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The Echinoid Directory

Contributed by Ildefonso Bajo Campos, November 2009

Tripneustes gahardensis (Seunes, 1896, p. 84)

[1884 Hipponoe sp. Bazin: 36, pl. 1, figs. 22-25.
1896 Hipponoe parkinsoni var. gahardensis Seunes: 84-86, pl. 1, fig. 1.
1906 Tripneustes gahardensis (Seunes): Lambert 75-77; fig. 1; pl. 5, figs. 12-13.
2009 Tripneustes gahardensis (Seunes): Bajo & Borghi 11-20; pl. 1, figs 1a-c, pl. 2, figs. 1a-c, 2a-c.]

Diagnostic Features
  • Test large, sub-hemispherical or slightly depressed, with almost flat oral surface.
  • Ambulacral area narrower than interambulacral ones at the ambitus and adorally, almost equal sized adapically. Ambulacral plates trigeminate, with broad poriferous zones.
  • Pore pairs arranged into three, almost straight, vertical series, separated by secondary tubercles decreasing in size towards the apical system.
  • A primary tubercle is present, on the average, every three ambulacral plates.
  • Each interporiferous area shows two series of large tubercles. Secondary tubercles are almost the same size as the primary ones, on the adoral surface. They decrease in size on the aboral face, and disappear adapically leaving almost naked areas, with only very small tubercles and grains.
  • Interambulacral area with 8-10 almost equal-sized tubercles at the ambitus. Only two series reach the apical system, the others disappear, leaving almost naked areas ornate only by few very small tubercles and grains.
  • Primary tubercles imperforated, not crenulated and surrounded by secondary tubercles and grains.
  • The diameter of the peristome is on25% of the diameter of the shell. Buccal notches clearly defined and deep, with thickened lips.
  • Spines rather long, gently tapering to a blunt tip. They are striated longitudinally, and stratified in cross section. The ring is not prominent.
Distribution Middle Miocene of France; Middle Miocene and upper Tortonian of Spain.
Type Whereabouts unknown.
Classification and/or Status A species of Tripneustes
Remarks Differs from Tripneustes planus by its larger size and less depressed test outline. The interporiferous tubercles are less developed, primary and secondary tubercles are more homogeneous and numerous. In T. planus the interambulacral areas are somewhat depressed aborally and the interambulacral plates are proportionally taller than those of T. gahardensis. Differs from T. ventricosus by the less dense secondary tuberculation and the occurrence of aboral naked interradial zones aborally. In T. gahardensis the ambulacral areas are narrower than the interambulacral ones also near the peristome, and the buccal notches are more developed.

Bajo, I. & Borghi, E. 2009. Tripneustes gahardensis (Echinoidea) en el Mioceno de la Cuenca del Guadalquivir. Batalleria, 14: 11-20.