The Echinoid Directory

Amphipneustes Koehler, 1900, p. 817

[=Antipneustes Koehler, 1926, p. 69 (nom. van.); = Pseudabatus Koehler, 1911, p. 60, type species P. nimrodi Koehler, 1911; ?=Parapneustes Koehler, 1912, p. 161, type species Parapneustes cordatus, Koehler, 1912 ]

Diagnostic Features	Test rounded to ovate in outline without distinct anterior sulcus; subpyramidal in profile. Apical disc ethmolytic with three gonopores (no opening in plate G2); subcentral. Sexual dimorphism in gonopore size. Anterior ambulacrum narrow with moderately large pore-pairs bearing simple thin-walled tube-feet. Paired ambulacra petaloid; straight, deeply sunken in females but flush in males. Petals long, extending almost to ambitus; anterior and posterior pairs subequal. Peristome kidney-shaped and facing forward. Labrum projecting to cover much of peristome in oral view. Surrounding phyllodes well developed. Plastron plating with symmetrical sternal plates. Labral plate stout, extending to the rear of the second ambulacral plate and usually to the third to fifth plate. Episternal plates offset and not indented by ambulacra. Periproct inframarginal on posterior truncate face or submarginal. Bound by interambulacral plates 4a/b on oral side. No subanal funnel-building tube-feet. No fascioles present.
Distribution	Recent, circum-Antarctic and subantarctic waters.
Name gender	feminine
Type	Amphipneustes lorioli Koehler, 1901, p. 12, by original designation.
Species Included	A. lorioli Koehler, 1901; Recent, Antarctic. A. tumescens (Koehler, 1926); Recent, Antarctic. A. rostratus (Koehler, 1926); Recent, Antarctic. A. marsupialis (Koehler, 1926); Recent, Antarctic. A. similis Mortensen, 1936; Recent, Antarctic. A. brevisternalis (Koehler, 1926); Recent, Antarctic. A. bifidus Mortensen, 1950; Recent, Antarctic. A. davidi Madon-Senez, 2002; Recent, Antarctic. A. mirnovi Markov, 1991; Recent, South Shetland and South Georgia.
Classification and/or Status	Spatangoida, Paleopneustina, Incertae sedis B. ?Paraphyletic, by exclusion of Brachysternaster.
Remarks	Differs from Abatus in having all five ambulacra subpetaloid aborally and a much longer and stouter labral plate. Brachysternaster differs in having the periproct opening framed on oral side by the episternal plates and a disjunct plastron. Amphipneustes comes closest to Pseudabatus but that genus retains fascioles into adulthood and has a longer labral plate that extends to the third or fourth ambulacral plate. Koehler, R. 1900. Note preliminaire sur les Echinides et les Ophiures de l'Expédition Antarctique Belge. Bull. Acad. Roy. Belgique, 11(3), 814-820. Mortensen, T. 1951. A monograph of the Echinoidea V. Spatangoida 2. C. A. Reitzel, Copenhagen.
Contributor comments:	Some species of Amphipneustes have developed a lateral fasciole in early ontogenetic stage. In A. rostratus it is present up to a test length of about 25 mm, in A. marsupialis it occurs at least in long-spined juveniles. In adult specimens it is lost . [Heinke Schultz, August 2007]