The Echinoid Directory

Pseudastrodapsis Durham, 1953, p. 121

[= Nipponaster Durham, 1952, p. 844, non Niponaster Lambert 1920, p. 26 (objective); = Pseudoastrodapsis Durham 1953, p. 756 (objective)]

Diagnostic Features	Test oval in outline with rounded margin, flat base and arched upper surface. Internal supports take the form of simple radial bars. Apical disc with 4 gonopores. Petals broad and open distally. Five simple perradial food grooves on oral surface. Ambulacral zones much wider than interambulacral zones at ambitus. Basicoronal circlet strongly pentastellate, with projecting interambulacral plates. Posterior interambulacrum disjunct; lateral and anterior paired interambulacra continuous adorally. Periproct submarginal. Opening bounded by second and third pairs of post-basicoronal interambulacral plates. Food grooves forming well-marked grooves to ambitus; unbranched to ambitus.
Distribution	Late Miocene - Pliocene of Japan and Kamchatka Peninsula.
Name gender	masculine
Type	Astrodapsis nipponicus Nisiyama, 1948, p. 602, by original designation.
Species Included	P. nipponicus (Nisiyama 1948); Mio-Pliocene, Japan. P. cf. fernandoensis Peck of Khomenko, 1931, Pliocene, Kamchatka. P. intermedius Nisiyama, 1968; Miocene, Japan. P. nitidiusculus Nisiyama, 1968; Upper Miocene or Lower Pliocene, Japan.
Classification and/or Status	Clypeasteroida; Scutellina; Scutelliformes; Echinarachniidae. Presumed monophyletic.
Remarks	Differs from Astrodaspis in having much narrower interambulacral zones, continuous interambulacral plating on oral surface in anterior and lateral interambulacral zones, and in having the periproct opening in the second paired post-basicoronal plates rather than the third or fourth. Distinguished from Echinarachnius by the narrowness of its interambulacral zones. The unbranched food grooves and simple internal partitions are not distinctive, since these are also found in small Echinarachnius. Nisiyama, S. 1948. Astrodaspis in Japan. Journal of Paleontology 22, 601-605. J. W. Durham 1955. Classification of clypeasteroid echinoids. University of California Publications in Geological Sciences 31(4), 73-198. Nisiyama, S. 1968. The echinoid fauna from Japan and adjacent regions. Part II. Palaeontological Society of Japan Special Papers 13, 1-491, pls 19-30.