of exterior sometimes with light spots and light and dark radial streaks, but not resembling a checkerboard 18
18a Interior of shell white or faintly bluish, with a continuous dark border, or with a border of dark spots, but without a blotch at the apex (exterior of shell often so badly pitted by a fungus that it is uniformly dull gray; length not often more than 1.5 cm; mostly mid-intertidal) Lottia strigatella
18b Interior of shell with a blotch at the apex (in Lottia painei, however, the blotch is small and faint) 19
19a Apical blotch on interior of shell large, dark brown; margin of interior with a continuous dark band; shell length commonly exceeding 3 cm; not regularly associated with coralline red algae or encrusted by an alga of this type 20
19b Apical blotch on interior of shell small, faint, grayish, margin of interior with short, nearly radial streaks, or with both streaks and a narrow band; shell length rarely exceeding 2 cm; associated with coralline red algae and typically encrusted by an alga of this type Lottia painei
20a Apex at the end of the first one-third, often inclined slightly forward; posterior and lateral slopes of shell markedly convex; lateral margins of shell often slightly higher than the anterior and posterior margins, so that the shell can be rocked from side to side when placed on a flat surface; apical blotch usually at least half the length of the shell; length up to about 5 cm; at higher levels of the intertidal region, and mostly at the edges of the undersides of boulders, except when foraging. Tectura persona
20b Apex slightly behind the end of the first one-third, not often inclined forward; posterior and lateral slopes of the shell slightly if at all convex; lateral margins of the shell usually at the same horizontal level as the anterior and posterior margins; apical blotch usually about one-third the length of the shell; length up to about 4 cj; mostly mid- and low intertidal Lottia pelta



Taxonomic Levels Represented in This Key:
  Discurria insessa
  Lottia asmi
  Lottia digitalis
  Lottia gigantea
  Lottia instabilis
  Lottia pelta
  Tectura fenestrata
  Tectura persona
  Tectura scutum


Page created by Ryan Lunsford, 7-26-2002
Edited by Hans Helmstetler 12-2002, Dave Cowles 12-2004, 2005, 2008