| Hiatella arctica (Linnaeus, 1767) |
 |
Arctic to Japan, to California, to Florida, to Angola; Azores to Mediterranean. Infralittoral to circalittoral. In Mediterranean sea, it is often found in association with Corallium rubrum.
Original taxon: Mya arctica. Suspension feeder. The shape is extremely variable.
80-100m deep, in coralligene, Mljet island, Dubrovnik-Neretva Comitat, S. Croatia. Size about 15mm. Original pictures provided by N. Lete (HR) – (CC BY-NC-SA). |
 |
Synonyms: barbata, biaperta, bicarinata, bilirata, byssifera…
Trawled off Marseille, Provence, S. France. 13mm. |
 |
| Other synonyms: minutus, monoperta, orientalis, sakhalinensis… 50m deep, Almería, Andalucia. 13mm. |
 |
The species is very variable in shape.
Trawled at 50-80m deep, off Almería. 9mm. |
 |
| The two red siphons of a specimen at Natural Bridges State Beach, Santa Cruz, California. Original picture provided by C. Schwarz for iNaturalist – (CC BY-NC). |
 |
| Distorted and inequivalve. San Pietro in Bevagna, Manturia, Taranto, Puglia, S. Italy. 7,5-9,5mm. |
 |
Specimens from English Channel.
Found in valves of dead Mytilus edulis, dredged on muddy bottom at 6-8m deep, in the bay of Mount St-Michael, NW. France. 12-13mm. |
 |
| Ligament short (MacGillivray, 1844) and less prominent than in H. rugosa. – Beachstormed, Grau de la Vieille Nouvelle, Gruissan, Occitania, S. France. 16,5mm. |
 |
| If arctica is inequivalve, rugosa is equivalve. But the high variability of these two species makes their identification never easy. – 50m deep, Scilla, Calabria, SW. Italy. 4-8mm. |
 |
| Málaga, attached to rock at 10m deep. 21mm. |
 |
| 30-40m deep, Málaga. 18mm. |
 |
| The unique cardinal tooth, characteristic of the family, and the minute prodissoconch. 55m deep, Ognina, Catania, E. Sicilia. |
 |
Right valve of a very juvenile, with the baby cardinal tooth and the translucent prodissoconch, found in a sediment of the low circalittoral, Kornati archipelago, Šibenik-Knin Comitat, W. Croatia. Original pictures provided by P. Hus (HR).
– (CC BY-NC-SA) – |
 |
| Rincon Point, south of Carpinteria, Santa Barbara County, S. California. Original picture provided by dlbowls for iNaturalist – (CC BY-NC). |
 |
| In reef at low tide, Pointe des Minimes, La Rochelle, W. France. 19,5mm. |
 |
Specimens from rocky infralittoral, S. Brittany, NW. France.
M. le Quement’s didactic showcases, ACO, AFC (FR). |
 |
| At low tide near the harbour, Lampaul, Ouessant Island, W. Brittany, NW. France. Original picture provided by P. Corbrion for iNaturalist – (CC BY-NC-SA). |