Species Account

Striarca lactea (Linnaeus, 1758)

Arcoidea : Noetiidae

Tebble name: Arca lactea Linnaeus
Smith & Heppell name: Striarca lactea (L., 1758)

To size: To 20mm. Shell Structure: Robust but not thick. Equivalve: Equivalve. Equilateral: Slightly inequilateral, beaks just infront of midline. Tumidity: Moderately inflated. Outline: Oblong; umbos prominent; dorsal margin straight; posterior oblique almost straight; ventral relatively long, gently curved to almost straight; anterior broadly rounded. Contour: Dorsal area wide, cleft; posterior area set off by a weak rounded carina.

Sculpture: Primary sculpture of very many fine radial riblets, all finely nodulose, those on anterior and posterior slopes more prominent and more widely spaced; secondary riblets added with growth. Margin: Inner margin smooth, some with indentations corresponding to radial riblets. Ligament: Duplivincular, arranged in parallel bands across the dorsal area, these added from between the beaks symmetrically. Hinge: Strong, of taxodont teeth set on an arched hinge plate; marginal teeth much stronger than medials. Pallial Musculature: Adductor muscles of roughly equal size, both a little raised and with myophoric flanges. Periostracum: Often persistent, of dense, brown, short hairs arising from between the riblets. Colour: White.

Distribution & Ecology

Attached by a weak strap-like byssus to undersides of stones in the intertidal and sublittoral. A southern species restricted to south and southwest coasts, apparently not in Ireland but should be expected from south and west coasts.

Depth Range
Continental Shelf (to 200m)

Additional Information & Related Species

Juvenile Description

Posterior carina more angular, ligament very small, amphidetic. Posterior margin straight. Juvenile Arca tetragona with ligament pit directed posteriorly, posterior deeply indented, carina prominent and sculpture stronger.

Key Features & Similar Species

The only arcoid in the region with a parallel banded ligament.

Related Species

Arcoidea : Noetiidae


Listed are literature citing Striarca lactea (Linnaeus, 1758). Reference containing the species Type Description is highlighted.

Linnaeus C 1758. Systema Naturae. Editio decima. 1. Regnum Animale Holmiae, Laurentii Salvii. 824pp.


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Record last modified: 22/03/2016