The Echinoid Directory

Archaeopneustes Gregory, 1892, p. 163

Diagnostic Features	Test ovate without anterior sulcus. Test low domal in profile. Apical disc ethmolytic with four gonopores; central. Madreporic plate extending far behind posterior oculars. Anterior ambulacrum narrow, flush; plates slightly wider than tall; pore-pairs minute. Paired ambulacra subpetaloid; enlarged pore-pairs extending almost to ambitus; parallel-sided and open distally; without occluded plates at ends. Peristome facing forward into frontal groove. Labrum projecting to cover peristome in oral view; perioral area sunken. Phyllodes very well developed; up to 11 lateral pores and 8 posterior pores per column; pores single. Labral plate subquadrate, relatively short and broad; extending to ambulacral plate 3. Episternal and post episternal plates opposite rather than alternate; episternal plates large, almost as long as the sternal plates; subquadrate and not indented by adjacent ambulacral plates. Posterior ambulacra on oral surface covered in tubercles rather than naked. Periproct inframarginal; circular and flush; bound by Iamb plates 4a/b orally. No fascioles in adults. Aboral surface covered in coarse and heterogeneous tuberculation.
Distribution	Recent, Caribbean.
Name gender	feminine
Type	Palaeopneustes hystrix Agassiz, 1880, p. 82, by original designation.
Species Included	Only the type species.
Classification and/or Status	Spatangoida, Paleostomatina, incertae sedis B. Monotypic: subjective junior synonym of Heterobrissus.
Remarks	Mortensen (1950) recognized that Heterobrissus was probably a senior synonym, but chose to retain the name Archaeopneustes for the Recent species because the type species of Archaeopneustes was much better known and had a slightly more inframarginal periproct. However, Stefanini (1908) refigured the type of Heterobrissus and showed its periproct to be inframarginal, as in Archaeopneustes. Consequently, there seems to be no basis for separating this taxon from Archaeopneustes. Gregory, J. W. 1892. Archaeopneustes abruptus, a new genus and species of Echinoid from the Oceanic Series in Barbados. Quarterly Journal of the Geological Society, 48, 163–169. Mortensen, T. 1950. A monograph of the Echinoidea. V Spatangoida 1. C. A. Reitzel, Copenhagen.