Male Morphological Description: Valves are oval in shape with deep incisur. Valve length = 1.88-2.10 mm. Valve height = 1.13-1.28 mm. Color: Mostly transparent, except for yellow light organ and yellow-brown to tan-brown gut. Eye: brown to maroon-brown color with 16 ommatidia. Infold setae: Rostral Row (RR) with 14-19 bristles; 3-8 bristles anterior to RR. Anteroventral Row (AVR) with 24-37 bristles; 1-9 bristles anterior to AVR; 0-1 bristles posterior to AVR. # of tiny suckers on 1st antenna: 2-4 on proximal filament of b-bristle; 3 or 4 on distal filament of b-bristle; 2-4 on proximal filament of c-bristle; 2-4 on distal filament of c-bristle. 7th limb: with 12-17 bristles. Furca: with 9 claws (few with 8 or 10 claws). Only claw 2 is fused to lamella.
Male Bioluminescent Display: Produce horizontal displays (but may be obliquely upward) 35-45 min after sunset. Displays begin 15 cm to 2 m above the sand. About 4 or 5 pulses, but up to 8-10, are visible during a train.
Female Morphological Description: Valves are egg-shaped with a dorsal margin that is steeply sloped posteriorly. Valve length = 2.78-2.81 mm. Valve height = 1.80-1.86 mm. Infold setae: Rostral Row with 16-20 bristles; 6-8 bristles anterior to RR. Anteroventral Row (AVR) with 45-50 bristles; 13-17 bristles anterior to AVR; 3-8 bristles posterior to AVR. 7th limb: with 22-28 bristles. Furca: with 9 claws (few with 8 or 10 claws). Only claw 2 is fused to lamella.