The Echinoid Directory

Argopatagus A. Agassiz, 1879, p. 209

[=Meijerea Doderlein, 1906, p. 242, type species, Meijerea humilis Doederlein, 1906 [=Argopatagus vitreus Agassiz, 1879; =Phrissocystis Agassiz, 1898, p. 80, type species Phrissocystis aculeata A. Agassiz, 1904 ]

Diagnostic Features	Test ovate and thin-shelled with only a faint anterior sulcus; very depressed in profile. Apical disc ethmolytic with four gonopores, but with the four genital plates apparently fused. In any case the madrepores extend to the posterior of the posterior ocular plates; central to slightly posterior. Ambulacra all similar; non-petaloid and flush; only the adapical-most five or so plates bearing pore-pairs and short cylindrical tube-feet; other plates with microscopic pores only. Peristome pentagonal and slightly overarched by labrum; wider than long. Labral plate elongate and wedge-shaped, tapering to posterior; extending to middle of second ambulacral plate. Shape of sternal plates not known, but presumably triangular. Episternals unknown. Periproct marginal. Subanal fasciole present in type species; broad. Absent in other species assigned to this taxon. Aboral plates with scattered primary tubercles over ambulacral and interambulacral plates. Sternal plates tuberculate. Ophicephalous pedicellariae with distinctive globular head with basal part of valves highly developed and blades reduced.
Distribution	Recent, Indo-Pacific c. 500-2250 m.
Name gender	masculine
Type	Argopatagus vitreus A. Agassiz, 1879, p. 209, by original designation.
Species Included	A. vitreus Agassiz; Recent, Indo-West Pacific. A. planus (Agassiz & Clark, 1907); Recent, Japan. A. aculeata (Agassiz, 1898); Recent, Cocos Islands, East Pacific. A. multispina (Agassiz & Clark, 1907); Recent, Hawaii Islands.
Classification and/or Status	Spatangoida, Micrasterina, ?Macropneustidae. ?
Remarks	Argopatagus and Phrissocystis are similar in all respects other than that Argopatagus has a subanal fasciole whereas Phrissocystis does not. Mortensen (1950) believed that the two should be synonymized. Agassiz, A. 1879. Preliminary report on the Echini of the exploring expedition H.M.S. Challanger. Proceedings of the American Academy of Arts and Science 14, 182-261. Mortensen, T. 1950. A monograph of the Echinoidea. V, Spatangoida 1. C. A. Reitzel, Copenhagen.