PANDORIDAE Rafinesque, 1815

Carole, Hickman, S. & Ca, 2014, Paleogene marine bivalves of the deep-water Keasey Formation in Oregon, part IV: The anomalodesmatans, PaleoBios 31 (3), pp. 1-21 : 5-6

PANDORIDAE Rafinesque, 1815

Pandorids are a neglected element in modern regional faunas, although documentation of their diversity in the Eastern Pacific ( Coan et al. 2000, Valentich-Scott and Skoglund 2010, Coan and Valentich-Scott 2012) indicates a need for renewed global efforts. Taxonomy of living species is confused ( Boss and Merrill 1965, Prezant 1998), although there are elegant studies of the behavior, unusual shell morphology and anatomy of shallow-water living species ( Allen 1954, Allen and Allen 1955, Morton 1984, Thomas 1994). However, the literature contains misconceptions regarding bathymetyric and latitudinal distribution. The generalization that all species inhabit “sheltered sandy areas around extreme low tide levels” ( Yonge and Morton 1980) and that the family is primarily a high-latitude cold-water group ( Boss and Merrill 1965) are incorrect.

Misconceptions about bathymetyric range seem to originate with the classic studies of living animals of Pandora inequivalvis ( Linnaeus, 1758) and P. pinna ( Montagu, 1803) from low water in the Mediterranean ( Allen 1954) and P.filosa ( Carpenter, 1864) and P.grandis Dall, 1877 from low tide levels at the Friday Harbor Laboratories, Washington ( Yonge and Morton 1980). However, subsequent studies of P.filosa at a lower latitude in Monterey Bay, California ( Thomas 1994) were from live-collected specimens trawled between 55 and 80 m. The genus ranges from intertidal to abyssal depths

( Valentich-Scott and Skoglund 2010).

The high latitude generalization does not apply to the fauna of the Eastern Pacific. A recent treatment of six pandorid genera and 16 species in the Panamic Province ( Valentich-Scott and Skoglund 2010) shows greater tropical diversity than the fauna of the northeastern Pacific, with only five species ( Coan et al. 2000).

Regarding the fossil record of the group, pandorids are generally rare and poorly preserved ( Prezant 1998). Although they are never abundant, their rarity in museum collections may result in part from failure to collect poorlypreserved specimens and fragments. However, shells are sufficiently distinctive, even when crushed or fragmental, that they should be recognized and collected. Although hinge features are not generally available for subgeneric assignment, the prismato-nacreous shell and the extremely compressed form, which is both inequivalve and inequilateral, is easily recognized in combination with the straight to convex posterior hinge margin, rounded anterior margin, and features of ornamentation. It is also the case that few specimens from the Pacific Coast Paleogene and Neogene strata have been figured. An exception is the superblyillustrated account of the Pliocene molluscan fauna of the San Diego Formation ( Hertlein and Grant 1972) in which there are eight illustrations of two pandorid species.

Vokes (1967) listed eight nomenclaturally valid genera, and Newell (1969) considered six of those names to be taxonomically valid, treating two of the eight available names as subjective synonyms. Valentich-Scott and Skoglund (2010) introduced a seventh name, although their genus Coania is known only from the type locality. Four of the seven have no recognized fossil record, and material from deep-water Paleogene strata in Washington and Oregon is here referred to Pandora s.l.

Stratigraphic range— Eocene to Holocene.