PBDB Taxon

Basic info	Taxonomic history	Classification	Included Taxa
Morphology	Ecology and taphonomy	External Literature Search	Age range and collections

Mactrotoma (surfclam)

Bivalvia - Cardiida - Mactridae

Taxonomy

Mactrotoma was named by Dall (1894). It is extant. Its type is Mactra fragilis.

It was reranked as Mactra (Mactrotoma) by Packard (1916), Hodson and Hodson (1931).

It was assigned to Mactra by Packard (1916), Hodson and Hodson (1931); and to Mactridae by Coan and Valentich-Scott (2012).

Species

M. angusta (syn. Mactra ovalina, Mactra (Micromactra) atacama), M. californica, M. fragilis, M. isthmica (syn. Mactra (Micromactra) fonsecana, Mactra (Micromactra) vanattae), M. nasuta (syn. Mactra hiantina, Mactra revellei), M. quirosana, M. velata (syn. Mactra paitensis)

Species lacking formal opinion data

Mactra cymata, Mactra undula, M. fragilus, M. maracaibensis

Synonyms

Mactroderma was named by Dall (1894). It is extant.

It was synonymized subjectively with Mactrotoma by Coan and Valentich-Scott (2012).

It was assigned to Mactridae by Dall (1894).
Micromactra was named by Dall (1894).

It was reranked as Mactra (Micromactra) by Pilsbry and Olsson (1941); it was reranked as Mactrotoma (Micromactra) by Coan et al. (2000); it was synonymized subjectively with Mactrotoma by Coan and Valentich-Scott (2012).

It was assigned to Mactra by Pilsbry and Olsson (1941); and to Mactrotoma by Coan et al. (2000).

Synonymy list

Year	Name and author
1894	Mactroderma Dall
1894	Mactrotoma Dall
1894	Micromactra Dall
1916	Mactra (Mactrotoma) Packard p. 278
1931	Mactra (Mactrotoma) Hodson and Hodson
1941	Mactra (Micromactra) Pilsbry and Olsson p. 11
2000	Mactrotoma (Micromactra) Coan et al.
2012	Mactrotoma Coan and Valentich-Scott p. 549

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Protostomia
—	Spiralia
superphylum	Lophotrochozoa
phylum	Mollusca
class	Bivalvia
—	Eubivalvia
subclass	Autobranchia	(Groblen 1894)
infraclass	Heteroconchia	(Gray 1854)
—	Cardiomorphi	Ferussac 1822

Rank	Name	Author
—	Cardioni	Ferussac 1822
—	Cardiidia	Ferussac 1822
—	Cardiata	Ferussac 1822
superorder	Cardiiformii	Ferussac 1822
order	Cardiida	Ferussac 1822
suborder	Cardiidina	Ferussac 1822
—	Veneroidei	(Gray 1854)
—	Veneroitei	Gray 1854
superfamily	Mactroidea	(Lamarck 1809)
family	Mactridae	Lamarck 1809
genus	Mactrotoma	Dall 1894

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

G. Mactrotoma Dall 1894 [surfclam]

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Mactrotoma angusta Reeve 1854

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Invalid names: Mactra (Micromactra) atacama Pilsbry and Olsson 1941 [synonym], Mactra ovalina Reeve 1854 [synonym]

Mactrotoma californica Conrad 1837 [California surfclam]

Mactrotoma fragilis Gmelin 1792

Mactrotoma isthmica Pilsbry and Lowe 1932

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Invalid names: Mactra (Micromactra) fonsecana Hertlein and Strong 1950 [synonym], Mactra (Micromactra) vanattae Pilsbry and Lowe 1932 [synonym]

Mactrotoma nasuta Gould 1851 [bent surfclam]

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Invalid names: Mactra hiantina Deshayes 1855 [synonym], Mactra revellei Durham 1950 [synonym]

†Mactrotoma quirosana Hodson 1931

Mactrotoma velata Philippi 1849

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Invalid names: Mactra paitensis Philippi 1853 [synonym]

Invalid names: Mactroderma Dall 1894 [synonym], Micromactra Dall 1894 [synonym]

Diagnosis

Reference	Diagnosis
E. L. Packard 1916	Shell with a depressed band on the dorsal area ; sculptured ; umbones adjacent ; gape pronounced ; resilifer large, shallow, apically roofed ; cardinals prominent, but thin ; posterior arm of the cardinals overhangs the chondophore ; accessories on the posterior arms anterior laminae arising from the dorsal sinus pallial line distant; epidermis thin and silky.