Tectura fenestrata (Reeve, 1855)

Common name(s): Fenestrate limpet, chocolate limpet
Synonyms: Acmaea fenestrata, A. cribraria, Colisella fenestrata, Notoacmaea fenestrata, Notoacmea fenestrata, Lottia fenestrata Tectura fenestrata
Class Gastropoda 
Suborder Nacellina 
Tectura fenestrata from a smooth, low intertidal boulder surrounded by sand at Shi Shi beach.
(Photo by: Dave Cowles, July 2008 )
Description:   This limpet has an apex as the highest part of the shell, and the height is usually more than 1/3 the width.  The apex is anterior to the middle of the shell.  The exterior is dark olive or brown (or with white spots, or blotchy), and has no prominent radial ribs.  The interior may be dark, but it is not uniformly dark and has an apical blotch (photo).  Frequently a dark blue-gray interior margin grades into a dark brown blotch at the apex.  The right and left margins are continuously curved without straight margins.  The length is usually not more than 1.3 times the width.  Usually not more than 2.6 cm long.

Note:  Kozloff's key says this species is usually uniformly brown or olive color.  Several of the other references, however, show a shell with a pattern of prominent white blotches.

Carlton (2007) lists this species as Lottia fenestrata, so its name may have been recently changed.

How to Distinguish from Similar Species:Tectura scutum usually has a height not more than 1/3 the width, usually has a pattern of blotches, and can grow to more than 5 cm diameter.

Geographical Range:  Aleutian Islands to lower Baja California

Depth Range:

Habitat:  Frequently found on smooth boulders surrounded by sand in the mid to lower intertidal.

Biology/Natural History:   Some references show a shell with an interior which is almost entirely white except for a small brown apical blotch; and a pattern of radiating white lines interspersed with brown on the outside.  Some say that the apex is slightly off center.  This species was formerly considered to be a subspecies of Notoacmaea (now Tectura) scutum.  The aperture is said to be nearly circular.  These limptes often crawl down the surface of the rock to below the surface of the sand at low tide.

The name "fenestrata" refers to the checkerboard pattern of white and brown that is seen around the exterior margin of at least some of these limpets.  Morris (1966) acknowledges the wide diversity of coloration within this species by recognizing two subspecies: A. fenestrata fenestrata, which is grayish green with flecks of pale yellowish.  Its inside is bluish white with a narrow brown inside border. A. fenestrata cribraria, the northern form, is dark within the shell (almost solid brown).  There are many intergrades where the two forms meet (central CA).


 
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References:

Dichotomous Keys:
  Carlton, 2007 (as Lottia fenestrata)
  Flora and Fairbanks, 1966 (as Acmaea cribraria)
  Kozloff, 1987, 1996
  Smith and Carlton, 1975 (as Notoacmea fenestrata)

General References:
  Harbo, 1997
  Lamb and Hanby, 2005
  Morris, 1966
  Rice, 1973 (as Notoacmea fenestrata)
  Ricketts et al., 1985 (as Notoacmea fenestrata)

Scientific Articles:

Web sites:

General Notes and Observations:  Locations, abundances, unusual behaviors:

Inside view

Inside view of the same two shells above.  Note how the inside is quite dark, blue-gray, with a large darker rown bblotch at the apex.


Authors and Editors of Page:
Dave Cowles (2008):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)