Trigonulina ornata, D'ORBIGNY, 1853

Machado, Fabrizio Marcondes, Passos, Flávio Dias & Giribet, Gonzalo, 2019, The use of micro-computed tomography as a minimally invasive tool for anatomical study of bivalves (Mollusca: Bivalvia), Zoological Journal of the Linnean Society 186, pp. 46-75 : 56-57

TRIGONULINA ORNATA D’ORBIGNY, 1853

( FIGS 8, 9)

Description

Shell: Oval, compressed, robust; external sculpture formed by prominent and irregularly spaced radial ribs; lunule deeply impressed; debris attached by the entire length of outer surface of the valves; lithodesma present.

BIVALVES AND MICRO-COMPUTED TOMOGRAPHY 57

Mantle: Mantlemarginmostlyunfusedanteriorlyforming a large pedal aperture; posteriorly there is a ventral fusion forming the siphons; without a fourth pallial aperture.

Siphons: Separated; inhalant siphon, muscular, short, thin, cone-shaped, contracted into the pallial cavity; exhalant, very small, barely visible; siphonal apertures surrounded at their base by siphonal tentacles, ~20 around the inhalant and three around the exhalant aperture.

Ctenidia: Highly reduced, non-plicate and horizontally aligned; complete, with inner and reduced outer demibranchs, extending from mouth to ventral side of the exhalant aperture.