The Echinoid Directory

Palaeotropus Loven, 1872, p. 1085

Diagnostic Features	Test elongate, ovate with convex anterior border; posterior face obliquely truncate. Test wedge-shaped in profile with strong subanal heel. Apical disc monobasal with genital plates fused; two gonopores (no gonopore in anterior genital plates; closer to anterior than centre. Hydropores few and confined to anterior part of disc. Ambulacra all similar; flush and apetaloid; composed of narrow plates that are taller than wide. Pores rudimentary. Ambulacral plating uniserial towards apex. Peristome D-shaped and facing downwards. Labral plate longitudinally elongate, extending to rear of ambulacral plate 1 only. Sternal plates bowed and symmetric. Episternal plates strongly tapered to posterior and indented by ambulacral plate 6 which is expanded. Periproct supramarginal, on posterior truncate face. Subanal fasciole well developed; rounded; enclosing 3 ambulacral plates (numbers 6-8). Row of larger spines and tubercles bordering the frontal ambulacrum. The remainder of aboral surface with scattered small tubercles set in a groundmass of granules.
Distribution	Recent, Central Atlantic; 350-1600 m.
Name gender	masculine
Type	Palaeotropus josephinae Loven, 1872, p. 1085; by original designation.
Species Included	P. josephinae Loven, 1872; Recent; Central Atlantic P. uniporum Mironov, 2006; Recent; Central Atlantic
Classification and/or Status	Spatangoida, Micrasterina, Palaeotropidae.
Remarks	Differs from Paleotrema by having uniserial ambulacral plating towards the apex, and in having two, not three, gonopores. Palaeotropus thomsoni Agassiz, 1880, as pointed out by Mortensen (1950, p. 298-299) has biserial ambulacra aborally and traces of a peripetalous fasciole. He thought it possibly a Rhinobrissus; it is certainly not a Palaeotropus. Palaeotropus differs from Palaeobrissus in having only microscopic perforations for tube-feet aborally, and in having a row of primary tubercles bordering the frontal ambulacrum aborally. Loven, S, 1872. Ofh. Svensk. Akad. Forh. 28, (for 1871) no. 8, p. 1085. Loven, S. 1874. Etudes sur les Echinoides. Kongl. Svenska Vertenskaps-Akademiens Handlingar 11, 1-91 pls 1-53. Mironov, A. N. 2006. Echinoids from seamounts of the north-eastern Atlantic; onshore/offshore gradients in species distribution. Pp. 96-133 in A. N. Mironov, A. V. Gebruk & A. J. Southward (eds) Biogeography of the North Atlantic Seamounts KMK Scientific Press, Russian Academy of Sciences, P.P. Shirshov Institute of Oceanology, Moscow. Mortensen, T. 1950. A monograph of the Echinoidea. V. Spatangoida 1. C. A. Reitzel, Copenhagen.