Aboral and diagrammatic oral view of Vaquerosella andersoni, from Durham (1966).

Belongs within: Clypeasteroida.

The Echinarachniidae are a group of sand dollars known from the Oligocene to the present of the North Pacific, as well as the present day north-western North Atlantic (Durham 1966).

Characters (from Durham 1966): Medium-sized to large; petals well developed, anterior petal more open than paired petals; interambulacrum 5 may be discontinuous; interambulacra 0.7 or less width of ambulacra at ambitus; four genital pores; periproct marginal to inframarginal; food grooves with central trunk.

<==Echinarachniidae D66
    |--Echinarachnius Gray 1825 (nom. cons.) M89 [=Phelsumaster Lambert & Thiéry 1914 D66, Phelsumia Pomel 1883 D66]
    |    `--*E. parma (Lamarck 1816) M89 [=Scutella parma M89, *Phelsumaster parma D66, *Phelsumia parma D66]
    |--Kewia Nisiyama 1935 D66
    |    `--*K. blancoensis (Kew 1920) [=Scutella blancoensis] M89
    |--Nipponaster Durham 1952 [=Pseudoastrodapsis Durham 1953] D66
    |    `--*N. nipponicus (Nisiyama 1934) M89 [=Astrodapsis nipponicus M89, *Pseudoastrodapsis nipponicus D66]
    |--Tenuiarachnius Durham 1955 D66
    |    `--*T. kleinpelli (Grant & Hertlein 1938) M89 (see below for synonymy)
    |--Remondella Durham 1955 D66
    |    |--*R. gabbi (Rémond 1863) [=Clypeaster gabbi] M89
    |    `--R. waldroni M89
    |--Astrodapsis Conrad 1856 [=Asterodapsis Agassiz 1872, Astrodaspis (l. c.)] D66
    |    |--*A. antiselli Conrad 1856 M89 [=*Asterodapsis antiselli D66]
    |    |--A. brewerianus D66
    |    `--A. spatiosus M89
    `--Vaquerosella Durham 1955 D66
         |--*V. andersoni (Twitchell 1915) [=Scutella andersoni] M89
         |--V. norrisi M89
         `--V. vaquerosensis D66

*Tenuiarachnius kleinpelli (Grant & Hertlein 1938) M89 [=Echinarachnius gabbii kleinpelli M89; incl. Scutella gabbi tenuis Kew 1915 non Echinarachnius tenuis Yoshikawa 1898 D66]

*Type species of generic name indicated


[D66] Durham, J. D. 1966. Clypeasteroids. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt U. Echinodermata 3 vol. 2 pp. U450–U491. The Geological Society of America, Inc., and The University of Kansas Press.

[M89] Mooi, R. 1989. Living and fossil genera of the Clypeasteroida (Echinoidea: Echinodermata): an illustrated key and annotated checklist. Smithsonian Contributions to Zoology 488: 1–51.

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